ALBERT

Description: There is strong evidence indicating that the existing measures which are designed to detect a single high leverage collinearity-reducing observation are not effective in the presence of multiple high leverage collinearity-reducing observations. In this paper, we propose a cutoff point for a newly developed high leverage collinearity-influential measure and two existing measures ( and ) to identify high leverage collinearity-reducing observations, the high leverage points which hide multicollinearity in a data set. It is important to detect these observations as they are responsible for the misleading inferences about the fitting of the regression model. The merit of our proposed measure and cutoff point in detecting high leverage collinearity-reducing observations is investigated by using engineering data and Monte Carlo simulations.

Description: In consideration of the significant role the brake plays in ensuring the fast and safe running of vehicles, and since the present parameter optimization design models of brake are far from the practical application, this paper proposes a multiobjective optimization model of drum brake, aiming at maximizing the braking efficiency and minimizing the volume and temperature rise of drum brake. As the commonly used optimization algorithms are of some deficiency, we present a differential evolution cellular multiobjective genetic algorithm (DECell) by introducing differential evolution strategy into the canonical cellular genetic algorithm for tackling this problem. For DECell, the gained Pareto front could be as close as possible to the exact Pareto front, and also the diversity of nondominated individuals could be better maintained. The experiments on the test functions reveal that DECell is of good performance in solving high-dimension nonlinear multiobjective problems. And the results of optimizing the new brake model indicate that DECell obviously outperforms the compared popular algorithm NSGA-II concerning the number of obtained brake design parameter sets, the speed, and stability for finding them.

Description: In Trinidad, oil production started just over 100 years ago and steam flood operations started just under 50 years ago. In steam flood operations, oil recovery by steam distillation can be in the range of 5 to 60 % and therefore requires separate experimental and mathematical studies for accurate steam flood predictions. The steam distillation apparatus required for the experimental study can be quite costly. In order to conduct steam distillation studies in the Petroleum Studies Unit in Trinidad, a steam distillation apparatus was designed, fabricated and tested to perform these studies, as an integral part of the experimental steam flood studies on Trinidad crude oils. The apparatus consist of a positive displacement pump, a steam generator, a steam distillation cell, a temperature measurement and control system, a back pressure valve and a condensing and liquid collection system. The steam generator and steam distillation cell were fabricated in-house, from stainless steel and were designed to conduct steam distillation studies at a safe working pressure of 4.654 MPa and temperature of 260 °C.  From the operational procedures outlined in this study and from repeat test runs conducted at 100 °C and 260 °C steam distillation results were reproduced with differences of less than ± 4.0 % between the original and repeat runs. Details of the apparatus design and operational procedures from this study can provide a useful guide for other Researchers on crude oil steam distillation studies. Key words : Steam distillation apparatus; Design; Operational procedures; Oil; Steam; Temperature; Pressure; Trinidad

Description: With superheated steam there is no direct relationship between temperature and pressure, and it can exist at a wide range of temperatures. Superheated steam with high degree( 〉50 °C) of superheat has similar thermal physical characteristics with ideal gas and the heat transfer coefficient is 1/150-1/250 as much as that of saturated steam during heat transferring. It could release less energy and transmitted longer distances than that of saturated steam in heavy oil reservoirs. Numerical simulation shows that under the condition of carrying the same heat, superheated steam huff and puff enlarged the heating radius by about 10 m, oil production increment by 1463 t, oil steam ratio increase by 0.7. Superheated steam huff and puff was put into Kazakstan’s heavy oil reservoir after saturated steam huff and puff and the average daily oil production was 2-4 times that of saturated steam huff and puff, which improved heavy oil production effectively. The secondary heavy oil thermal recovery by superheated steam huff and puff applicated in marginal heavy oil reservoirs achieved satisfactory effect. Key words : Heavy oil; Superheated steam huff and puff; Heat transfer coefficient; Degree of superheat; Ideal gas

Description: Trinidad and Tobago is a small country and our remaining known reserves now stand at 570 million barrels of oil and about 27 trillion cubic feet of gas. These reserves are both on land and offshore. The challenge of ensuring long-term growth of the energy sector has been great. This country has been endowed with energy resources and as a result, oil and natural gas play a central role in the socio-economic development of the country. Simultaneously they provide the necessary infra-structural economic base for the country becoming an attractive host for foreign investments in the energy sector. In the face of declining crude oil production, relatively modest natural gas prices and no deepwater success to date, the development of our unconventional resources should now be placed into the forefront of our energy future. The large volume and long-term potential of our unconventional resources pose a big challenge today but increasing prices and improved technology is the key to their development in the future. The current worldwide trend is a move from conventional to unconventional resources due to technology advances. This paper will evaluate the potential of developing our unconventional resources which include heavy oil, tar sands, tight sands and gas hydrates. The demand for oil and natural gas will continue to increase for the foreseeable future and we must now rely on unconventional resources to fill the gap between demand and supply. This analysis looks at the implications for the future and the technologies required for developing our unconventional resources. The research required and the technology advancement would also be discussed. Key words : Unconventional resources; Heavy oil; Tar sands; Tight sands; Gas hydrates; Trinidad and Tobago

