Abstract

The injection of carbon dioxide (CO2) in the subsurface is one of the many possible solutions to address the increasing concentration of greenhouse gases (GHG) in the atmosphere. Saline aquifer reservoirs present substantial storage capacities for trapping CO2 that would have otherwise entered the atmosphere. Long-term integrity and practical storage of CO2 are contingent on seal performance and the dynamic sealing capacity of faults for CO2 storage sites. In this article, the petrophysical and geomechanical properties of a local reservoir in the Cruse formation located in Trinidad are applied to a 2D model using the commercial compositional simulator (CMG-GEM). During the injection of supercritical CO2, the effects on fault reactivation and sensitivities of the resulting change in permeability were modeled to evaluate efficacy of storage and leakage of CO2. The model simulates the opening of a conductive fracture through tensile failure as pore pressure increases under total stress and also the migration of CO2 along the fault using the Barton–Bandis failure criterion. The simulation results show that the effective normal stress decreases extensively, resulting in tensile failure in which the rock is in effect being separated on grain-level creating channels and increasing permeability along the fault. In this model, the storage of CO2 was quantified by starting the injection rate from 500 and increased in increments of 100, up to 1,000 scf/day. Fault reactivation of the saline aquifer caused by pressurization by the injection of supercritical CO2 is observed. The model showed that no leakage to surface occurred over 1,000 years.