The Development and Application of a Demulsifier Used for ASP Flooding–Produced Liquid from the Xing 2 Area of the Daqing Oilfield

Abstract

Alkaline surfactant polymer (ASP) flooding was successfully used in Daqing oilfield, and its incremental recovery was more than 20% original oil in place (OOIP) over water flooding. But the ASP flooding–produced liquid contains oil displacement agents, such as alkaline, surfactant, and polymer, which result in emulsions having higher stability and more complex properties than water flooding emulsions, so ASP flooding technology has resulted in some new problems in the treatment of the produced liquid, such as the difficulty of oil–water separation, and this problem has become a factor that limits the applications of ASP flooding technology. The development of a demulsifier for use with ASP flooding–produced liquid has a significant function for improving the economic benefit of ASP flooding technology. By analyzing the components and structure of the ASP flooding–produced liquid from Xing 2 of Daqing oilfield, meanwhile, considering the relationship between the structure and properties of demulsifier, demulsifier (called DX) was developed. DX demulsifier has been successfully applied in the ASP flooding treatment station in Xing 2 of Daqing oilfield. The results of field tests showed that DX demulsifier had better demulsification performance on the ASP flooding–produced liquid from Xing 2 of Daqing oilfield and was better than that of the polyether demulsifier commonly used in Daqing oilfield. After separating oil and water, the water content in emulsions was less than 20% (which meets the requirement of electrical dehydrator) and oil content in sewage water was less than 200 mg/L (if using other polyether demulsifiers, the oil content in sewage water is greater than 2,000 mg/L), so it provides a good foundation for sewage water treatment.