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  • GFZ German Research Centre for Geosciences  (36)
  • English  (36)
  • 2015-2019  (36)
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  • 2019  (36)
  • 1
    Publication Date: 2020-02-12
    Description: In summer 2017, the ICDP SUSTAIN project (Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative concretes), drilled three cored boreholes (Table 1) through Surtsey at sites ≤10 m from a cored hole obtained in 1979. Drilling through the still hot volcano was carried out with an Atlas Copco CS1000 drill rig, whose components were transported by helicopter to Surtsey and re-assembled on site. The first vertical borehole, SE-02a, was cored in HQ diameter to 152 meters below surface (m b.s.) during August 7-16. It was terminated due to borehole collapse. A second vertical (SE-02b) cored borehole was then drilled in HQ diameter to 192 m during August 19-26. Wireline borehole logging in SE-02b was performed August 26. The anodized NQ-sized aluminum tubing of the Surtsey Subsurface Observatory was installed in SE-02b to 181 m depth on August 27. A third borehole, SE-03, angled 35° from vertical and directed 264°, was drilled from August 28 to September 4 and reached a measured depth of 354 m (~290 m vertical depth) under the eastern crater. The core is HQ diameter to a measured depth of 213 m and NQ diameter from 213-354 m measured depth. The core traverses the deep conduit and intrusions of the volcano to a total vertical depth of 290 m b.s. Seawater drilling fluid for boreholes SE-02a and SE-02b was filtered and doubly UV-sterilized at the drill site. No mud products were employed while coring SE-02a, while small amounts of attapulgite mud were used in SE-02b and SE-03. Core samples for geochemical analyses of pore water and microbiological investigations were collected on site from all three boreholes. About 650 m of core was transported by helicopter to Heimaey, 18 km northeast of Surtsey, to a processing laboratory where the core was scanned, documented, and described. Additional core processing has taken place at the Náttúrufraedistofnun Íslands, the Icelandic Institute of Natural History in Gardabaer, where both the 1979 and 2017 cores are stored.
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  • 2
    Publication Date: 2020-02-12
    Description: Length: 32 min What forms the landscapes of the Earth with its mountains, rivers, soils, the places we live in? Is Earth’s surface shaped when rocks are uplifted by geologic forces, and are then destroyed by rain, ice, and wind; or do plants with their roots, animals that dig into soil and the vast number of microorganisms shape the landscapes? Watch the scientists of the German-Chilean “EarthShape” project study these questions along a fascinating landscapes in Chile, and in their home laboratories. A science movie designed and produced by Friedhelm von Blanckenburg from GFZ Potsdam, Germany, Kirstin Übernickel from Universität Tübingen, and Wolfgang Dümcke from Filmbüro Potsdam, Germany, within the DFG-funded research network “EarthShape – Earth Surface Shaping by Biota” which is coordinated by Todd Ehlers (Universität Tübingen) und Friedhelm von Blanckenburg (GFZ Potsdam).
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  • 3
    Publication Date: 2020-05-26
    Description: Deliverable D5.2 presents the experimental outcome of jetting experiments at simulated reservoir conditions. Different rock types are tested under various conditions with the use of three different types of test bench. At first jetting experiments are conducted under submerged conditions in order to derive a better understanding of the governing erosion mechanism. Therefore pitting tests are combined with PIV measurements in order to derive and explain the erosion pattern of the occurring cavitation erosion and why the rock is more like to be eroded by the stagnation pressure of the impinging jet. Second, jetting experiments under pressure controlled conditions are performed. Rate of penetrations (ROP) of up to 100 m/h can be achieved which proofs the successful application of RJD technology especially in sand stone reservoir rock types. Especially the rotating nozzle design bears the highest potential for jetting operations where the static nozzle designs tend to fail, especially when pore pressure increases. The third experimental series under application of a bi- axial stress field show that the current RJD technology, as being used by project partner WSG, is not able to penetrate harder sandstone rock types (e.g. Dortmund sandstone) when field operating conditions are applied. The induced stress in the specimen does not initiate or enhance ROP. A second experiment thereby shows that higher nozzle exit speeds can lead to massive breakouts. Fourth, experiments are performed under a tri-axial stress field in collaboration with TU DELFT. Rock cubes are tested under different and very severely stress regimes while jetting into them. Compared to tests at atmospheric conditions it can be stated that the application of a stress field does not enhance the erosion of rock. At last experiments are conducted with the project partner WSG in order to determine the jetability of the Icelandic Basalt rock type and Icelandic inter basalt sediment layer. The experiments show that already higher pump pressures result in higher jetting performance, hence making them jetable as previously not expected. Furthermore the experiments approved the feasibility of the planned field test in Iceland when the soft sediment layer is the target zone. All in all the experiments conducted with the RJD technology show different results at simulated reservoir conditions compared to those at atmospheric which are described in deliverable D5.1 (Hahn & Wittig, 2017). Therefor, further testing at conditions representing the reservoir conditions more closer are needed in order to better understand and analyze the jetting process downhole.
