Experimental Investigation of CO₂–Brine–Rock Interactions in Mishrif Carbonate Reservoir, Southern Iraq

Carbon dioxide injection into carbonate reservoirs is a process widely considered for mitigating CO₂ emissions. The objective of this study is to evaluate the feasibility of geologic CO₂ sequestration in terms of CO₂ -brine-rock interactions. Static pressurized experiments were conducted with carbonate rocks at 25°C and 60 bar pressure for 7, 14, and 21 days.CO₂ -brine-rock interactions were inferred from the evaluation of Ca²⁺ and Mg²⁺ and by observing brine density and viscosity. The rock's porosity was measured before and at the end of the experiment. The result showed an increase in rock porosity and brine ion concentrations, viscosity, density, and pH after 7 days; however, the intensity of these changes almost stabilized after 14 days and 21 days. Chemical analysis of brine suggested the dissolution of calcite and dolomite. This study provides experimental insights into the time-dependent interactions of carbon dioxide with brine and rock, relevant to Iraqi carbonate reservoirs and similar geological environments.