Experimental Study of CO2-Low Salinity WAG Injection in Heavy Oil Reservoirs

Although low salinity water flooding has been newly attended for improving oil recovery in both secondary and tertiary modes, a little is known about the performance of CO2-low salinity WAG injection. The advantage of presence of CO2 during WAG injection is prevention of pH increase which is a controversial mechanism for increasing oil recovery in low salinity floods. A set of core flood tests including a pair of carbon dioxide WAG and a pair of water injection tests are conducted and, the efficiency of low and high salinity water injection were compared for each of theses pairs. All the tests were in secondary mode except secondary high salinity which is followed by low salinity injection in tertiary mode. Results showed that the oil recovery was not significantly affected by pH increase mechanism in case of low salinity flooding which is in contrast with the most of reported results in the literature. Also it has been found that the bufferic phase developed by contact of carbon dioxide with water during WAG injection did not prevent the oil recovery improvement and also showed performance improvement compared to other modes of injection

Keywords:

Low salinity water flooding , WAG , CO2 , Experimantal , Heavy oil