ALBERT

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Shuai Zhao, Wanfen Pu, Mikhail A. Varfolomeev, Chengdong Yuan, Shan Qin, Liangliang Wang, Dmitrii A. Emelianov, Artashes A. Khachatrian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Because the thermal release correlates directly with the success of in-situ combustion (ISC) technology, this research performs a series of investigations concerning thermal behavior and kinetics of heavy crude oil during combustion using high pressure differential scanning calorimetry (HP-DSC) and accelerating rate calorimetry (ARC). The results obtained from HP-DSC profiles indicated that for oil alone and its mixtures with quartz sand/crushed core, the peak temperature was lowered, and the heat flow increased with increasing oxygen partial pressure. The heat enthalpy of low temperature oxidation (LTO) was higher than that of high temperature oxidation (HTO) under oxygen partial pressures of 0.5, 1 and 1.5 MPa, and the increase in heat enthalpy of LTO with oxygen partial pressure was more pronounced than that of HTO. Unlike the crushed core, the addition of quartz sand delayed exothermic oxidation reactions. Compared with oil only and oil + quartz sand, the LTO and HTO peak temperatures of oil + crushed core were considerably lowered, and the effect of crushed core on increasing heat release for LTO at oxygen partial pressure of 1.5 MPa was more prominent. It was observed that the heat enthalpy of LTO and HTO increased quasi-linearly with the oxygen partial pressure in both the presence and absence of quartz sand/crushed core. ISC might be considered as an appropriate candidate for Jiqi block, based on exothermic continuity of the ARC curves, with the near-wellbore zone of target block heated to 180 °C where the exothermic oxidation activity is notably intensified. The kinetic results showed that the LTO and HTO intervals were divided into 6 and 2 subintervals, respectively, which facilitated more precise modelling of the ISC process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Zan Chen, Menglu Lin, Shuhua Wang, Shengnan Chen, Linsong Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Studies have shown that the gas huff and puff injection potentially perform better than the continuous gas flooding in enhancing the hydrocarbon recovery in the liquid rich tight reservoirs. During the fracturing stimulation, only part of the induced hydraulic fractures is propped because proppants cannot be carried to the fracture tips. Moreover, some secondary and tertiary fractures may be too narrow to accommodate any proppants. The conductivity of the unpropped fractures is highly dependent on the variation of the in-situ pressure and may be open and close periodically during the huff-n-puff cycles. In this study, the stress-dependent fracture conductivity and its impact on the produced gas huff-n-puff performance are investigated in a liquid rich tight reservoir, considering the existence of the large amount of the unpropped fractures. The experimental data of stress-dependent fracture conductivity is employed first to simulate the dynamic conductivity during the depletion and the gas huff and puff cycles. A reservoir model is then constructed and history-matched based on the reservoir fluid samples and the field production data collected from the Montney liquid rich tight reservoir in Western Canada. Performance of the produced gas huff-n-puff is examined in the targeted reservoir and results show that contributions of the unpropped fractures cannot be ignored, which leads to 7.8% more condensate (i.e., oil) production and 2.8% higher in barrel of oil equivalent (BOE), compared to the case with propped fractures only. The effects of complex fracture geometry and the cluster completion are also investigated and results show that the unpropped fracture contributions towards the condensate production and BOE are even more pronounced in the complicated scenarios. The condensate oil and BOE are 42.0% and 22.9% higher in complex fracture geometry case and 12.4% and 5.6% higher in the fractures with multiple clusters than those scenarios with propped fractures only. This paper provides a better understanding on the potential performance of enhanced hydrocarbons recovery in liquid rich tight gas reservoirs via gas huff-n-puff operations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Abdelrahman Elkhateeb, Reza Rezaee, Ali Kadkhodaie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Traditionally, prediction of facies and permeability for a reservoir rock was one of many challenges in the industry that necessitates advanced and sophisticated evaluation for effective reservoir description. Three wells have been studied in the Perth Basin in Western Australia across the shaly sand of the Irwin River Coal Measures Formation, which contain a comprehensive suite of advanced and conventional logs. Due to the reservoir heterogeneity and the clay distribution, it is very challenging to resolve the effective pore volume, the reservoir facies and how the high permeability zones are distributed within the formation.〈/p〉 〈p〉In this paper, a new technique has been successfully tested on the Shaly Sand by integrating the nuclear magnetic resonance (NMR) and the conventional density log. The method allows the establishment of high-resolution facies classification for the reservoir using an Equivalent Flow Zone Indicator Index (EFZI). The studied core facies have been integrated with the EFZI into a new workflow to distribute facies on a larger scale in the uncored wells.〈/p〉 〈p〉Four hydraulic flow units (HFU) have been defined from one cored well using Flow Zone Indicator approach, with each has a unique FZI value and different permeability model based on core measurements. The EFZI-based high-resolution facies have been validated at several formation depths using the core thin sections to ensure the best calibration will be obtained for facies log, hence the permeability log-to-core match.〈/p〉 〈p〉The methodology will help running an advanced petrophysical analysis for the zone of interest and will reduce the parameters uncertainty. Application of this methodology in the uncored wells has shown very encouraging results, which is believed it can be used in the absence of any core data to resolve the rock typing from the well logs.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Atousa Heydari, Kiana Peyvandi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the stainless steel mesh was used to study the effect of metallic porous media on the formation of methane hydrate and some parameters such as induction time, the kinetics growth and the mole of gas consumed have been investigated at a temperature of 3 °C (276.15 K) and a pressure of 760 psi (5.24Mpa). The metallic porous media was able to show better results on the methane hydrate formation relative to the silica gel. Hence the induction time and, eventually, the total time of the hydrate formation process decreased by about 60%. The kinetics growth and the amount of gas consumed increased significantly. Also, the effect of two types of anionic and nonionic surfactants as kinetics promoters studied in this porous media. The result of adding SDS and SDBS at a concentration near the CMC designated that the induction time lasted nearly zero and the total time of the process by SDBS was minimal. It should be noted that the non-ionic surfactant SPAN 80 could not have a positive effect on this porous media. In general, therefore, the results of this research attempts to show that the stainless steel mesh with SDBS possessed high potential in obtaining the industrial purpose of gas hydrate growth and also was significant in the field of energy storage and transport.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920410519306473-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Shuaishuai Jiang, Xuehua Chen, Yingkai Qi, Wei Jiang, Jie Zhang, Zhenhua He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The frequency-dependent attenuation and velocity dispersion of seismic responses are closely related to hydrocarbon reservoirs. To further investigate the characteristics of seismic responses caused by pore fluid-bearing reservoirs, the role of gas saturation is analyzed in seismic responses of sand reservoirs characterized by the patchy saturation model. To this end, a novel wave extrapolation method is developed based on the diffusive-viscous wave equation (DVWE) as well as a scheme for an extended local Rytov Fourier (ELRF) approximation within the extrapolation depth interval. Our proposed method considers the presence of fluid mixtures in the porous media, resulting in seismic attenuation and dispersion by the mechanism generally known as wave-induced fluid flow (WIFF). This method enables an accommodation for the lateral variations in slowness, diffusion coefficient and viscosity. Subsequently, the extrapolation is adopted to model the synthetic seismic data of a distributary channel model. During this modeling, a gas-water saturated sand reservoir embedded into one of the channels was used to comparatively analyze the distinct features on its seismic synthetic data. We exhibited the numerical simulation results using the proposed wave extrapolation method here and the traditional acoustic wave equation (AWE) method. A comparison of the simulation results, demonstrates that our proposed numerical method can depict the seismic dispersion and frequency-dependent attenuation as well as the phase delay effects associated with gas-water-saturated sand reservoirs. Furthermore, we compare the seismic responses by changing the gas saturations of the sand reservoir. The gas saturation of the reservoir has significant effects on the seismic characteristics of the numerical modeling data. The numerical modeling method improves our understanding of the mechanisms of seismic frequency-dependent characteristics associated with gas saturations and potentially contributes to better insights into gas reservoir indicators derived from seismic field data.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Hiral D. Shah, J.A. Bhalodia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this communication, we report the structural and electrical transport properties of (1-〈em〉x〈/em〉) La〈sub〉0.7〈/sub〉Sr〈sub〉0.3〈/sub〉Mn〈sub〉0.95〈/sub〉Co〈sub〉0.05〈/sub〉O〈sub〉3〈/sub〉 (LSMCO) + (〈em〉x〈/em〉) ZnO (〈em〉x〈/em〉 = 0%, 6%, 9%, 12%, 15% & 18%) composites. For the preparation of (1-〈em〉x〈/em〉) LSMCO + (〈em〉x〈/em〉) ZnO (〈em〉x〈/em〉 = 6%, 9%, 12%, 15% & 18%) composites, sample of LSMCO was prepared by the auto combustion technique/inexpensive modified sol-gel technique. The results of Rietveld refined XRD data show that LSMCO sample possesses a rhombohedral structure with the 〈em〉R-3c〈/em〉 space group whereas ZnO compound remains with hexagonal structure with the 〈em〉P6〈/em〉〈sub〉〈em〉3〈/em〉〈/sub〉〈em〉mc〈/em〉 space group in all the composite samples. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that no any extra unwanted phase was observed in each composite excluding the LSMCO and ZnO phases. ZnO is mostly distributed at the grain boundaries and on the surface of the LSMCO grains. Elemental presence and ratio was confirmed through the EDX analysis. The electrical resistivity of LSMCO and each composite was measured in the temperature range of 2 K–320 K at 0 Oe, 10 kOe, 50 kOe & 90 kOe magnetic field. The results indicate that the ZnO addition increases the resistivity of all the composites compare to that of pure LSMCO. The electrical resistivity explored by the theoretical model below 〈em〉T〈/em〉〈sub〉MI〈/sub〉 and fitting enlightenment for the observed behavior is transmitted here in detail.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Dezhi Yang, Weihua Liu, Dingfu Cheng, Jieshi Chen, Hao Lu, Chun Yu, Jijin Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉(Co, Cr)23C6 type carbide is a typical metallic compound in many cobalt bearing alloys, and it acts as the strengthening phase in the form of bulk eutectic carbides or precipitated carbides. In this work, first-principles calculations were carried out to investigate the electronic structure, phase stability, mechanical and magnetic properties of (Co, Cr)23C6 with different cobalt occupation. Some of the calculated values are compared with previous studies and, they are found to be in a good agreement. The method considering curvature radius is firstly used to describe the degree of anisotropy. The hardness calculated through elastic constants presents an approximate downtrend with the cobalt concentration. Analysis of the density of states (DOS), overlapped population and electron density maps, indicates that the bonds in (Co, Cr)23C6 are the mixture of covalent, ionic and metallic bonds, the interactions of 〈em〉d-d〈/em〉 orbits between metallic atoms contribute most to the hybridization mode. According to the population analysis, the reduction in hardness can attribute to the increase of metallicity and iconicity of the interacted metallic atoms. In addition, the formation of a large quantity of antibonding also plays a negative role in intrinsic hardness of (Co, Cr)23C6 when massive substitution of cobalt atom.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Morteza Alizadeh, Andisheh Shakery, Erfan Salahinejad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research, the structure and mechanical properties of 1050 aluminum strips reinforced with E-glass fibers, processed by the cross accumulative roll bonding (CARB) process, were investigated from microscopic, hardness, tensile and peeling viewpoints. The results indicated that the incorporation of the glass fibers in the Al matrix increases strength and micro-hardness but decreases elongation. In addition, it was realized that some of these fibers are broken and changed to short fibers during the CARB process. The presence of the glass fibers strongly also reduces the bond efficiency of the Al strips, typically from 50% to 5%. To compensate this deleterious effect, it was found that at least 25% should be increased to the normal thickness reduction used in CRAB.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): J.Y. Oh, Tien M. Le, A.T. Pham, D.H. Tran, D.S. Yang, B. Kang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we investigated a correlation between superconductivity and interlayer coupling of two different alkaline (Na and K)-substituted Bi〈sub〉1·6〈/sub〉Pb〈sub〉0·4〈/sub〉Sr〈sub〉2〈/sub〉Ca〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉10+δ〈/sub〉 (BSCCO) polycrystalline samples. The excess conductivity analysis by the Aslamazov-Larkin (AL) and Lawrence-Doniach (LD) theories showed that Na substitution at the Ca site induced a gradual broadening of 3D fluctuation region with increasing interlayer coupling strength, which explains a systematic increase of 〈em〉T〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 and a decrease of normal state resistivity. On the other hand, exactly the opposite results were observed in the K-substituted samples in place of Sr. Extended x-ray absorption fine structure (EXAFS) studies revealed that substitution of Na and K generated completely different effects on the local structure around Cu atoms. It is noticeable that the Cu–O bond distance was found to decrease monotonically with the varying amounts of Na, which indicates that the CuO〈sub〉2〈/sub〉 layer is stabilized. On the while, the opposite was observed to occur with the varying amounts of K. Unlike the Cu–Ca bond which was the least affected by the substitution, the Cu–Sr bond distance increased drastically with K substitution. All these findings indicate that Na substitution at the Ca site enhances superconductivity with no loss of interlayer interaction, while K substitution at the Sr site weakens superconductivity due to the diminished interlayer interaction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Moara M. Castro, Shima Sabbaghianrad, Pedro Henrique R. Pereira, Eric M. Mazzer, Augusta Isaac, Terence G. Langdon, Roberto B. Figueiredo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A magnesium/aluminium composite was produced by room temperature consolidation through high-pressure torsion (HPT) processing. Half-discs of the pure metals were placed side-by-side and subjected to different numbers of turns. The initially reduced interface between the phases gradually increased with increasing rotation. The composite displayed a significant ductility even after 10 turns. The distribution of hardness in the HPT-processed discs was bi-modal in the early stages of processing. As the number of turns increased and the thickness of the phases decreased there was a noticeable increase in hardness. The hardness values of the composite further increased after thermal treatment due to the formation of intermetallics within the interface between the magnesium and aluminium-rich phases.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Lipeng Xu, Fei Zhou, Jizhou Kong, Haobin Zhou, Qian Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of testing temperature on the electrochemical properties of Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 are investigated in detail. When the testing temperature is 40 °C, the Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 cathode material possesses the highest initial discharge capacity of 162.4 mAh·g〈sup〉−1〈/sup〉 at 0.5C rate, but their cycling stability decreases markedly. When the test temperature rises up to 60 °C, the side reaction between electrolyte and cathode material becomes serious, and the Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 cannot work. When the testing temperature decreases, the electrochemical impedances like R〈sub〉ct〈/sub〉 values increase, and then the discharge capacity at 0 °C, −10 °C and −20 °C is only 80%, 53% and 23% of that at 25 °C. Based on the electrochemical impedance spectra at different temperatures, four kinds of equivalent circuit models are classified. The cycle and rate performance of Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 cathode material could be improved obviously through Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉(OH)〈sub〉2〈/sub〉 modification in an extreme environment, and especially in sub-zero environment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Kenji Yoshii, Naoshi Ikeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dielectric and magnetocaloric measurements are carried out for the chromite TmCrO〈sub〉3〈/sub〉. This oxide was reported to be multiferroic below the Néel temperature (〈em〉T〈/em〉〈sub〉N〈/sub〉) of ∼125 K, likely due to a structural transformation. The dielectric response shows large dielectric constants below 300 K. However, from the analyses of loss tangent, AC conductivity and dielectric modulus, this behavior is rooted in hopping of charge carriers rather than electric dipoles, as proposed for some other chromites. No dielectric anomaly is found at 〈em〉T〈/em〉〈sub〉N〈/sub〉. The magnetocaloric effect shows that the magnetic transitions at 〈em〉T〈/em〉〈sub〉N〈/sub〉 as well as the spin reorientation temperature are of a second order. This result strongly suggests the absence of magnetostructural transition at 〈em〉T〈/em〉〈sub〉N〈/sub〉 in accord with no observation of ferroelectric transition at this temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Rattiya Hongtong, Panya Thanwisai, Rattakarn Yensano, Jeffrey Nash, Sutham Srilomsak, Nonglak Meethong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Core-shell olivine-type electrospun and doped LiFePO〈sub〉4〈/sub〉/FeS/C composite fibers were synthesized via a single-step process employing an electrospinning method using LiOH·H〈sub〉2〈/sub〉O, metal sul phates, H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉, citric acid, and polyvinylpyrrolidone (PVP) as the starting materials. Electron microscopy studies showed that the mean diameter of the core-shell composite fibers was about 280 ± 20 nm with a LiFePO〈sub〉4〈/sub〉 phase forming a core with a diameter of about 100 ± 20 nm and a carbon shell with a thickness of 80 ± 20 nm. An FeS phase was formed by a direct reduction of iron (II) sulfate (FeSO〈sub〉4〈/sub〉) that was evenly distributed within the core region of the composite fibers and further improved the electronic conductivity of the fibers. Na〈sup〉1+〈/sup〉, Mg〈sup〉2+〈/sup〉, and Al〈sup〉3+〈/sup〉 doping ions affected fiber morphology and electrochemical performance. All composite fibers showed excellent electrochemical performance. However, Al〈sup〉3+〈/sup〉 ions improved the electrochemical performance of the composite fibers to a significantly greater degree than Na〈sup〉1+〈/sup〉 and Mg〈sup〉2+〈/sup〉 doping ions, increasing the electronic and ionic conductivities of the material while maintaining their core-shell composite fiber characteristics.