Transport characteristics of shale gas under the interaction of roughness and water saturation in amorphous kerogen nanopores

Shale gas is generally regarded as a potential clean energy. Kerogen is an organic material that mainly produces and stores gas in shale, and an accurate understanding of shale gas transport characteristics in kerogen is the basis for the accurate prediction of shale gas production. In this regard, previous studies of shale gas transport have generally been conducted in smooth graphite slits or kerogen without considering the roughness in amorphous kerogen nanopores. In addition, for kerogen nanopores with water saturation, consideration of the roughness will result in a more reasonable nanopore structure. Herein, amorphous organic nanopores are constructed based on the Gaussian rough surface. The transport characteristics of shale gas under the interaction of roughness and water saturation is systematically studied. The results showed that the transport capacity of shale gas decreased significantly (80%, 61.7%, 56.9%) with the increase in roughness (6.26%, 9.62%, 12%) compared with ideally smooth nanopores. Based on molecular dynamics simulation, an analytical model reflecting the influence of roughness on shale gas transport is established. The roughness and water saturation can affect each other to form a complex surface. In particular, both roughness and water saturation are found to influence methane transport mechanisms by affecting the morphology of the adsorption layer in organic nanopores.