On the Production Behavior of Enhanced Geothermal Systems with CO2as Working Fluid PDF Download
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Languages : en
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Numerical simulation is used to evaluate mass flow and heatextraction rates from enhanced geothermal injection-production systemsthat are operated using either CO2 or water as heat transmission fluid. For a model system patterned after the European hot dry rock experimentat Soultz, we find significantly greater heat extraction rates for CO2 ascompared to water. The strong dependence of CO2 mobility (=density/viscosity) upon temperature and pressure may lead to unusualproduction behavior, where heat extraction rates can actually increasefor a time, even as the reservoir is subject to thermal depletion. Wepresent the first-ever three-dimensional simulations of CO2injection-production systems. These show strong effects of gravity onmass flow and heat extraction, due to the large contrast of CO2 densitybetween cold injection and hot production conditions. The tendency forpreferential flow of cold, dense CO2 along the reservoir bottom can leadto premature thermal breakthrough. The problem can be avoided byproducing from only a limited depth interval at the top of thereservoir.
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Languages : en
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Book Description
Numerical simulation is used to evaluate mass flow and heatextraction rates from enhanced geothermal injection-production systemsthat are operated using either CO2 or water as heat transmission fluid. For a model system patterned after the European hot dry rock experimentat Soultz, we find significantly greater heat extraction rates for CO2 ascompared to water. The strong dependence of CO2 mobility (=density/viscosity) upon temperature and pressure may lead to unusualproduction behavior, where heat extraction rates can actually increasefor a time, even as the reservoir is subject to thermal depletion. Wepresent the first-ever three-dimensional simulations of CO2injection-production systems. These show strong effects of gravity onmass flow and heat extraction, due to the large contrast of CO2 densitybetween cold injection and hot production conditions. The tendency forpreferential flow of cold, dense CO2 along the reservoir bottom can leadto premature thermal breakthrough. The problem can be avoided byproducing from only a limited depth interval at the top of thereservoir.
Author:
Publisher:
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Category :
Languages : en
Pages :
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Book Description
Numerical simulation is used to evaluate mass flow and heatextraction rates from enhanced geothermal injection-production systemsthat are operated using either CO2 or water as heat transmission fluid. For a model system patterned after the European hot dry rock experimentat Soultz, we find significantly greater heat extraction rates for CO2 ascompared to water. The strong dependence of CO2 mobility (=density/viscosity) upon temperature and pressure may lead to unusualproduction behavior, where heat extraction rates can actually increasefor a time, even as the reservoir is subject to thermaldepletion.
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Languages : en
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Book Description
Responding to the need to reduce atmospheric emissions of carbon dioxide, Donald Brown (2000) proposed a novel enhanced geothermal systems (EGS) concept that would use CO2 instead of water as heat transmission fluid, and would achieve geologic sequestration of CO2 as an ancillary benefit. Following up on his suggestion, we have evaluated thermophysical properties and performed numerical simulations to explore the fluid dynamics and heat transfer issues in an engineered geothermal reservoir that would be operated with CO2. We find that CO2 is superior to water in its ability to mine heat from hot fractured rock. CO2 also has certain advantages with respect to wellbore hydraulics, where larger compressibility and expansivity as compared to water would increase buoyancy forces and would reduce the parasitic power consumption of the fluid circulation system. While the thermal and hydraulic aspects of a CO2-EGS system look promising, major uncertainties remain with regard to chemical interactions between fluids and rocks. An EGS system running on CO2 has sufficiently attractive features to warrant further investigation.
