Carbonate rocks account for more than half the world’s hydrocarbon proven reserves. Oil recovery from these reservoirs is a challenge due to their complex nature. This complexity is due to the mixed-to-oil wet rocks, low permeability with high heterogeneity, added to the harsh conditions of high temperature and high salinity. Water injection in these reservoirs results in low recovery due to water channeling in high permeability layers and bypassing oil in the low permeability matrix. Consequently, several enhanced oil recovery techniques have been proposed for improving the oil recovery from carbonate reservoirs and overcoming the high negative capillary pressure that holds oil in place.
This project aims to enhance oil recovery from carbonate reservoirs using different chemicals, namely chemical enhanced oil recovery (CEOR). The chemicals improve oil recovery from carbonate reservoirs through enhancing both displacement efficiency as well as volumetric sweep efficiency. Surfactants reduce trapped residual oil saturation, polymers target unswept (bypassed) oil saturation, and low salinity water was proven to enhance both. In this project, the effect of polymer flooding on improving oil recovery will be mainly investigated; however, hybrid injection of other chemicals such as surfactant and low salinity water is within the scope to investigate the synergistic effect if the project time permits.
The enhanced oil recovery from carbonates will be investigated through numerical simulation and modeling. This helps in understanding the controlling mechanism including interfacial tension (IFT) reduction, mobility ratio (M) improvement, as well as wettability alteration to a more water-wetting state. The needed rock and fluid data can be obtained from ADNOC for one of the potential reservoirs in the UAE or from the published data in the literature for similar reservoirs in the Middle East region.