Fault Stability Assessment of CO2CRC Otway Project, Australia – A Geomechanical Approach

Abstract

Summary The CO2CRC Otway Project, established in Victoria, Australia in 2005, is the first carbon dioxide pilot project of the southern hemisphere. The main objective of CO2CRC (Cooperative Research Centre for Greenhouse Gas Technologies) is to demonstrate that carbon capture and storage (CCS) is technically and environmentally safe. Among others, factors of risk that could affect geosequestration are represented by fault stability and potential fault reactivation as a response to CO2 injection. Two different approaches have been followed in order to characterize the CO2CRC Otway Project site from a geomechanical point of view. A 3D structural geomechanical model is used to accurately describe the stresses acting in the area of injection and its surrounding, and to assess fault stability in terms of slip and dilatation tendency. Reservoir response to CO2 injection is analysed through a one-way coupled flow and geomechanical simulation, as changes in pressure correspond to changes in effective stress. State of stress on the faults is checked against Mohr-Coulomb failure criterion at different time steps during injection and at different reservoir pressures, respectively.