Fracturing-hydraulic coupling in transversely isotropic rocks and a case study on CO2 sequestration

Abstract

This paper outlines a two-dimensional displacement discontinuity method (DDM) for transversely isotropic elastic materials and a direction-dependent criterion for fracturing in anisotropic rocks. These are combined to analyse fracturing processes in transversely isotropic rocks. The fracturing analysis is then coupled with equations for fluid flow in fractures to study the interactions of the fluid flow and rock mass deformation. These functionalities have been implemented into an existing computing code FRACOD.We describe results from application of the fracturing-hydraulic coupling model for transversely isotropic rocks in a detailed case study of a CO2 geo-sequestration project in Australia. Existing fault re-activation and the cap-rock stabilities have been studied in detail. Modelling predicts that the site is stable under the injection conditions and this agrees with other simulations and site monitoring data.