A Review of the Seepage Mechanisms of Heavy Oil Emulsions during Chemical Flooding

Abstract

Chemical flooding plays an important role in enhancing oil recovery due to many reasons, including the viscosity-increment effect of polymer, wettability alteration effect of surfactant, and the formation of emulsions, which have been known to effectively increase the swept area and oil displacement efficiency, hence increasing heavy oil recovery. Laboratory tests and pilot trials of alkali–surfactant–polymer (ASP) injection show that the oil recovery of the emulsified system is 5% more than the cases where no emulsions existed. Therefore, it is of great significance to study heavy oil emulsions and its field application for enhanced heavy oil recovery. This paper discusses a thorough overview of the most fundamental ASP flooding mechanisms, along with some examples of laboratory experiments and field trials. In addition, the formation conditions and the interfacial characteristics of heavy oil emulsions are also discussed, mainly ASP flooding, and then the seepage mechanisms of these emulsions are investigated. The relationship between the formation of heavy oil emulsions and the enhanced heavy oil recovery effect by chemical flooding is discussed through core flooding experiments at the reservoir temperature and some field pilots to reach the optimum heavy oil recovery.