Abstract In order to study surfactants suitable for a heavy oil reservoir and further improve the degree of heavy oil reservoir production, this paper provides a concentration optimization and compound study on anionic surfactant, nonionic surfactant, and zwitterionic surfactant based on the three major mechanisms of surfactant oil dispersing: reduced interface tension, oil-water emulsification and wetting reversal. Combined with the characteristics of a heavy oil reservoir, the concentration optimization and complex study of anionic surfactant, nonionic surfactant, and zwitterionic surfactant are conducted, respectively. Through the performance test of different ionic surfactants and composite systems, the best oil displacement system is preferred. The results show that the oil-repellent system formed by the zwitterionic surfactant cocoa aminobetaine (CB) is combined with alkali, polymer, and nanomaterial at a concentration of 0.5 wt%. It has high viscosity and low interfacial tension, oil-repellent properties. After the on-site test of a heavy oil reservoir, the daily oil production of the well group in the test area increased from 35.2 t to 68.5 t, and the moisture content decreased from 54.2% to 38.6%, achieving a good oil-increasing and precipitation effect. At the same time, the production liquid was analyzed, and a large amount of emulsions were observed, which confirmed that the compound system had a good emulsification effect. The research results are of great guiding significance for improving the recovery rate of heavy oil reservoirs.
Kai Huang (Fri,) studied this question.