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Reinjection Model Studies In Fractured And Homogeneous Geothermal Systems
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Book Synopsis Reinjection Model Studies in Fractured and Homogeneous Geothermal Systems by :
Download or read book Reinjection Model Studies in Fractured and Homogeneous Geothermal Systems written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reinjection of geothermal waste waters has become an important topic of interest for industry as well as for research. The environmental concerns due to chemical composition of geothermal waste waters had urged the industry to dispose it underground. In several field applications no interference due to thermal front breakthrough was observed on the other hand some cases are reported where reinjection had caused severe declines in energy production due to unexpected breakthrough of injected water. Several analytical and numerical studies are available where the effect of fractures on the movement of thermal front are discussed. It was shown that when the conduction heat transfer from matrix to fracture dominates, retardation of the thermal front movement will be observed. Bodvarsson and Pruess considered the above problem in a five-spot well pattern. They observed as the amount of fluid injected reaches the amount produced, the long-term energy output of the system increases. Pruess in his study compares the behavior of porous medium and fractured medium in terms of pressure decline due to production. Temperature and pressure profiles are presented between an injector and a producer where heating of the injected water in porous medium and in fractured medium with small fracture spacing was high compared to a larger fracture spacing. Such observations from the numerical studies were checked against some limited field examples. However understanding of the injection effects in fractured reservoirs is limited. This work presents the results of laboratory experiments where effects of reinjection on temperature and pressure behavior of a porous medium and a fractured medium were investigated. The porous medium was a crushed limestone pack, with 10 mm average particle size, packed in a 3-D box model where injection and production ports are located on the diagonal ends simulating a five-spot pattern. The fractured medium was made from uniformly cut marble blocks packed in such a way to permit uniform fracture geometry. The pressure and temperature response of both models are analyzed as a function of (1) depth of injection and production; and (2) injection rate where 20 C injection water is injected into 110 C reservoir.
Book Synopsis Geothermal Reservoir Engineering by : E. Okandan
Download or read book Geothermal Reservoir Engineering written by E. Okandan and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the oil crisis of 1973, we suddenly became aware that fossil fuel resources are limited and will be exhausted soon if new alternatives are not put into use immediately. Conservation measures and extensive research on new sources of energy has eased the demand on fossil fuels, especially crude oil. Geothermal energy as an alternative; source had its share in this devel opment and electricity producing capacity increased from 700 to 4700 MWe during 1970 to 1985. Geothermal reservoir engineering emerged as an impor tant field in the assessment of geothermal sources. During the 25 years of its development, several areas were identified that needed further at tention for the correct description and interpretation of reservoir be havior. This fact as accepted by all operators is vital for the steady and continuous operation of power plants. During this NATO ASI, a detailed review of theory and field case his tories on geothermal reservoir engineering was presented. In understanding .the reservoir, conceptual models, natural state models, well bore measure ments, transient and tracer testing provide data which are indispensable. They are powerful tools in understanding reservoir behavior provided we know how to interpret them. During lectures the theory and practical applications of these interpretive methods were discussed.
Download or read book Workshop Report written by and published by . This book was released on with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fracture Propagation and Permeability Change Under Poro-thermoelastic Loads & Silica Reactivity in Enhanced Geothermal Systems by :
Download or read book Fracture Propagation and Permeability Change Under Poro-thermoelastic Loads & Silica Reactivity in Enhanced Geothermal Systems written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Therefore, knowledge of the conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fractures are created in the reservoir using hydraulic fracturing. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result, it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have developed advanced poro-thermo-chemo-mechanical fracture models for rock fracture research in support of EGS design. The fracture propagation models are based on a regular displacement discontinuity formulation. The fracture propagation studies include modeling interaction of induced fractures. In addition to the fracture propagation studies, two-dimensional solution algorithms have been developed and used to estimate the impact of pro-thermo-chemical processes on fracture permeability and reservoir pressure. Fracture permeability variation is studied using a coupled thermo-chemical model with quartz reaction kinetics. The model is applied to study quartz precipitation/dissolution, as well as the variation in fracture aperture and pressure. Also, a three-dimensional model of injection/extraction has been developed to consider the impact poro- and thermoelastic stresses on fracture slip and injection pressure. These investigations shed light on the processes involved in the observed phenomenon of injection pressure variation (e.g., in Coso), and allow the assessment of the potential of thermal and chemical stimulation strategies.
Book Synopsis Numerical and Analytical Modeling of Heat Transfer Between Fluid and Fractured Rocks by : Wei Li (S.M.)
