| Title | Seismic Mapping and Geomechanical Analyses of Faults Within Deep Hot Granites, a Workflow for Enhanced Geothermal System Projects |
|---|---|
| Authors | Hani ABUL KHAIR, Martin HAND, Dennis COOKE |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | Enhanced Geothermal System, Curvature, Seismic, Fault and fracture network, Geomechanics. |
| 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 due to granitic or granodioritic bodies. 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. In this study we investigated the use of 3D seismic amplitudes and attributes to map deep granitic bodies and faults. We established a workflow for possible geomechanical fluid flow susceptibility analyses for faults that intersect granites. Far field stress tensor must be interpreted through analyses of image logs and formation tests. Our geomechanical analyses procedure models how this stress tensor affects basement faults interpreted from 3D seismic. Normal stresses, shear stresses, slip tendency, and distance to failure should be modelled for the faults that cut the granites. Optimal orientation of faults that can be possible conduits are then located if the faults are not sealed. 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, we generated a workflow to evaluate the relative merit of future enhanced geothermal systems projects. |