Application of wettability alteration in the exploitation of unconventional liquid resources

This study investigates the wettability measurement methods suitable for unconventional reservoirs, summarizes the wettability characteristics of unconventional reservoir rocks, overviews the current state-of-the-art applications of wettability alteration in unconventional liquid resources, and recommends experimental procedures for evaluating effects of surfactants on wettability in unconventional liquid resources. Contact angle determination, NMR (Nuclear Magnetic Resonance) method and Zeta potential measurement are the most appropriate means to estimate wettability in unconventional reservoirs. Unconventional reservoirs exhibit mixed wettability from intermediate-wet to oil-wet. To this date, surfactants are the only ones experimentally reported on applications of wettability alteration in unconventional liquid resources. Altering wettability in unconventional liquid resources as an improved oil recovery method can be reached by adding surfactants to fracturing fluids. Stability test, wettability alteration experiment, interfacial tension experiment, spontaneous imbibition experiment, forced imbibition experiment and adsorption experiment can be used when evaluating the efficiency of surfactants in altering wettability and recovering hydrocarbons from unconventional reservoirs.