Analysis of a Complex Faulted CO2 Reservoir Using a Three-dimensional Hydro-geochemical-Mechanical Approach

This work applies a three-dimensional (3D) multiscale approach recently developed by Nguyen et al. (Int. J. Greenhouse Gas Control, 2016, 46:100-115; Greenhouse Gases: Sci. & Technol., DOI: 10.1002/ghg.1616) to analyze a complex CO2 faulted reservoir that includes some key geological features of the San Andreas and nearby faults. The approach couples the STOMP-CO2-R code for flow and reactive transport modeling to the ABAQUS® finite element package for geomechanical analysis. The objective is to examine the coupled hydro-geochemical-mechanical impact on the risk of hydraulic fracture and fault slip in a complex and representative CO2 reservoir that contains two nearly parallel faults. STOMP-CO2-R/ABAQUS® coupled analyses of this reservoir are performed assuming extensional and compressional stress regimes to predict evolutions of fluid pressure, stress and strain distributions as well as potential fault failure and leakage of CO2 along the fault damage zones. The tendency for the faults to slip and pressure margin to fracture are examined in terms of stress regime, mineral composition, crack distributions in the fault damage zones and geomechanical properties. This model in combination with a detailed description of the faults helps assess the coupled hydro-geochemical-mechanical effect.