Efficient development strategies for heavy oil reservoirs with a focus on rational utilization of water resources

Abstract

Accurately judge and predict oil-in-water O/W emulsions performance in different flooding stages and reservoir locations is immense significance in the rational utilization and preservation of water resources during chemical flooding for heavy oil development. In this study, we initially delve into the impact of chemical agents on emulsification, focusing on interfacial tension (IFT), emulsification states, and droplet size distributions. Additionally, we elucidate the microscale migration patterns of O/W emulsions. Chemical flooding experiments aid in determining the critical stages of emulsification, flocculation, and coalescence. Ultimately, we analyze the influence of reservoir and injection parameters factors on oil distribution in porous media through long sand-packed tube and micro-model flow experiments. The findings indicate that an increase of chemical agents’ concentration leads to a significant reduction in IFT and a concurrent decrease in droplet size. The coalescence process of droplet is influenced by the degree of difficulty in interface fusion as well as its speed. The transformation in the oil’s distribution state typically progresses through five distinct stages: preliminary emulsification, stable emulsification, flocculation, coalescence, and ultimately retention and adhesion. Enhancing emulsification capacity can be achieved by increasing the concentration or the injection pressure. Low reservoir permeability, extended flow distances, high injection rates, and appropriate injection techniques all contribute to a rise in pressure. Elevated injection pressures strengthen the stability of oil-in-water emulsions, thereby delaying the flocculation and coalescence processes. During chemical flooding operations in oilfields, it is crucial to focus on the following aspects: (1) Boosting the volume of O/W emulsions. (2) Reducing the droplet size. (3) Enhancing the stability of O/W emulsion. The outcomes of this study furnish invaluable theoretical foundations and offer valuable guidance for the rational utilization of water resources and the promotion of cleaner oil reservoir production practices.