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Electrospun LiFePO〈sub〉4〈/sub〉/FeS/C and 5% doped 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉L〈/mi〉〈mi〉i〈/mi〉〈mi〉F〈/mi〉〈msubsup〉〈mrow〉〈mi〉e〈/mi〉〈/mrow〉〈mrow〉〈mn〉1〈/mn〉〈mo linebreak="badbreak"〉−〈/mo〉〈mrow〉〈mo stretchy="false"〉(〈/mo〉〈mi〉n〈/mi〉〈mi〉x〈/mi〉〈mo linebreak="badbreak"〉/〈/mo〉〈mn〉2〈/mn〉〈mo stretchy="false"〉)〈/mo〉〈/mrow〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈mo linebreak="badbreak"〉+〈/mo〉〈/mrow〉〈/msubsup〉〈msubsup〉〈mrow〉〈mi〉M〈/mi〉〈/mrow〉〈mrow〉〈mi〉x〈/mi〉〈/mrow〉〈mrow〉〈mi〉n〈/mi〉〈mo linebreak="badbreak"〉+〈/mo〉〈/mrow〉〈/msubsup〉〈mi〉P〈/mi〉〈msub〉〈mrow〉〈mi〉O〈/mi〉〈/mrow〉〈mrow〉〈mn〉4〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉/FeS/C (M = Na〈sup〉1+〈/sup〉, Mg〈sup〉2+〈/sup〉, Al〈sup〉3+〈/sup〉) composites with a unique core-shell structure were synthesized via a simple single-step process to improved electrochemical properties for high performance and low cost Li-ion batteries.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324946-fx1.jpg" width="287" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): L.V.B. Diop, O. Isnard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of Fe substitution on the structural and magnetic properties of the HoCo〈sub〉12-〈em〉x〈/em〉〈/sub〉Fe〈sub〉〈em〉x〈/em〉〈/sub〉B〈sub〉6〈/sub〉 (0 ≤ 〈em〉x〈/em〉 ≤ 2) series of intermetallic compounds have been studied. All of the compounds form in the rhombohedral SrNi〈sub〉12〈/sub〉B〈sub〉6〈/sub〉-type structure, the lattice constants increasing linearly with 〈em〉x〈/em〉. These compounds are ferrimagnets with a small transition metal magnetic moment and exhibit a spin reorientation transition. The Curie temperature decreases from 147 K for 〈em〉x〈/em〉 = 0–105 K for 〈em〉x〈/em〉 = 2. The Fe for Co substitution leads also to a progressive decrease of the spontaneous magnetization. The spin reorientation transition temperature is significantly reduced upon Fe for Co substitution whereas the compensation temperature is much less sensitive to the Fe composition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Maxim S. Likhanov, Vladislav O. Zhupanov, Valeriy Yu Verchenko, Andrei A. Gippius, Sergei V. Zhurenko, Alexey V. Tkachev, Dina I. Fazlizhanova, David Berthebaud, Andrei V. Shevelkov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a new Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 solid solution, in which a 5〈em〉d〈/em〉-metal––rhenium––partially substitutes for iron to the limiting composition of 〈em〉x〈/em〉 = 0.10. The crystal structure refined for the composition Fe〈sub〉0.91〈/sub〉Re〈sub〉0.09〈/sub〉Ga〈sub〉3〈/sub〉 shows the expected increase in the unit cell parameters compared to the parent FeGa〈sub〉3〈/sub〉 compound, however the M–M (M = Fe, Re) distance decreases within the M–M dumbbell, indicating an increased M–M bonding density. Therein, investigation of the local structure by means of 〈sup〉69,71〈/sup〉Ga NQR spectroscopy revealed the formation of homonuclear Fe–Fe and Re–Re dumbbells. Transport and thermoelectric properties have been investigated for the Re-substituted FeGa〈sub〉3〈/sub〉. Electrical transport measurements showed preservation of the nonmetallic conductivity of Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 despite the decrease of the valence electron concentration from 17 to 16.9 electrons per formula. At low temperatures, Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 is a 〈em〉p〈/em〉-type semiconductor with the band gap of 0.4 eV, but with increasing temperature the sign of the dominant charge carriers changes. Owing to the alloying effect, Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 displays 1.5 times lower thermal conductivity than FeGa〈sub〉3〈/sub〉, which increases at high temperatures because of the growing contribution of the electronic term.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325198-fx1.jpg" width="454" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Jiashu Zhang, Weiyao Zhao, Zhenjie Feng, Jun-Yi Ge, Jincang Zhang, Shixun Cao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the crystal growth, structure analysis and magnetic phase transitions in the single crystal Sm〈sub〉0.15〈/sub〉Dy〈sub〉0.85〈/sub〉FeO〈sub〉3〈/sub〉. The high-quality of the crystal is verified by X-ray diffraction technique. Our research reveals that: 1) the iron sublattice spin reorientation (SR) transition emerges at 25 K, and ends at 10 K; 2) the rare earth antiferromagnetic (AF) order transition happens at 2.6 K; 3) there is a special wasp-waist hysteresis loop at low temperatures. Knowledge of such phase transitions in rare earth orthoferrite system is of potential importance for applications and theoretical studies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Yuliang Jiang, Xueyan Fu, Zidong Zhang, Wei Du, Peitao Xie, Chuanbing Cheng, Runhua Fan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon nanofibers embedded with magnetic Fe〈sub〉3〈/sub〉C nanoparticles have been synthesized using electrospinning technique, followed by one-step carbonization. By using Fe〈sub〉3〈/sub〉C/C nanofibers as filler with 10% content, the sample can achieve a minimum reflection loss (RL) of −54.94 dB with a thickness of 1.36 mm, as well as the broad effective absorption bandwidth (EAB) can reach to 4.5 GHz (13.3–17.8 GHz) at the thickness of 1.55 mm. The superior properties might be due to the synergistic effects of dielectric loss, magnetic loss, multiple scattering and reflection. This work presents a facile and promising method to produce high performance microwave absorption materials with thin thickness, light weight and strong absorption.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): E.J. Pickering, K.A. Christofidou, H.J. Stone, N.G. Jones〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to reduce the environmental impact of air travel, it is desirable that the efficiencies of gas turbine engines are increased. One way to achieve this goal is to increase the operating temperatures of the engine cores. Unfortunately for aero-engine manufacturers, the temperature capability limits of the Ni-base superalloys used currently have been reached. Hence, new alloys need to be developed that are capable of operating at significantly higher temperatures. In this article, the potential of tantalum-base superalloys is discussed and explored. A suite of alloys based on the Ta-Al-Co system was investigated. It was found that an array of fine carbide precipitates was formed in the Ta-rich matrix in a subset of the alloys, which is promising in terms of developing a strong and damage-tolerant microstructure, but that the elemental partitioning of Al out of the matrix accompanying precipitation is likely to degrade environmental resistance. Nevertheless, it is believed that the design principles described have the potential to facilitate the development of the next generation of high-temperature alloys based on systems of this type.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): C.Q. Zhou, Q.A. Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to understand the effect of Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 nanoparticles on crystallite growth kinetics of nanocrystalline Mg, the crystallite growth characteristics in a Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite and a pure Mg sample were comparatively investigated in this work. The crystallite growth exponents of nanocrystalline Mg in the Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite and pure Mg were determined as 〈em〉n〈/em〉 = 5 and 〈em〉n〈/em〉 = 4, respectively. Meanwhile, the activation energy for crystallite growth in Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite was calculated to be 118.8 kJ/mol, which is higher than 97.1 kJ/mol in pure nanocrystalline Mg. Further studies reveal that the rise of crystallite growth exponent and increase of activation energy in the Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite are primarily attributed to the pinning effect of Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 nanoparticles at crystallite boundaries of Mg.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Liming Tan, Yunping Li, Wenkai Deng, Yong Liu, Feng Liu, Yan Nie, Liang Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three Ni-base powder metallurgy superalloys have been developed recently, and tensile tests at temperatures ranging from room temperature (RT) to 815 °C were conducted on them. The results conformed their excellent tensile properties, in comparison with several other existed polycrystalline superalloys. In this work, by means of microstructure characterization, thermal dynamic calculations, and theoretical modeling, different strengthening mechanisms including precipitation strengthening, grain boundary strengthening, solid solution strengthening, and Orowan strengthening, were found to contribute to the yield strength in different degrees, which would help to further enhance the tensile properties of these alloys through composition design and processing optimization thereafter.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324892-fx1.jpg" width="459" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Jingyi Zhu, Zhaozhong Yang, Xiaogang Li, Zhichao Song, Ziwei Liu, Shiyi Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Liquid foam is an alternative to water-based fracturing fluid due to its great proppant suspension ability. In this work, theoretical and experimental investigations on the settling behavior of the proppants in viscoelastic foams were analyzed on bubble scale. Settling trajectory was captured over time by optical microscope to calculate proppant settling velocity. At room temperature, proppants kept suspended well, but noticeable changes in proppant position could be observed at 70 °C. We concluded that the sedimentation of the proppants at high temperature was divided into three stages, that were drainage-dominated, structure-dominated and fluid-dominated regimes. For the large proppants, quick settling velocity was seen at first due to fast drainage rate. Then bubble pressure force and network force served as drag force exerting on the proppants when the proppants stretched or squeezed the liquid films. During this regime, bubble distribution, the existence of nodes, the length and the orientation of Plateau border leaded to the fluctuation in settling velocity. Lastly, the proppants would also flow freely along Plateau border over time, and the properties of the foam fluid such as viscosity and elasticity provided the drag force to prevent the proppants from settling. It's more likely for small proppants to change to this stage called fluid-dominated regime, but elasticity also guaranteed their low settling velocity. Moreover, in the existence of proppants, the analysis into drainage rate and bubble structure demonstrated the high stability of viscoelastic foams. These results helped understand the sedimentation of proppants in wet foams and broadened the application of viscoelastic foams in hydraulic fracturing.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Zhong-Zhen Chen, Hong-Ze Gang, Jin-Feng Liu, Bo-Zhong Mu, Shi-Zhong Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A thermal-stable and salt-tolerant biobased zwitterionic surfactant 〈em〉N, N〈/em〉-Dimethyl-〈em〉N〈/em〉-[2-hydroxy-3-sulfo-propyl]-〈em〉N〈/em〉′-phenyloctadecanoyl-1, 3-diaminopropane (SPODP) was successfully obtained from modification of oleic acids which can be regenerated from waste cooking oils, and its structure was characterized using GC-MS, ESI-MS and 〈sup〉1〈/sup〉H NMR approaches. The biobased zwitterionic surfactant demonstrated a strong interfacial activity at high salinity and high temperature conditions at a very low surfactant dosage in formation brine. The ultralow interfacial tension (≤10〈sup〉−3〈/sup〉 mN/m) between crude oil and brine was reached at 0.5 g/L in brine with a wide range compatibility of NaCl up to saturation, Ca〈sup〉2+〈/sup〉 up to 500 mg/L, and temperature up to 95 °C. Meanwhile, it also exhibited strong wetting ability and resistance against adsorption on sands. All the results from this study suggest that the biobased zwitterionic surfactant is promising over varieties of traditional surfactants in applications in alkali free systems in enhanced oil recovery (EOR).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Zhihua Wang, Ye Bai, Hongqi Zhang, Yang Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Waxy crude oil emulsions exhibit gelation behavior, with nucleation observed within a certain temperature range. A kinetic model was developed and validated based on the thermal parameters obtained from differential scanning calorimetry cooling thermograms, and the nucleation rates of various water-in-waxy crude oil emulsions were determined in the temperature range in which gelation occurs. Although temperature had a dominant effect on the gelation and nucleation behavior of waxy crude oil emulsions, the nucleation rate also increased as the water volume fraction in the emulsion increased. Emulsified water droplets with smaller radii can be completely covered by wax particles, inducing a greater nucleation rate. Subjecting the emulsions to a greater shearing strength also increased the nucleation rate. This study provided new insights into the nucleation processes that occur during the formation of waxy crude oil emulsion gels and, in particular, the role of the emulsification properties.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920410519306424-fx1.jpg" width="496" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Ulf Jakob F. Aarsnes, Nathan van de Wouw〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present paper studies the effect of an axial elastic tool (known as a shock sub), mounted downhole in the drill-string, on the occurrence of axial and torsional self-excited vibrations. In particular, we evaluate the feasibility of stabilizing the axial dynamics, dominated by a bilateral (feedback) coupling between the bit-rock interaction and the drill-string wave-equations, through the insertion of a passive down-hole tool. We consider the problem of unwanted drill-string vibrations and explain how these vibrations relate to the so-called axial instability using a distributed parameter (infinite dimensional) model. The equations describing the feedback system causing this instability are derived and then extended to accommodate for the inclusion of the effect of the shock sub. Conditions for the design parameters of the shock sub needed to avoid axial instability are then derived and their practical feasibility are considered.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): S. Mohammadi, M. Papa, E. Pereyra, C. Sarica〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mechanistic modeling is one of the most popular approaches for the prediction of flow pattern, pressure gradient and liquid holdup in multiphase flow problems. Mechanistic models utilize the mass and momentum conservative equations in combination with a set of closure relationships. These closures, which are developed based on specific experimental setups, considerably affect the performance of the mechanistic models. Moreover, new closure relationships continue to be developed to improve the current mechanistic models. Thus, there is a need for a tool that allows the selection of a set of closure relationships for a given set of conditions. In this direction, this paper presents a methodology that relies on a genetic algorithm to search and select a set of closure relationships for a given experimental (field data) that minimize the error between measured and predicted pressure gradient. The results show the applying the genetic algorithm can improve the performance of the mechanistic model by about 277% when compared to selections of closure relationships made by a subject matter expert for the given data set.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Christopher S. Daniel, Peter D. Honniball, Luke Bradley, Michael Preuss, João Quinta da Fonseca〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The properties and performance of Zr-2.5 Nb alloys are strongly influenced by their crystallographic texture. As in similar Ti alloys, the texture evolution during hot-processing depends on the complex interactions between the α and β phases and involves deformation, annealing and phase transformation. Although the effect of temperature and deformation has been studied for extruded tube in this alloy, there is no data for texture development during rolling. There is some rolling data for Ti-64 (Ti–6Al–4V), but it is usually for just one of the phases and for a limited set of temperatures. We carried out hot-rolling trials from 700 °C–900 °C to reductions of 50%, 75% and 87.5% and found that the texture in both phases strengthens sharply before the β-transus and when both phases are present in similar amounts. At this point, the texture in α is a strong 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mn〉0002〈/mn〉〈mo〉|〈/mo〉〈mo〉|〈/mo〉〈mtext〉TD〈/mtext〉〈/mrow〉〈/math〉 and the texture in β a strong 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mrow〉〈mn〉001〈/mn〉〈/mrow〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mn〉110〈/mn〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 rotated cube component. The results suggest there might be a synergistic effect between the two components, which includes dynamic phase transformation. The texture evolution towards stable α 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mrow〉〈mn〉11〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mn〉10〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 or 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mrow〉〈mn〉11〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉1〈/mn〉〈/mrow〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mn〉10〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 crystallographic components and their final intensity depend on the starting texture. Texture was measured using electron-backscatter diffraction (EBSD) over large areas, with a β reconstruction software used to determine the high temperature β orientations. The texture development in Zr-2.5Nb appears similar to that reported for rolled Ti-64 at temperatures with equivalent phase fractions, although it is difficult to compare the two because of the lack of a titanium dataset as detailed as the one presented here.