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  • 4
    Publication Date: 2020-05-27
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  • 5
    Publication Date: 2020-05-26
    Description: In this deliverable, the objectives of the Imperial College team are to consider jetted boreholes in the context of conventional borehole wall-rock stability analysis and to utilise an in-house advanced combined finite-discrete element code to examine the wall-rock failure process for jetted holes. The geomechanical modelling of Lateral Stability in D7.2 presented here is in addition to the main focus on modelling the water-jetting breakdown of the rock itself, reported in D7.1.
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  • 6
    Publication Date: 2020-05-26
    Description: The aim of this research is to investigate the failure mechanism for different types of rock in the context of water jet drilling and to predict the jet-ability or assess the radial jet drilling (RJD) performance prior to drilling and at the well petrophysical analysis stage. The main approach is to numerically simulate the water jet drilling for different types of rock using ICL’s in-house fluid-solid coupling codes. The rock properties, CT-scan data and jetting results obtained from D4.1 (Bakker et al., 2018) and D5.1 (Hahn et al., 2017) provide a good foundation for the related numerical results.
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  • 7
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    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR
    Publication Date: 2020-08-10
    Description: The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides real-time seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. Like all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.
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  • 8
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    GFZ German Research Centre for Geosciences
    Publication Date: 2020-02-12
    Description: Length: 32 min What forms the landscapes of the Earth with its mountains, rivers, soils, and the places we live in? One view holds that Earth’s surface is shaped when rocks are uplifted by geologic forces, and are then destroyed by rain, ice, and wind that carve landscapes by erosion and weathering. Another view suggests that the green layer of life between rocks below and climate above is the key player. Do plants with their roots, animals that dig into soil and the vast number of microorganisms shape the landscapes? Or do minerals, soil, and water provide the environment for them to live? Or are they both interdependent? Can they together resist the massive climate change imposed by humans today? Watch the scientists of the German-Chilean “EarthShape” project study these questions along a climate gradient in Chile, in the National Parks Pan de Azúcar, La Campana, and Nahuelbuta. Take a tour through fascinating landscapes and see the young scientists study the interactions between geology and biology, from the dry Atacama Desert to dense forests, and in their sophisticated home laboratories. See how feedbacks control Earth’s climate. A science movie designed and produced by Friedhelm von Blanckenburg from GFZ Potsdam, Germany, Kirstin Übernickel from Universität Tübingen, and Wolfgang Dümcke from Filmbüro Potsdam, Germany, within the German National Science Foundation (DFG) funded research network “EarthShape – Earth Surface Shaping by Biota” which is coordinated by Todd Ehlers (Universität Tübingen) und Friedhelm von Blanckenburg (GFZ Potsdam).
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  • 9
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    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report - STR Data
    Publication Date: 2020-02-12
    Description: There has been growing recognition of the importance of the accurate seismic locations in quantitative seismological studies, such as seismic hazard analyses, fault zone characterization, and Earth's deformation. Accurate estimation of seismic locations is critical since a wrong estimate of the seismic source location will result in wrong interpretations in the subsequent analyses. We present SCOTER, an open-source Python program package that is designed to relocate multiple seismic events by using P- and S-wave station correction terms. The package implements static and shrinking-box source-specific station terms techniques extended to regional and teleseimic distances and adopted for probabilistic, non-linear, global-search location for large-scale multiple-event location. This program provides robust relocation results for seismic event sequences over a wide range of spatial and temporal scales by applying empirical corrections for the biasing effects of 3-D velocity structure. Written in the Python programming language, SCOTER is run as a stand-alone command-line tool (requiring no knowledge of Python) and also provides a set of sub-commands to develop inputs (dataset, configuration etc) and export results (hypocenter parameters, travel-time residuals etc) { routine but non-trivial tasks that can consume much user time. This package can be used for relocation in local, regional, and teleseimic scales. We describe SCOTER's functionality, design and technical implementation, accompanied by an overview of its use cases. As an illustration, we demonstrate the applicability of this tool through two examples based on (1) a catalogue of several hundred events in the Arctic plate boundary region using regional and teleseismic arrival times and (2) a small dataset of low-magnitude seismic events recorded by dense, local stations at the western Iberia, central Portugal. The relocated datasets highlight the future potential for applying the SCOTER relocation tool to greatly improve the relative location accuracy among nearby events.
