Modeling interaction between CO2, brine and chalk reservoir rock including temperature effect on petrophysical properties

Abstract

Carbon dioxide (CO2) capture and sequestration through CO2 enhanced oil recovery (EOR) in oil reservoirs is one of the approaches considered to reduce CO2 emission into the atmosphere. The injection of CO2 into a subsurface geological formation may lead to chemical reactions that may affect the formation pore structure and characteristics. In this study, the effect of CO2–brine–rock interaction on the rock petrophysical properties and mineral volume fraction was numerically investigated during CO2 injection into a chalk reservoir rock. A 3D numerical modeling and simulation were conducted using COMSOL® Multiphysics commercial software of computational fluid dynamics (CFD) to simulate CO2–brine core flooding process in a chalk core. The model was validated against a core–scale experimental data from literature. Simulation differential pressure data matched the literature experimental data closely and consistently indicating good agreement between them. Temperature effect on the performance of CO2–brine–chalk sequestration was also evaluated in the present study. Results indicated that porosity was only slightly affected by temperature increase during CO2 injection in contrast to permeability that was substantially affected by temperature. Moreover, chemical reactions enhanced as temperature increased leading to significant increase in permeability. Thus, carbonated brine sequestration excelled at elevated temperature due to increased acidity which governs the sequestration process. The developed model maybe considered as a reliable tool to optimize various operating parameters of CO2–brine sequestration.