Download or read book Numerical and Analytical Modeling of Heat Transfer Between Fluid and Fractured Rocks written by Wei Li (S.M.) and published by . This book was released on 2014 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling of heat transfer between fluid and fractured rocks is of particular importance for energy extraction analysis in EGS, and therefore represents a critical component of EGS design and performance evaluation. In conventional fracture dominated geothermal systems with reinjection, this modeling process is also helpful for understanding how the thermal front migrates and for optimizing of reservoir management strategies. Both numerical and analytical approaches are used to help us get a better understanding of the heat transfer process between the fluid and the fractured rocks in a geothermal reservoir. In the numerical approach, a stochastic discrete fracture network model, GEOFRAC, is used to generate a fracture network. GEOFRAC-FLOW, is used to calculate the flow path in the fracture network and flow rate in each fracture. On the basis of the two, a heat transfer model, GEOFRAC-THERMAL, is developed. Parametric studies with the three models are conducted to analyze the sensitivity of the parameters. A case study with the three models on the Fenton Hill project is conducted to demonstrate the capability of the three models in modeling the heat and mass transfer in the geothermal reservoir. In the analytical approach, a conceptual geothermal reservoir model is introduced. The heat transfer process in the fluid and the fractured rock is formulated based on energy conservation. With the assumption of uniform rock temperature, the 0-D solution is obtained. Parametric studies and case study on the Fenton Hill project are conducted with the 0-D solution. With the assumption of heat conduction happening only in the transverse direction of the rock, the 1-D solution is obtained. Parametric studies are conducted with the 1 -D solution and useful conclusions are obtained. A simply configured heat transfer problem is used to compare the results of the finite element analysis and the 1-D solution. The effect of the simplification in the 1 -D solution is analyzed based on the comparison.
Book Synopsis Geothermal Reservoir Engineering by : Malcolm Alister Grant
Download or read book Geothermal Reservoir Engineering written by Malcolm Alister Grant and published by Academic Press. This book was released on 2011-04-01 with total page 379 pages. Available in PDF, EPUB and Kindle. Book excerpt: As nations alike struggle to diversify and secure their power portfolios, geothermal energy, the essentially limitless heat emanating from the earth itself, is being harnessed at an unprecedented rate. For the last 25 years, engineers around the world tasked with taming this raw power have used Geothermal Reservoir Engineering as both a training manual and a professional reference. This long-awaited second edition of Geothermal Reservoir Engineering is a practical guide to the issues and tasks geothermal engineers encounter in the course of their daily jobs. The book focuses particularly on the evaluation of potential sites and provides detailed guidance on the field management of the power plants built on them. With over 100 pages of new material informed by the breakthroughs of the last 25 years, Geothermal Reservoir Engineering remains the only training tool and professional reference dedicated to advising both new and experienced geothermal reservoir engineers. - The only resource available to help geothermal professionals make smart choices in field site selection and reservoir management - Practical focus eschews theory and basics- getting right to the heart of the important issues encountered in the field - Updates include coverage of advances in EGS (enhanced geothermal systems), well stimulation, well modeling, extensive field histories and preparing data for reservoir simulation - Case studies provide cautionary tales and best practices that can only be imparted by a seasoned expert
Book Synopsis Injection and Energy Recovery in Fractured Geothermal Reservoirs by : Lawrence Berkeley Laboratory
Download or read book Injection and Energy Recovery in Fractured Geothermal Reservoirs written by Lawrence Berkeley Laboratory and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical studies of the effects of injection on the behavior of production wells completed in fractured two-phase geothermal reservoirs are presented. In these studies the multiple-interacting-continua (MINC) method is employed for the modeling of idealized fractured reservoirs. Simulations are carried out for a five-spot well pattern with various well spacings, fracture spacings, and injection fractions. The production rates from the wells are calculated using a deliverability model. The results of the studies show that injection into two-phase fractured reservoirs increases flow rates and decreases enthalpies of producing wells. These two effects offset each other so that injection tends to have small effects on the usable energy output of production wells in the short term. However, if a sufficiently large fraction of the produced fluids is injected, the fracture system may become liquid-filled and an increased steam rate is obtained. Our studies show that injection greatly increases the long-term energy output from wells, as it helps extract heat from the resrvoir rocks. If a high fraction of the produced fluids is injected, the ultimate energy recovery will increase manyfold.
