Quantification of oil recovery efficiency, CO 2 storage potential, and fluid-rock interactions by CWI in heterogeneous sandstone oil reservoirs

摘要

AbstractSignificant interest exists in improving recovery from oil reservoirs while addressing concerns about increasing CO2concentrations in the atmosphere. The combination of Enhanced Oil Recovery (EOR) and safe geologic storage of CO2in oil reservoirs is appealing and can be achieved by carbonated (CO2-enriched) water injection (CWI). So far, through several flooding experiments, the potential of carbonated water injection as an EOR scenario has been investigated. While several coreflood experiments on homogeneous cores have been performed, there is no information on the effectiveness of CWI for oil recovery and CO2storage potential on heterogeneous cores. Since not all the oil reservoirs are homogenous, understanding the potential of CWI as an integrated EOR and CO2storage scenario in heterogeneous oil reservoirs is essential.With this objective, a series of high-pressure and high-temperature coreflood experiments were performed on a heterogeneous sandstone core. Based on the results, the heterogeneity of rock dominated water and carbonated water flow paths led to early breakthrough. However, interestingly, the ultimate oil recovery by CWI, either as the secondary or tertiary injection scenario, was higher than that of conventional waterflooding. Both secondary and tertiary CWI showed a strong potential for increasing oil recovery from the heterogeneous core and re-mobilized part of the trapped oil. In addition to the strong oil recovery by CWI, CWI demonstrated the good potential