Download or read book A Study of Fracturing and Heat Transfer in Enhanced Geothermal Systems written by Seth Lorenzo Craig and published by . This book was released on 2016 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heat Transfer Investigations for Optimal Harnessing of Enhanced Geothermal Systems written by Esuru Rita Okoroafor and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhanced Geothermal Systems (EGS) offer the opportunity of exploiting the vast energy resources contained in hot impermeable rocks. In such rocks, the natural flow capacity of the system may not be sufficient to support adequate geothermal applications until it is enhanced by opening up existing fractures and propagating new fractures. Cold fluid is injected into the reservoir to exploit the energy resource, whose permeability has been enhanced. The increased permeability allows the fluid to circulate through the opened fractures to production or extraction well(s), thereby capturing and transporting the heat contained in the hot impermeable rock for power generation. Accurate prediction of the thermal performance of EGS depends on an understanding of how the heat transport is affected by the presence of the fracture(s) -- the primary flow conduit of EGS. These fractures may have aperture variability that could create channels and alter flow paths, affecting the availability of surface area for heat transfer. The overall goal of this study was to understand the fracture topology, investigate how it can impact flow and heat transport, and demonstrate ways Enhanced Geothermal Systems can be harnessed to optimize thermal performance. To achieve the goal of this study, a systematic fracture characterization approach was used, and numerical simulation models were used to study the physical processes that govern the interaction between the fluid and the rock during heat extraction from Enhanced Geothermal Systems. Using variogram modeling and Sequential Gaussian Simulation method, fracture apertures representing actual fractures were generated for lab-scale and field-scale investigations. Fracture characterization metrics such as the Joint Roughness Coefficient (JRC) and Hurst exponent were used in analyzing the data. Geometric anisotropy was a vital character of the generated fracture aperture distributions, which was seen to originate from the process of shearing or slip. Flow and heat transport relative to the direction of fracture shear was studied, with the perpendicular flow configuration being perpendicular to the direction of fracture shear. In contrast, the parallel flow configuration had flow in the same direction as the fracture shear direction. It was demonstrated in this study that the flow wetted surface area had a direct and significant contribution to the amount of heat extracted. For the lab-scale fractures, the JRC confirmed geometric anisotropy of the fracture aperture and was seen to have a direct correlation with the flow contact area. The lower the difference in JRC values between the perpendicular and parallel flow configurations, the more flow contact area expected in the perpendicular flow direction, which will lead to more heat extracted from the rock. From the variogram model parameters, it was deduced that high geometric anisotropy results in high differences in thermal drawdown and consequently a high difference in energy extracted. The thermal performance appeared to be better in the perpendicular flow configuration with a ratio of 70:30 for the lab-scale fractures. For the field-scale fractures, it was seen that most of the fracture aperture distributions with a geometric anisotropy ratio of 2 had Hurst exponents of fracture surface aperture variability found in nature. For all the fracture aperture distributions analyzed for the field scale, the perpendicular flow configuration resulted in better thermal performance than the parallel flow configuration with a ratio of 58:42. Furthermore, for the geometric anisotropy ratio of 2, the ratio was 70:30. The perpendicular flow configuration had the injected fluid move through tortuous flow paths. These tortuous flow paths contributed to more fracture surface area being contacted by the flowing fluid, leading to an improved thermal performance in that flow configuration. Throughout this study, temperature-dependent viscosity was used. However, a section of this study investigated the impact of using a constant viscosity in the thermohydraulic model. It was seen that for fractures with smooth, uniform apertures, for all temperature ranges and at the operating conditions being modeled, there was no significant difference between using a constant viscosity or a temperature-dependent viscosity in modeling an Enhanced Geothermal System. However, for fractures with spatial variations, it was determined that modeling with a temperature-dependent viscosity was necessary, especially for systems with high differences in reservoir and injection temperatures, and