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324351-fx1.jpg" width="248" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): E.M.M. Ibrahim, M.A.A. Mohamed, H.M. Ali, Vyacheslav O. Khavrus, Silke Hampel, M.M. Wakkad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrothermal synthesis as a commonly bottom-up growth method has considerable advantages for manufacturing thermoelectric nanomaterials with advanced thermoelectric properties. However, the hydrothermally synthesized thermoelectric nanostructures often show a low thermoelectric performance due to their low power factor. In this work, we report on using a hydrothermal method for the growth of n-type Bi〈sub〉2-x〈/sub〉Sb〈sub〉x〈/sub〉Se〈sub〉3〈/sub〉 nanoflakes with a fixed thickness of ∼16 quintuple-layers. The controlling of the stoichiometric composition, phase purity and crystallinity of the Bi〈sub〉2-x〈/sub〉Sb〈sub〉x〈/sub〉Se〈sub〉3〈/sub〉 nanoflakes are demonstrated by the X-ray diffraction, Raman spectroscopy, and high resolution transmission electron microscopy. We further prove that adding of antimony into Bi〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 compound mostly influences the in-plane vibration mode. The optical energy gap is sharply increased as the Sb content increases. The effect of the antimony incorporation on the electrical conductivity, Seebeck coefficient and power factor of Bi〈sub〉2-x〈/sub〉Sb〈sub〉x〈/sub〉Se〈sub〉3〈/sub〉 nanoflakes is systematically investigated. The Bi〈sub〉1.92〈/sub〉Sb〈sub〉0.08〈/sub〉Se〈sub〉3〈/sub〉 sample is found to have the highest power factor ∼13.17 μW/cm.K〈sup〉2〈/sup〉 at 470 K which is much higher than those published for other various nanostructured or bulk Bi〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 compounds. The results propose a great prospect for further enhancing the thermoelectric power factor of the Bi〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 nanostructures synthesized by this hydrothermal method. Taking into consideration the progress in Bi–Se compounds, the results of this work advocate the promise of Bi–Se nanostructures towards producing high performance thermoelectric devices.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Javed Rehman, Roshan Ali, Nisar Ahmad, Xiaodong Lv, Chunlei Guo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It poses a great challenge to design anode materials with large capacity, excellent cyclic stability and high rate performance. In this paper, through first principle calculations, we computed electronic properties of monolayer WSe〈sub〉2〈/sub〉 with and without strain effects. Our results show that the electronic band gap decreases with strain percent. At 0% tensile strain the value of the band gap is 1.4 eV while at 10% tensile strain the band gap decreases to 0.7 eV. Therefore, the strain effect enhances the electronic conductivity and leads to an increase in the charge carrier transport. In addition, our predictions show that the adsorption energy increases with the strain. Finally, we computed the diffusion barrier for the migration of Li on the surface of a strain engineered WSe〈sub〉2〈/sub〉 monolayer. The lower barrier energy (0.24 eV) reveals that Li can easily overcome this barrier. Our results show that the strain-engineered WSe〈sub〉2〈/sub〉 monolayers are promising anode material for Li-ion battery.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Seyedeh Marjan Bararpour, Hamed Jamshidi Aval, Roohollah Jamaati〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉AA5083 and AA5052 alloys were utilized as consumable rod and substrate, respectively, in Friction Surfacing (FS) process and a three-dimensional finite element software known as ABAQUS was employed to anticipate the materials thermo-mechanical behavior over this procedure. At that point, in order to investigate the mechanical and microstructures characteristics of the coated samples, the experimental observations and model predictions have been implemented. The results clarified that the strain rate and temperature values are not high at the interface of the substrate and coating layer, also, we observed their maximum values in a layer nearby the upper surface of the coating in the advancing side (AS). Regardless of the irregular strain rate and temperature profiles, there are no important differences in the microstructure of the materials detected in the center of the cross-sections in the direction of advancing and retreating sides (RS). It should be noted that the grain structure is not influenced by the strain energy effect which is kept in the coating layer all through the FS procedure. Moreover, we can consider the grain structure recrystallization as a contributing factor in improving the material strength of the coating which is anticipated to be proportional to the grain size in reverse.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Aref Alqahtani, Shahid Husain, Anand Somvanshi, Wasi Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Perovskite-type GdCr〈sub〉1-〈em〉x〈/em〉〈/sub〉Mn〈sub〉〈em〉x〈/em〉〈/sub〉O〈sub〉3〈/sub〉 (0.0 ≤ 〈em〉x〈/em〉 ≤ 0.4) nano-crystalline samples are synthesized using sol-gel auto combustion process. The effect of Mn-doping in GdCrO〈sub〉3〈/sub〉is investigated in term of structural, morphological, optical and thermal properties. X-ray diffraction (XRD) patterns confirm orthorhombic crystal structure of all the samples. The lattice parameters bond lengths and bond angles as obtained from Rietveld refinement analysis are found to vary systematically with Mn concentration. The crystallite sizes as calculated from the Scherrer's equation are found to decrease with Mn content. The Williamson-Hall (W–H) analysis reveals that the crystallite sizes decrease whereas lattice strain, stress, and energy density become more with the increase in Mn doping except for 〈em〉x〈/em〉 = 0.3.The particle size estimated using transmission electron microscopy (TEM) are consistent with that obtained through W–H analysis. Scanning electron microscopy (SEM) images with energy dispersive x-ray (EDX) analysis exhibit significant change in the surface morphology with Mn doping and ensure the elemental compositions of the samples. The Fourier transform infrared (FTIR) spectra of these samples confirm the formation of desired crystal structure with two main characteristic bands at 476 and 586 cm〈sup〉−1〈/sup〉. The optical band gap is found to reduce whereas Urbach energy increases with the increase in Mn concentration. The values of refractive index decrease in the ultraviolet region as a function of wavelength for all the samples and minimizes at the main absorption peak position as observed in the UV/Vis. spectra. The value of heat capacity at constant pressure (〈em〉C〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉) decreases with Mn doping except for 30% Mn concentration. Therefore, the present investigation suggests that the properties of GdCrO〈sub〉3〈/sub〉 system can be tuned with the appropriate doping of Mn for the potential applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Xinghua Zhu, Qingshuang Xie, Haibo Tian, Ming Zhang, Zongyan Gou, Shuai He, Peng Gu, Haihua Wu, Jitao Li, Dingyu Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Usually, ZnO thin films used in ultraviolet photodetector exhibit good photoresponse property when ultraviolet signal is strong enough. However, due to the high dark current, pure ZnO is insusceptible to weak ultraviolet signal. To address this problem, lithium-doped ZnO (LZO) thin films were prepared using the sol-gel method in this study. Results revealed that the LZO thin film doped with low concentration (2 at.%) had a dark current about 10 times lower than the pure ZnO. In addition, the ultraviolet with a low irradiance of 90 μW/cm〈sup〉2〈/sup〉 was used. According to the results of the investigations on the external quantum efficiency and responsivity, the inherent photocurrent generation ability of ZnO was not deteriorated through low concentration lithium doping. LZO thin film doped with 2 at.% exhibited a high sensitivity to weak ultraviolet signal --- the signal-to-noise ratio was enhanced by approximately 10 times compared with that of pure ZnO. This study indicates that LZO thin films with low doping concentration are promising application on weak ultraviolet signal photodetector.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Jian Lan, Weidong Xuan, Yu Han, Yongshun Li, Huaizhou Wu, Wei Shao, Chuanjun Li, Jiang Wang, Zhongming Ren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of hot isostatic pressing on the tensile property of single crystal superalloys at elevated temperature is studied experimentally. The results show that the high temperature elongation of nickel based single crystal superalloys is obviously enhanced by hot isostatic pressing, while the yield strength is unchanged. Besides, it is found that the hot isostatic pressing causes the change of fracture surface. The enhancement of elongation and the change of fracture behavior are discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Z.M. Li, X.N. Li, C.Y. Wang, Y.H. Zheng, Q.X. Yu, X.T. Cheng, N.J. Li, L.X. Bi, Q. Wang, C. Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The heat resistance of copper alloys is desirable to improve while it services at high temperature as electrically and thermally conductive components. In present paper, the strengthening pattern of nickel-based superalloys is expected to be applied in copper alloys. Here the Cu〈sub〉50〈/sub〉Ni〈sub〉37.5〈/sub〉〈em〉M〈/em〉〈sub〉12.5〈/sub〉 (〈em〉M〈/em〉 = Al, Cr, Mo) alloys were prepared by vacuum arc melting and heat-treated in the corresponding conditions to obtain three different kinds of typical microstructure. The room temperature (RT) properties (hardness and resistivity) and high temperature properties (melting point, softening temperature and variable temperature resistivity) of the three alloys are contrasted and analyzed in detail. The Cu〈sub〉50〈/sub〉Ni〈sub〉37.5〈/sub〉Al〈sub〉12.5〈/sub〉 alloy strengthened through the γ′ phase coherent precipitation shows the best conductivity and highest hardness (5.47 %IACS (International Annealed Copper Standard) and 310.1 HV). The splitting of the γ′ phase is contributing to hardening at high aging temperature. The resistivity-temperature behavior of the three alloys shows that the resistivity with rising temperature consists of the ideal lattice resistivity and the resistivity increment due to the defects. The Cu〈sub〉50〈/sub〉Ni〈sub〉37.5〈/sub〉Al〈sub〉12.5〈/sub〉 alloy has the smallest room temperature resistivity and its resistivity maintains the lowest during the whole heating process (RT-1077K). Therefore, the coherent precipitated γ′ phase is expected to improve the heat resistance of the copper alloys while maintaining its electrical conductivity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325708-fx1.jpg" width="282" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Cui-Ning Feng, Xiao-Ye Zhan, Pan Li, Xiao-Feng Guo, Dan Li, Xiu-Cheng Zheng, Guang-Ping Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Glucose-derived porous activated carbon materials (AGC-600-4 and AGC-180-〈em〉x〈/em〉) are prepared using ZnCl〈sub〉2〈/sub〉 as the etching agent via impregnation treatment and hydrothermal method followed by the calcination process. The analytic results indicate that the obtained materials exhibit higher specific surface area and superior double-layer capacitive behavior than the corresponding pristine carbon (GC-600 and GC-180) when used as electrode materials for supercapacitors. Moreover, compared with the AGC-600-4 nanosheets, the optimal AGC-180-4 microspheres have a high specific surface area of 1713 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉 and a maximum specific capacitance of 235.9 F g〈sup〉−1〈/sup〉 at a current density of 1.0 A g〈sup〉−1〈/sup〉 in the three-electrode system. Meanwhile, AGC-180-4 also exhibits better capacitive properties than AGC-600-4 in the two-electrode system, showing an excellent cyclic stability with a high energy density of 24.63 Wh kg〈sup〉−1〈/sup〉 at the power density of 949.5 W kg〈sup〉−1〈/sup〉. It is thus demonstrated that AGC-180-4 could be ideal electrode materials for supercapacitor due to its unique etched spherical structure and excellent electrochemical properties.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325903-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Ilham Bezza, Erwann Luais, Fouad Ghamouss, Mustapha Zaghrioui, François Tran-van, Joe Sakai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An 〈em〉in-situ〈/em〉 temperature-controlled Raman spectroscopy aided unique electrode fabrication technique has been developed for Li-ion battery applications, ensuring superior electrochemical quality of the multi-porous LiCoO〈sub〉2〈/sub〉 films with higher stoichiometric purity of high temperature (HT)-LiCoO〈sub〉2〈/sub〉 phase, by observing the structural changes during the fabrication process and thus confirming the transformation from the low temperature (LT)-LiCoO〈sub〉2〈/sub〉 phase. This much desired simple process is not only free of any sort of binders or carbon additives but also works at atmospheric pressure, leading to a very simple deposition technique using a homemade and inexpensive set-up. Also, the time of depositions were varied and resultant films we investigated for their electrochemical performance. The high-resolution scanning electron microscope (SEM) observation has revealed not only a μm-size porous structure but also three-dimensional cross-link with 10 nm-level pores of the material, which ensured the much-desired porosity for high-performance cathodes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): S.C. Ram, K. Chattopadhyay, I. Chakrabarty〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Functionally graded in-situ A356-Mg〈sub〉2〈/sub〉Si composites by centrifugal casting method have been studied with varying percentage of extra Mg additions during synthesis. The coarse primary Mg〈sub〉2〈/sub〉Si particles and the Si morphology in eutectic do not yield appreciable mechanical properties. Solution treatment and artificial ageing (T6) are effective means to improve mechanical properties by refining the as-cast structure with additional formation of very fine precipitates during ageing. The microstructural evolution has been assessed by optical, scanning and transmission electron microscopy and X-ray diffraction analysis. Ageing curves are plotted with hardness versus ageing time. High temperature tensile properties are evaluated at room temperature, 150 °C and 300 °C at different layers of the graded composites and are compared between as-cast and T6 conditions. The tensile fracture mechanisms are explained from fractographs. A remarkable improvement in high temperature tensile strength at 150 °C with adequate ductility is observed in T6 condition with respect to as-cast condition.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325721-fx1.jpg" width="264" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Taiqian Mo, Zejun Chen, Boxin Li, Hongtao Huang, Weijun He, Qing Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The impact of strain path on microstructure and mechanical properties in AA1100/AA7075 laminated metal composite was investigated in present work. The results indicate that the plastic instabilities occurred in the hard layer can be inhibited effectively and the mechanical properties of the composite were improved obviously after the cross rolling (CR) process. The formation of continuous and straight interface was attributed to the difference in flow properties between the constituent layers was decreased after CR process. It is found that the strain path change during CR results in the typical rolling texture is shifted from the ideal Brass (110)〈112〉 along the 〈em〉α〈/em〉-fiber to the near ND-rotated Brass (011)〈755〉 component, promoting a better mechanical isotropy of the AA1100/AA7075 laminated metal composite. In addition, the Al/Al alloy laminated metal composite with continuous layer structure exhibits better load-bearing capacity in hard layers than the wave layer structure during deformation, which is a main reason for increasing of the strength.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): N. Patra, C.L. Prajapat, P.D. Babu, S. Rai, S. Kumar, S.N. Jha, D. Bhattacharyya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heusler alloy of Co〈sub〉2〈/sub〉FeSi (CFS) is a promising candidate for spintronics applications due to its high magnetic moment and high spin polarization. In this report two series of CFS thin films of approximate thickness of 1000 Å were prepared using Pulsed Laser Deposition (PLD) technique by two separate routes, viz., (i) by depositing at elevated substrate temperature and (ii) by depositing at room temperature followed by post-deposition annealing under vacuum. The effects of these two thermal growth processes on the structural and magnetic properties of the films have been studied in detail here. X-ray diffraction study suggests that similar to the bulk target cubic Heusler phase is maintained in the thin films prepared by both the processes, however, X-ray reflectivity study shows that the films deposited at elevated substrate temperatures have higher density and surface roughness than the other set. Co/Fe atomic ratio in the films was found to remain near stoichiometry up to high temperature in both the series of samples though atomic percentage of Si is found to be higher in the samples. Synchrotron based Extended X-ray absorption fine structure (EXAFS) measurements indicate higher 〈em〉3d-3p〈/em〉 (Co-Si) hybridization for the series of samples prepared at elevated temperature while stronger 3〈em〉d-3d〈/em〉 (Co-Fe) hybridization for the samples prepared with post deposition annealing. EXAFS study also indicated presence of Co/Fe type antisite disorder which increases with increase in the substrate temperature. Finally from detail magnetic measurements it was observed that the films prepared by post-deposition annealing process have lesser crystallinity, magnetic ordering and magneto crystalline anisotropy in comparison to the films grown with elevated substrate heating.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Hao Guo, Taotao Sun, Liguo Yue, Ning Wu, Qi Li, Wenqing Yao, Wenhu Yang, Wu Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a kind of energy storage device, supercapacitors have attracted the attention of researchers, and the development of high-performance electrode materials is also the focus of attention. In this paper, template synthesis and pyrolysis were combined to prepare high performance porous carbon electrode materials. The carbonized electrode material effectively increased the capacitance storage capacity and charge transfer rate. The results revealed that the derivative had a relatively low charge-transfer resistance and high specific capacitance of 1059 F·g〈sup〉−1〈/sup〉 at a current density of 1.0 A·g〈sup〉−1〈/sup〉 in a three-electrode system. To further exploring practical application, a device based on the derivative and hemp-activated carbon asymmetric supercapacitor was assembled in 0.1 M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 neutral electrolyte, which exhibited an energy density of 20.35 Wh·kg〈sup〉−1〈/sup〉 at a power density of 400 W·kg〈sup〉−1〈/sup〉. Interestingly, it showed capability retention of nearly of 91.7% and columbic efficiency of 100% even after 10000 charging/discharging cycles in the neutral electrolyte.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325691-fx1.jpg" width="365" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Nejeh Hamdaoui, Yashar Azizian-Kalandaragh, Mouadh Khlifi, Lotfi Beji〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of Cd-doping on physical properties of Ni〈sub〉0.6-〈em〉x〈/em〉〈/sub〉Cd〈sub〉〈em〉x〈/em〉〈/sub〉Mg〈sub〉0.4〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 spinel ferrite has been investigated. Scanning electron spectroscopy (SEM) confirms the formation of grain and grain boundaries in these samples and the presence of all chemical elements introduced was confirmed by EDS. The X-ray analyses indicate that all the compounds have the cubic structure with 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉F〈/mi〉〈mi〉d〈/mi〉〈mrow〉〈mover accent="true"〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/mrow〉〈mi〉m〈/mi〉〈/mrow〉〈/math〉 space group, cell parameter increase which Cd content. A ferromagnetic state at room temperature for all compounds is detected by a magnetization measurement of hysteresis loops. We note that the saturation magnetization increases with Cd content, however, the remnant magnetization, and the corrective field decreases. DC electrical conductivity analysis shows a semiconductor behavior for all sample. In addition, non-overlapping small polaron tunneling (NSPT) and the overlapping large polaron tunneling (OLPT) are the dominants conductions mechanisms in our samples.