Analysis of Saturation Pressure Variation of Volatile Reservoir in Gas Injection and Pressure Maintaining Development

Abstract For the volatile reservoir with gas injection and pressure maintaining development mode, the saturation pressure of volatile fluid in the process of gas injection is the key factor to determine the gas injection effect and the type of injected gas. At present, the prediction of saturation pressure is mainly based on experimental measurement, state equation and empirical formula. However, the indoor experiment is time-consuming and expensive, the calculation of state equation is cumbersome, and there are many parameters, which is not convenient for the actual operation of the mine. Therefore, the empirical formula method has been widely used. However, the existing empirical formulas for predicting saturation pressure do not consider the effects of injected gas, porous media and component gradient, which has a great impact on the prediction results. Therefore, based on the idea of multiple regression, based on the experimental test results, considering the effects of injected gas properties, injection volume, porous media, component gradient and fluid properties, this paper establishes the saturation pressure prediction model of volatile reservoir for gas injection and pressure maintaining development. Through example calculation and analysis, within a certain range of application, the saturation pressure predicted by the newly established model is close to the measured value, and the error is small. It also limits the applicable conditions of the model in this paper. The research results are helpful to the in-depth study of gas injection development mechanism of volatile reservoir and are of great significance.