Ground Heaving and Leakage Analysis for Sequestration of CO2 in Geological Media Considering Fractures in Caprock

Abstract

In the context of Carbon Capture and Storage (CCS), injection of CO2 induces the geomechanical change of reservoir and this is an important issue for the mechanical integrity and storage security of CO2 sequestration. The injection of CO2 makes the fluid pressure increase, and because of this increased fluid pressure, ground heaving occurs. Also the increased fluid pressure is expected to be a source of shear slip of fractures in the caprock, and that makes permeability increase which leads leakage of CO2 and microseismicity. In this study, we conduct coupled multiphase fluid flow and geomechanical modeling to investigate geomechanical changes. After that, we evaluate the probability of shear slip considering the statistical fracture distribution and a Coulomb failure analysis. For this analysis, fracture reactivation in terms of shear slip was analyzed by implicitly considering the fracture orientations generated, in one case using published fracture statistics from a CO2 storage site. Our analysis showed that a reverse faulting stress field would be most favorable for avoiding fracture shear reactivation, but site-specific analyses will be required because of strong dependency of the local stress field and fracture orientations.