Pressure response and production performance for multi-fractured horizontal wells with complex seepage mechanism in box-shaped shale gas reservoir

Abstract

The development of shale gas reservoir has becoming tremendously thrived around the world in recent years. The horizontal well drilling, advanced completion and massive hydraulic fracturing are the key technologies. How to accurately evaluate the production performance of the wells in these reservoirs, especially for multi-fractured horizontal wells, has always been the hot topic for the engineers and relevant researchers. In this paper, we presented a mathematical model to describe a horizontal well with multiple fractures in rectangular outer-boundary reservoir, which uses the Knudsen diffusion to describe the gas flow in nano-pores and also takes the slippage effect into account. By the method of point source function, Laplace transform and numerical discrete fracture methods, a semi-analytical solution of the model is obtained. Thereafter, the well test type curves and the production performance curves are plotted through Gauss elimination and Stehfest numerical inversion methods. Finally, the effects of related influential factors on well performance are also analyzed. It can be concluded that the Knudsen diffusion coefficient and slippage factor mainly affect the interporosity flow period when well producing with constant rate. When well producing with constant bottom hole pressure, the bigger the values of Knudsen diffusion coefficient and slippage factor are, the larger production rate will be. The research results summarized in this paper have significant theoretical meanings for the development, well test interpretations and production performance analysis of such unconventional gas reservoirs.