Theoretical analysis and verification of the influence of bubble, pore throat and water film on pore water seepage characteristics-taking sandstone as the research object

Bubble, pore throat and water film will significantly affect the seepage characteristics of pore water. Based on the theory of porous media and mass and momentum conservation of pore water, this research investigates the blocking effects of bubble, pore throat and water film on the seepage water. According to the bubble force balance relationship, there exists a threshold Δ P at the pore throat. It is discovered through theoretical analysis that the small bubble cannot obstruct the pore throat, while the large bubble could pass through the pore throat after deforming and rupturing as the water pressure is greater than Δ P . In contrast, the bubble cannot pass through the pore throat and will block the water seepage. Meanwhile, the energy will be consumed in the aforementioned process, which will cause a drop in the pressure and seepage velocity of pore water along the seepage path, resulting in the non-uniform seepage characteristics of pore water. Combined with theoretical analysis, considering the factors of water injection pressure and pore size, the seepage and distribution characteristics of pore water are evaluated from macro- and micro-levels through sandstone water injection tests and numerical simulation analysis. Two experimental findings are very consistent, both reflect the non-uniform seepage characteristics of pore water and validate the rationality and precision of the theoretical analysis about the throat threshold Δ P . The findings of this study have certain theoretical reference significance for the theoretical research and practical engineering application about pore water seepage.