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  • 10
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    GFZ German Research Centre for Geosciences
    Publication Date: 2020-02-12
    Description: Length: 3 min Watch the fascinating cycle through which plants obtain the mineral nutrients that they need to grow. Plants “eat” mineral nutrients like phosphorous or potassium from the soil and rock that their roots grow in. But this natural resource is limited. To prevent running out of nutrients, hyphae (long thread-like cells of fungi that are attached to roots) recycle phosphorus from falling leaves, and return it to the trees. In dry landscapes plants take up their phosphorus directly from rock. See the fundamental difference of ecosystems in different climates. An animated science movie designed and produced by Friedhelm von Blanckenburg from GFZ Potsdam, Germany, Michaela Dippold from Universität Göttingen, Germany, and Andreas Schulz from Filmbüro Potsdam, Germany within the DFG Project ““EarthShape – Earth Surface Shaping by Biota”.
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  • 11
    Publication Date: 2020-02-12
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  • 12
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    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR - Data | GIPP Experiment- and Data Archive
    Publication Date: 2020-02-12
    Description: Glacial contribution to eustatic sea level rise is currently dominated by loss of the smaller glaciers and ice caps, about 40% of which are tidewater glaciers that lose mass through calving ice bergs. The most recent predictions of glacier contribution to sea level rise over the next century are strongly dependent upon models that are able to project individual glacier mass changes globally and through time. A relatively new promising technique for monitoring glacier calving is through the use of passive seismology. CalvingSEIS aims to produce high temporal resolution, continuous calving records for the glaciers in Kongsfjord, Svalbard, and in particular for the Kronebreen glacier laboratory through innovative, multi-disciplinary monitoring techniques combining fields of seismology and bioacoustics to detect and locate individual calving events autonomously and further to develop methods for the quantification of calving ice volumes directly from the seismic and acoustic signals.
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  • 13
    Publication Date: 2020-02-12
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  • 14
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    GFZ German Research Centre for Geosciences
    Publication Date: 2020-02-12
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  • 15
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    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR - Data
    Publication Date: 2020-02-12
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  • 16
    Publication Date: 2020-02-12
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  • 17
    Publication Date: 2020-02-12
    Description: The Collisional Orogeny in the Scandinavian Caledonides (COSC) scientific drilling project focuses on mountain building processes in a major mid‐Paleozoic orogen in western Scandinavia and its comparison with modern analogues. The project investigates a subduction‐generated complex (Seve Nappes) and how these in part under ultra‐high pressure conditions metamorphosed outer continental margin and continent‐ocean transition zones (COT) assemblages were emplaced onto the Baltoscandian platform and there influenced the underlying allochthons and the basement in a section provided by two fully cored 2.5 km deep drill holes. This operational report concerns the first drill hole, COSC‐1 (ICDP 5054‐1‐A), drilled from early May to late August 2014. It sampled a thick section of the lower part of the Seve Complex and was planned to penetrate its basal thrust zone into the underlying lower grade metamorphosed allochthon. The drill hole reached a depth of 2495.8 m and nearly 100 % core recovery was achieved. Although planning was based on existing geological mapping and new high‐resolution seismic surveys, the drilling resulted in some surprises: the Lower Seve Nappe proved to be composed of rather homogenous gneisses, with only subordinate mafic bodies and its basal thrust zone was unexpectedly thick (〉 800 m). The drill hole did not penetrate the bottom of the thrust zone. However, lower grade metasedimentary rocks were encountered in the lowermost part of the drill hole together with garnetiferous mylonites tens of metres thick. The tectonostratigraphic position is still unclear and geological and geophysical interpretations are under revision. The compact gneisses host only 8 fluid conducting zones of limited transmissivity between 300 m and total depth. Downhole measurements suggest an uncorrected average geothermal gradient of ~20°C/km. The drill core was documented on‐site and XRF scanned off site. During various stages of the drilling, the borehole was documented by comprehensive downhole logging. This operational report provides an overview over the COSC‐1 operations from drilling preparations to the sampling party and describes the available datasets and sample material.
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  • 18
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    GFZ German Research Centre for Geosciences
    Publication Date: 2020-02-12
    Description: Length: 4 min Imagine a planet without plants. Would a landscape on that planet differ from a landscape with plants as we know it? There are two ways to tell: we can either compare natural landscapes with each other, or use computer models. We show one model for a landscape that is covered with a dense forest and one that carries almost no vegetation. Be surprised by the large difference you see in these between these two landforms! An animated science movie designed and produced by Todd Ehlers from the University of Tübingen, Germany, Andreas Schulz from Filmbüro Potsdam, Germany, with contributions of Manuel Schmid Willi Kappler, and Friedhelm von Blanckenburg, Germany within the DFG Project ““EarthShape – Earth Surface Shaping by Biota”.