Description: Growing demand for oil and gas is driving the exploration and production industry to look for new resources in un-explored areas, and in deeper formations. According to the Bureau of Ocean Energy Management, Regulation and Enforcement, former Minerals Management Service (MMS), over 50% of proven oil and gas reserves in the United States lie below 14,000 ft. subsea. In the Gulf of Mexico some wells were drilled at 27,000 ft below seabed with reservoir temperatures above 400 °F and reservoir pressures of 24,500 psi. As we drill into deeper formations we will experience higher pressures and temperatures. Drilling into deeper formation requires drilling fluids that withstand higher temperatures and pressures. The combined pressure-temperature effect on drilling fluid’s rheology is complex. This provides a wide range of difficult challenges and mechanical issues. This can have negative impact on rheological properties when exposed to high pressure high temperature (HPHT) condition and contaminated with other minerals, which are common in deep drilling. High Pressure and High Temperature (HPHT) wells have bottom hole temperatures of 300 °F (150 °C) and bottom hole pressures of 10,000 psi (69 MPa) or higher. Water-Based mud (WBM) and Oil-Based mud (OBM) are the most common drilling fluids currently used and both have several characteristics that qualify them for HPHT purposes. This paper compares the different characteristics of WBM and OBM to help decide the most suitable mud type for HPHT drilling by considering mud properties through several laboratory tests to generate some engineering guidelines. The tests were formulated at temperatures from 100 °F up to 600 °F and pressures from 5,000 psi to 25,000 psi. The comparison will mainly consider the rheological properties of the two mud types of mud and will also take into account the environmental feasibility of using them.  Key words : Oil-based mud; Water-based mud; HPHT fields

Description: From 2007 to 2008, Research Institute of Petroleum Exploration & Development, Langfang Branch launched oil sand resource exploration and the study of hot water separation technology in Fengcheng area, Northwest of Junggar Basin, and the recoverable oil-sand oil resource is 54.98 million tons with the oil content in 7.1-10%, which is distributed in Cretaceous and Jurassic with the thickness of 80-140 meters, the cover depth of oil sand is 50-90 meters. Combining with the characteristics of the oil sand in this area and based on the research of hot water separation mechanism in oil sand, the hot water separation reagent for the oil sand in this area has been successfully developed, and its separation rate reaches 90%, provided that the concentrations of the agent is 4% and the separation temperature is 85 °C. Based on series of study, the construction of testing site, which is capable of processing 10,000 tons oil sand in this area, is completed, and the on-site separation tests of oil sand are launched with the recovery rate of 90% in normal operation, and the hot water separation technology and equipment research & development are successful. Key words : Oil sand; Hot water separation technology; Separation reagent; Tests

Description: The ensemble-based history matching technique has been successfully applied to simultaneously estimate multiple petrophysical parameters for hydrocarbon reservoirs. The tuning petrophysical properties include horizontal and vertical permeability, porosity and three-phase relative permeability curves. Four scenarios with different combination of the tuning parameters have been evaluated. The ensemble-based history matching technique is found to be capable of estimating multiple petrophysical parameters by conditioning the reservoir geological models to production history. The uncertainty range of production data generated from the updated models is reduced compared to that of initial models. However, the history-matched models may not always provide good production prediction results, especially when absolute permeability and relative permeability are tuned simultaneously. This further illustrates the non-uniqueness of the history matching solutions. In addition, three-phase relative permeability curves are found to be estimated with good accuracy when absolute permeability fields are known. Key words : Petrophysical parameters; Assisted history matching; Ensemble kalman filter (EnKF); PUNQ-S3 model

Description: This paper presents a series of new results in modeling of the Grünwald-Letnikov discrete-time fractional difference by means of discrete-time Laguerre filers. The introduced Laguerre-based difference (LD) and combined fractional/Laguerre-based difference (CFLD) are shown to perfectly approximate its fractional difference original, for fractional order . This paper is culminated with the presentation of finite (combined) fractional/Laguerre-based difference (FFLD), whose excellent approximation performance is illustrated in simulation examples.

Description: The design of unpredictable trajectories for autonomous patrol robots when accomplishing surveillance missions represents, in many situations, a key desideratum. Solutions to this problem had often been associated with chaotic dynamics. While for area surveillance missions, relevant techniques to produce chaotic motion had been reported, in the case of monitoring a number of precise locations no viable solutions had been proposed. The present paper covers this research gap by offering a complex methodology that involves a mixture of two types of chaotic trajectory segments, based on Lorenz and Chen systems, in obtaining unpredictable trajectories when an arbitrary number of specified locations have to be monitored. The developed path-planning strategy produces trajectories that can cope efficiently with dynamical degradation of chaos or with obstacle avoidance issues.