Analytical method for estimating reservoir pressure distribution and fault stability in porous rock during fluid injection

It is a well-known fact that an injection of the borehole fluids into surrounding porous rocks often results in fault reactivation (microseismic activity), such as during hydrocarbon production from a reservoir, fluid injection for enhanced oil recovery, hot dry rock geothermal energy extraction and waste disposal or carbon dioxide sequestration. However, no rigorously derived method for the description of spatial and temporal distribution of seismic events and for the estimation of the critical value of pore pressure of a porous rock sufficient for the generation of an microseismic has ever been developed. Model developed within the context of Biot's theory of poroelasticity is used to obtain the distribution of pore pressure, then the pore pressure is substituted into a Mohr-Coulomb failure criterion to predict the fault stability and the spatio-temporal cluster of microseismic events in a reservoir. In this model, the Biot system of equations is formulated for the radial symmetry case and is supplemented by the relevant boundary conditions, then the solution is constructed analytically.