Current Status and Prospect of Imbibition of Slippery-water Effect on Shale Pore Structure Research

Shale gas is an emerging clean energy source. Effective shale gas extraction requires large-scale fracking of shale reservoirs. Due to the difficulty of extracting shale reservoirs with low porosity and permeability, hydraulic fracturing is an effective measure to increase production, and slippery water is a commonly used fracturing fluid system of shale. Some studies have revealed that the pore structure of shale reservoirs is a key factor affecting the flow of shale gas, but they can't fully explain the anomalous engineering phenomenon of "low flowback rate of slippery water and high gas production". In order to comprehensively grasp the influence of slippery water seepage and suction on the pore structure of shale reservoir, and to realize the effective increase of shale gas production. The article investigates the research results of the previous researchers, summarizes the pore structure evaluation method, and focuses on analyzing the influence of three factors on shale pore structure, namely, slippery water injection, slippery water retention, and forced seepage and suction. It is concluded that: slippery water injection promotes the generation and expansion of cracks, and makes the pore throat smooth; slippery water retention destroys the original microstructure and changes the physicochemical properties of the rock; and forced seepage improves the effect of seepage by changing the pressure difference. The effect of pressurized seepage of slippery water in shale reservoirs can effectively improve shale gas recovery, but there are fewer studies in this area, and there are great prospects for future research.