Title: |
Fracture Stimulation in Enhanced Geothermal Systems |
Author: |
Mark W. McClure |
Year: |
2009 |
Degree: |
MS |
Adviser: |
Horne |
File Size: |
1.7 MB |
View File: |
|
Access Count: |
1354 |
Abstract:
Enhanced Geothermal Systems (EGS) are geothermal reservoirs formed by hydraulic stimulation of low permeability rock. In faulted crystalline formations, the mechanism of stimulation is induced shear on preexisting fractures, which increases their transmissibility by orders of magnitude.
The processes that create fractured rock are discussed from the perspective of geology and rock mechanics. The European EGS project at Soultz-sous-Forêts, France is used as a case study of an EGS project. The focus is developing a solid conceptual understanding of the mechanism of hydraulic stimulation.
The second half of the report is concerned with stimulation modeling. Computer modeling offers tremendous power to describe the process of stimulation. It is argued that discrete fracture modeling, as opposed to an effective continuum, is the best approach for modeling EGS stimulation. This report lays out in detail how to construct a discrete fracture EGS stimulation model. Topics include geometry of the preexisting fractures, mass and energy transport, elastostatics (including the Displacement Discontinuity method), Coulomb frictional failure, and thermoelasticity. Finite difference, boundary element, and analytical approximations are applied where appropriate.
Applications of EGS stimulation modeling are numerous. They include (1) investigation of novel strategies for stimulation design, (2) optimization of wellbore orientation and spacing, (3) prediction of thermal breakthrough, (4) sensitivity study on the effect of different parameters, (5) prediction of intensity and location of microseismic events, (6) identification of geological settings that are advantageous for EGS.
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Copyright 2009, Mark W. McClure: Please note that the reports and theses are copyright to their original authors. Authors have given written permission for their work to be made available here. Readers who download reports from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the author, Mark W. McClure.
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