Surfactant flooding in carbonate rock

Abstract

Studies with surfactant flooding in sandstones have been done. These studies have reported that surfactants can alter the flow functions in mixed wet cores. Carbonate rocks are usually not water wet and have microfractures. If a surfactant with properties to alter wettability in the carbonates is injected, then an improvement in the oil production could be obtained. If the mechanism of changing wettability can enhance spontaneous imbibitions then it will improve and achieve an increase on oil recovery. In this thesis two different surfactant processes were studied in chalk cores. In the core flooding experiments it was used a wettability alteration surfactant. This process was compared with water flooding. The result showed that the system with wettability alteration properties brings a later water breakthrough. The wettability alteration process was also compared in two different aging times, giving as a result a more efficient performance in the rock that was more oil wet. And the second process was the interfacial tension reduction surfactant system that showed on the experiments a lower saturation of oil in the cores than the wettability system. Further work is recommended to perform surfactant flooding experiments in chalks: to vary wettability; and to study wettability alteration and reduction of interfacial tension by surfactant for other oil reservoirs with different oil, brine and rock composition.