Download or read book Reservoir scale Fracture Permeability in the Dixie Valley Nevada Geothermal Field written by and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wellbore image data recorded in six wells penetrating a geothermal reservoir associated with an active normal fault at Dixie Valley, Nevada, were used in conjunction with hydrologic tests and in situ stress measurements to investigate the relationship between reservoir productivity and the contemporary in situ stress field. The analysis of data from wells drilled into productive and non-productive segments of the Stillwater fault zone indicates that fractures must be both optimally oriented and critically stressed to have high measured permeabilities. Fracture permeability in all wells is dominated by a relatively small number of fractures oriented parallel to the local trend of the Stillwater Fault. Fracture geometry may also play a significant role in reservoir productivity. The well-developed populations of low angle fractures present in wells drilled into the producing segment of the fault are not present in the zone where production is not commercially viable.
Download or read book Fracture Permeability and in Situ Stress in the Dixie Valley Nevada Geothermal Reservoir written by and published by . This book was released on 1999 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have collected and analyzed fracture and fluid flow data from wells both within and outside the producing geothermal reservoir at Dixie Valley. Data from wellbore imaging and flow tests in wells outside the producing field that are not sufficiently hydraulically connected to the reservoir to be of commercial value provide both the necessary control group of fracture populations and an opportunity to test the concepts proposed in this study on a regional, whole-reservoir scale. Results of our analysis indicate that fracture zones with high measured permeabilities within the producing segment of the fault are parallel to the local trend of the Stillwater fault and are optimally oriented and critically stressed for frictional failure in the overall east-southeast extensional stress regime measured at the site. In contrast, in the non-producing (i.e., relatively impermeable:) well 66-21 the higher ratio of S{sub hmin} to S{sub v} acts to decrease the shear stress available to drive fault slip. Thus, although many of the fractures at this site (like the Stillwater fault itself) are optimally oriented for normal faulting they are not critically stressed for frictional failure. Although some of the fractures observed in the non-producing well 45-14 are critically stressed for frictional failure, the Stillwater fault zone itself is frictionally stable. Thus, the high horizontal differential stress (i.e., S{sub Hmax}-S{sub hmin}) together with the severe misorientation of the Stillwater fault zone for normal faulting at this location appear to dominate the overall potential for fluid flow.
Download or read book Fracture Permeability and in Situ Stress in the Dixie Valley Nevada Geothermal Reservoir written by Mark D. Zoback and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tectonic Controls on Fracture Permeability in a Geothermal Reservoir at Dixie Valley Nevada written by and published by . This book was released on 1998 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: To help determine the nature and origins of permeability variations within a fault-hosted geothermal reservoir at Dixie Valley, Nevada, the authors conducted borehole televiewer logging and hydraulic fracturing stress measurements in six wells drilled into the Stillwater fault zone at depths of 2--3 km. Televiewer logs from wells penetrating the highly permeable portion of the fault zone revealed extensive drilling-induced tensile fractures. As the Stillwater fault at this location dips S45°E at (approximately) 53° it is nearly at the optimal orientation for normal faulting in the current stress field. Hydraulic fracturing tests from these permeable wells show that the magnitude of S{sub hmin} is very low relative to the vertical stress S{sub v}. Similar measurements conducted in two wells penetrating a relatively impermeable segment of the Stillwater fault zone 8 and 20 km southwest of the producing geothermal reservoir indicate that the orientation of S{sub hmin} is S20°E and S41°E, respectively, with S{sub hmin}/S{sub v} ranging from 0.55--0.64 at depths of 1.9--2.2 km. This stress orientation is near optimal for normal faulting on the Stillwater fault in the northernmost non-producing well, but (approximately) 40° rotated from the optimal orientation for normal faulting in the southernmost well. The observation that borehole breakouts were present in these nonproducing wells, but absent in wells drilled into the permeable main reservoir, indicates a significant increase in the magnitude of maximum horizontal principal stress, S{sub Hmax}, in going from the producing to non-producing segments of the fault. The increase in S{sub Hmaz}, coupled with elevated S{sub hmin}/S{sub v} values and a misorientation of the Stillwater fault zone with respect to the principal stress directions, leads to a decrease in the proximity of the fault zone to Coulomb failure. This suggests that a necessary condition for high reservoir permeability is that the Stillwater fault zone be critically stressed for frictional failure in the current stress field.
Download or read book Stress and Permeability Heterogeneity Within the Dixie Valley Geothermal Reservoir written by and published by . This book was released on 1999 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We collected borehole televiewer, temperature and flowmeter logs and conducted a hydraulic fracturing test in a well (82-5) that penetrated the SFZ within the known boundaries of the geothermal field but which failed to encounter significant permeability. Although stuck drill pipe prevented direct access to the SFZ, borehole breakouts and cooling cracks indicated a (approximately)90 degree rotation in the azimuth of the least horizontal principal stress (Shmin) in well 82-5 at about 2.7 km depth. This rotation, together with the low (Shmin) magnitude measured at 2.5 km depth in well 82-5, is most readily explained through the occurrences of one or more normal faulting earthquakes in the hanging wall of the SFZ in the northern part of the reservoir. The orientation of (Shmin) below 2.7 km (i.e., (approximately)20 to 50 m above the top of the SFZ) is such that both the overall SFZ and natural fractures directly above the SFZ are optimally oriented for normal faulting failure. If these fracture and stress orient ations persist into the SFZ itself, then the existence of a local stress relief zone (i.e., anormalously high (Shmin) magnitude) is the most likely explanation for the very low fault zone permeability encountered in well 82-5.
