PRESSURE CHANGE AND GAS-LIQUID MASS TRANSFER LAWS IN SHALE GAS EXTRACTION

Based on the occurrence and flow mechanism of shale gas, this article establishes a flow equation that considers shale infiltration and adsorption, as well as seepage and diffusion. The pressure distribution generated by fracturing is used as the initial condition of the equation using line source superposition solution. Unstructured perpendicular bisection (PEBI) grids are used to divide the multi-fractured horizontal wells, and the finite volume method is used for discretization. The reliability of the algorithm program was verified by using the shut-in pressure by high-frequency pressure monitoring. The study has drawn important conclusions: (1) discovering the double pressure funnel and gas-liquid two-way mass transfer laws in shale gas development; (2) Based on this theory, provide the optimal shut- in time and optimal drainage system for shale gas production.