A SIMPLIFIED MODEL FOR INJECTION – INDUCED SEISMICITY: AN EVALUATION OF INFLUENCING FACTORS

The proposal of a simplified hybrid Thermo-Hydro-Mechanical model to investigate poroelastic and thermoelastic stresses induced due to water injection and the different parameters affecting their evolution is presented. The operating mode of the numerical model is starting with a set of implicit fractures, with different adjustable random orientations, then an elastic continuum medium is built, and shear and normal effective stresses perturbations, poroelastic and thermoelastic stresses, are calculated and evaluated. Both reversible (pseudo-elastic opening) and irreversible (shear dilation) fracture aperture changes are considered to estimate the equivalent continuum permeability evolution. Seismic events magnitudes are statistically distributed over grid cells according to Gutenberg-Richter magnitude-frequency distribution.