Study of CO2 injection in a depleted oil reservoir using geomechanically coupled and non-coupled simulation models

Abstract

This study seeks to understand CO2 injection into a depleted reservoir through multiphase fluid flow and geomechanical modeling simulations using field data. A comparison of the one-way geomechanically coupled and non-coupled models is presented. Results suggest that computed fluid pressure response and CO2 distribution in the reservoir are significantly influenced by reservoir geomechanical properties. The non-coupled model shows <50% of CO2 penetration distance and laterally shallower reservoir pressure changes compared to the coupled model after 53 days of injection. However, in the non-coupled model, CO2 concentration is significantly higher at short distances from the injection well compared to the coupled model. This reservoir behavior was attributed to the alteration in relative permeabilities caused by changes in geomechanical properties in the coupled model. Therefore, upon the availability of computing resources, one should use more computationally intensive but accurate models involving two-way-coupling. Finally, accurate determination of engineering properties and proper geological characterization is desirable for meaningful prediction models.