Study on Quantitative Construction of Ionized Water Concentration Based on Molecular Kinetics Oil Flooding

The commonly used tertiary oil recovery technology in oilfields is difficult to meet the demands. Ionized water flooding technology has received extensive attention due to its advantages of low cost, green environmental protection, and simple operation; it also has beneficial effects on sandstone reservoirs. However, there are few reports on the application of ionized water flooding technology in unconventional oil and gas reservoirs. In addition, there are still no quantitative optimization methods for the composition and concentration of various ions in the displacement fluid, which leads to the lack of effective guidance in the field application design and affects the field application effect of this technology. In this paper, the molecular dynamics method is used to establish the ionized water flooding model based on the construction of the rock model and crude oil molecular model to study the oil displacement efficiency in the pores of unconventional reservoirs, and combined with single-factor and multifactor research methods, the quantitative optimization method of ionized water was constructed by changing the types and concentrations of ions in ionized water. The oil displacement efficiency of ionized water was 7.5% higher than that of pure water under the optimal conditions, and the total salinity of the best ionized water was 3790 mg/L, of which the cation was 1880 mg/L and the anion was 1910 mg/L. The research results not only perfect the basic theory of ionized water flooding technology but also have important value for developing ionized water flooding technology and its application in unconventional oil and gas reservoirs.