Download or read book Dixie Valley Synthesis written by David Blackwell and published by Lulu.com. This book was released on 2014-09-18 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this report is to summarize U.S. Department of Energy (DOE) supported studies in the Dixie Valley geothermal area and to relate the results of those studies to other, non-DOE-supported studies that have been done in the valley during the past 40 to 50 years. This compilation of past research includes new analysis resulting in a more in-depth understanding of the geothermal system in Dixie Valley. The focus is on the basin geology and structure, thermal regime, and geothermal system geochemistry. Reservoir studies are briefly discussed.
Download or read book Hydrologic Properties of the Dixie Valley Nevada Geothermal Reservoir from Well test Analyses written by and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Temperature, pressure, and spinner (TPS) logs have been recorded in several wells from the Dixie Valley Geothermal Reservoir in west central Nevada. A variety of well-test analyses has been performed with these data to quantify the hydrologic properties of this fault-dominated geothermal resource. Four complementary analytical techniques were employed, their individual application depending upon availability and quality of data and validity of scientific assumptions. In some instances, redundancy in methodologies was used to decouple interrelated terms. The methods were (1) step-drawdown, variable-discharge test; (2) recovery analysis; (3) damped-oscillation response; and (4) injection test. To date, TPS logs from five wells have been examined and results fall into two distinct categories. Productive, economically viable wells have permeability-thickness values on the order of 105 millidarcy-meter (mD-m) and storativities of about 10−3. Low-productivity wells, sometimes located only a few kilometers from their permeable counterparts, are artesian and display a sharp reduction in permeability-thickness to about 10 mD-m with storativities on the order of 10−4. These results demonstrate that the hydrologic characteristics of this liquid-dominated geothermal system exhibit a significant spatial variability along the range-bounding normal fault that forms the predominant aquifer. A large-scale, coherent model of the Dixie Valley Geothermal Reservoir will require an understanding of the nature of this heterogeneity and the parameters that control it.
Download or read book Treatise on Geophysics Volume 6 written by Anthony B Watts and published by Elsevier. This book was released on 2010-05-13 with total page 627 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics: Crust and Lithosphere Dynamics, Volume 6, provides a comprehensive review of the state of knowledge on crust and lithosphere dynamics, which is defined as the study of how the outermost layers of the Earth respond to loads that are emplaced on, within, and below it and its implications for plate mechanics and mantle flow. The book begins with a chapter on plate kinematics, which shows how new observations and methodologies have improved the resolution of relative and absolute plate motions. This is followed by studies of plate mechanics, focusing on the long-term rheology of the plates and response of the plates to both relatively short-term and long-term loads. The book also includes chapters that examine the evidence from surface heat flow, borehole breakouts, and magma models for the thermal and mechanical structure of the lithosphere; the deformation of the lithosphere in extensional and compressional settings. The final two chapters deal with the structural styles of faulting in the shallow brittle part of the lithosphere, the brittle-ductile transition, and the shear zone in the ductile part of the lithosphere; and how developments in plate mechanics have impacted our understanding of geological processes. - Self-contained volume starts with an overview of the subject then explores each topic with in depth detail - Extensive reference lists and cross references with other volumes to facilitate further research - Full-color figures and tables support the text and aid in understanding - Content suited for both the expert and non-expert
Download or read book Thermal Depletion of a Geothermal Reservoir with Both Fracture and Pore Permeability written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A method for estimating the useful lifetime of a reservoir in porous rock where the injection and production wells intersect a fracture system is presented. Equations were derived for the pore-fluid and fracture-fluid temperatures averaged over large regions of the geothermal field. Problems such as incomplete areal sweep and interfingering of cool and hot fluids are ignored. Approximate equations relating average temperatures to the heat flowing from rock to fluid were developed, and their use is justified by comparing the results with solutions of the exact equations. The equations for the temperature decline can be solved quickly. In the model, fractures are characterized by three parameters: aperture w, permeability k/sub fr/, and spacings between fractures D. For certain values of these parameters, cool reinjected fluid in fractures may reach the production wells long before all the warm pore fluid has been tapped, shortening the useful lifetime of the field. The traditional (and important) problems of reservoir engineering, flow rate determination, drawdown, sweep patterns, etc. were ignored. Thus the results are most useful in providing a correction factor which can be applied to lifetime estimates obtained from a detailed simulation of a field assuming porous rock. That correction factor is plotted for clean fractures (k/sub fr/ = w2/12) as a function of w and D for several lifetime ranges. Small-scale fractures seen in cores from the Salton Sea Geothermal Field are too closely spaced to reduce lifetime estimates. However, large-scale fault systems exist within that field, and they are attractive drilling targets because they produce large flow rates. If large scale faults communicate between injection and production wells, they may reduce the useful lifetime of those wells.
