Lawrence Berkeley National Laboratory

This paper describes and demonstrates the use of the coupled TOUGH-FLAC simulator for geomechanical shear-slip (failure) analysis in multiphase fluid-flow reservoir-engineering applications. Two approaches for analyzing shear-slip are described, one using continuum stress-strain analysis and another using discrete fault analysis. The use of shear-slip analysis in TOUGH-FLAC is demonstrated on application examples related to CO2 sequestration and geothermal energy extraction. In the case of CO2 sequestration, the shear-slip analysis is used to evaluate maximum sustainable CO2-injection pressure under increasing reservoir pressure, whereas in the case of geothermal energy extraction, the shear-slip analysis is used to study induced seismicity during steam production under decreasing reservoir pressure and temperature.