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Beiyue Ma, Chang Su, Xinming Ren, Zhi Gao, Fan Qian, Wengang Yang, Guoqi Liu, Hongxia Li, Jingkun Yu, Qiang Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fly ash is a typical industrial solid waste that seriously affects human health and ecological balance. In order to recycle the fly ash, in this work, porous mullite ceramics were successfully fabricated with fly ash and bauxite via reaction synthesis process. Effects of firing temperature (1450–1550 °C), silicon carbide addition amount (0–15 wt%), and potash feldspar addition amount (0–16 wt%) on the mullite porous ceramics were systematically investigated. It was found that increasing the silicon carbide addition amount or raising firing temperature was favourable for improving the cold compressive strength and thermal shock resistance of the porous ceramics. Consequently, the porous ceramics with 10 wt% silicon carbide, 4–12 wt% potash feldspar had optimal overall performances. The closed porosity and cold compressive strength ranges were 14.79%–18.57% and 217.18–236.67 MPa, respectively. The thermal cycles were 7–9 times, and the thermal conductivity was reached to 2.19–2.52 W m〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉 at 800 °C. This work provides a convenient and promising method for the utilization of fly ash.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881932362X-fx1.jpg" width="496" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Daria N. Vtyurina, Irina A. Kaurova, Galina M. Kuz'micheva, Victor B. Rybakov, Dmitry Yu. Chernyshov, Evgeny V. Khramov, Sergey V. Firstov, Vladimir N. Korchak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Promising luminescent CsCd〈em〉X〈/em〉〈sub〉3〈/sub〉 (〈em〉X〈/em〉 = Cl, Br) single crystals, both nominally-pure and doped with bismuth, have been studied comprehensively by X-ray diffraction, X-ray synchrotron radiation, and X-ray absorption spectroscopy. Crystal structure refinement shows vacancies in the Cs crystallographic site and partial substitution of Cd〈sup〉2+〈/sup〉 ions by Bi〈sup〉3+〈/sup〉 ones in both CsCdCl〈sub〉3〈/sub〉 and CsCdBr〈sub〉3〈/sub〉 (point defects Bi〈sub〉Cd〈/sub〉〈sup〉•〈/sup〉), which is consistent with the results of X-ray absorption spectroscopy. The assumed presence of Bi〈sup〉1+〈/sup〉 ions in the Cs〈sup〉1+〈/sup〉 sites of doped CsCd〈em〉X〈/em〉〈sub〉3〈/sub〉 (〈em〉X〈/em〉 = Cl, Br) crystals is not confirmed. In the photoluminescence spectra of Bi-doped CsCdCl〈sub〉3〈/sub〉 and CsCdBr〈sub〉3〈/sub〉 crystals, a single band in the near-IR spectral range with a maximum around 1000 nm is caused by point defects Bi〈sub〉Cd〈/sub〉〈sup〉•〈/sup〉. Photoluminescence spectra and decay kinetics of Bi-doped CsCd〈em〉X〈/em〉〈sub〉3〈/sub〉 (〈em〉X〈/em〉 = Cl, Br) indicate their promising use as luminescent materials.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Sung-Hsiu Huang, Cheng-Yi Tong, Tsung-Eong Hsieh, Jyh-Wei Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For the development of advanced nanoscale multilayer protective coatings, proper design of microstructure and chemical composition of carbon containing sequential transition metal nitride nanolayers is an important issue. In this work, five different nanostructured CrCN/ZrCN multilayer coatings were deposited periodically by cathodic arc evaporation. The bilayer period of the CrCN/ZrCN multilayer coatings was kept at 20 nm. The C〈sub〉2〈/sub〉H〈sub〉2〈/sub〉 gas flow ratio was adjusted from 6.3 to 20.0% for achieving CrCN/ZrCN multilayer coatings with 2.3–4.2 at.% carbon content. Nanolaminated CrCN and ZrCN nitride layers and thin amorphous carbon nitride mixed nanolayers ∼5 nm thick were obtained as the carbon content reached 4.2 at.%. It was found that the hardness and adhesion quality were strongly improved by the carbon addition to the CrCN/ZrCN multilayer coatings. An increase of 2.6–4.6 GPa in hardness was found for the CrCN/ZrCN multilayer coatings due to the balance of solution hardening effect of carbon atoms and the softening by the amorphous mixed nanolayer. An optimal combination of high hardness, 28.9 GPa, and good adhesion, 41 N of upper critical load were achieved when the carbon content was 4.2 at.% for the CrCN/ZrCN multilayer coatings.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Hanfei Zhu, Yuyao Zhao, Yingying Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Epitaxial BiFeO〈sub〉3〈/sub〉 thin films with (100), (110) and (111) orientations were grown on the SrRuO〈sub〉3〈/sub〉-buffered SrTiO〈sub〉3〈/sub〉 substrates by using an off-axis magnetron sputtering. Unlike the BiFeO〈sub〉3〈/sub〉(110) and BiFeO〈sub〉3〈/sub〉(111) thin films that exhibited a single rhombohedral phase structure, a dominant rhombohedral phase accompanying with a small amount of tetragonal phase was identified in the BiFeO〈sub〉3〈/sub〉(100) thin film. In particular, the leakage currents and ferroelectric polarizations of sputtered BiFeO〈sub〉3〈/sub〉 thin films were focused on and these films showed utterly different current density-electric field (〈em〉J〈/em〉-〈em〉E〈/em〉) behaviors whether in the positive or negative electric field. Among the three films, the ferroelectric polarization of the BiFeO〈sub〉3〈/sub〉(100) thin film presented a good frequency stability and had the maximum remnant polarization of 〈em〉P〈/em〉〈sub〉r〈/sub〉 ∼ 78 μC/cm〈sup〉2〈/sup〉 @ 10 kHz, which could be further demonstrated by pulsed polarizations of films. The distinct differences in electrical properties of orientation-engineered BiFeO〈sub〉3〈/sub〉 thin films in present case can be attributed to their different crystallographic orientations and microstructures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324405-fx1.jpg" width="329" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Lihong Wang, Hongtao Guan, Jianqiao Hu, Qiang Huang, Chengjun Dong, Wei Qian, Yude Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous jute biomass carbon (PJBC) composited by Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles were successfully prepared by a chemical coprecipitation method at a low temperature of 60 °C, which is very simple to prepare a high degree of purity of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles. The structure, morphology, and microwave absorption performances of the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites were investigated in detail. Due to the porous structure and large interfaces between Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 and PJBC, the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites show excellent microwave absorption performances. The minimum reflection loss (RL) value of −39.5 dB is obtained for the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites at the frequency of 6.4 GHz. When the thickness is only 1.6 mm, an effective absorption bandwidth (RL ≤ −10 dB) for 5 GHz is achieved from 13.8 to 17.8 GHz. The excellent microwave absorption performances for the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites are rooted in enhanced impedance matching, large interfaces, ionic polarization, eddy loss, natural resonance, and multiple reflection and scattering. Consequently, considering market applications and the cost, the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composite in this work can be a promising candidate for microwave absorber.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites prepared by a chemical coprecipitation method at a low temperature of 60 °C exhibit the microwave absorbing performance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881932448X-fx1.jpg" width="476" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): N.E. Dubinin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The concentration dependencies of the self-diffusion coefficients in liquid Na–K and K–Cs alloys at 〈em〉T〈/em〉 = 373 K are calculated in the framework of the linear trajectory approximation in conjunction with the square-well (SW) model treated by the mean spherical approximation in the semi-analytical representation. It is shown that this approach allows to achieve a good description of diffusion properties for liquid binary metal alloys at the same values of the SW parameters that lead to a good description of the structure and entropy for alloys under consideration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Xiang Wu, Richu Wang, Chaoqun Peng, Yan Feng, Zhiyong Cai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Gas atomized Cu-3Ag-0.5Zr and Cu-3Ag-0.5Zr-0.4Cr-0.35Nb (wt.%) powders were compacted by hot isostatic pressing (HIP) and followed by forging. The microstructures and tensile properties at room and elevated temperatures (400 °C, 450 °C and 500 °C) were investigated. The continuous Ag precipitates (5–25 nm) and Cu〈sub〉4〈/sub〉AgZr (200–500 nm) particles are the main strengthening phases in the Cu-3Ag-0.5Zr alloy. The yield strength and ultimate tensile strength at room temperature are enhanced by 104 MPa and 83 MPa, respectively, due to the introduction of Cr〈sub〉2〈/sub〉Nb (50–80 nm) particles. Besides, the strength at elevated temperatures is also improved. For both the alloys, the discontinuous Ag precipitates near the grain boundaries result in a weak grain boundary cohesion when tested at 450 °C, leading to the lowest elongation. The Cr〈sub〉2〈/sub〉Nb and Cu〈sub〉4〈/sub〉AgZr particles are extremely stable when tested at 500 °C, which benefits to the performance enhancements at elevated temperatures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Wenjing Zhang, Huihong Liu, Hua Ding, Hidetoshi Fujii〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The rolled Ti–15V–3Cr–3Sn–3Al (Ti-15-3) alloy (metastable 〈em〉β〈/em〉 titanium alloy) sheet with an average grain size of 44.0 μm was subjected to friction stir processing (FSP) at a tool rotation speed of 250 rpm and a tool traverse speed of 100 mm/min (250–100). Thereafter, a fine-grained (∼6.6 μm) and relatively equiaxed microstructure with a high angle grain boundary (HAGB) ratio of 74.5% was observed in the stir zone (SZ). Superplastic tensile tests were then conducted on this microstructure at the temperatures ranging from 600 °C to 800 °C and strain rates range of 1 × 10〈sup〉−4〈/sup〉-1 × 10〈sup〉−2〈/sup〉 s〈sup〉−1〈/sup〉, and an excellent low-temperature superplasticity (LTSP) with the elongation of 463% was obtained at 650 °C and 1 × 10〈sup〉−4〈/sup〉 s〈sup〉−1〈/sup〉. In addition, the microstructure in the gauge section of the tensile specimens interrupted at different engineering strains of 20%, 50%, 200%, and 463% (tensile fractured) at the optimal superplastic tensile condition of 650 °C and 1 × 10〈sup〉−4〈/sup〉 s〈sup〉−1〈/sup〉 was studied. It was found that the precipitated 〈em〉α〈/em〉 phase increased with the increasing strain, which contributed to the achievement of an enhanced LTSP by inhibiting the grain growth. Moreover, the α grains with a finer grain size of 4.4 μm was observed in the gauge section of the tensile fractured specimen and this was attributed to the occurrence of continuous dynamic recrystallization (CDRX). Therefore, the superplastic deformation mechanism of the Ti-15-3 alloy is recognized as grain boundaries sliding (GBS) accompanied with dislocation movement and CDRX at 650 °C and 1 × 10〈sup〉−4〈/sup〉 s〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): G.E. Nikiforova, O.N. Kondrat'eva, A.V. Tyurin, M.A. Ryumin, V.N. Guskov, K.S. Gavrichev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lutetium orthotantalate with 〈em〉M′〈/em〉-fergusonite type structure was synthesized using a reverse coprecipitation method. Phase and chemical composition, as well as microstructure of the synthesized sample, were characterized by X-ray diffraction (XRD), μ-X-ray fluorescence and Fourier-transform infrared spectroscopies, and scanning electron microscopy. Heat capacity of 〈em〉M′〈/em〉-LuTaO〈sub〉4〈/sub〉 was first studied by adiabatic and differential scanning calorimetry (DSC) in the temperature range from 10 to 1300 K. Using a temperature dependence of heat capacity, the standard thermodynamic functions (entropy 〈em〉S〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(〈em〉T〈/em〉), enthalpy change 〈em〉H〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(〈em〉T〈/em〉)〈em〉–H〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(0) and derived Gibbs energy 〈em〉Ф〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(〈em〉T〈/em〉)) were calculated in the range of 〈em〉T〈/em〉→0–1300 K. The standard molar entropy of 〈em〉M′〈/em〉-LuTaO〈sub〉4〈/sub〉 at 298.15 K is 123.12 ± 0.50 J K〈sup〉−1〈/sup〉 mol〈sup〉−1〈/sup〉. A comparison of the experimental heat capacity values, obtained by DSC, with those calculated using the empirical Neumann-Kopp rule showed a reasonable agreement between the two sets of data only up to ≈1000 K. The high-temperature evolution of the lattice parameters for 〈em〉M′〈/em〉-LuTaO〈sub〉4〈/sub〉 was studied by high-temperature XRD (HTXRD). According to the high-temperature heat capacity study and the HTXRD measurements, there were no phase transformations up to 1300 K. Based on the HTXRD data, the linear and volume thermal expansion coefficients were obtained for the first time.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): V.I. Voronkova, E.P. Kharitonova, E.I. Orlova, N.I. Sorokina, T.A. Sorokin, A.M. Antipin, E.D. Baldin, V.V. Grebenev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Undoped and Mg-doped Nd〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉 oxymolybdate single crystals and polycrystalline samples have been prepared by flux growth and solid-state reactions. The materials have been characterized by X-ray diffraction, EDS microanalysis, X-ray structure analysis, differential scanning calorimetry, thermogravimetry, and impedance spectroscopy. The (MgO)〈sub〉〈em〉x〈/em〉〈/sub〉(Nd〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉)〈sub〉(1–〈em〉x〈/em〉)/2〈/sub〉 solid solution series has been shown to extend to 〈em〉x〈/em〉 = 0.20. Doping of Nd〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉 single crystals with Mg leads to splitting of the Mo, Nd1, and O2 sites. A structural model in which the Mg atoms partially substitute for Mo atoms and reside near the Mo site, 0.28 Å from it, ensures the best agreement with the observed diffraction pattern. The conductivity of the undoped and doped polycrystalline samples approaches 10〈sup〉−4〈/sup〉 S/cm at 800 °C and is assumed to have an anionic nature.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324764-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Chaocheng Liu, Xucai Kan, Xiansong Liu, Shuangjiu Feng, Jiyu Hu, Wei Wang, Khalid Mehmood Ur Rehman, Mudssir Shezad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Conventional permanent hexagonal ferrites may prohibit the soft magnetic properties through the effort of doping behavior. A typical case of this magnetic conversion is Co–Ti doped M-type strontium hexaferrites. On the basis of this system, we developed a novel foundation of La doped CoTi-strontium hexaferrites in present work and a promising result were obtained. Polycrystalline Sr〈sub〉1-〈em〉x〈/em〉〈/sub〉La〈sub〉〈em〉x〈/em〉〈/sub〉Fe〈sub〉10〈/sub〉CoTiO〈sub〉19〈/sub〉 (〈em〉x〈/em〉 = 0.00–0.10) hexaferrites present the admirable characteristics as general soft ferrites (high permeability 〈em〉μ〈/em〉, low core loss 〈em〉P〈/em〉〈sub〉cv〈/sub〉), and retain the properties of permanent ferrites simultaneously. This extraordinary performance exhibit more appropriate candidate for multilayer inductors contrast to normal soft magnetic materials. Meanwhile, we presented a series of measurement results to investigate the morphology and texture of the sample, which revealed the internal structural feature systematically.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Magnetoplumbite crystal structure and spin directions of 2〈em〉a〈/em〉 and 4〈em〉f〈/em〉〈sub〉2〈/sub〉 sites for M-type strontium hexaferrites.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324235-fx1.jpg" width="278" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Chinedu I. Ossai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To advance the prognosis of progressing cavity Pumps (PCPs) used for artificial lifting, the pump-off need to be identified to forestall failure. This study developed a new technique for determining the Pump-off events Activation Times (PATs) of the PCPs using the transient Water Discharge Rates (WDRs) from coal seam gas producing wells. The Gaussian distribution function parameters of the rolling standard deviations of the water discharge rate (RSWR) and the transition probability of the rolling standard deviations of the water discharge rate (TP_RSWR) were used to build the model. By determining the anomalies in the RSWR signals with the bottom-up segmentation technique and computing the statistical characteristics at the changepoint locations, the steady-state of the WDR signals was established. This steady-state signal, which represents the Operation Transition Level (OTL) between the Normal Operation (NOP) and the Pump-off Event (POE) was used for monitoring the transition of the PCPs' operating status. An algorithm was developed in Python and tested it on field data from 36 coal seam gas wells. The performance of my technique was determined with precision, recall and F1 score, which gave an average value of 94.94%, 92.63%, and 93.56% respectively. It is expected that the implementation of this technique in the real-time estimation of PATs will be vital for reducing PCPs faults seeing that poor PATs detection results in PCPs running dry and consequently failures due to the extreme temperatures and abrasions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Fuwei Yu, Hanqiao Jiang, Fei Xu, Zhen Fan, Hang Su, Junjian Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a new fabrication method was reported for establishment of a 2.5D reservoir micromodel, which incorporated 3D geometry of porous media and visualization of 2D microfluidic chips. Flow physics such as imbibition, rison and rheon were visualized in the new 2.5D reservoir micromodel through water flooding experiments in water-wet and oil-wet 2.5D reservoir micromodels. Corresponding results demonstrated the strong capacity of the presented 2.5D reservoir micromodel to mimic the real 3D porous media. Besides, four theoretical patterns concerning residual oil distributions were obtained based on water flooding, surfactant flooding and polymer flooding experiments. Furthermore, imbibition of a Winsor I type surfactant system was investigated, accompanied by explanation and visualization of two major enhanced oil recovery (EOR) mechanisms, namely microemulsion imbibition and residual oil solubilization, which confirmed the assumptions made based on core imbibition experiments.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Mohamed R. Shalaby, Liyana Nadiah Osli, Stavros Kalaitzidis, Md Aminul Islam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal maturity and palaeodepositional environment of the Taratu Formation has been studied by evaluating its geochemical properties and organic petrographical features. Geochemical properties of the Cretaceous-Palaeocene Taratu source rock that are identified through pyrolysis indicate that this formation has excellent organic matter quality, quantity and hydrocarbon generation potential. Only the Cretaceous-aged sequence from this formation is thermally mature, with Tmax values ranging from 429 °C to 459 °C, while Palaeocene samples are found to be thermally immature. Organic matter of the Taratu Formation comprises primarily of oil and gas prone kerogen type II-III and gas prone kerogen type III, which is reflected by high HI (165.0–327.5 mg HC/g TOC) and low OI (5.00–25.7 mg CO2/g TOC) values. Tissue Preservation Index (TPI) and Gelification Index (GI) indicates that the Taratu Formation was previously deposited in a limnic environment. Further assessment of the source rock's palaeodepositional environment through correlating cross-plots of various biomarker data and evaluation of organic petrography suggests that the formation was subjected to brackish water influx.