The study of components mass transfer mechanism and the rules of fluid phase alteration in the process of hydrocarbon gas drive

To determine the mechanism of component mass transfer among the phases in EOR and fluid phase change principles, this study chose an oil field in western China as the research object for forward or backward contact experimentation on the mechanisms by which injected gas fronts displace oil and enriched input gas displaces residual oil. Slim tube displacement experiments were also conducted to examine the regulation of phase state alteration and the characteristics of dynamic displacement efficiency during gas injection. Results show that the mechanism through which hydrocarbon gas drive occurs is the dual action of evaporation and condensation, with the former as the primary mechanism. The intermediate component of produced gas exhibits a decreasing and then increasing trend. Both miscible flooding and immiscible flooding exist in the inter-phase mass transfer zone of oil and gas. The size of the mass transfer zone determines the oil displacement efficiency of gas injection.