for fractures with high correlation lengths. The impact of thermal stresses on heat extraction was also investigated. An analog Enhanced Geothermal System, the Altona Field Laboratory, was also studied for thermo-mechanical influences. It was found out that the injection of hot water into the cold rock resulted in thermal stress generation and reduction in the aperture but did not cause significant changes to the temperature profile due to the small volumetric flow rate through the system. Also, anisotropic aperture distributions were studied to determine the impact of thermoelasticity on the heat extraction of Enhanced Geothermal Systems. It was shown that when thermoelasticity is taken into consideration, the thermal drawdown could either be improved or deteriorated depending on the nature of the aperture distribution. The impact of fracture aperture variability was investigated for Enhanced Geothermal Systems using supercritical CO2 as working fluids. It was established that CO2 as an EGS working fluid would result in better heat extracted from the system if the fractures are considered smooth, which agrees with related studies. However, where there is spatial variation in the fracture aperture, channeling could be detrimental to CO2, especially at high fracture correlation lengths and high mass flow rates, due to the high mobility of CO2. The following are the main contributions from this study. First, it has been demonstrated that heat transport is affected by the geometric anisotropy of fracture surfaces. It was determined that in most cases, flowing perpendicular to the direction of shear or slip results in more heat extracted due to more contact of the fluid with the rock while moving through tortuous flow paths. Secondly, the conditions under which a constant viscosity can be used in modeling EGS were determined. If the fractures are known to be smooth, have low correlation lengths, or have distributed surface areas, a constant viscosity can be used in the model, especially if the difference between the reservoir temperature and the injection water temperature is small. However, for anisotropic fracture surfaces, surfaces with high correlations lengths or high tortuosity, and when the difference between the reservoir temperature and injection water temperature is large, the use of constant viscosity could result in significant computational errors from the actual. Thirdly, it has been shown that thermal drawdown could either be improved or deteriorate when thermoelasticity is considered. This finding is different from studies previous studies that have looked into coupling thermohydromechanical processes for fractures with spatial variations and suggests that Enhanced Geothermal Systems may benefit from thermal stimulation. Finally, this work shows the first comparison between CO2 and water at a field scale considering fracture aperture variability. Recommended future work includes modeling of vertical fractures with spatial variations in fracture aperture to investigate how convection may impact the current findings; considering multiple fractures with spatial variations in the fracture aperture; considering non-Darcy flow in the simulation models; coupling geomechanics with the study of CO2 on fractures with spatial variations, and developing proxy models that are quicker to perform the thermohydraulic and thermohydromechanical simulations.
Download or read book Hydraulic fracturing and geothermal energy written by S. Nemat-Nassar and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 519 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic fracturing has been and continues to be a major techno logical tool in oil and gas recovery, nuclear and other waste disposal, mining and particularly in-situ coal gasification, and, more recently, in geothermal heat recovery, particularly extracting heat from hot dry rock masses. The understanding of the fracture process under the ac tion of pressurized fluid at various temperatures is of fundamental scientific importance, which requires an adequate description of thermomechanical properties of subsurface rock, fluid-solid interaction effects, as well as degradation of the host rock due to temperature gradients introduced by heat extraction. Considerable progress has been made over the past several years in laboratory experiments, analytical and numerical modeling, and in-situ field studies in various aspects of hydraulic fracturing and geothermal energy extraction, by researchers in the United States and Japan and also elsewhere. However, the results have been scattered throughout the literature. Therefore, the time seemed ripe for bringing together selected researchers from the two countries, as well as observers from other countries, in order to survey the state of the art, exchange scientific information, and establish closer collaboration for further, better coordinated scientific effort in this important area of research and exploration.
