Effects of Rock Mechanical Behaviors and Silica Precipitations on the Permeability Development in High-Temperature Granitic Rock Bodies: Numerical Studies

Abstract

Recent laboratory experiments suggest that, at very high-temperature conditions, the permeability of a granitic rock can significantly be affected by rock mechanical behaviors and geochemical reactions, namely the brittle-ductile transition, the elastic-plastic transition, and silica precipitations. A better understanding of spatial and temporal permeability development in high-temperature granitic rocks is desired for the exploration of supercritical geothermal resources in the continental crust. In this study, we numerically investigated effects of those mechanisms on the permeability development in the high-temperature granitic rock bodies. The simulations were conducted with the multiphase flow simulator HYDROTHERM which we extended to include the new stress-dependent permeability models and silica reactive transport modeling. Current results indicate that the mechanical behaviors may play a dominant role in the permeability development and subsequently control the formation of supercritical geothermal resources in granitic rocks.