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  • 19
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    GFZ German Research Centre for Geosciences
    Publication Date: 2020-05-19
    Description: Based on the aviailable material we come to the conclusion that jetting has no direct influence on the surrounding area. Analysis on multiple scales: μm (porosity); cm (mechanical and acoustical properties); dm scale (elastic properties with and without a jetted hole) do not show a significant changes compared to in-tact material, nor can a significant change be detected with respect to distance to a jetted hole. Results fall within the intra-block variability, and differences between blocks can be well explained by block-to-block variation. True-triaxial elastic deformation tests have been designed and ran to test the effect of a lateral (jetted hole) on the elastic properties. The jetted hole itself was jetted with a rotating nozzle type, producing cilindrical holes. Comparing laboratory tests with a numerical model proved that the laboratory results may be well compared to a model with cylindrical hole embedded in a rock mass, much like a conventional borehole. The stress field around the jetted hole can therefore be well aproximated by the Kirsh-equations, modified for compression.
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  • 20
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    GFZ German Research Centre for Geosciences
    Publication Date: 2020-05-19
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  • 21
    Publication Date: 2020-05-19
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  • 22
    Publication Date: 2020-05-26
    Description: Work at GZB (International Geothermal Centre) had been focused on several potential, novel micro type drilling technologies. These technologies have been investigated and discussed to determine possible future options. In this report the different technologies are being presented, starting with abrasive enhanced jetting, followed by pulsation and mechanically supported drilling, ending with percussion type mechanical rock destruction and drilling. Their influence on rock disintegration and drilling efficiency have been investigated in several laboratory experiments. These were carried out to manifest a better understanding of each potential technology. The results are being presented and discussed regarding the potential increase in drilling performance versus lessons learned within WP 5.1 as well as their applicability in the field. Water jets enhanced with abrasive particles have the ability to penetrate into virtually any rock type with rather low hydraulic power. However, the (downhole) applicability in the field is commonly a challenge due to extremely fast and high wear on the pertinent material and equipment other than the rock itself, including the jetting BHA (bottom hole assembly) and nozzles. In order to partly overcome this dilemma a dedicated nozzle for abrasive mixing has been designed and patented. It may be found under patent number DE 10 2016 125 916.0. Pulsating water jets are a different approach to enhance the efficiency of rock destruction via water jet. Both techniques are based on pure high pressure jets, one adding particles to a constant jet (abrasive jetting), the other one dividing and cutting a constant jet into small, short sections to generate not constant impulses (pulsation). Various tests were carried out under reservoir type conditions inside the autoclave system “iBOGS mini”. So far the effect of pulsation seems to be low compared to the suppressed cavitation erosion mechanism under elevated pressure conditions. A very different approach is the use of micro turbines powered by the high pressure water, combined with a mechanical drill bit. The hydraulic energy of the intensified water is not directly used to penetrate the rock, but rather to generate rotation even with substantial torque via a micro turbine system. Thus, the jetting action is neglectable, as the mechanical bit does the cutting into the rock mass with rather high rotation speeds. Testing showed rather high efficiency regarding drilling speed. The technology works also independently of the rock type. All tested rock types including granite were drilled successfully with rather low hydraulic power of 10 kW (e.g. turbine differential pressures of 150 bar and flow rates of about 40 l/min). Future testing at macro and meso scale levels are being planned to verify reliability, drilling direction and more. As of now, this technology seems to be the most promising for hard rock formations in the very near future. One challenge may be their slightly larger geometrical shape and size regarding the current downhole installation scheme. But this is underway to be solved in the near future. On the final end of the possible spectrum for high pressure jet drilling from pure jetting (e.g. SURE WP 5.1 to 5.3) to transforming the intensified, high pressure water to eventually generate and gain more mechanical support over jetting are percussion engines as being known and used in so called DTH (down-the-hole) hammers. Here, the intensified water does generate medium frequency mechanical blows (“pulses”, e.g. 50 – 70 Hz) by powering a piston and drill bit for rock disintegration with very high drilling speeds. The differential pressure across such a hammer with approx. 180 bar is at the same level as for the before mentioned micro turbines and thus, much lower than for direct high pressure water jetting. Compared to the turbine, the hammer works with a highly dynamic force and low rotation, whereas the turbine is based on a very constant load or weight on bit (WOB) with rather high rotation speed (RPM), generating more of a grinding effect. However, the hammer ́s geometrical shape, namely its length, makes it much more difficult to be deployed downhole for micro drilling, while also some rotation needs to be generated. Here is more work underway as well. To summarize high pressure jet drilling, the full scale of currently possible solutions from pure high pressure jetting to mechanically enhanced or supported jet type drilling including abrasives, pulsation, micro turbines and percussion motors were considered and being looked at regarding their possible application in hard rock formations and future potential.