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 180〈/p〉 〈p〉Author(s): Zulong Zhao, Yu Shi, Daoyong Yang, Na Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel and pragmatic technique has been developed and validated to quantify gas exsolution of alkane solvent(s)–CO〈sub〉2〈/sub〉–heavy oil systems with consideration of interface mass transfer for each gas component under nonequilibrium conditions. Experimentally, constant composition expansion (CCE) tests of three alkane solvent(s)–CO〈sub〉2〈/sub〉–heavy oil systems are conducted with a visualized PVT cell under equilibrium and nonequilibrium conditions. The liquid height and pressure of the system are continuously monitored and recorded during experiments to measure, respectively, the bubblepoint pressure, pseudo-bubblepoint pressure, and the entrained gas volume. With the assumption of instantaneous nucleation, a mathematical model which integrates Peng-Robinson equation of state (PR EOS), Fick's second law, and nonequilibrium boundary condition has been developed to quantify not only the amount of the evolved gas and entrained gas, but also the dynamic composition of gas phase as a function of time. Once the deviations between the measured gas volumes and the calculated ones have been minimized, the mass transfer Biot number, individual diffusion coefficient, and interface mass transfer coefficient of each gas component as well as the gas bubble number are determined. Increases in experimental temperature and pressure are found to impose opposite effects on diffusion coefficient during gas exsolution processes. The diffusion of each gas component is found to be faster when the temperature becomes higher or the initial pressure becomes lower. Either CO〈sub〉2〈/sub〉 or C〈sub〉3〈/sub〉H〈sub〉8〈/sub〉 diffuses faster than CH〈sub〉4〈/sub〉 in the liquid phase under the same condition. In addition, the interface mass transfer coefficients, with an order of CO〈sub〉2〈/sub〉 〉 CH〈sub〉4〈/sub〉 〉 C〈sub〉3〈/sub〉H〈sub〉8〈/sub〉, obtained in this study are much higher than those collected in the literature since the nonequilibrium conditions greatly facilitate gas exsolution. The determined mass transfer Biot numbers in this study are large, indicating that the bulk resistance due to molecular diffusion inside the heavy oil dominates the gas exsolution process compared to the interfacial resistance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Jingdong Liu, Tao Liu, Youlu Jiang, Tao Wan, Ruining Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The distribution, origin, and evolution of overpressure in the petroliferous basin are important problems that need to be addressed for oil and gas exploration. The distribution and origin of overpressure in the Shahejie Formation in the northern Dongpu Depression are analyzed based on geological studies, logs, and pressure data. The contribution ratios of different overpressure origins are quantified, and the evolutionary stages of overpressures of different origins are further divided. The results show that the formation pressure coefficients of Shahejie Formation in the Dongpu Depression are mainly within the range of 0.9–1.5. The overpressures are mainly distributed in the Sha-3 and Sha-4 Members of the Haitongji sag, the Central uplift belt and the Qianliyuan sag. From the sag to its surrounding area, the formation pressure coefficient gradually decreases. The high deposition rate and strong hydrocarbon generation are the main causes of overpressure formation in the Shahejie Formation in the Dongpu Depression. Based on the stress–strain characteristics of different origin overpressures and the log response parameters, two models, acoustic travel time-effective vertical stress and electrical resistivity-effective vertical stress, are established to identify and quantify the different origin overpressures. The calculation results for the area from the Haitongji sag and Qianliyuan sag to the Central uplift belt show that the main cause of overpressure gradually changes from both disequilibrium compaction and hydrocarbon generation to disequilibrium compaction as the main factor, with the contribution of disequilibrium compaction to overpressure in the Central uplift belt at about 87%. The Sha-3 Members of the Shahejie Formation in the Haitongji sag and the Qianliyuan sag are more strongly affected by hydrocarbon generation, which accounts for 42% and 47.5% of overpressure origin, respectively. There are five stages in the evolution of overpressure in the Shahejie Formation in the northern Dongpu Depression: normal compaction (before 35 Ma), mixed pressurization (35-27 Ma), uplift and pressure release (27-17 Ma), disequilibrium compaction (17-11 Ma), and secondary mixed pressurization (12 Ma-present).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Zhiwei Zeng, Hongtao Zhu, Lianfu Mei, Jiayuan Du, Hongliu Zeng, Xinming Xu, Xiaoyun Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Few studies have focused their attentions on the source-to-sink (S2S) system from a multiple-level perspective. We have proposed an effective multilevel S2S subdivision approach based on the integrated study of seismic geomorphology, well-based facies, seismic facies and multi-attribute. The inspiration of multilevel S2S subdivision method is drawn mainly from the modern Diancang Mountain- Lake Erhai S2S system with different-orders of drainage divides. The Paleogene Central Uplift system during the syn-rift stage in Xijiang Sag, Pearl River Mouth Basin, South China Sea, provides a suitable example to test the approach and analyze the multilevel S2S characteristics of an ancient uplift system. The result shows that the Central Uplift system can be divided into three second-level sub-S2S systems (R-A, R-B and R-C), and can be further sub-divided into twelve third-level sub-S2S systems (A1∼A5, B1∼B5 and C1∼C2). Generally, the A1∼A5 and B1∼B4 systems are developed at the gentle slopes and deposited a series of narrow-shaped braided deltas with higher exploration potential, whereas the B5 and C1∼C2 systems are developed at the relatively steep slopes and deposited a series of lobate shaped turbidite and fan deltas with lower reservoir quality. Based on the multilevel S2S analysis, the ancient uplift can be scientifically sub-divided and compared with each sub-S2S system, including the sediment-transport type and distance, sedimentary facies characteristics and stacking relationship with the hydrocarbon source rocks. These in-depth and detailed studies have practical significance for the exploration of favorable reservoir sandbodies and stratigraphic-lithologic traps.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Min-Su Lee, Yong-Taek Hyun, Tea-Sung Jun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have performed macroscopic tensile and nanoindentation tests to investigate the effect of oxygen content on the global and local strain rate sensitivity of grades 1, 2 and 4 commercially pure titanium (CP–Ti). Electron backscatter diffraction (EBSD) was used to characterise the crystallographic texture of target samples and orientation of target grains. Slip activities were anticipated by Schmid factor analysis, indicating the relative incidence of 〈a〉 type prismatic and basal slips in the macroscopic region, and similarity of potential local deformation between comparative grain orientations. Further slip trace analysis around the residual impressions showed similar slip activity in equivalent orientations regardless of oxygen content. Global and local strain rate sensitivity were evaluated with respect to the influence of texture and grain orientations, respectively. Significant oxygen-dependent rate sensitivity is observed such that the rate sensitivity is inverse to the oxygen content and this effect is agreed on at both macro- and microscopic levels. These findings are potentially important for understanding the influence of oxygen content on the dwell fatigue of Ti alloys and correlating the intrinsic mechanism at the microscopic level to the macroscopic deformation behaviours.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324107-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Y. Al-Hadeethi, S.A. Tijani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nuclear medicine makes use of different gamma emitting radioactive sources which necessitates a reliable way of reducing unnecessary exposure of nuclear medicine personnel and the general public in the vicinity of these radioactive sources. Radiation shielding is one of the major ways through which the medical personnel and the public are protected from the harmful effects of ionizing radiation. A material that combines transparency, non-toxicity and radiation shielding ability is of high interest presently in the medical environment. This work aims to determine the suitability of lead-free transparent 50BaO-(50-x)borosilicate-xBi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 glass system for radiation shielding purposes at diagnostic nuclear medicine energies and to compare its properties with that of transparent lead glass and ordinary concrete. The results of this work show that while all the glass samples show comparable shielding properties with the lead glass, glass sample G5 is the best lead glass substitute. All the studied glasses are lighter than lead glass and showed better shielding properties than ordinary concrete.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Liang Zheng, Wenjie Zhang, Qi Wang, Hong Zhang, Zhou Yu, Cuihua Cheng, Yong Zhang, Ming Lei, Yong Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉MgB〈sub〉2〈/sub〉 bulks with NaCl doping amount ranging from 0–30 at% have been prepared by hot pressed sintering process. With the increase of NaCl doping amount, the 〈em〉c〈/em〉 axis lattice parameter of MgB〈sub〉2〈/sub〉 monotonously increases, indicating the substitution of Mg atoms by larger Na atoms. Meanwhile, the intensity of diffraction peaks of both NaCl and impurity phase of MgO increases. More compact morphology was found in the NaCl doped MgB〈sub〉2〈/sub〉 samples. The critical transition temperature (〈em〉T〈/em〉〈sub〉c〈/sub〉) decreases from 38.2 K to 36.8 K with the increase of NaCl doping amount from 0 to 30 at%, and the corresponding transition width of 〈em〉T〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 (Δ〈em〉T〈/em〉〈sub〉c〈/sub〉) increases from 0.5 K to 1.8 K. When the doping amount of NaCl is not exceeding 10 at%, the 〈em〉J〈/em〉〈sub〉c〈/sub〉 value is about 10〈sup〉6〈/sup〉 A/cm〈sup〉2〈/sup〉 at 4.2 K, 3 T, and 5 × 10〈sup〉5〈/sup〉 A/cm〈sup〉2〈/sup〉 at 10 K, 3T. 〈em〉J〈/em〉〈sub〉c〈/sub〉 performance of the 5 at% NaCl doped MgB〈sub〉2〈/sub〉 sample (NC05) reaches 6.8 × 10〈sup〉5〈/sup〉 A/cm〈sup〉2〈/sup〉 at 20 K, 2T, which improves approximately 20% compared to the pure one, attributing to the better grain connectivity of MgB〈sub〉2〈/sub〉 and enhancement of flux pinning force by NaCl doping.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Yu Wang, Chao Fang, Xiang Li, Zhou Peng Li, Bin Hong Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉LaB〈sub〉6〈/sub〉 is a unique plasmonic material, for which the localized surface plasmon resonance (LSPR) absorption band intrinsically lies in the near infrared (NIR) region. In this work, we synthesized spherical LaB〈sub〉6〈/sub〉 nanoparticles with a tunable size within 50–200 nm. The optical properties of these LaB〈sub〉6〈/sub〉 nanospheres were found to be sensitive to the thickness of surface oxide layer that was formed during the synthesis, purification and dispersion processes. In order to enhance the stability of LaB〈sub〉6〈/sub〉 nanoparticles in aqueous environment, LaB〈sub〉6〈/sub〉@SiO〈sub〉2〈/sub〉 with a core-shell structure was successfully prepared. Both LaB〈sub〉6〈/sub〉 and LaB〈sub〉6〈/sub〉@SiO〈sub〉2〈/sub〉 demonstrated low cytotoxity in biomedical tests when their concentrations were limited to 0.2 mg mL〈sup〉−1〈/sup〉. The in vitro photothermal therapy experiment showed that 4T1 cancer cells were eventually apoptotic after being exposed to a 980 nm laser for 5 min at a considerably low power density of 0.82 W cm〈sup〉−2〈/sup〉 and a low dose of 0.1 mg mL〈sup〉−1〈/sup〉 for LaB〈sub〉6〈/sub〉@SiO〈sub〉2〈/sub〉. The results suggest that these LaB〈sub〉6〈/sub〉 nanospheres are viable photothermal agents for biomedical applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Nabil M. Al-Areeq, Abubakr F. Maky, Ahmed S. Abu-Elata, Mahmud A. Essa, Salem S. Bamumen, Gamal A. Al-Ramisy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Masilah oilfields are rich-oil provinces in the Sayun-Masilah Basin. The petroleum system including essential elements and processes is a very important for understanding and development of oilfield to further explore hydrocarbons in the whole basin. Integrated geochemical, geological, petrological and petrophysical analyses were performed on the source and reservoir rocks in the Masilah oilfields to gives information about the complete petroleum system. The Masilah oilfields filled with syn- and post-rift sediments, including a self-contained source-reservoir system. The geochemical results indicate that the organic-rich shales of the Madbi Formation are considered as oil-source rocks, with high total organic carbon content of more than 5.0 wt% TOC and oil-prone kerogen Types II and I. The Madbi shales are currently characterized by thermally mature level, within the oil generation window. Geochemical biomarker correlations of oil-source rock indicate that there is a genetic link between the oils and the Late Jurassic Madbi shale source rock in the Masilah oilfields. Therefore, the geochemical characteristics of the Madbi source rock have been collaborated into basin models and illustrate that the Madbi source rock had passed the peak-oil generation window during the Late Cretaceous to present-day and that large amounts of oil were generated. The generated oil was expelled and migrated to the overlain Early Cretaceous Qishn clastic reservoir rocks through faults during the Oligocene-Middle Miocene. The oil was then accumulated and trapped into horst and tilted fault blocks that initial formed during the Late Jurassic-Early Cretaceous rifting.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Jeffrey O. Oseh, M.N.A. Mohd Norddin, Issham Ismail, Abdul R. Ismail, Afeez O. Gbadamosi, Augustine Agi, Shadrach O. Ogiriki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With increasing strict environmental laws, there is a need for operators to design a benign oil-based muds (OBMs). In this study, oil extracted from non-edible sweet almond seed (SASO) was used as the continuous phase to formulate biodiesel-based drilling mud (BBDM). Different properties of the BBDM including the economic viability were evaluated and compared with those of the diesel OBM to determine the applicability of these properties for drilling fluids and their level of toxicity to the environment. The results indicate that the rheology, filtration properties, electrical stability, thermal stability and shale swelling inhibition performance of the BBDM are comparable with those of the diesel OBM. The biodiesel has a significantly higher flash point of 169 °C than the diesel with 78 °C; demonstrating that it can supply better fire safety than the diesel. The data of the toxicity test indicate SASO to be safer and less harmful compared to diesel #2 type used. After the 28-day period of biodegradation tests, the BBDM and the diesel OBM showed 83% and 25.2% aerobic biodegradation with 〈em〉Penicillium〈/em〉 sp., respectively. The low branching degree and absence of aromatic compounds in the BBDM contributes for its higher biodegradation. The economic evaluation of the BBDM indicates low cost of formulation and waste management. The general outcome of the tests illustrates that SASO has the potentials of being one of the technically and environmentally feasible substitutes for the diesel OBM.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Bao Jia, Jyun-Syung Tsau, Reza Barati〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molecular diffusion is an important EOR mechanism in naturally fractured reservoirs. However, the laboratory-measured diffusion coefficient in the fractured porous media is still limited; and grid sensitivity analysis is missing in the literature when the single-porosity system is applied to history match the pressure decline curve. We aimed to fill the gaps using Radial Constant Volume Diffusion (RCVD) method experimentally to investigate diffusion coefficients at different pressures in hydrocarbon saturated porous media. A special in-house cell is designed to hold the core sample in the center with the annulus around simulating the fracture. The core is initially saturated with oil while the annulus is filled with CO〈sub〉2〈/sub〉 at the same pressure. During the measurements, the system pressure declines as gas diffuses into the oil phase until it reaches chemical equilibrium. The pressure decline curve is history matched to determine the diffusion coefficient. The initial pressure is 597 psi, and the diffusion coefficient is determined in numerical models accordingly. Molecular diffusion coefficients are estimated at different experiment periods to reveal the pressure-dependency. A workflow is proposed to obtain effective diffusion coefficients in dual-porosity models that could be extended to multi-component systems. Besides, flow characteristics in the RCVD system are characterized and capillary pressure effect is investigated in this study.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): R. Farajzadeh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To mitigate the negative impacts of hydrocarbon fuels on climate change complementary decision tools should be considered when selecting or evaluating the performance of a certain production scheme. The exergy analysis can give valuable information on the management of the oil and gas reservoirs. It can also be used to calculate the CO〈sub〉2〈/sub〉 footprint of the different oil recovery mechanisms. We contend that the concept of exergy recovery factor can be used as a powerful sustainability indicator in the production of the hydrocarbon fields. The exergy-zero recovery factor is determined by considering exergy balance of full cycle of hydrocarbon-production systems and defines boundaries beyond which production of hydrocarbons is no longer sustainable. An example of the exergy analysis is presented in the paper.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Ahmad Ghasemi, Hossein Jalalifar, Saeid Norouzi Apourvari, Mohammad Reza Sakebi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Wellbore instability is a big challenge in shale formations. The objective of this study is to investigate the effectiveness of a natural additive as a shale inhibitor. The capability of this additive for reducing ion movement into shale and plugging its pore throats has been tested and compared with salts and nano particles. The ions and water movement into shale and resultant swelling was measured by modified gravimetric, swelling and modified immersion tests. The results showed that using Henna extract could reduce the ion and water movement into shale. In addition, the results of pore pressure tests showed that 3 wt % of Henna extract are more effective than nano particles and could completely plug the pore throats of shale while the mud rheological properties are still maintained. The findings of this study show that the Henna extract could be considered as a cost-effective and an environmentally-friendly shale inhibitor.