Download or read book Enhanced Geothermal Systems EGS written by Dornadula Chandrasekharam and published by CRC Press. This book was released on 2023-10-02 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: Peter Meisen, Past President, Global Energy Network Institute, asked in 1997, “What if there was an existing, viable technology, that when developed to its highest potential could increase everyone’s standard of living, cut fossil fuel demand and the resultant pollution?” After 23 years of sustained effort by the global scientific community, this is becoming a reality. The technology to extract heat from granite has been revolutionized in the last few years. The classical method of creating fracture networks by hydrofracturing is being replaced by a closed-loop method where fluids are not in contact with the hot granite. Supercritical CO2 is replacing water as a circulating fluid. Certainly, the future energy road is going to be led by highly radiogenic granites. While hydrothermal sources are site-specific and have their limitations, EGS can be initiated anywhere on earth. EGS is removing all such obstacles and, in the future, will provide uninterrupted electricity for all. Energy-deficient countries can have surplus electricity; water-stressed countries can have a perennial freshwater supply; and countries can become food-secure and rise above poverty levels. Countries need not depend on energy imports and can independently evolve into carbon neutral or low carbon societies. The contributions made by experts will help researchers and investors to close the energy demand and supply gap in the very near future by tapping the unlimited energy of the Earth. Opportunities available for investors in Turkey are well documented with field, geophysical, and geochemical data and information on the energy generating capacity of the granite intrusive spread over a cumulative area of 6,910 km2 in western Anatolia. With the signing of the Global Geothermal Alliance (GGA) by several countries during the December 2015 CoP 21 (Conference of Parties) summit in Paris, countries are obliged to reduce CO2 emissions by increasing the footprint of renewable energy in the primary source mix. Information provided in this book will lead the way to establishing a clean energy future for millions of people for sustainable development and help to mitigate crises arising due to food, water, and energy shortage issues. Academic and research institutes will benefit to a large extent from the expertise of the top contributors in this book. This information provided in this book will help to lay the foundation for super-hot EGS research in future.
Download or read book Flow and Heat Transfer in Geothermal Systems written by Aniko Toth and published by Elsevier. This book was released on 2016-10-11 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow and Heat Transfer in Geothermal Systems: Basic Equations for Description and Modeling Geothermal Phenomena and Technologies is the ideal reference for research in geothermal systems and alternative energy sources. Written for a wide variety of users, including geologists, geophysicists, hydro-geologists, and engineers, it offers a practical framework for the application of heat and flow transport theory. Authored by two of the world's foremost geothermal systems experts, whose combined careers span more than 50 years, this text is a one-stop resource for geothermal system theory and application. It will help geoscientists and engineers navigate the wealth of new research that has emerged on the topic in recent years. - Presents a practical and immediately implementable framework for understanding and applying heat and flow transport theory - Features equations for modelling geothermal phenomena and technologies in full detail - Provides an ideal text for applications in both geophysics and engineering
Download or read book Geothermal Energy Systems written by Ernst Huenges and published by John Wiley & Sons. This book was released on 2011-08-24 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geothermal Energy Systems The book encounters basic knowledge about geothermal technology for the utilization of geothermal resources. The book helps to understand the basic geology needed for the utilization of geothermal energy, shows up the practice to make access to geothermal reservoirs by drilling and the engineering of the reservoir by enhancing methods. The book describes the technology to make use of the Earth?s heat for direct use, power, and/or chill and gives boundary conditions for its economic and environmental utilization. A special focus is made on enhanced or engineered geothermal systems (EGS) which are based on concepts which bring a priori less productive reservoirs to an economic use. From the contents: Reservoir Definition Exploration Methods Drilling into Geothermal Reservoirs Enhancing Geothermal Reservoirs Geothermal Reservoir Simulation Energetic Use of EGS Reservoirs Economic Performance and Environmental Assessment Deployment of Enhanced Geothermal Systems plants and CO2-mitigation
Download or read book Heat Mining written by H. Christopher H. Armstead and published by Spon Press. This book was released on 1987 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Very Good,No Highlights or Markup,all pages are intact.
