Comparative studies on enhanced oil recovery by alkali–surfactant and polymer flooding

Chemical flooding methods are now getting importance in enhanced oil recovery to recover the trapped oil after conventional recovery. In the present study, a comprehensive study has been carried out on alkali, surfactant and polymer flooding. The chemicals with different compositions and combinations were used to recover the oil after conventional water flooding. It has been observed that increase in concentration of alkali, surfactant and polymer increases the additional recovery, but beyond a certain limit, the increase in recovery is only marginal. A series of flooding experiments using the combination of the above methods have been performed with additional recoveries more than 25 %. An analysis has been made on the relative cost of the different chemical slugs injected and the corresponding additional oil recovery. Based on the analysis, an optimum composition of the alkali–surfactant–polymer system has been recommended.