Download or read book Preliminary Investigation of Scale Formation and Fluid Chemistry at the Dixie Valley Geothermal Field Nevada written by and published by . This book was released on 1997 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemistry of geothermal, production, and injection fluids at the Dixie Valley Geothermal Field, Nevada, was characterized to address an ongoing scaling problem and to evaluate the effects of reinjection into the reservoir. Fluids generally followed mixing-dilution trends. Recharge to the Dixie Valley system apparently originates from local sources. The low-pressure brine and injection waters were saturated with respect to amorphous silica, which correlated with the ongoing scaling problem. Local shallow ground water contains about 15% geothermal brine mixed with regional recharge. The elevated Ca, Mg, and HCO3 content of this water suggests that carbonate precipitation may occur if shallow groundwater is reinjected. Downhole reservoir fluids are close to equilibrium with the latest vein mineral assemblage of wairakite-epidote-quartz-calcite. Reinjection of spent geothermal brine is predicted to affect the region near the wellbore differently than it does the region farther away.
Download or read book Understanding the Micro to Macro Behaviour of Rock fluid Systems written by Richard Paul Shaw and published by Geological Society of London. This book was released on 2005 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding how fluids flow through though rocks is very important in a number of fields. Almost all of the world's oil and gas are produced from underground reservoirs. Knowledge of how they got where they are, what keeps them there and how they migrate through the rock is very important in the search for new resources, as well as for maximising the extraction of as much of the contained oil/gas as possible. Some contributors to this volume have been trying to understand real rocks in real situations and others have been working on computer models and laboratory simulations. Put together, these approaches have yielded very useful results, many of which are discussed in this volume.
Download or read book Publications of the Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1999 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dipmeter and Borehole Image Log Technology written by Michael Poppelreiter and published by AAPG. This book was released on 2010-08-25 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: Borehole imaging is among the fastest and most accurate methods for collecting high resolution subsurface data. Recent breakthroughs in acquisition, tool design, and modeling software provide real-time subsurface images of incredible detail, from the drill bit straight to a workstation. This text portrays key applications of dipmeter and image log data across the exploration and production life cycle.
Download or read book Underground Injection Science and Technology written by C-F. Tsang and published by Elsevier. This book was released on 2005-12-28 with total page 731 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapters by a distinguished group of international authors on various aspects of Underground Injection Science and Technology are organized into seven sections addressing specific topics of interest. In the first section the chapters focus on the history of deep underground injection as well regulatory issues, future trends and risk analysis. The next section contains ten chapters dealing with well testing and hydrologic modeling. Section 3, consisting of five chapters, addresses various aspects of the chemical processes affecting the fate of the waste in the subsurface environment. Consideration is given here to reactions between the waste and the geologic medium, and reactions that take place within the waste stream itself. The remaining four sections deal with experience relating to injection of, respectively, liquid wastes, liquid radioactive wastes in Russia, slurried solids, and compressed carbon dioxide. Chapters in Section 4, cover a diverse range of other issues concerning the injection of liquid wastes including two that deal with induced seismicity. In Section 5, Russian scientists have contributed several chapters revealing their knowledge and experience of the deep injection disposal of high-level radioactive liquid processing waste. Section 6 consists of five chapters that cover the technology surrounding the injection disposal of waste slurries. Among the materials considered are drilling wastes, bone meal, and biosolids. Finally, four chapters in Section 7 deal with questions relating to carbon dioxide sequestration in deep sedimentary aquifers. This subject is particularly topical as nations grapple with the problem of controlling the buildup of carbon dioxide in the atmosphere.* Comprehensive coverage of the state of the art in underground injection science and technology* Emerging subsurface waste disposal technologies* International scope
Download or read book SPE Reservoir Evaluation Engineering written by and published by . This book was released on 2002 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrocarbon Seal Quantification written by A.G. Koestler and published by Elsevier. This book was released on 2002-04-29 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains 17 selected papers reflecting the flavour of the Norwegian Petroleum Society conference on hydrocarbon seals quantification and showing the recent significant advances in the understanding and application of hydrocarbon seal methodologies.Three broad categories are covered in this book: methodologies addressing cap-rock integrity, methodologies relating to fault seal and case studies both from the hydrocarbon basins of Northwestern Europe and in the form of outcrop examples. With the North Sea, Norwegian Sea and Atlantic Margin moving along their respective basin maturity and development curves, exploration is being forced deeper into high pressure/high temperature terrains, while exploitation and development requires greater precision and realism in reservoir simulations to maximise drilling strategies to prolong field life. In all instances the need for predictive tools and methodologies that address the integrity and behaviour of top and lateral (fault) seals to hydrocarbon traps, both in the static and dynamic state, have been identified as key risk factors and this is reflected in this volume.
Download or read book Global Geothermal Resources written by Geothermal Resources Council. Annual Meeting and published by . This book was released on 1999 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:
