Pore-scale modelling of storage and seepage in the northern fuling shale gas field

Abstract

Accurate estimation of shale gas content and production rate is crucial for large-scale shale gas commercialisation. However, limited understanding of shale pore structures and gas accumulation mechanisms has hindered prediction accuracy. This study focuses on the northern Fuling shale gas field in China, where pore size distribution (PSD) models were constructed using literature data. Combined with gas storage and flow behaviour and the phase equilibrium model, a simplified pore structure model was used to develop a storage and seepage model. Results indicate that PSD can be reasonably fitted by both single and segmented curve models. As maximum pore size increases, free gas becomes more dominant and flows mainly in slip flow. Permeability rises linearly with temperature and drops exponentially with pressure, while gas content decreases with temperature and increases with pressure. The material of pore walls significantly influences gas content and apparent permeability, with silicon atoms offering more realistic results. The choice of adsorption model also matters; the Langmuir model yields higher permeability values.