Download or read book Modeling of Heat Extraction from Variably Fractured Porous Media in Enhanced Geothermal Systems written by and published by . This book was released on 2016 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling of heat extraction in Enhanced Geothermal Systems is presented. The study builds on recent studies on the use of directional wells to improve heat transfer between doublet injection and production wells. The current study focuses on the influence of fracture orientation on production temperature in deep low permeability geothermal systems, and the effects of directional drilling and separation distance between boreholes on heat extraction. The modeling results indicate that fracture orientation with respect to the well-pair plane has significant influence on reservoir thermal drawdown. As a result, the vertical well doublet is impacted significantly more than the horizontal well doublet.
Download or read book Geothermal Energy written by Ingrid Stober and published by Springer Science & Business Media. This book was released on 2013-12-03 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The internal heat of the planet Earth represents an inexhaustible reservoir of thermal energy. This form of energy, known as geothermal energy has been utilized throughout human history in the form of hot water from hot springs. Modern utilization of geothermal energy includes direct use of the heat and its conversion to other forms of energy, mainly electricity. Geothermal energy is a form of renewable energy and its use is associated with very little or no CO2-emissions and its importance as an energy source has greatly increased as the effects of climate change become more prominent. Because of its inexhaustibility it is obvious that utilization of geothermal energy will become a cornerstone of future energy supplies. The exploration of geothermal resources has become an important topic of study as geology and earth science students prepare to meet the demands of a rapidly growing industry, which involves an increasing number professionals and public institutions participating in geothermal energy related projects. This book meets the demands of both groups of readers, students and professionals. Geothermal Energy and its utilization is systematically presented and contains the necessary technical information needed for developing and understanding geothermal energy projects. It presents basic knowledge on the Earth’s thermal regime and its geothermal energy resources, the types of geothermal energy used as well as its future potential and the perspectives of the industry. Specific chapters of the book deal with borehole heat exchangers and with the direct use of groundwater and thermal water in hydrogeothermal systems. A central topic are Enhanced Geothermal Systems (hot-dry-rock systems), a key technology for energy supply in the near future. Pre-drilling site investigations, drilling technology, well logging and hydraulic test programs are important subjects related to the exploration phase of developing Geothermal Energy sites. The chemical composition of the natural waters used as a heat transport medium in geothermal systems can be used as an exploration tool, but chemistry is also important during operation of a geothermal power plant because of potential scale formation and corrosion of pipes and installations, which needs to be prevented. Graduate students and professionals will find in depth information on Geothermal Energy, its exploration and utilization.
Download or read book Geoenergy Modeling III written by Norihiro Watanabe and published by Springer. This book was released on 2016-11-10 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on numerical modeling of deep hydrothermal and petrothermal systems in fractured georeservoirs for utilization in Geothermal Energy applications. The authors explain the particular challenges and approaches to modeling heat transport and high-throughput flow in multiply fractured porous rock formations. In order to help readers gain a system-level understanding of the necessary analysis, the authors include detailed examples of growing complexity as the techniques explained in the text are introduced. The coverage culminates with the fully-coupled analysis of real deep geothermal test-sites located in Germany and France.
Download or read book Mining the Earth s Heat Hot Dry Rock Geothermal Energy written by Donald W. Brown and published by Springer Science & Business Media. This book was released on 2012-04-23 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mining the Earth's Heat: Hot Dry Rock Geothermal Energy describes the work carried out by the Los Alamos National Laboratory to turn an idealistic concept - that of drawing useful amounts of energy from the vast underground store of hot rock at reachable depths - into a practical reality. This book provides comprehensive documentation of the over two decades of experiments carried out at the test site at Fenton Hill, New Mexico, where the feasibility of accessing and extracting this vast natural resource was finally demonstrated. It also discusses the numerous technical, administrative, and financial hurdles that had to be overcome along the way. This publication will no doubt prove invaluable to researchers around the world as they strive to move this now-proven technology toward commercial viability. In addition, it is a valuable source of relevant information for anyone interested in the world energy outlook for the 21st century and beyond.