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920410519306345-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 30 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 811〈/p〉 〈p〉Author(s): Miqi Wang, Zehua Zhou, Qijie Wang, Zehua Wang, Xin Zhang, Yuying Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉FeCrMoCBY amorphous coating with a high volume fraction of amorphous phase (90%) was prepared on Q235 steel by atmospheric plasma spraying. Influence of passivation potential on the corrosion resistance of passive films on the coating surface was estimated by electrochemical measurements, capacitance analysis, AFM and XPS technique. The results revealed that increasing potential promoted the growth of a more compact and thicker film due to the formation of more bounded water and oxides. Reduction in hydroxides further decreased point defects density significantly in the passive layer when passivated at a higher potential. A low diffusivity (1.67 × 10〈sup〉−15〈/sup〉 cm〈sup〉2〈/sup〉 s〈sup〉−1〈/sup〉) corresponding to point defects could suppress both the growth and degradation processes of passive film in chloride containing electrolyte, and thus enhance the film resistance to local thinning.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Yongqiang Li, Jianfang Sun, Hehua Wei, Suihong Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on the analysis of the characteristics of modern karst and paleokarst outcrops, this study summarizes the features of subsurface reservoirs by using core, logging, seismic and production data, establishes the structural model of fault-controlled karst reservoirs, and points out the guiding significance of this structural model for development and production in the Tahe oilfield. Modern karst in southern China shows the three-component structural characteristics of fault-controlled karst which are fault core, damage zone, and host rock. The cavern is developed in the fault core and the fracture-vugs are fully developed. Paleokarst outcrops reveal the evolutionary process of fault-controlled karst reservoirs, the characteristics of caverns along the fault and the surrounding fracture-vuggy features. Seismic structure tensor attributes, ant-track attributes and amplitude spectrum gradient attributes are used to describe the external geometry, caverns, and large-scale fractures of fault-controlled karst reservoirs, and the small fractures and vugs can be described by using cores. According to the characteristics of modern karst, paleokarst and subsurface reservoirs, three architectural patterns of fault-controlled cavern complexes, fault-controlled caverns and fault-controlled vugs are summarized. Different architectural patterns of karst reservoirs lead to different production capacities. The architectural patterns have important guiding significance for new drilling and water or gas injection to improve oil recovery.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): M.E. Emetere〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recently, significant reserves of oil were discovered off the coast of Lagos State, southwest Nigeria. The lateral situation or compositions of the oil-bearing deposits is not clear because these findings are based on a particular position of a single well. The conventional methods of oil exploration have shown a fundamental theoretical shortcoming that may not be resolved, hence scientists or professionals may have to keep modifying the theories to explore different geological terrain. In this study, the remote sensing technique was adopted. The dataset were adopted from MERRA, Landsat 8 OLI and ETM imagery. The temperature distributions (soil and geothermal temperature) over the research area were calculated using existing algorithms to compliment the satellite remote sensing results. A prospective hydrocarbon deposits was suggested for further research work.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): T.N. Phan, Y.M. Zapata, C.S. Kabir, J.D. Pigott, M.J. Pranter, Z.A. Reza〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Despite the recent growth in oil production from unconventional reservoirs, existing hydraulically-fractured horizontal wells face challenges of poor recovery with the rapid production decline over a short life span. Enhanced recovery techniques, such as cyclic CO〈sub〉2〈/sub〉 injection can be a solution to this impending problem and lead to energy independence for the foreseeable future. However, mechanisms occurring around the hydraulically fractured wells are far from fully understood. The primary motivation of this study revolves around addressing this limitation. Specifically, we explored the evolution of various thermophysical properties occurring around hydraulically-fractured wells in liquid-rich unconventional reservoirs using a holistic, integrated modeling framework.〈/p〉 〈p〉Available well-logs and other data from Howard County in the Midland Basin formed the basis for constructing representative 3D structural models that capture the Midland Basin stratigraphy. We used a simulator to create multistage hydraulic fractures that allowed integration into numerical reservoir-flow simulation models. Then, both convective and diffusive flow within a multicomponent compositional simulation modeling paradigm is used to examine the role of molecular diffusion in performance under cyclic CO〈sub〉2〈/sub〉 injections in hydraulically-fractured well.〈/p〉 〈p〉The simulation results indicate that molecular diffusion yields an incremental oil recovery of 6% compared to models that do not. Our analysis reveals different thermophysical properties transition from near wellbore regions to outer regions into the rock matrix. Changes in total mole fractions of CO〈sub〉2〈/sub〉, methane, and hydrocarbons with C7+ fraction, pressure and saturation variation, viscosity reduction and the surface tension over 14 injection-soaking-production cycles are tracked. The analyses of the evolution of these thermophysical properties provide us with means to evaluate the efficiency of the solvent injection process. The simulation results explain how, when, and where CO〈sub〉2〈/sub〉 disperses into the reservoir.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 180〈/p〉 〈p〉Author(s): Wanderson Lambert〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we propose a technique to solve the system of equations of mass balance for the salt solution and mass balance for salt in the solid phase introduced in the paper “Mathematical model of dissolution of particles of NaCl in well drilling: Determination of mass transfer convective coefficient”. In that paper, authors claimed that there is no technique to solve analytically the provided system of equations (actually, authors claimed that is possible an analytical solution for the “steady state” solution), however, from the mathematical viewpoint, the system of equations modelling this transport is a linear hyperbolic system of equations and it is possible to obtain the solution of this system by using the technique of characteristic waves. Since the model proposed in the paper cited can be used for several different transport equation models, it worth to present the general technique and solution that can be applied in other models in the context of transport phenomena.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Ahmed Gamal El-Shamy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel conductive PVA/CQDs nanocomposite films were synthesized through the casting technique for the electromagnetic (EM) wave protection at microwave band. The surface morphology, thermal and mechanical properties were briefly studied. The SEM micrograph showed an excellent distribution, dispersion and a high adhesion property of the CQDs in the PVA chains. Also, DSC analysis showed an increase in the〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mtext〉glass〈/mtext〉〈mspace width="0.25em"〉〈/mspace〉〈mtext〉temperature〈/mtext〉〈mspace width="0.25em"〉〈/mspace〉〈mrow〉〈mo stretchy="true"〉(〈/mo〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi〉g〈/mi〉〈mi〉l〈/mi〉〈mi〉a〈/mi〉〈mi〉s〈/mi〉〈mi〉s〈/mi〉〈/mrow〉〈/msub〉〈mo stretchy="true"〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 from 83.2 °C for fresh PVA to 95.4 °C for 8 wt% of CQD and the increase in melting temperature from 215 °C for fresh PVA to 227.7 °C for the same CQDs concentration. It was found that Young's modulus is directly proportional to CQD nano-particles concentration in the nano-composites from 0.14 GPa for fresh PVA to 4.48 GPa for 8 wt% of CQDs. It was found that the strength at break increases, but the elongation declines with the increase of CQDs nano-particles. The EM shielding effectiveness (SE) of (PVA/CQDs) nanocomposite is measured in the microwave frequency range, and it is found around 36.8 dB with the CQDs concentration (8 wt%). Finally, the PVA/CQDs nano-composite is of promising potential applications in electronics and microwave devices at an affordable cost.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819331846-fx1.jpg" width="148" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): A. Rajabi, A.R. Mashreghi, S. Hasani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, non-isothermal kinetic analysis of high temperature oxidation of Ti–6Al–4V alloy by thermogravimetric analysis (TGA) at heating rates of 10, 15, and 20 °C/min up to 1550 °C in air atmosphere was studied. The results revealed that the formed oxide layer consists of several different parts; an inner part of TiO〈sub〉2〈/sub〉, an outer part of TiVO〈sub〉4〈/sub〉, and an intermediate part of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. Also, the thickness of oxide layer increased by an increase in the maximum heating temperature, while its density decreased by formation of the pores and cracks in higher maximum temperature due to the mismatch between the thermal expansion coefficient of the oxide layer and the substrate. This mismatch led to formation of large stresses in the oxide layer at high temperatures (≥1000 °C) and thereby isolation of the oxide layer during cooling. The microhardness profiles shift to higher microhardness values by an increase in the maximum temperature due to the increasing of oxygen solubility in the substrate. On the other hand, the kinetic results performed by isoconversional Starink, KAS, FWO, Tang, and Friedman methods in combination with the invariant kinetic parameters (IKP) method and fitting model estimated the activation energy (〈em〉E〈/em〉) and pre-exponential factor (ln〈em〉A〈/em〉) of the oxidation process equal to 205–235 kJ/mol and 12-13 min〈sup〉−1〈/sup〉, respectively. Furthermore, it was approved that this reaction is controlled by a diffusion control model (D1 model).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Yuejun Chen, Shizhen Zhu, Yanqi Ji, Zhuang Ma, Hengyong Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to avoid infrared emissivity deterioration of MoSi〈sub〉2〈/sub〉 particles result from its high-temperature oxidation, a satisfactory electrostatic self-assembly process was presented to synthesize MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉 particles. A thermally stable and transmitting infrared SiO〈sub〉2〈/sub〉 shell was formed with tetraethyl orthosilicate (TEOS) as a precursor and tetrabutyl ammonium bromide (TBAB) as an electrostatic adsorbent after heat treatment at 1200 °C. The oxidation resistance, composition, micro-morphology and infrared emissivity of MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉 were studied using thermogravimetric analysis, X-ray diffraction, energy disperse spectroscopy, scanning electron microscopy, and ultraviolet–visible near-IR spectrophotometer. The results demonstrated that MoSi〈sub〉2〈/sub〉 particle was thoroughly encapsulated by a SiO〈sub〉2〈/sub〉 glass shell, consequently, it exhibited great oxidation resistance compared with that of unencapsulated. More importantly, the emissivity of MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉 particles had no obvious recession due to the intact encapsulation with TBAB. In addition, the electrostatic self-assembly mechanism of core-shell (MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉) particles was discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Jingui Zong, Fei Wang, Guannan Liu, Mingshu Zhao, Sen Yang, Xiaoping Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molybdenum disulfide (MoS〈sub〉2〈/sub〉), has aroused people's much research interest as an anode candidate for next generation of Li-ion batteries because of special layered structure and high theoretical capacity. However, MoS〈sub〉2〈/sub〉 suffers from a poor cycling stability and an inferior rate capability upon charge/discharge processes. So we have successfully synthesized a more stable expanded nanocomposite with superior electrical conductivity by intercalating moderate amorphous carbon between two adjacent S–Mo–S interlayer via a simple method which exhibits excellent lithium storage performance with high capacity (858.9 mA h g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉 for 1000 cycles), and superior rate capability (518 mA h g〈sup〉−1〈/sup〉 at 4 A g〈sup〉−1〈/sup〉). This superior electrochemical performance is attributed to the special structure (few layers, 2H phase, expanded interlayer spacing, amorphous carbon between S–Mo–S layers, C–O–Mo bond in the layer), small size and evenly distributed MoS〈sub〉2〈/sub〉 nanosheets. Besides, we study the 2H-1T phase transformation mechanism by controlling the ratio of ethylene glycol to water and O–C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O bond plays an important role in promoting 2H-1T phase transformation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Qinjiang He, Renli Fu, Xiufeng Song, Haitao Zhu, Xinqing Su, Chaoqun You〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, Ce〈sup〉3+〈/sup〉 and Ce〈sup〉3+〈/sup〉/Dy〈sup〉3+〈/sup〉 co-doped Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 phosphors have been designed and synthesized via a facile citrate-based sol-gel technique, and their structural, photoluminescence properties and energy transfer phenomenon were investigated comprehensively. The XRD analysis indicated that pure Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 phase can be synthesized at low temperature (1000 °C) for merely 2 h. The photoluminescence spectra showed the dominant emission of Ce〈sup〉3+〈/sup〉 singly doped phosphors is located in the blue region even at low Ce〈sup〉3+〈/sup〉 doping level, which indeed favors the energy transfer from Ce〈sup〉3+〈/sup〉 to other luminescent centers. When Dy〈sup〉3+〈/sup〉 is co-doped into Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉:Ce〈sup〉3+〈/sup〉 phosphors, the remarkable sensitizing effect of Ce〈sup〉3+〈/sup〉 on Dy〈sup〉3+〈/sup〉 is validated by comparatively analyzing the excitation, emission spectra and average lifetimes of the series of samples. Through the concentration quenching theory, the critical distance between Ce〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉 is calculated to be 13.50 Å. Furthermore, the energy transfer mechanism between them is most likely ascribed to electric dipole-dipole interaction. In virtue of the variation of the emission intensities of Ce〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉, the emitting colors of Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉:Ce〈sup〉3+〈/sup〉, Dy〈sup〉3+〈/sup〉 phosphors can realize tunable luminescence from deep blue to bluish-white region through controlling the Dy〈sup〉3+〈/sup〉 content. Based on these analysis, Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉:Ce〈sup〉3+〈/sup〉, Dy〈sup〉3+〈/sup〉 phosphors could potentially be applied as a single-phase color-tunable phosphors pumped by near-ultraviolet (n-UV) radiation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Zhaohui Ma, Jiandong Zhang, Guoqing Yan, Hai Liu, Jingcun Huang, Lijun Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Thermodynamic properties of zirconium-oxygen (Zr–O) solid solution and its deoxidation by calcium in CaCl〈sub〉2〈/sub〉 molten salt were studied using a chemical equilibration technique. In the temperature range from 1173 to 1373 K, the equilibrium oxygen contents in Zr were measured experimentally under coexistence of Ca and CaO in CaCl〈sub〉2〈/sub〉 molten salt. The oxygen content in Zr was reduced from about 800 ppm to a minimum of less than 100 ppm. Then 〈em〉a〈/em〉〈sub〉CaO〈/sub〉 sensor — niobium-oxygen (Nb–O) solid solution was employed to equilibrate with Zr–O solid solution to determine the oxygen activity coefficient in Zr–O solid solution. Zr and Nb specimens were submerged in Ca-saturated CaCl〈sub〉2〈/sub〉 molten salt containing different amounts of CaO. CaCl〈sub〉2〈/sub〉 melt was used for a homogeneous reaction and composition. The experimental results shown that Henry's law held and the activity coefficient of oxygen was constant within the concentration range of this study. Based on the result, the standard formation Gibbs free energy of Zr–O solid solution was obtained as a function of temperature:〈span〉〈span〉1/2O〈sub〉2〈/sub〉 (g) = O (in Zr)〈/span〉〈/span〉〈span〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si17.svg"〉〈mrow〉〈mi〉Δ〈/mi〉〈msubsup〉〈mi〉G〈/mi〉〈mrow〉〈mi〉Z〈/mi〉〈mi〉r〈/mi〉〈mo linebreak="badbreak"〉−〈/mo〉〈mi〉O〈/mi〉〈/mrow〉〈mi〉θ〈/mi〉〈/msubsup〉〈mo linebreak="badbreak"〉=〈/mo〉〈mo linebreak="goodbreak"〉−〈/mo〉〈mn〉543577〈/mn〉〈mo linebreak="goodbreak"〉+〈/mo〉〈mn〉64〈/mn〉〈mtext〉.〈/mtext〉〈mn〉3〈/mn〉〈mi mathvariant="italic"〉T〈/mi〉〈mrow〉〈mo〉(〈/mo〉〈mtext〉1173−1373K〈/mtext〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉〈/span〉〈/p〉 〈p〉The 〈em〉p-t-x〈/em〉 relationship of the deoxidation system was obtained simultaneously, which make the deoxidation limit and variation trend of oxygen content in Zr–O solid solution predictable and controllable under different conditions. Oxygen distribution coefficient between Zr–O solid solution and Nb–O solid solution was found in agreement with the theoretical value and independent of oxygen potential of the system.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Liang Ma, Shu-Shen Lyu, Yao Dai, Xian-Yinan Pei, Dong-Chuan Mo, Yuan-Xiang Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transition metal oxide/reduced graphene oxide (TMO/RGO) composites have been explored for development as anode materials for lithium-ion batteries (LIBs); TMOs have high theoretical capacities, and the oxidation degrees of RGO sheets can directly affect the lithium storage performance of TMO/RGO composites. In this work, several NiO/reduced graphene oxide composites (NiO/RGO) are prepared based on oxidation degrees of graphite oxide sheets (GOs) through an ultrasonic agitation method. These composites are then explored as anodes for LIBs. Results show that the reversible capacity of NiO/RGO composites increases gradually to 1046 mA h/g and then declines to 956 mA h/g after 50 cycles at 100 mA/g. The variation rule of lithium storage properties of NiO/RGO samples can be attributed to the surface functional groups of RGO sheets, which can affect interfacial interaction between NiO and RGO sheets due to the different oxidation degrees of GO. Different RGO sheets also show distinct abilities to hinder NiO pulverisation and promote lithium-ion/electron diffusion during repeated charge and discharge processes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): Kaixuan Chen, Shiwei Pan, Xiaohua Chen, Zidong Wang, Rolf Sandström〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure evolution in the as-cast pure Cu and Cu-(1.0–3.0)Fe-0.5Co and Cu-1.5Fe-0.1Sn (wt. %) alloys was characterised in the previous work. Herein, the plastic deformation characteristics were examined by uniaxial tensile tests at room temperature. Along with the microstructure evolution, the yield strength increased with increasing Fe content and reached a peak value at 1.5 wt % Fe, but thereafter decreased with the further addition of Fe in the Cu–Fe–Co alloys. Nevertheless, the tensile strength and elongation synchronously improve with increasing Fe content. In particular, the Cu-1.5Fe-0.1Sn alloy achieved the optimal strength–ductility combination. In terms of the strengthening mechanism, the (Fe, Co)- or (Fe, Sn)-doped copper encouraged impediment, trapping, and storage of dislocations by the iron-rich nanoparticles and grain boundaries, which enhanced the strength and sustained the work hardening and elongation. The evolution of mechanical properties under an alloying effect was quantitatively described by the strengthening models. The results indicate that the optimum balance between strength and ductility was achieved by designing a microstructure containing fine grains, intragranular smaller spherical nanoparticles, and a minor solute element with higher misfit and higher growth restriction effect. The necessities for engineering a microstructure to achieve simultaneously strong and ductile bulk metals were discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819331500-fx1.jpg" width="443" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Natalia Pawlik, Barbara Szpikowska-Sroka, Tomasz Goryczka, Wojciech A. Pisarski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present paper, the nanocrystalline transparent oxyfluoride SrF〈sub〉2〈/sub〉:Eu〈sup〉3+〈/sup〉 glass-ceramic materials (nGCs) were synthesized via a low-temperature sol-gel method, in which trifluoroacetic acid (TFA) was used as a fluorination reagent. The thermal degradation of precursor xerogels was examined by TG/DSC analysis and the formation of SrF〈sub〉2〈/sub〉 nanocrystals inside silicate xerogel host was proved by XRD measurements. Additionally, to verify the structural changes within silicate network during ceramization process, the IR-ATR measurements were also carried out. The optical properties of Eu〈sup〉3+〈/sup〉 ions in precursor xerogels and fabricated nGCs were investigated based on photoluminescence excitation (PLE: λ〈sub〉em〈/sub〉 = 611 nm) and emission (PL: λ〈sub〉exc〈/sub〉 = 393 nm) spectra as well as luminescence decay analysis of the 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 excited level. It was observed, that for precursor silica xerogels the electric-dipole transition (ED) 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉2〈/sub〉 was dominant, meanwhile the magnetic-dipole transition (MD) 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉1〈/sub〉 had the greatest intensity for SrF〈sub〉2〈/sub〉:Eu〈sup〉3+〈/sup〉 nGCs. Thus, the R/O-ratio (R/O = I(〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉2〈/sub〉)/I(〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉1〈/sub〉)) was calculated to estimate the symmetry in the local framework around Eu〈sup〉3+〈/sup〉 ions. Moreover, the reddish-orange photoluminescence is long-lived (about 30-fold longer) for SrF〈sub〉2〈/sub〉:Eu〈sup〉3+〈/sup〉 nGCs compared with xerogels. The changes in emission spectra as well as double-exponential character of luminescence decay curves recorded for obtained nGCs indicated the successful migration of optically active Eu〈sup〉3+〈/sup〉 ions from amorphous silica framework to low phonon energy SrF〈sub〉2〈/sub〉 nanocrystal phase.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): Ping Song, Wen-bin Li, Yu Zheng, Zhong-wei Guan, Xiao-ming Wang, Wen-xu Xu, Peng Ge〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The compressive and tensile stress–strain relationship and fracture behavior of a new low-cost titanium alloy Ti–5Al–3V–2Cr–2Fe (Ti–5322) at 286–573 K, a strain rate of 0.0001–4300 s〈sup〉−1〈/sup〉 and a stress triaxiality of 0.43–1.6 were studied. Based on the experimental data, the flow and fracture behavior of Ti–5322 was established based on the Johnson–Cook (J–C) equation. Ballistic impact tests were used to study the ballistic performance of a 7-mm-thick Ti–5322 target and the accuracy of the constitutive model was verified from the ballistic test results. The experimental results showed that the yield strength and strain rate of the Ti–5322 were related logarithmically. As the strain rate increased, the rate-strengthening behavior of the material weakened gradually. The material had an obvious thermal-softening behavior and the yield strength decreased linearly with an increase in deformation temperature. The stress triaxiality and strain rate had a significant effect on the fracture behavior of Ti–5322. The material fracture strain decreased with the stress triaxiality and an increase in strain rate. The J–C constitutive model was a good predictor for the ultimate penetration velocity of the Ti–5322 target and the velocity decay of fragments during penetration. The ballistic limit velocity of the 10-mm-diameter tungsten-alloy ball to the 7-mm-thick Ti–5322 target at 0° and 30° was 416.0 m/s and 484.8 m/s, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Dongqing Liu, Yimin Yin, Haifeng Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transient memristor is highly desirable for secure memory system and secure neuromorphic computing. Here, a transient memristor with the MgO thin film as resistive dielectric material and the Ni as electrode material is reported. The memristor shows reversible and nonvolatile bipolar resistive switching performance, narrow distribution of low resistance state (LRS) and high resistance state (HRS), uniform switching voltages and stable retention at room temperature. It is indicated that the resistive switching mechanism of the memristor is conductive filament in LRS and space charge limiting current in HRS. In addition, the memristor can be failed after immersed in deionized water for 5 min due to the film damage resulting from large frizzle and the dissolution of Ni and MgO film. The prepared memristor has potential for secure memory system application.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Lei Zhang, Shan Ji, Rongfang Wang, Dan J.L. Brett, Hui Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A flexible cathode with highly electrochemical performance for bendable supercapacitors have been achieved by electrochemical depositing hierarchical nanostructured Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 compounds on the surface of commercial conductive textile. The morphology and physical properties of as-prepared electrode are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS). Based on its unique nanostructure, the obtained flexible Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 electrode exhibits a highly electrochemical capacitance of 1800 F g〈sup〉−1〈/sup〉 at 3 mA cm〈sup〉−2〈/sup〉 with good rate capability, excellent stability and bendability. Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 electrode as cathode is assembled with active carbon as anode and PVA/KOH as electrolyte into an asymmetric capacitor to evaluate its performance in a real supercapacitor. The obtained supercapacitor cell delivers a high energy density of 0.49 mWh cm〈sup〉−2〈/sup〉 at 3.54 mW cm〈sup〉−2〈/sup〉 and maintains the energy density at 0.38 Wh cm〈sup〉−2〈/sup〉 when power density increases to 21.53 mW cm〈sup〉−2〈/sup〉. When the assembled cells are connected in series, these connected cells can work safely and properly at a much higher voltage window due to their good stability and consistency. Considering its low-cost, facile fabrication and highly electrochemical performance, the obtained Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 electrode is a promising flexible material.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881933110X-fx1.jpg" width="255" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Runchen Jia, Weidong Zeng, Shengtong He, Xiongxiong Gao, Jianwei Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fracture toughness and fracture mechanism of Ti60 alloy with duplex microstructure under different temperature conditions were investigated in the present work. The experimental result shows that the fracture toughness of CT samples increases from the room temperature (40  MPa m〈sup〉1/2〈/sup〉) to 400 °C (71.45  MPa m〈sup〉1/2〈/sup〉) but declines at 600 °C (62.55  MPa m〈sup〉1/2〈/sup〉). It is observed from fracture surface through SEM that the predominant fracture mechanism has changed from quasi-cleavage fracture at room temperature to ductile fracture at higher temperatures. In addition, the tortuosity of crack propagation path has a limited impact on the fracture toughness. Path selections for crack propagation are obtained through SEM observation which can be summarized as: cut through lamellar 〈em〉α〈/em〉, parallel to lamellar 〈em〉α〈/em〉, bypass the equiaxed 〈em〉α〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉 and cut through the equiaxed 〈em〉α〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉. Moreover, it is found that the intrinsic contribution is the primary reason leading to the change of the fracture toughness of Ti60 alloy under different temperatures. Meanwhile, it is noteworthy that the area of the crack tip plastic zone increases from RT to 400 °C but decreases at 600 °C, which is seen as the main impact of temperature on fracture toughness. To be exact, the CT sample with a larger area of the plastic zone could provide a higher 〈em〉K〈/em〉〈sub〉〈em〉1C〈/em〉〈/sub〉 value. Furthermore, a prediction model of 〈em〉K〈/em〉〈sub〉〈em〉1C〈/em〉〈/sub〉 based on tensile properties is established, which has a good accuracy with experimental results. The model is useful in predicting the fracture toughness of Ti60 alloy at different test temperatures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Shuying Dong, Longji Xia, Fangyuan Zhang, Fengzi Li, Yuyao Wang, Lingfang Cui, Jinglan Feng, Jianhui Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ZnSn(OH)〈sub〉6〈/sub〉 nanocubes were prepared under different pH (3–12.4) by liquid precipitation, well characterized and further used for wastewater treatment. The results indicated that the ZnSn(OH)〈sub〉6〈/sub〉 nanocubes prepared at pH = 11.1 possessed of uniform size distribution and excellent photocatalytic activity, the degradation efficiency to MB reaches 76.3% after 5 h natural sunlight irradiation. Subsequently, the prepared ZnSn(OH)〈sub〉6〈/sub〉 nanocubes was further thermal treated (200 °C, 24 h) in four different solvents, containing deionized water, stock solution, mixed solution (V〈sub〉water〈/sub〉: V〈sub〉ethanol〈/sub〉: V〈sub〉glacial acetic acid〈/sub〉 = 3:1:1) and ethanol, named as H-1, H-2, H-3 and H-4, respectively. H-2 and H-3 showed superior photocatalytic performance and the removal efficiency of MB improved to be almost 100%, as well as red-shifted light absorption edge and the band gap energies reduced 0.9 and 0.93 eV, respectively. Moreover, free radical capture experiments showed that the h〈sup〉+〈/sup〉 and ·O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 are the main active species for the ZnSn(OH)〈sub〉6〈/sub〉 nanocubes and H-2, respectively, while all these three ·OH, ·O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 and 〈sup〉1〈/sup〉O〈sub〉2〈/sub〉 radicals for H-3. Those results suggested that both pH regulation and thermal treatment could efficiently improve the microscopic morphology, crystal structure and photocatalytic activity of the ZnSn(OH)〈sub〉6〈/sub〉, which might pave the way for the artful design of other high-performance catalysts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819332013-fx1.jpg" width="312" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 182〈/p〉 〈p〉Author(s): Sheng Fu, Zhen Liu, Yi-ming Zhang, Xin Wang, Ning Tian, Ling Li, Hui-lai Wang, Tao Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Wulan-Hua Sag in the south of Erlian Basin has large oil and gas resource, whereas the source rocks genetic potential and oil-rock correlation in its Aershan Formation (K1ba) and First member of Tengge'er Formation (K1bt1) are still unclear. We performed organic geochemistry analyses of oil and mudstone samples to divide crude oil types, evaluate source rock potential, and establish relatively accurate oil-source correlation. The results indicate that the source rocks in K1ba and the Lower interval in First member of Tengge'er Formation (LK1bt1) belong to good source rocks, characterized by high organic matter abundance, oil-prone kerogen type, and relatively high thermal maturity. K1ba and K1bt〈sub〉1〈/sub〉 crude oil samples were divided into two types sourced from different Wulan-Hua source rocks. Type A oil is distributed in the K1ba and LK1bt1 of Saiwusu uplift and Hongjing uplift, and featured by a low gammacerane amounts (the majority of gammacerane/C〈sub〉30〈/sub〉H 〈 0.30), and high Pr/Ph (ranging from 0.18 to 1.18, with mean value of 0.78). It has high mature organic matter mainly originated from terrestrial plant and dominant terrestrial plant. This type of oil was sourced from the K1ba source rocks in the Saiwusu uplift. Type B oil occurs in the LK1bt1 of the Tumuer Uplift and north sub-sag, and have high gammacerane abundance (the majority of gammacerane/(C〈sub〉30〈/sub〉 〉 0.3), and low Pr/Ph (ranging from 0.38 to 0.76, with mean value of 0.63). Its organic matter includes dominant terrestrial plant source, and this oil type should be sourced from the LK1bt1 source rocks in the Saiwusu uplift.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 182〈/p〉 〈p〉Author(s): Wei Liu, Wei David Liu, Jianwei Gu, Xinpu Shen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The sedimentary rhythm of Chinese oilfields is complicated and the heterogeneity is extremely strong. Allocating water absorption of each sublayer by dividing coefficient or numeric simulation cannot accurately reflect the actual water injection of the reservoir. Calculation based on water absorption profile monitored on site is the most commonly used method in oil field. However, access to these type of data is limited due to its cost and time related to acquisition. In this study, a machine learning approach was adopted to predict water absorption in sublayer based on geologic and production parameters of injectors and producers. On the one hand, it can save test costs. On the other hand, it can continuously predict water absorption of sublayers, and make up for water injection wells with insufficient injection profiles. A handful of training observations are obtained from on-site monitoring. Interwell connectivity is first conducted to identify connected producers for injectors. Introducing interwell connectivity helps to constitute predictor variables and yield significant improvements in feature selection. Connectivities in the well group are represented by similarity between injection sequence and production sequence, which is computed by Dynamic Time Warping. Average importance of predictors are then measured based on Mean Decrease Impurity, Mean Decrease Accuracy, and Ridge regression. Some relative important features are selected to consist the final predictors. The Extreme Gradient Boosting model is developed and then trained for making predictions given any set of observations. The proposed approach is validated by using actual field case from SL oilfield, China. Results show a significant correlation between predictions and actual value from on-site monitoring.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 183〈/p〉 〈p〉Author(s): Isty Adhitya Purwasena, Dea Indriani Astuti, Muhamad Syukron, Maghfirotul Amaniyah, Yuichi Sugai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microbial enhanced oil recovery (MEOR) is a proven tertiary recovery technique. Biosurfactant is a microbial bioproduct that plays an important role in MEOR applications. This study aimed to test biosurfactant stability using a design experiment based on response surface methodology. First, isolation and screening for potential biosurfactant-producing bacteria from crude oil samples was performed, followed by their characterization. A biosurfactant core flooding experiment was also conducted to examine bacterial activity on MEOR. Thirty-one sequential isolates of bacteria were screened based on qualitative and semi-qualitative parameters. One selected biosurfactant-producing bacterium was identified as 〈em〉Bacillus licheniformis〈/em〉 DS1 based on phylogenetic analysis of the 16S rRNA gene. This bacterium had the highest emulsification activity (E〈sub〉i24〈/sub〉 = 65.19%) in light crude oil and could reduce the interfacial tension between oil and water with an effective critical-micelle concentration of 157.5 mg/L. The biosurfactant was observed as a growth-associated metabolite type and the Fourier transform infrared spectrum revealed that the biosurfactant produced belonged to a group of lipopeptides. The biosurfactant has good stability in maintaining emulsification activity at pH 4–10, high temperatures up to 120 °C, and with an NaCl concentration up to 10% (w/v). Based on response surface methodology using the Box–Behnken experimental design, the optimum condition for the most stable biosurfactant is pH 12, a 40 °C temperature and 10% salinity, with an E〈sub〉i24〈/sub〉 value of 94.28%. Core flooding experiments with biosurfactant resulted in 5.4% additional oil recovery. Therefore, this biosurfactant shows a high potential application for MEOR.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 183〈/p〉 〈p〉Author(s): Jiangfeng Cui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The pre-Darcy flow phenomena in porous media is still not well understood, and the liquid slip mechanism in shales is controversial. Both issues need more exploration. In the field of microfluidic research, the concept of the slip length is widely employed to characterize the deviation from the no-slip flow, and it is recognized that the slip is rate-dependent. For the first time, the rate-dependent slip is proposed as an explanation for the pre-Darcy flow phenomena in porous media and the compromise between existing controversial views with regard to the liquid slip flow in shales based on careful analysis, and then such slip is incorporated in the one-dimension unsteady diffusion equation for liquids. The finite difference method is employed to numerically solve the equation, and detailed sensitivity analysis is conducted for the critical shear stress, the pore radius and the slip length. The results are summarized, and suggestions for future research are provided. This work can provide new insight into the pre-Darcy flow phenomena in the nanoporous media, and can compromise between existing controversial views regarding the liquid slip mechanism in shales. More importantly, this subject is also significant to research and develop EOR methods in shale reservoirs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 183〈/p〉 〈p〉Author(s): Yongfei Yang, Yingwen Li, Jun Yao, Kai Zhang, Stefan Iglauer, Linda Luquot, Zengbao Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The incompatibility between workover fluid and reservoir rock is one of the causes of formation damage. Fines migration and clay swelling are considered as the major mechanisms responsible for formation damage, which results in declining productivity. However, there has been limited visualized evidence of pore structural changes during formation damage. This paper establishes a formation damage evaluation method for sandstone reservoirs based on X-ray micro-computed tomography (CT) analysis. We presented conclusive evidence for clay swelling and fines migration during workover fluid flooding and formation liquid flooding. Water sensitivity and flow rate sensitivity tests were performed on a Dongying sandstone (heterogeneous argillaceous sandstone) plug. In addition, the plug was micro-CT imaged before and after flooding with workover fluid and formation liquid at medium resolution (24 μm voxel size); the changes in core permeability and the associated changes in 2D and 3D pore space were analyzed. We found that the sandstone pore space was partially blocked by clay minerals and moving particles, leading to significantly decreased porosity (5.17%–4.19% for sample 1, 5.38%–2.76% for sample 2) and permeability (3.38 × 10〈sup〉−3〈/sup〉 μm〈sup〉2〈/sup〉 to 1.28 × 10〈sup〉−3〈/sup〉 μm〈sup〉2〈/sup〉 for sample 1, 13.30 × 10〈sup〉−3〈/sup〉 μm〈sup〉2〈/sup〉 to 3.15 × 10〈sup〉−3〈/sup〉 μm〈sup〉2〈/sup〉 for sample 2). This permeability decrease was caused by a decrease in the average pore radius and coordination number. Moreover, increased micro-CT intensity was measured by comparison of initial and final tomogram images, representing clay swelling & blockage of pores during the displacement and a generally lower porosity. This work visualized microscale formation damage, which reminds that incompatibility between workover fluid and reservoir rock damages formation seriously and the fluid injection rate should be lower than the critical flow rate when developing a reservoir with a strong water sensitivity and flow rate sensitivity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920410519307776-fx1.jpg" width="245" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 183〈/p〉 〈p〉Author(s): Xin Li, Deli Gao, Baoping Lu, Yijin Zeng, Jincheng Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Maximum extension length prediction model for horizontal wells can be used to evaluate the horizontal well's extension capability and predict its maximum measured depth, which is of great significance to the production and economic benefits of horizontal wells. However, the differential sticking is not considered in previous prediction model. To overcome this shortcoming, a modified model considering differential sticking is established based on constraints of wellbore stability, differential pressure, and filtration loss simultaneously during the drilling, tripping processes and static state. Then a horizontal well is analyzed and its maximum extension length is predicted. Results show that within the conventional mud weight window, three ranges of drilling fluid density can be determined, including the first range, the second range and the reasonable range of drilling fluid density. However, only the reasonable range of drilling fluid density can satisfy all constraints of the modified prediction model, including the wellbore stability, differential pressure, and filtration loss simultaneously. Compared with the original model, the predicted well's maximum extension length decreases when the differential sticking is considered. However, it is more accurate, avoiding drilling hazards in actual drilling operation due to the excessive designed measured depth and unreasonable drilling parameters. Moreover, the maximum speeds of casing running down/pulling out are also determined and added to the modified model. Therefore, the modified model with reasonable drilling fluid density and adjusted running down/pulling out speed is the optimal modified model to predict maximum extension length and avoid differential sticking, which can also ensure that the horizontal well's designed measured depth can be successfully achieved. This study is of great significance to improve the prediction accuracy of horizontal well's maximum extension length and avoid drilling hazards, especially the differential sticking. Moreover, it also plays a guiding role in the selection of reasonable drilling fluid density during horizontal drilling.