Multi-scaled pore network modeling of gas-water flow in shale formations

Multiphase flow is commonly encountered within shale reservoirs, however, the previous studies are more focused on single phase flow. Due to the extremely low permeability of shale formations, the experimental measurements are not capable to be performed. Attempts are made by applying the techniques of digital rock analysis and pore network modeling to investigate the multiphase flow mechanisms in shale reservoirs. This work follows this way. Firstly, a stochastic pore network generation algorithm and a two-phase flow simulation method are presented. This algorithm is applied and validated in Berea sandstone. By applying the proposed algorithm, the organic and inorganic pore networks are generated for shale formations, then the multi-scaled pore network is established after upscaling the organic pores to an organic path. Finally, the gas-water flow is simulated within this established multi-scaled pore network and some analysis and discussions are conducted. The results imply that the characteristics of pore systems in shale formations pose an extreme impact on the gas-water flow mechanisms, especially the proportion of organic pores and pore-throat aspect ratio.