A damage mechanics approach to modeling failure in Greywacke rock

Abstract

Fracture networks within greywacke basement rocks often control fluid flow in geothermal reservoirs in New Zealand. Thermal, hydrological, chemical, and mechanical processes affect the evolution of these fracture networks. Damage mechanics offers a framework that can be used in the numerical modeling of failure and permeability evolution of geothermal rocks. However, no damage mechanics model has been utilized to describe the complex mechanical behavior of greywacke basement rock. In this work, we apply a damage mechanics THM simulation technique to model stress-strain data for greywacke rock from laboratory uniaxial compression and confined compression tests. Calibration of solid mechanics properties for greywacke rock in THM modeling is a necessary step in the simulation of damage and permeability evolution for heat transport in enhanced geothermal systems.