Download or read book Utilization of Thermal Potential of Abandoned Wells written by Younes Noorollahi and published by Academic Press. This book was released on 2022-03-30 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Utilization of Thermal Potential of Abandoned Wells: Fundamentals, Applications and Research is a lucid treatment of the fundamental concepts related to the energy harvesting of abandoned wells. The book provides a journey through recent technological developments to harvest energy from abandoned geothermal wells and allows the reader to view the process from a thermodynamic and numerical modeling perspective. Various applications and future prospects are also discussed to help inform reader's future work and research. Students, researchers and engineers will gain a thorough understanding on how to harvest energy from abandoned geothermal wells, particularly to make sound thermodynamic and economic evaluations. System designers and others engaged in the energy sector will understand how to design and choose the most appropriate technology, how to determine its efficiency, monitor the facility, and how to make informed physical and economical decisions for necessary improvements and environmental assessments. - Logically works through fundamentals, with various examples throughout - Provides instruction to simulate thermodynamic models and design efficient systems - Presents feasibility studies and applications
Download or read book Fully Coupled Geomechanics and Discrete Flow Network Modeling of Hydraulic Fracturing for Geothermal Applications written by and published by . This book was released on 2011 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of our current research is to develop a computational test bed for evaluating borehole techniques to enhance fluid flow and heat transfer in enhanced geothermal systems (EGS). Simulating processes resulting in hydraulic fracturing and/or the remobilization of existing fractures, especially the interaction between propagating fractures and existing fractures, represents a critical goal of our project. To this end, we are continuing to develop a hydraulic fracturing simulation capability within the Livermore Distinct Element Code (LDEC), a combined FEM/DEM analysis code with explicit solid-fluid mechanics coupling. LDEC simulations start from an initial fracture distribution which can be stochastically generated or upscaled from the statistics of an actual fracture distribution. During the hydraulic stimulation process, LDEC tracks the propagation of fractures and other modifications to the fracture system. The output is transferred to the Non-isothermal Unsaturated Flow and Transport (NUFT) code to capture heat transfer and flow at the reservoir scale. This approach is intended to offer flexibility in the types of analyses we can perform, including evaluating the effects of different system heterogeneities on the heat extraction rate as well as seismicity associated with geothermal operations. This paper details the basic methodology of our approach. Two numerical examples showing the capability and effectiveness of our simulator are also presented.
Download or read book Geothermal Energy written by William E. Glassley and published by CRC Press. This book was released on 2011-06-03 with total page 553 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historically, cost effective, reliable, sustainable, and environmentally friendly, use of geothermal energy has been limited to areas where obvious surface features pointed to the presence of a shallow local heat source, such as hot springs and volcanoes. However, recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as modular power generation, home heating, and other applications that can use heat directly. These recent developments have greatly expanded opportunities for utilizing geothermal energy. Reflecting current interest in alternative energy, Geothermal Energy: Renewable Energy and the Environment explores where geothermal energy comes from and how to find it, how it can be accessed, successful applications, and improvements for future uses. The author reviews the background, theory, power generation, applications, strengths, weaknesses, and practical techniques for implementing geothermal energy projects. He stresses the links between acquisition and consumption and the environment. Packed with real world case studies and practical implementation steps, the book covers geosciences principles, exploration concepts and methods, drilling operations and techniques, equipment needs, and economic and environmental topics. Each chapter includes an annotated list of key sources that provide useful information beyond that contained in the text. The minor environmental impacts caused by geothermal energy gives it the potential to play an important role in the transition from fossil fuels to more sustainable fuels. Successful deployment, however, requires that the resource be matched to the application being developed. Rigorously covering all aspects of geothermal energy, this book provides up-to-date scientific information that can be used to discern applications and regions best suited for geothermal energy. Author William E. Glassley was recently interviewed on The Kathleen Show about using geothermal energy to heat and cool our homes.
