Shale gas resources in China are abundant. The geological conditions of shale gas reservoirs in China, however, are more complex than those in the United States. In this paper, a triple-porosity medium model of gas shale was established firstly. A seepage mathematical model of shale gas extraction was established, in which adsorption, desorption, diffusion and seepage processes of the methane were taken into account. Shale gas development in Fuxin, Liaoning province was studied by numerical simulation. The informations of actual geological conditions on the shale-gas reservoir were introduced to the geological model where the special geological structures on rock fracture zone and metamorphism strings respectively resulted from the faults and the magmatic intrusion were considered. According to the simulation results, geological conditions affect the shale gas production and well arrangement; therefore, geological conditions should be considered in shale gas development.
Shale gas, which is an unconventional natural gas, mainly exists in free and adsorbed states and is stored in organic-rich mud shale and its intercalation. Its main composition is methane. Shale gas is one kind of energies with huge potential. At present, systematic and deep research on basic theory of shale gas is scarce. Theoretical research lags behind exploration and development, which is the bottleneck in restricting the development of shale gas. The numerical simulation for shale gas development is an efficient measure for determining the relationship among characteristics of shale reservoir, exploration pattern and the production of shale gas wells. Meanwhile, it can provide the optimizing development program of shale gas resource. The numerical simulation plays a vital role for the exploitation of shale gas.
There are two major approaches to predict shale production. One approach mainly depends on statistical analysis, analytical method and semi-analytical method to predict production based on accurate parameter analysis. Gringarten et al. (1974) developed some early analytical models for fluid through a single vertical fracture and a single horizontal fracture. Blasingame & Poe Jr. (1993) developed a more accurate semi-analytical model for single vertical fracture. Ilk et al. (2008) put forward an empirical model and Valkó (2009) developed the decline curve model. Bello andWattenbarger (2008), Mattar (2008) and Anderson (2010) proposed the analytical model. Morales-German (2012) established a comprehensive reservoir model based on statistical analysis of major U.S. shale gas basins.