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  • 23
    Publication Date: 2020-05-27
    Description: Radial Jet Drilling (RJD) is a technique to stimulate wells by creating small-diameter laterals from vertical or deviated wells using hydraulic jets. The laterals, also called radials, can be up to 100 m in length. To analyze under which sub-surface conditions the radials improve the well performance most, a step-wise approach is followed in which first the performance of a single stimulated well is analyzed and in a second step, the performance of a doublet system is analyzed. Finally, case studies that are more detailed are simulated. For the single well case, a good first estimate of radial stimulation performance for different reservoir conditions can be obtained from (semi-) analytical solutions. These results show that the anisotropy in the permeability and the thickness of the reservoir influence the relative increase in productivity/injectivity most. The permeability influences in particular the absolute performance of the stimulated well. Many aspects not included in the semi-analytical solution also influence the performance of the radial stimulation: - Since the radials are open hole, stability for friable rocks or deep reservoirs is unlikely. This depends on the in-situ stress conditions. Collapsed radials probably have much lower performance or no effect at all. - The uncertainty in the radial path and diameter decreases the expected benefits from radials significantly depending on the type of reservoir. For example for a layered reservoir, the expected increase may be tens of percent lower. - Due to the small diameter (0.02-0.05 m) and rough surface of the radials and the high rates of geothermal wells, viscous pressure drop due to flow in the radials has to be taken into account for prediction of performance. For example for a radius of 0.04 m and well rate of 3600 m3/d, expected increase in performance is halved when taking into account pressure drop. - Heterogeneity in the permeability has a strong impact on the performance of the radials. Performance of individual radials depends in first approximation on the local permeability. However, this is difficult to capture in general terms. - Near well bore damage (positive skin) and prior stimulation (negative skin) have a large impact on the expected increase due to stimulation. In case the radials can be used to by-pass near well damage, performance can be much higher than predicted using the analytical equations. - Heterogeneity due to fault and/or fractures, voids, sharp transitions or layering all make potential success more uncertain and predictability lower due to potential issues with jetting. Whether increased performance for a single well can be translated to similar increased performance of a doublet depends on the doublet settings and subsurface conditions. For a fixed doublet distance or field size, an increase in rate due to improved performance of the wells will result in a reduced field life. The increased well performance can also be used to lower pumping cost at a fixed rate and thus improve performance of the doublet. It was found, that for most subsurface systems, the impact of the radials on production temperature was minor (for constant rate). Only for some fractured systems, short-circuiting can be increased due to radials. Overall, the ideal candidate for radial stimulation is a reservoir which is not too deep, in homogeneous, competent rock with a well with near well bore damage or in a not too deep anisotropic reservoir in which the main well is not drilled beneficially compared to the main direction of permeability.
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  • 24
    Publication Date: 2020-05-26
    Description: This report describes activity connected to radial jet drilling (RJD) in Iceland in WP6 – Macro Scale in the SURE project. Well HN-13, located in N-Iceland close to the town of Akureyri was selected as a candidate for RJD trials within the SURE project. It was drilled in between two prior drilled low-temperature geothermal wells, HG-10 (a.k.a. HN-10) and BO-01 (a.k.a. BN-01), that are both productive and used for district heating of Akureyri and nearby communities. Although the location was in between two producing wells, it was a poor producer only producing 5-6 liters per minute (0,1 l/s) while being air lifted. For comparison, the mean production from well HG-10 that sits 20 m NNE of HN-13, is about 25 l/s of 90°C hot water. HN-13 was therefore valued as an excellent candidate for demonstration of the stimulation technology, as any increased production after RJD will clearly be revealed. Jetting experiments in WP5 into basalt rock types sent from Iceland to Bochum were shown to be impractical as high pressure and velocities are required. Therefore, softer inter-basaltic layers were targeted. Main information on well HN-13, nearby wells, target depth as well as the RJD field testing are described in this report.
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  • 25
    Publication Date: 2020-05-28
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  • 26
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    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR - Data | GIPP Experiment and Data Archive
    Publication Date: 2020-05-20
    Description: This report describes the passive seismic data acquired by the TOPASE network deployed over Rittershoffen geothermal field (Alsace, France). The monitoring period extends from March 2013 to November 2014, which includes the stimulation of the first well of the doublet, the drilling of the second well and well tests. These data were acquired using 31 Earth Data Loggers PR6-24 and MARK-SERCEL L-4C-3D 1 Hz seismometers of the Geophysical Instrument Pool Potsdam (GIPP), which were provided to the KIT-AGW-Geothermal research division.
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  • 27
    Publication Date: 2020-05-19
    Description: To date, information about the wellbore integrity of high temperature and high pressure geothermal wells is scarce. Hardly any measurement data is available about the thermal and mechanical load onto the subsurface installation (casing and cemented annulus) during the operation of such wells. In order to monitor the response of the subsurface installation to changing load conditions, a fiber optic cable was installed behind casing of a geothermal well. To increase the knowledge about the wellbore integrity and to benefit from the combined application of different fiber optic sensing technologies, temperature, strain as well as acoustic noise measurements were performed during well completion and testing. These include the distributed temperature sensing (DTS) technology, based on Raman scattering, as well as the distributed strain and distributed acoustic sensing (DAS) technologies, both based on Rayleigh scattering. Here, we present information about the laboratory experiments, the cable installations and downhole measurement campaigns together with results of our analysis. It could be shown that the fiber optic measurements are well suited to monitor the well completion procedures. In addition, the technology offers a possibility to monitor well integrity throughout the lifetime of a geothermal well.
