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Seismic Mapping and Geomechanical Analyses of Faults within Deep Hot Granites, Workflow for Enhanced Geothermal Systems
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 76th EAGE Conference and Exhibition 2014, Jun 2014, Volume 2014, p.1 - 5
Abstract
Areas with deeply seated radioactive granites are considered targets for enhanced geothermal system (EGS) projects. These areas normally exhibit high heat flow and temperature anomaly. High concentration of uranium within the granites is usually the cause of anomalous temperatures. A cover of specific sediments including insulating coals and gas reservoirs combined with high heat flow result in elevated temperatures.
We used 3D seismic amplitudes and attributes to map deep granitic bodies and faults. We conducted geomechanical fluid flow susceptibility analyses for faults that intersect granites. Far field stress tensor was interpreted through analyses of image logs and formation tests. Our geomechanical analyses procedure models how this stress tensor affects basement faults. Normal stresses, shear stresses, slip tendency, and distance to failure were modelled for the faults that cut the granites. Optimally oriented faults that can be possible conduits are then located. We suggest that the optimal injection and production wells should be located at both tips of shallower faults that still penetrate granites. We anticipate that short horizontally extending faults that are located far from other faults will form a more secure fluid conduit. Finally, this study is a workflow to evaluate the relative merit of future EGS projects.