An Integrated Framework for Optimizing CO2 Sequestration and Enhanced Oil Recovery

CO2-enhanced oil recovery (CO2-EOR) is a technique for commercially producing oil from depleted reservoirs by injecting CO2 along with water. Because a large portion of the injected CO2 remains in place, CO2-EOR is an option for permanently sequestering CO2. This study develops a generic integrated framework for optimizing CO2 sequestration and enhanced oil recovery based on known parameter distributions for a depleted oil reservoir in Texas. The framework consists of a multiphase reservoir simulator coupled with geologic and statistical models. An integrated simulation of CO2 - water-oil flow and reactive transport is conducted, followed by a global sensitivity and response surface analysis, for optimizing the CO2-EOR process. The results indicate that the reservoir permeability, porosity, thickness, and depth are the major intrinsic reservoir parameters that control net CO2 injection/storage and oil/gas recovery rates. The distance between injection and production wells and the sequence of alternating CO2 and water injection are the significant operational parameters for designing a five-spot CO2-EOR pattern that efficiently produces oil while storing CO2. The results from this study provide useful insights for understanding the potential and uncertainty of commercial-scale CO2 sequestrations with a utilization component.