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  • 28
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report
    Publication Date: 2020-05-22
    Description: This study contributes to the effort of space geodesy to reach the 1mm accuracy level on a global scale. This stringent requirement is vital to realize a global reference system upon which phenomena such as sea-level rise can be reliably monitored. The study deals with two interrelated challenges: modeling geophysical loads imposed on the crust of the Earth and quantifying the atmospheric propagation delay of signals employed by space geodetic techniques, namely VLBI, SLR, GNSS, and DORIS. If not adequately modeled, both geophysical loading and propagation delay corrupt space geodetic data analysis results, thus distorting the implied reference frame and compromising the physical interpretation of other parameters. The explicit purpose of this work is to understand how these effects propagate into the parameters estimated within the geodetic adjustment, and to develop models that alleviate geodetic results from these effects. To achieve this goal, the scientific framework was divided into two contributions to be understood and enhanced: the theory governing the effects of geophysical loading and atmospheric propagation, and the space geodetic technique data analysis pipeline, largely using VLBI as a test-bed. In essence, the research conducted here includes: (i) the development of software capable of realistically simulating VLBI, SLR, GNSS, and DORIS observations within a Monte Carlo framework, (ii) the homogenization of in situ meteorological data recorded at VLBI and SLR stations, (iii) the development of ray-traced delays, mapping functions and higher-order gradients for all four space geodetic techniques, (iv) the comprehensive investigation of inter-frequency and inter-system atmospheric ties, (v) the development of models to describe the displacement induced by mass redistribution within Earth’s fluid envelope including the atmosphere, the ocean, and the continental hydrology, (vi) the development of empirical models to describe the signal propagation delay (GFZ-PT) and the non-tidal geophysical loading displacement (EGLM), and (vii) the study of the impact of the atmospheric refraction and non-tidal geophysical loading models in space geodetic data analysis on station coordinates, the terrestrial reference frame, the Earth orientation, and the integrated water vapour trends. A number of developments were carried out herein for the first time, for example, the simulation of space geodetic measurements based on ray-traced delays, the study of systematic errors on the reference frame induced by not properly accounting for the orbital altitude of the satellites in the calculation of atmospheric refraction corrections, and the assessment of the probability of successful laser ranges based on integrated cloud fraction along the ray path. It was found that microwave and optical atmospheric gradients are starkly different both spatially and temporally, and cannot be scaled to fit each other. Failing to account for non-tidal geophysical loading and atmospheric asymmetries induces a scale bias in the SLR reference frame as well as a spurious geocenter motion predominantly along the Z-axis. Employing a VLBI-tailored atmospheric refraction model to reduce DORIS observations displaces stations in the radial component thus inducing a large scale bias in the implied frame. Employing homogeneous in lieu of raw meteorological data in VLBI data analysis reduces the scatter of station coordinates and improves the baseline length repeatability. Employing the mapping functions developed herein in lieu of VMF1 yields an overall improvement in VLBI data analysis. Applying the geophysical loading models developed herein reduces the response of almost all station coordinate and baseline length series at seasonal and synoptic timescales. Based on the investigations carried out herein, differences in Earth orientation induced by the quality of the atmospheric refraction and geophysical loading models — or their very application for the latter — are not statistically significant in the framework of the modern VLBI system. Nevertheless, to fulfill the 1mm requirement, proper treatment of geophysical loading and atmospheric refraction is a necessity.
