A comprehensive review of the potential of rock properties alteration during CO2 injection for EOR and storage

Abstract

Enhanced oil recovery (EOR) by carbon dioxide (CO2) injection is a critical technique in the decarbonization process of the world. This method involves injecting CO2 into existing hydrocarbon reservoirs to increase oil recovery. CO2-EOR has been used as a tertiary oil recovery technique for many years, and it has proven to be effective in enhancing oil recovery while reducing greenhouse gas emissions since the reservoir could serve as permanent storage site for CO2 sequestration. The composition of CO2 allows it to dissolve in crude oil, reducing its viscosity and promoting hydrocarbon flow. However, when CO2 is injected into the reservoirs, it can react with the rock minerals and water, leading to the alteration of petrophysical properties of the hydrocarbon reservoirs. The precipitation of certain minerals can lead to pore blockage in the reservoir formation, which could reduce the performance of the CO2-EOR injection process and the integrity of the reservoir for storage. The complex nature of the tight pore throat of hydrocarbon reservoirs indicates that the pore structure could vary significantly in size from the microscale to the nanoscale, affecting the properties of the reservoir and oil-displacement efficiency. The magnitude of the rock property alteration during CO2 injection has been reported to vary depending on the rock type and injection strategies adopted. Thus, to evaluate the effects of CO2 injection in rocks, laboratory experiments are being used to analyse the processes using core samples, while numerical simulation approaches have also been employed to model the processes of fluid migration from the reservoir to the caprock layer. The dynamics of fault opening and mechanical failure in rocks have also been addressed using coupled thermo-hydro-mechanical-chemical (THMC) processes modelled on different scales. Overall, CO2-EOR and carbon sequestration is an important technique for enhancing oil recovery and reducing greenhouse gas emissions. However, it is essential to prioritize the effects of the CO2 injection on different rock types, pore type, and technology used to achieve efficient results as reviewed in this paper.