Experimental investigation of CO2-brine-rock interactions in relation with CO2sequestration in an Iranian oil reservoir

The main purpose of this study is to evaluate the feasibility of geologic CO(2)sequestration in terms of CO2-brine-rock interactions in Ramin oil field, Iran. Static experiments were conducted with carbonate rocks at 70 degrees C and atmospheric pressure for 14, 30, and 60 days. CO2-brine-rock interactions were inferred from the evaluation of Ca2+, Mg2+,Cl-, andSO42-concentrations and a thorough characterization of the carbonate rocks before and after treatment. Scanning electron microscopy (SEM) micrographs revealed the formation of dissolution pits and the growth of new structures. Energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) indicated these minerals to be calcite. Porosity of the carbonate rocks increased from an initial value of 4.72% to the maximum value of 11.83%. Then, it decreased to a value of 5.48% until the end of the experiments, that is, 60 days. Chemical analysis of brine suggested the precipitation and dissolution of calcium sulfate. In addition, dolomite dissolution and halite precipitation/dissolution were inferred. Calcite precipitation and porosity reduction suggested that CO(2)can be stored via mineral entrapment in the Ramin oil field, which is desired from the perspective of CO(2)geologic sequestration. (c) 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.