    Language: English
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  • 29
    Publication Date: 2020-05-22
    Description: The Collisional Orogeny in the Scandinavian Caledonides (COSC) project supported by the International Continental Scientific Drilling Program (ICDP) and the Swedish Scientific Drilling Program (SSDP) drilled a borehole through the Seve Nappe in Sweden to investigate mountain building processes. It recovered 2.5 km of drill core. Five core samples from the depth from 1682 to 2469 m were analyzed in this thesis. A hyperspectral imaging spectrometer (HySpex) was used to conduct the measurements. It is a two sensor system which combines a VNIR and a SWIR sensor. The measurements were taken with a resolution of 0.22 mm/ pixel. As a comparison, mineral maps based on Laser Induced Breakdown Spectroscopy (LIBS) element measurements of approximately the same resolution were used. This thesis developed a working process chain which includes 1) the adjustment of the measurement parameters of the sensors to acquire optimal data cubes, 2) the "unrolling" of a drill core to depict and analyze the whole core mantle surface and to map the distribution of minerals accurately not only over the length but also the whole surface of the core and 3) the mineral mapping based on spectral absorption features with the EnGeoMap algorithm. This can be seen as the beginning of the development of a stand-alone drill core scanner including the geological evaluation by EnGeoMap. The measurements revealed a basic approach to determine the integration time for the VNIR and the SWIR sensor based on the signal-to-noise ratio of the white reflectance standard. An approach of a step-wise rotation of the core and a translation measurement and a mosaicking based on the rectification of the core surface was developed. The stitching of several core images via key points was deployed. The duration of the unrolling amounts to 22 h/ m of core and results in an hyperspectral mosaic of the core mantle surface. Relative to the approximately 550 h needed to measure the surface area of 1 m of core with the LIBS system, 22 h seems tolerable. The feasibility of the unrolling and the mosaicking of drill cores varies. In scientific operations the accuracy is valued higher than the time-consumption, in industrial operations the time is a big factor to make a project profitable. The mineral mapping with EnGeoMap proved to be very precise in case of detecting the abundance of single minerals. When mapping multiple minerals, a bias towards a few minerals showed which were mapped with higher abundances than in reality. This is due to mineral-dependent fit value thresholds and has to be investigated further. When choosing few but distinct proxy minerals, EnGeoMap is a valuable tool to evaluate the mineral abundances and the distribution over the course of a drill core, to highlight changes and to give information about mineral assemblages.
    Language: English
    Type: info:eu-repo/semantics/masterThesis
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  • 30
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report
    Publication Date: 2020-05-22
    Description: The spectral characteristics of Rare Earth Elements (REEs) have been poorly researched although the economic interest in these elements is increasing. This study investigates the detection of REEs using remote sensing data. For this purpose the spectral response of each individual REE has been studied with four spectrometers (HySpex (VNIR-1600, SWIR-320m-e), ASD Field Spec 3, Perkin Elmer LAMBDA 950, FTIR Spectrum GX) using a spectral range of 350 to 16000 nm to incorporate different techniques. The relationship between the spectral response and the REE concentration as well as the influence of other materials on the detection of REEs was examined using mixtures of calcium carbonate (the main component of REE ore rocks) and iron (III) oxide (hematite). Finally, characteristic absorption bands have been employed on an EO-1 Hyperion satellite image, covering the REE Mountain Pass mine in California and a HySpex image of a rock sample from Norway (soevite) to evaluate their potential use as REE detectors. The results show that the REEs lanthanum, neodymium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium and ytterbium cause several and differing absorption features in the visible near-infrared (VNIR) and shortwave-infrared (SWIR) region. However, in wavelength ranges between 2500 and 16000 nm no absorption bands distinctive of REEs appeared. In most cases, the concentration of REEs and the absorption depth show a logarithmic relationship for different absorption features. The mixtures of neodymium and iron (III) oxide show that in presence of hematite the absorption features of neodymium are superimposed by those features caused by iron (III) oxide. In comparison to hematite, calcium carbonate has had no influence on the detection of neodymium in the VNIR. The application of characteristic absorption bands on the satellite image shows that the REE signal causes only, if any, very small absorption bands in the spectrum at higher REE concentrations. In the rock sample, however, REEs related absorption bands are detectable and can be seen clearly in the spectrum with a neodymium concentration of around 0.14%. This study shows that imaging spectroscopy serves as a helpful tool for the characterization and detection of REE concentrations in the laboratory and field environment. The detection of REEs via satellite images is limited by the low intensity of the absorption features, despite the high REEs concentration. Nevertheless, the detection of REEs by means of remote sensing is a non-invasive method that saves both money and time for sample preparation, underlining its economic value.
    Language: English
    Type: info:eu-repo/semantics/masterThesis
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  • 31
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR
    Publication Date: 2020-08-10
    Description: The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides real-time seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. Like all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.
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  • 32
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    Publication Date: 2020-12-17
    Description: In geosciences 3D geomechanical-numerical models are used to estimate the in-situ stress state. In such a model each geological unit is populated with the rock properties Young’s module, Poisson ratio, and density. Usually, each unit is assigned a single set of homogeneous properties. However, variable rock properties are observed and expected within the same geological unit. Even in small volumes large variabilities may. The Python script HIPSTER (Homogeneous to Inhomogeneous rock Properties for Stress TEnsor Research) provides an algorithm to include inhomogeneities in geomechanical-numerical models that use the solver Abaqus®. The user specifies the mean values for the rock properties Young's module, Poisson ratio and density, and their variability for each geological unit. The variability of the material properties is individually defined for each of the three rock properties in each geological layer. For each unit HIPSTER generates a normal or uniform distribution for each rock property. From these distri-butions for each single element HIPSTER draws individual rock properties and writes them to a separate material file. This file defines different material properties for each element. The file is included in the geomechanical-numerical analysis solver deck and the numerical model is solved as usual.