Book Synopsis Injection and Energy Recovery in Fractured Geothermal Reservoirs by : Lawrence Berkeley Laboratory
Download or read book Injection and Energy Recovery in Fractured Geothermal Reservoirs written by Lawrence Berkeley Laboratory and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings Geothermal Program Review XV by :
Download or read book Proceedings Geothermal Program Review XV written by and published by . This book was released on 1997 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Rock Fractures and Fluid Flow by : National Research Council
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Book Synopsis Physical Model Studies of Explosion-Fractured Geothermal Reservoirs by :
Download or read book Physical Model Studies of Explosion-Fractured Geothermal Reservoirs written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Large scale utilization of geothermal energy will require means for enhanced energy extraction from geothermal reservoirs since the higher quality hydrothermal resources adequate for commercial electricity generation represent only a small fraction of the estimated resource base. Technologies are being developed for artificial fracturing of hydrothermal and dry hot rock geothermal resources to obtain adequate permeability for water circulation and to expose new rock surface area. Non-isothermal processes such as in-place boiling or artificial circulation of cooler fluids can be used to extract the energy from the fractured formation. To evaluate non-isothermal heat transfer processes, physical model studies were conducted in the Stanford Geothermal Program fractured-rock reservoir model capable of operating at a maximum pressure of 800 psig at 500oF. The 17-ft3 physical model has been described previously [Hunsbedt, Kruger, and London (1975), Hunsbedt (1975), and Hunsbedt, Kruger and London (1976)]. A summary of the characteristics of the relatively large fracture-permeability rock systems tested in the model are summarized in Table 1. The porosity and permeability characteristics of these systems resembled those of fracture-stimulated ones created by high-energy explosives. 1 tab., 4 refs., 2 figs.
Book Synopsis Some Mismatches Occurred when Simulating Fractured Reservoirs as Homogeneous Porous Media by :
Download or read book Some Mismatches Occurred when Simulating Fractured Reservoirs as Homogeneous Porous Media written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The understanding of transport processes that occur in naturally fractured geothermal systems is far from being complete. Often, evaluation and numerical simulations of fractured geothermal reservoirs, are carried out by assuming equivalent porous media and homogeneous petrophysical properties within big matrix blocks. The purpose of this paper, is to present a comparison between results obtained from numerical studies of a naturally fractured reservoir treated as a simple porous medium and the simulation of some real aspects of the fractured reservoir. A general conclusion outlines the great practical importance of considering even approximately, the true nature of such systems. Our results show that the homogeneous simplified evaluation of the energy resource in a fractured system, could result in unrealistic estimates of the reservoir capacity to generate electricity.
Book Synopsis Injection Technology by : Jesús Rivera
Download or read book Injection Technology written by Jesús Rivera and published by . This book was released on 1995 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Application of Thermal Depletion Model to Geothermal Reservoirs with Fracture and Pore Permeability by :
Download or read book Application of Thermal Depletion Model to Geothermal Reservoirs with 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: The useful lifetime of a geothermal resource is usually calculated by assuming fluid will be produced from and reinjected into a uniform porous medium. However, most geothermal systems are found in fractured rock. If the reinjection and production wells intersect connected fractures, then reinjected fluid may cool the production wells much sooner than would be predicted from calculations of flow in a porous medium. We have developed a "quick and dirty" method for calculating how much sooner that cooling will occur (Kasameyer and Schroeder, 1975, 1976). In this paper, we discuss the basic assumptions of the method, and show how it can be applied to the Salton Geothermal Field, the Raft River System, and to reinjection of supersaturated fluids. 6 refs., 6 figs.
Book Synopsis Federal Geothermal Research Program Update, Fiscal Year 1995 by : Geothermal Research Program (U.S.)
Download or read book Federal Geothermal Research Program Update, Fiscal Year 1995 written by Geothermal Research Program (U.S.) and published by . This book was released on 1996 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fracture Characterization in Enhanced Geothermal Systems by Wellbore and Reservoir Analysis by :
Download or read book Fracture Characterization in Enhanced Geothermal Systems by Wellbore and Reservoir Analysis written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report highlights the work that was done to characterize fractured geothermal reservoirs using production data. That includes methods that were developed to infer characteristic functions from production data and models that were designed to optimize reinjection scheduling into geothermal reservoirs, based on these characteristic functions. The characterization method provides a robust way of interpreting tracer and flow rate data from fractured reservoirs. The flow-rate data are used to infer the interwell connectivity, which describes how injected fluids are divided between producers in the reservoir. The tracer data are used to find the tracer kernel for each injector-producer connection. The tracer kernel describes the volume and dispersive properties of the interwell flow path. A combination of parametric and nonparametric regression methods were developed to estimate the tracer kernels for situations where data is collected at variable flow-rate or variable injected concentration conditions. The characteristic functions can be used to calibrate thermal transport models, which can in turn be used to predict the productivity of geothermal systems. This predictive model can be used to optimize injection scheduling in a geothermal reservoir, as is illustrated in this report.