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Languages : en
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It has been suggested that enhanced geothermal systems (EGS) may be operated with supercritical CO2 instead of water as heat transmission fluid (D.W. Brown, 2000). Such a scheme could combine recovery of geothermal energy with simultaneous geologic storage of CO2, a greenhouse gas. At geothermal temperature and pressure conditions of interest, the flow and heat transfer behavior of CO2 would be considerably different from water, and chemical interactions between CO2 and reservoir rocks would also be quite different from aqueous fluids. This paper summarizes our research to date into fluid flow and heat transfer aspects of operating EGS with CO2. (Chemical aspects of EGS with CO2 are discussed in a companion paper; Xu and Pruess, 2010.) Our modeling studies indicate that CO2 would achieve heat extraction at larger rates than aqueous fluids. The development of an EGS-CO2 reservoir would require replacement of the pore water by CO2 through persistent injection. We find that in a fractured reservoir, CO2 breakthrough at production wells would occur rapidly, within a few weeks of starting CO2 injection. Subsequently a two-phase water-CO2 mixture would be produced for a few years, followed by production of a single phase of supercritical CO2. Even after single-phase production conditions are reached, significant dissolved water concentrations will persist in the CO2 stream for many years. The presence of dissolved water in the production stream has negligible impact on mass flow and heat transfer rates.
Author: Association of Scientists, Developers and Faculties
Publisher: Association of Scientists, Developers and Faculties
ISBN: 8192974235
Category : Computers
Languages : en
Pages : 183
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Book Description
Proceedings of the combined volumes of International Congress (IntCongress 2014) held at Holiday Inn Silom, Bangkok, Kingdom of Thailand between 19th November, 2014 and 21st November, 2014.
Author: Tushar K. Ghosh
Publisher: Springer Science & Business Media
ISBN: 9400714025
Category : Business & Economics
Languages : en
Pages : 736
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Book Description
This second volume of Energy Resources and Systems is focused on renewable energy resources. Renewable energy mainly comes from wind, solar, hydropower, geothermal, ocean, bioenergy, ethanol and hydrogen. Each of these energy resources is important and growing. For example, high-head hydroelectric energy is a well established energy resource and already contributes about 20% of the world’s electricity. Some countries have significant high-head resources and produce the bulk of their electrical power by this method. However, the bulk of the world’s high-head hydroelectric resources have not been exploited, particularly by the underdeveloped countries. Low-head hydroelectric is unexploited and has the potential to be a growth area. Wind energy is the fastest growing of the renewable energy resources for the electricity generation. Solar energy is a popular renewable energy resource. Geothermal energy is viable near volcanic areas. Bioenergy and ethanol have grown in recent years primarily due to changes in public policy meant to encourage its usage. Energy policies stimulated the growth of ethanol, for example, with the unintended side effect of rise in food prices. Hydrogen has been pushed as a transportation fuel. The authors want to provide a comprehensive series of texts on the interlinking of the nature of energy resources, the systems that utilize them, the environmental effects, the socioeconomic impact, the political aspects and governing policies. Volume 1 on Fundamentals and Non Renewable Resources was published in 2009. It blends fundamental concepts with an understanding of the non-renewable resources that dominate today’s society. The authors are now working on Volume 3, on nuclear advanced energy resources and nuclear batteries, consists of fusion, space power systems, nuclear energy conversion, nuclear batteries and advanced power, fuel cells and energy storage. Volume 4 will cover environmental effects, remediation and policy. Solutions to providing long term, stable and economical energy is a complex problem, which links social, economical, technical and environmental issues. It is the goal of the four volume Energy Resources and Systems series to tell the whole story and provide the background required by students of energy to understand the complex nature of the problem and the importance of linking social, economical, technical and environmental issues.
Author: Dornadula Chandrasekharam
Publisher: CRC Press
ISBN: 1000959945
Category : Science
Languages : en
Pages : 215
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Book Description
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.
