Solubility Variation and Prediction Model of CO2-Water-Oil System

For the effective development of CO2 flooding and efficient lifting technology of CO2-containing producing wells, the dissolution ability of CO2 in water-bearing crude oil is of major importance. The miscibility experiment of CO2-water-crude oil system was conducted to ascertain the solubility change of CO2 in water-bearing crude oil, using the CO2 test area of Hei 125 block in Daqingzijing oilfield as a demonstration. In addition, on the basis of the current solubility model, a combined model for forecasting the solubility of CO2 in water-bearing crude oil was put forth. The findings indicate that: at the equal temperature, the solubility of CO2 in pure water, pure oil and water-bearing crude oil increases with the increase of pressure. The solubility of CO2 in pure oil and pure water at equal pressure circumstances reduces as the temperature rises. The solubility of CO2 in water-bearing crude oil reduces as the water cut rises under the equal temperature and pressure. The solubility prediction model of CO2 in water-bearing crude oil was established by combining the Duan model with the modified Methrotra model. Compared with the existing solubility models, the new combined model is more comprehensive and applicable, and the calculation accuracy is 95.14%.