GAS DESORPTION-DIFFUSION-SEEPAGE COUPLED EXPERIMENT OF SHALE MATRIX AND MATHEMATIC MODEL

Gas desorption-di usion-seepage coupled experiment was designed and carried out with Longmaxi shale samples collected from South of Sichuan, and both the gas flow characteristics and pressure propagation were then obtained. Shale gas desorption-di usion-seepage coupling mathematical model was derived and numerical solution of the mathematical model using finite difference method was obtained. Numerical simulation results compared with the experimental results show that the model can well describe the gas transport in the shale matrix. And shale matrix permeability, di usion coe cient, desorption constants and other factors can a ect the gas flow through shale matrix as well as pressure propagation, which should be taken into consideration in the development of shale gas reservoir. The presented mathematical model provides a new method to calculate the production capability of shale gas well.