Challenges of CO2EOR Design for a Triple Porosity Reservoir in Sub-Miscible Conditions

Abstract This paper illustrates the challenges in designing carbon dioxide (CO2) injection on a triple porosity reservoir with partial/limited data for reservoir & fluid characterization. Conductive faults coupled with unfavorable miscibility conditions add significant complexity to an already challenging system. Developing predictive finite-difference reservoir simulation models incorporating complex recovery physics to design CO2Enhanced oil recovery (CO2EOR) implementation, including a CO2Pilot design, was the scope of this project. This paper outlines the comprehensive design for a full cycle CO2 development, culminating in an ongoing CO2 field pilot. We start reviewing reservoir performance, heterogeneity, and existing characterization of the reservoir complex, including the presence of different porosity types and its impact on CO2 injection performance. Insights gained from digital-physical core experiments provided significant input on conceptualization of the recovery system in the vuggy environment. A selection process was then done to determine the optimal numerical representation of triple porosity within an otherwise dual or composite finite-difference formulation, focusing on the impact on the field injection. It concludes with the results of an on-going CO2 injection pilot specifically designed to address the remaining challenges of the injection.