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  • 33
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  WSM Technical Report
    Publication Date: 2021-04-10
    Description: In geosciences the discretization of complex 3D model volumes into finite elements can be a time-consuming task and often needs experience with a professional software. Es-pecially outcropping or out-pinching geological units, i.e. geological layers that are rep-resented in the model volume, pose serious challenges. Changes in the geometry of a model may occur well into a project at a point, when re-meshing is not an option any-more or would involve a significant amount of additional time to invest. In order to speed up and automate the process of discretization, Apple PY (Automatic Portioning Preventing Lengthy manual Element assignment for PYthon) separates the process of mesh-generation and unit assignment. It requires an existing uniform mesh together with separate information on the depths of the interfaces between geological units (herein called horizons). These two pieces of information are combined and used to assign the individual elements to different units. The uniform mesh is created with a standard meshing software and contains no or only very few and simple structures. The mesh has to be available as an Abaqus input file. The information on the horizons depths and lateral variations in the depths is provided in a text file. Apple PY compares the ele-ment location and depth with that of the horizons in order to assign each element to a corresponding geological unit below or above a certain horizon.
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  • 34
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  WSM Technical Report
    Publication Date: 2021-04-10
    Description: The distribution of data records for the maximum horizontal stress orientation SHmax in the Earth’s crust is sparse and very unequally. To analyse the stress pattern and its wavelength and to predict the mean SHmax orientation on regular grids, statistical interpolation as conducted e.g. by Coblentz and Richardson (1995), Müller et al. (2003), Heidbach and Höhne (2008), Heidbach et al. (2010) or Reiter et al. (2014) is necessary. Based on their work we wrote the Matlab® script Stress2Grid that provides several features to analyse the mean SHmax pattern. The script facilitates and speeds up this analysis and extends the functionality compared to the publications mentioned before. This script is the update of Stress2Grid v1.0 (Ziegler and Heidbach, 2017). It provides two different concepts to calculate the mean SHmax orientation on regular grids. The first is using a fixed search radius around the grid points and computes the mean SHmax orientation if sufficient data records are within the search radius. The larger the search radius the larger is the filtered wavelength of the stress pattern. The second approach is using variable search radii and determines the search radius for which the standard deviation of the mean SHmax orientation is below a given threshold. This approach delivers mean SHmax orientations with a user-defined degree of reliability. It resolves local stress perturbations and is not available in areas with conflicting information that result in a large standard deviation. Furthermore, the script can also estimate the deviation between plate motion direction and the mean SHmax orientation.
    Language: English
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  • 35
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  Scientific Technical Report STR
    Publication Date: 2021-03-28
    Description: The MT repository contains geophysical data sets collected in field experiments from all over the world. The acronym MT stands for magnetotelluric, a geophysical method used to probe the Earth's deep interior for its electrical conductivity distribution through electromagnetic (EM) induction. MT is based on EM fields generated by natural processes in the Earth's atmosphere and magnetosphere. But the repository also contains data from Controlled Source Electromagnetic (CSEM) projects, for which man-made EM sources are used. The principle form of data in the repository are time-series of EM field components acquired with heterogeneous sets of sensors, recording instruments, and sampling rates. It is the main purpose of this archive or repository to provide the links between the data and their physical meaning by means of metadata. To achieve this, the repository is organized as a combination of data files and associated meta-data in a well defined folder (directory) structure, with the data files being sorted into subfolders. Meta-data are provided as XML (Extensible Markup Language) formatted file.
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  • 36
    facet.materialart.
    Unknown
    GFZ German Research Centre for Geosciences
    In:  WSM Technical Report
    Publication Date: 2023-01-31
    Description: In geosciences 3D geomechanical-numerical models are used to estimate the in-situ stress state. In such a model each geological unit is populated with the rock properties Young’s module, Poisson ratio, and density. Usually, each unit is assigned a single set of homogeneous properties. However, variable rock properties are observed and expected within the same geological unit. Even in small volumes large variabilities may. The Python script HIPSTER (Homogeneous to Inhomogeneous rock Properties for Stress TEnsor Research) provides an algorithm to include inhomogeneities in geomechanical-numerical models that use the solver Abaqus®. The user specifies the mean values for the rock properties Young's module, Poisson ratio and density, and their variability for each geological unit. The variability of the material properties is individually defined for each of the three rock properties in each geological layer. For each unit HIPSTER generates a normal or uniform distribution for each rock property. From these distributions for each single element HIPSTER draws individual rock properties and writes them to a separate material file. This file defines different material properties for each element. The file is included in the geomechanical-numerical analysis solver deck and the numerical model is solved as usual. The HIPSTER script files and example files are provided for download at http://github.com/MorZieg/hipster. Table 0-1 Structure of the GitHub repository gives an overview of the repository and files including a short explanation.
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