Residual oil recovery via injection of biosurfactant and chemical surfactant following hot water injection in middle east heavy oil field

The complexity of reservoir rock and fluid properties in Oman led the operating companies to consider different technologies such as thermal and chemical methods to enhance oil recovery. Microbial Enhanced Oil Recovery (MEOR) is one of the proposed technologies that can potentially be implemented as an effective alternative for enhancing oil recovery. This research study investigates experimentally the potential of enhancing oil recovery from Middle East heavy oil field via hot water injection followed by injecting a biosurfactant produced by a Bacillus subtilis strain which was isolated from oil contaminated soil from Oman. The biosurfactant was stable over wide range of pH, salinity and temperatures and gave stable emulsions with wide range of hydrocarbons including light and heavy crude oil. Additionally, comparison was made with reducing the heavy oil residual saturation using chemical surfactant and mixture of both bio/chemical surfactants. All core flooding experiments were conducted under reservoir condition and using oil, water and core samples from the field of interest. The results reveal that the biosurfactant and the chemical surfactant reduced hot water injection residual heavy oil saturation. Using bio-surfactant, the maximum reduction in residual oil saturation obtained was 19% and the minimum was 7%. On the other hand, via chemical surfactant, the maximum reduction in residual oil saturation obtained was 11% and the minimum was 1.0%. Moreover, it was found that the performance of the biosurfactant increased by mixing it with the chemical surfactant where the maximum reduction in residual oil saturation reached 34% at mixing ratio of (50:50). This work, additionally, proved that it is preferable and more feasible to inject the surafactants as tertiary recovery stage and not at secondary recovery mode. As evidenced by this study, the bio-surfactant worked better than the chemical surfactant in reducing the hot water residual heavy oil saturation under reservoir conditions of interest. Thus, there is a high potential of applying the MEOR technology in this Middle East heavy oil field via the injection of the pure biosurfactant or by mixing it with the chemical surfactant following hot water injection where production scale-up and pilot test are recommended to better evaluate its applicability in the field scale.