咸水层CO2残余埋存机理的微观数值模拟研究

Geological CO2 storage can be divided into tectonic storage, residual gas storage, dissolution storage and mineralization storage, among which residual gas storage is the most stable storage one. In this paper, a two-dimensional gas-liquid two-phase seepage model is established based on the binarized images generated from the electron microscopy scans of the core casts at the mine site, and the influence of factors such as reservoir wettability, gas-liquid two-phase interfacial tension and formation water reflux rate on the effect of CO2 residual storage is analyzed using the phase field method. The results of the study show that after the reflux of water, a large amount of CO2 is sequestered, and the CO2 storage state is mainly in the form of column, solitary drop and blind end; the speed of water reflux has a greater influence on the residual gas saturation, while reservoir wettability and gas-liquid interfacial tension have a smaller influence on the residual gas saturation. This study is useful for understanding the CO2 residual storage mechanism from a microscopic perspective.