Core Flooding Tests to Investigate the Effects of IFT Reduction and Wettability Alteration on Oil Recovery: Using Mulberry Leaf Extract

Many carbonate reservoirs are oil wet in nature. In oil or mixed-wet reservoirs, however, the capillary driving force for the spontaneous imbibition process is weak and therefore, the waterflooding oil recoveries are low. The recovery efficiency can be improved by dissolving low concentrations of surfactants in the injected water to alter the wettability of the reservoir rock or reduce the interfacial tension (IFT). Due to the high cost of industrial surfactants, chemical flooding is not economically attractive in petroleum industry. In this paper a new plant surfactant (extracted from mulberry tree leaves) was introduced and its effects on wettability alteration, IFT reduction, and oil recovery were experimentally investigated. Carbonate and sandstone rocks were employed to core flooding experiments in order to investigate the effect of mulberry leaf extract on oil recovery. Mulberry leaf extract could reduce the IFT between distilled water and kerosene from about 42 dyne/cm to 20 dyne/cm. Wettability of oil wet carbonate rocks, in the best state was altered from about 150 degrees to 30 degrees. Using mulberry leaf extracts into the injected water enhanced ultimate oil recovery about 7% and 1.5% of original oil in place for carbonate and sandstone rocks, respectively.