Download or read book Thermomechanical Analysis of Rock Asperity in Fractures of Enhanced Geothermal Systems written by Chao Zeng and published by . This book was released on 2019 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Enhanced Geothermal Systems (EGS) offer great potential for dramatically expanding the use of geothermal energy and become a promising supplement for fossil energy. The EGS is to extract heat by creating a subsurface system to which cold water can be added through injection wells. Injected water is heated by contact with rock and returns to the surface through production well. Fracture provides the primary conduit for fluid flow and heat transfer in natural rock. Fracture is propped by fracture roughness with varying heights which is called asperity. The stability of asperity determines fracture aperture and hence imposes substantial effect on hydraulic conductivity and heat transfer efficiency in EGS. Firstly, two rough fracture surfaces are characterized by statistical method and fractal analysis. The asperity heights and enclosed aperture heights are described by probability density function before cold water is pumped into fracture. Secondly, when water injection and induced cooling occurs, the thermomechanical analysis of single asperity is studied by establishing an un-symmetric damage mechanics model. The deformation curve of asperity under thermal stress is determined. Thirdly, deformation of fracture with various asperities on it in response to thermal stress is analyzed by a new stratified continuum percolation model. This model incorporates the fracture surface characteristics and preceding deformation curve of asperity. The fracture closure and fracture stiffness can be accurately quantified by this model. In addition, the scaling invariance and multifractal parameters in this process are identified and validated with Monte Carlo simulation"--Abstract, page iii.
Download or read book Crustal Permeability written by Tom Gleeson and published by John Wiley & Sons. This book was released on 2016-11-30 with total page 557 pages. Available in PDF, EPUB and Kindle. Book excerpt: Permeability is the primary control on fluid flow in the Earth’s crust and is key to a surprisingly wide range of geological processes, because it controls the advection of heat and solutes and the generation of anomalous pore pressures. The practical importance of permeability – and the potential for large, dynamic changes in permeability – is highlighted by ongoing issues associated with hydraulic fracturing for hydrocarbon production (“fracking”), enhanced geothermal systems, and geologic carbon sequestration. Although there are thousands of research papers on crustal permeability, this is the first book-length treatment. This book bridges the historical dichotomy between the hydrogeologic perspective of permeability as a static material property and the perspective of other Earth scientists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions.
Download or read book Geothermal Energy written by William E. Glassley and published by CRC Press. This book was released on 2014-10-13 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: An In-Depth Introduction to Geothermal Energy Addressing significant changes in the energy markets since the first edition, Geothermal Energy: Renewable Energy and the Environment, Second Edition expounds on the geothermal industry, exploring the expansion, growth, and development of geothermal systems. This text covers every area of geothermal energy, including environmental and economic issues, and technological advancements. Considers the Vast Technological Achievements within the Geothermal Industry Factoring in new concepts for distributed generation, hybrid technologies, and the development of Enhanced Geothermal Systems (EGS), the book incorporates real-world examples designed to illustrate the key aspects of chapter topics. It provides case studies in nearly every chapter, and includes examples from the U.S., Iceland, France, and Japan. Contains comprehensive, quantitative, and rigorous treatment of the geology, geochemistry, and geophysics of geothermal resources, and how they impact exploration, resource assessment, and operations Provides a state-of-the-art description of current Enhanced Geothermal Systems (EGS) Presents an objective description of the most recent economic comparisons including all energy resources Covers environmental issues of energy use and quantitative descriptions of the relative impacts of all renewable and non-renewable energy resources Describes geothermal resources from a global perspective, including direct use and geothermal heat pump applications, as well as power production Geothermal Energy: Renewable Energy and the Environment, Second Edition can be used for undergraduate coursework; as a reference for designers, planners, engineers, and architects; and as a source of background material for policymakers, investors, and regulators.