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 183〈/p〉 〈p〉Author(s): Liang Mu, Hans Ramløv, T. Max M. Søgaard, Thomas Jørgensen, Willem A. de Jongh, Nicolas von Solms〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Antifreeze proteins (AFPs) are characterized by their ability to protect organisms from subfreezing temperatures. They constitute a class of promising candidates as environmentally kinetic hydrate inhibitors (KHIs). In this study, the effectiveness of an insect cell expressed novel monomeric streptavidin fusion protein version of 〈em〉Rhagium mordax〈/em〉 RmAFP1 antifreeze protein (mSA-RmAFP1), and four amino acids (histidine, lysine, tyrosine and proline), on CH〈sub〉4〈/sub〉 hydrate nucleation, growth and decomposition was investigated using a rocking cell apparatus, then compared with the commercial inhibitors Polyvinylpyrrolidone (PVP) and Luvicap Bio. It was found that CH〈sub〉4〈/sub〉 hydrate nucleation and growth exhibited good repeatable results under experimental conditions. The results showed that 2250 ppm mSA-RmAFP1 can inhibit CH〈sub〉4〈/sub〉 hydrate nucleation as effectively as PVP at the same concentration. The histidine, lysine, tyrosine and proline exhibited weak inhibition effect on CH〈sub〉4〈/sub〉 hydrate nucleation. The mSA-RmAFP1 decreased CH〈sub〉4〈/sub〉 hydrate growth rate and production in the fresh and memory solutions. The CH〈sub〉4〈/sub〉 hydrate formed in the solutions containing various tested KHIs present slightly lower onset decomposition temperatures than the non-inhibited system under experimental conditions. The promising performance of the insect cell expressed mSA-RmAFP1 could promote the further development of green hydrate inhibitors. The production of this protein through insect cell line fermentation provides a platform for the future production and optimization of AFPs for hydrate inhibition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Chao Gan, Wei-Hua Cao, Min Wu, Xin Chen, Yu-Le Hu, Kang-Zhi Liu, Fa-Wen Wang, Suo-Bang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rate of penetration (ROP) prediction is crucial for the optimization and control in drilling process due to its vital role in maximizing the drilling efficiency. This paper proposes a novel intelligent model to predict the drilling ROP considering the process characteristics. First, the geological background and the drilling process of the case study are described. Based on the mechanism and frequency spectrum analysis, the strong nonlinearity and different low-frequency and high-frequency data noises between the data variables are detected. After that, the intelligent model is established via three stages. In the first stage, a wavelet filtering method is introduced to reduce these noises in the drilling data. In the next stage, the model inputs are determined by the mutual information method, which significantly decreased the model redundancy. In the last stage, a hybrid bat algorithm is proposed to optimize the hyper-parameters of the support vector regression model. Finally, the proposed model is validated by using the data from a drilling site in the Shennongjia area, Central China. The results demonstrate that the proposed method outperforms eight well-known methods and another three methods without different data preprocessing procedures in prediction accuracy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Zheng Sun, Keliu Wu, Juntai Shi, Yuanhong Li, Tianying Jin, Qingyang Li, Xiangfang Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A detailed study for production prediction methods under various drainage schedules for under-saturated coalbed methane wells is performed. In terms of the relationship between the value of average reservoir pressure and the critical desorption pressure, whole production life of under-saturated coalbed methane wells is divided into two periods, and the material balance equation in each period is derived respectively. Combining the two-period material balance equation and productivity equation under pseudo-steady state, a novel production prediction method is developed. Excellent agreements between predicted water/gas production rates from the proposed method and those from numerical simulator clarify the reliability successfully. Results demonstrate that (a) matrix shrinkage effect and effective permeable capability can significantly contribute to the production rise; (b) For the drainage schedule (FWFB), with the increase of the fixed water production rate, the drainage period will shorten; (c) For the drainage schedule (RDFB), sharp decrease of formation pressure will take place.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Matthew Morte, Berna Hascakir〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Candidacy of any reservoir as a microwave absorber is predicated on the complex permittivity of the sample. Modeling both the penetration and absorption dynamics of the electromagnetic wave in the reservoir is dependent on realistic estimation of this parameter. Therefore, it becomes necessary to understand the inherent intricacies of complex permittivity in the reservoir. Reservoirs are comprised of both a void space represented by the porosity parameter as well as the rock matrix and can be treated as a binary mixture of the two. Mixing rules can then be introduced and have been shown to be a viable means of estimating the dielectric response. The behavior of the bulk material is considered to be an extension of the isolated contribution of the separate parts. Therefore, by characterizing the response of the individual components of the mixture, the overall response can be estimated. Utilization of mixing rules enables efficient estimation of the dielectric properties anywhere in the reservoir as a function of the rock matrix, fluid saturation, and porosity. The absorptive capacity of the reservoir can then be described which is used to screen the efficacy of the material for microwave introduction. Both the real and imaginary components of complex permittivity are measured on nine consolidated core samples of varying lithology and fluid saturation over the frequency range of 400 MHz to 6 GHz. Experimental data is compared to various mixing rules commonly implemented to determine validity and viability of the estimation of complex permittivity for consolidated samples.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Qingsong Cheng, Min Zhang, Hongbo Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Test analyses such as pyrolysis, soluble organic matter extraction, group component separation and GC-MS were conducted to 22 source rock samples and 28 crude oil samples from deep lacustrine facies of Funing Formation in Subei Basin. Source rocks stayed at the low maturity-mature stage (Ro:0.58%–0.71%), while crude oil stayed at the mature stage (Rc:0.71%–0.88%). The Pr/Ph values of samples in the research area ranged between 0.16 and 0.62. These samples could be classified as Sterane/Hopane〉1 and Sterane/Hopane〈1. For all the samples, the C〈sub〉29〈/sub〉 Steranes content was high; had inverse “L” distribution in ααα20RC〈sub〉27〈/sub〉-ααα20RC〈sub〉28〈/sub〉-ααα20RC〈sub〉29〈/sub〉 regular sterane; αα20R-Sterane played a dominant role; abundances of ββ- and 20S-Sterane were low. As for samples of Sterane/Hopane〉1, G/C〈sub〉30〈/sub〉H ranged between 0.63 and 2.56, and the Sterane isomerization was very low. As for samples with Sterane/Hopane〈1, G/C〈sub〉30〈/sub〉H ranged between 0.04 and 0.46 and the Sterane isomerization was higher than the former. Abnormal distribution of Sterane isomerization was rarely influenced by thermal dynamic effects and sources, but was mainly influenced by the sedimentary environment. A lot of references reported Sterane isomerization with abnormally high abundance under the high-salinity environment. However, the finding obtained by the research that the higher water salinity corresponded to the lower degree of Sterane isomerization was discovered for the first time. The C〈sub〉29〈/sub〉 Sterane abundance was high and the C〈sub〉29〈/sub〉/C〈sub〉27〈/sub〉 regular sterane ratio was constant and would not vary with changes of environmental parameters and biological source parameters. Sterane content was not correlated with tricyclic terpene of algae sources, but was positively correlated with ETR of the aquatic organism source, while it had very good positive correlation with Gammacerane. In addition, samples with the high Sterane content had high abundance in Carotene, C〈sub〉24〈/sub〉+alkyl-cyclohexane and C〈sub〉21〈/sub〉+isoprenoid alkanes. Through profound analysis and reference survey, it is found that the abnormally high abundance of C〈sub〉29〈/sub〉 Sterane of samples in the research area may be correlated with halophilic protozoon in salinized deepwater lakes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Ahmed Farid Ibrahim, Hisham A. Nasr-El-Din〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉After hydraulically fracturing of shale gas wells, theoretical and experimental studies showed that over 75% of the injected water-based fracture fluids left unrecovered. The trapped water causes permeability damage and productivity impairment. The flowback water also tends to be highly saline, often with TDS contents of as much as 200,000 ppm. This study aims to investigate the effect of well shut-in before flowback stage (the soaking process) on the production of shale and tight sandstone formations.〈/p〉 〈p〉Shale and sandstone samples were analyzed by X-ray diffraction (XRD). Marcellus shale and Kentucky sandstone cores were used. A modified core flood setup was used to allow porosity measurements by gas expansion method, then pulse decay permeability measurements, and fluid injection during the leak-off process. Nitrogen was used for gas expansion and permeability measurements, while 5 wt% KCl brine was used as representative of the leak-off fracturing fluid. The fracturing fluid was injected under a constant pressure gradient (300 in the case of sandstone cores and 1500 psi in the case of shale cores. After removing the pressure gradient, gas permeability was measured at different soaking times. Computed tomography (CT) was used to scan the cores during the experiment to observe the propagation of fracturing fluid in the core with time.〈/p〉 〈p〉The results show that the regained permeability for sandstone formation was 60% of its initial value directly after the leak-off stage. Then, the regained permeability decreased with increasing the soaking time 38% of its initial value after the core completely invaded with leak-off fluid. The propagation rate of water saturation front from CT-scan data decreased with time until reaching the core outlet. The regained permeability on shale cores was 15% of its initial value and decreased with soaking time, due to depressed relative permeability curve on this tight pore-space cores.〈/p〉 〈p〉This study addresses the mechanism of production enhancement or reduction as a result of the soaking process for shale and tight sandstone formations.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Arash Azamifard, Fariborz Rashidi, Mohammad Ahmadi, Mohammadreza Pourfard, Bahram Dabir〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Different sources of data are used to construct a reliable model of reservoir for oil/gas production. This model ought to be matched with the production history of reservoir and also show reliable predictions for future performance. To this end, permeability modeling (characterization of heterogeneity) is crucially important which is proved to be done by Multiple Point Statistics (MPS) recently. Furthermore, deep learning methods are massively used as a promising tool for regression applications. In this study, one MPS method is employed for generating the reservoir realizations. Realizations, alongside their simulation outputs, are utilized for training a convolutional deep network. In this manner, MPS is joined with deep learning to find the most appropriate realization(s) of the reservoir based on the fluid flow simulation. Moreover, unseen MPS realizations as well as another MPS realizations are used to verify the selection ability of trained network. The detailed architecture of convolutional network is illustrated in this study.〈/p〉 〈p〉The purpose of training this network and combination with MPS is to generate the matched realization(s) in history period that also show acceptable reservoir behavior in the future times of reservoir simulation. After training, the actual production data of selected realizations are obtained by simulation the reservoir for history and also future times. The results show that selected realizations efficiently capture the trend of reference behavior. Although these realizations lack identical permeability values, they have same texture of permeability (permeability heterogeneity). Meanwhile, they show acceptable match in reservoir simulation outputs. By proposed workflow, the uncertainty of permeability modeling is considered more exhaustively. It is done by selecting the realizations from enormous possible realizations dataset and providing a deep learning tool which is capable for screening quite large number of realizations. Interesting finding is satisfactory behavior of realization(s) in both history and future periods of reservoir performance.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920410519305467-fx1.jpg" width="351" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 181〈/p〉 〈p〉Author(s): Chean Xing Liew, Raoof Gholami, Mehdi Safari, Arshad Raza, Minou Rabiei, Nikoo Fakhari, Vamegh Rasouli, Jose Varghese Vettaparambil〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Certain polymers are often used during water based mud (WBM) drilling to reduce the filtration loss in permeable intervals. Although they often provide a good performance but cannot totally stop the fluid loss and mud invasion into the reservoir may cause significant formation damage including unfavourable changes of surface wettability. As a result, the two phase relative permeability of the near wellbore region changes and production may face difficulties in the later stages. In this paper, a new mud design is proposed to reduce the surface wettability alteration posed by WBM in sandstone reservoirs. The results obtained from performing a series of contact angle measurements indicated that clean and dirty sandstones are strongly water wet systems but mud invasion can make them a weakly water wet surface. It was also found that Cetyltrimethylammonium bromide (CTAB), as a cationic surfactant, prevents surface alteration of rocks and reduce the formation damage, but it may isolate the clay and creates a huge mud cake around the borehole. It was also observed that the salinity of the mud has a great impact on the surface wettability and adding CaCl〈sub〉2〈/sub〉 can reduce the formation damage in the reservoir intervals during drilling, although caution must be taken to maintain the cost of the mud.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920410519306333-fx1.jpg" width="134" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Petroleum Science and Engineering, Volume 183〈/p〉 〈p〉Author(s): Ning Li, Yushi Zou, Shicheng Zhang, Xinfang Ma, Xingwang Zhu, Sihai Li, Tong Cao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Evaluating the brittleness of rock is significant for strategy determination of hydraulic fracturing, such as candidate selection and parameter optimization. A series of definitions and indices of brittleness have been proposed to characterize the mechanical behavior rock failure. However, these existing indices failed to consider the residual state and the confinement effect. Based on the analysis of energy evolution during the whole process of rock failure, the brittleness was redefined in this study as the comprehensive capability of dissipating little energy during the pre-peak stage and self-sustaining complete failure during the post-peak stage. Accordingly, a new energy-based brittleness index 〈em〉B〈/em〉 was proposed in terms of the complete stress-strain curve to quantify this capability from following three aspects: the ratio of accumulated elastic strain energy and total absorbed energy during the pre-peak stage (〈em〉B〈/em〉〈sub〉1〈/sub〉); the proportion of elastic strain energy in all energy source consumed for sustaining rock failure (〈em〉B〈/em〉〈sub〉2〈/sub〉); and the dissipation extent of accumulated elastic strain energy during the post-peak stage (〈em〉B〈/em〉〈sub〉3〈/sub〉). To verify the reliability of the new method, uniaxial and triaxial compression tests were performed on different types of rock samples. The application and comparison of various indices showed that the new brittleness index precisely characterized the stress-strain curves and failure behavior of rock samples under different confinement levels. The variation trends of brittleness with confining pressure were obviously distinct among different rock types. Three independent brittleness indices 〈em〉B〈/em〉〈sub〉1〈/sub〉, 〈em〉B〈/em〉〈sub〉2〈/sub〉, and 〈em〉B〈/em〉〈sub〉3〈/sub〉 were helpful for analyzing sensitivity difference of brittleness to confining pressure among different rock types. Accordingly, this new energy-based method can provide reliable evaluation of rock brittleness.〈/p〉〈/div〉 〈/div〉