Author: Benjamin Loret
Publisher: Springer
ISBN: 3319942174
Category : Technology & Engineering
Languages : en
Pages : 774
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Book Description
This book offers an introduction to the geomechanical issues raised by both the extraction of actual and potential energy resources, and by the treatment of the ensuing environmental concerns. Discussions of the operations of injection of fluids into, and withdrawal from, geological formations link the chapters, each devoted to a particular technical aspect or scientific issue, or to a particular energy resource. Subjects are ordered according to their industrial applications, including enhanced oil and gas recovery, gas hydrates, enhanced geothermal systems, hydraulic fracturing, and carbon dioxide sequestration. An overview of the industrial, research and simulation aspects for each subject is provided. Fluid Injection in Deformable Geological Formations will be of interest to academic and industrial researchers in a wide variety of fields, including computational mechanics, civil engineering, geotechnical engineering and geomechanics, engineering seismology, petroleum engineering, reservoir engineering, and engineering geology.
Author: James H. Biagi
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 75
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Book Description
With rising concerns surrounding CO2 emissions from fossil fuel power plants, there has been a strong emphasis on the development of safe and economical Carbon Capture Utilization and Storage (CCUS) technology. Two methods that show the most promise are Enhanced Gas Recovery (EGR) and Enhanced Geothermal Systems (EGS). In Enhanced Gas Recovery a depleted or depleting natural gas reservoir is re-energized with high pressure CO2 to increase the recovery factor of the gas. As an additional benefit following the extraction of natural gas, the reservoir would serve as a long-term storage vessel for the captured carbon. CO2 based Enhanced Geothermal Systems seek to increase the heat extracted from a given geothermal reservoir by using CO2 as a working fluid. Carbon sequestration is accomplished as a result of fluid losses throughout the life of the geothermal system. Although these technologies are encouraging approaches to help in the mitigation of anthropogenic CO2 emissions, the detailed mechanisms involved are not fully understood. There remain uncertainties in the efficiency of the systems over time, and the safety of the sequestered CO2 due to leakage. In addition, the efficiency of both natural gas extraction in EGR and heat extraction in EGS are highly dependent on the injection rate and injection pressure. Before large scale deployment of these technologies, it is important to maximize the extraction efficiency and sequestration capacity by optimizing the injection parameters. In this thesis, numerical simulations of subsurface flow in EGR and EGS are conducted using the DOE multiphase flow solver TOUGH2 (Transport of Unsaturated Groundwater and Heat). A previously developed multi-objective optimization code based on a genetic algorithm is modified for applications to EGR and EGS. For EGR study, a model problem based on a benchmark-study that compares various mathematical and numerical models for CO2 storage is considered. For EGS study a model problem based on previous studies (with parameters corresponding to the European EGS site at Soultz) is considered. The simulation results compare well with the computations of other investigators and give insight into the parameters that can influence the simulation accuracy. Optimizations for EGR and EGS problems are carried out with a genetic algorithm (GA) based optimizer combined with TOUGH2, designated as GA-TOUGH2. Validation of the optimizer was achieved by comparison of GA based optimization studies with the brute-force run of large number of simulations. Using GA-TOUGH2, optimal time-independent and time-dependent injection profiles were determined for both EGR and EGS. Optimization of EGR problem resulted in a larger natural gas production rate, a shorter total operation time, and an injection pressure well below the fracture pressure. Optimization of EGS problem resulted in a precise management of the production temperature profile, heat extraction for the entire well life, and more efficient utilization of CO2. The results of these studies will hopefully pave the way for future GA-TOUGH2 based optimization studies to improve the modeling of CCUS projects.
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Languages : en
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Book Description
There is growing interest in the novel concept of operating Enhanced Geothermal Systems (EGS) with CO2 instead of water as heat transmission fluid. Initial studies have suggested that CO2 will achieve larger rates of heat extraction, and can offer geologic storage of carbon as an ancillary benefit. Fluid-rock interactions in EGS operated with CO2 are expected to be vastly different in zones with an aqueous phase present, as compared to the central reservoir zone with anhydrous supercritical CO2. Our numerical simulations of chemically reactive transport show a combination of mineral dissolution and precipitation effects in the peripheral zone of the systems. These could impact reservoir growth and longevity, with important ramifications for sustaining energy recovery, for estimating CO2 loss rates, and for figuring tradeoffs between power generation and geologic storage of CO2.
