A review on mechanisms of CO2-fluid-rock interaction during CO2 injection into carbonate reservoirs

Abstract

CO₂ injection into carbonate reservoirs is regarded as a promising technology for enhanced oil recovery (EOR) and CO₂-emission reduction. Currently, due to the unknown relationships between CO₂ EOR and storage, petrophysical properties and induced formation damage, the application of CO₂ EOR and storage in carbonate reservoirs is still limited. In this work, we comprehensively review the CO₂ injection into carbonates reservoirs for EOR and storage from reservoir characteristics, CO₂-fluid-rock interaction mechanisms and induced changes of petrophysical properties. The in-situ fluid properties and mineralogical characteristics of carbonate reservoirs are first described. The CO₂ storage mechanisms in carbonate reservoirs are addressed, including structural trapping, residual trapping, solubility trapping and mineral trapping. Mechanisms of CO₂-oil interaction and CO₂-fluid-rock interaction are discussed to reveal the performance of CO₂ EOR in carbonate reservoirs. Variations in petrophysical properties of carbonate reservoirs obtained from the published experimental and numerical simulations are reported during CO₂ injection in this review. Meanwhile, formation damage issues caused by CO₂-fluid-rock interaction in heterogeneous and homogeneous carbonate reservoirs are highlighted, referring to mineral precipitation, fine detachment and migration, which have the negative effects on CO₂ EOR. Finally, the future challenges of CO₂ injection into carbonate reservoirs are pointed out, mainly including CO₂-fluid-rock interaction mechanisms with complex mineral compositions, and formation damage control during CO₂ injection. This review provides the significant sights into the CO₂-fluid-rock interaction mechanisms and its effect on reservoir characteristics, in a manner the reader can use for future work on technology optimization for CO₂ EOR and storage in carbonate reservoirs.