Stripping Mechanism of Surfactant System Based on Residual Oil on the Surface of Sand-Conglomerate Rocks with Different Grain Size Mineral Compositions

During the development of a sand-conglomerate reservoir, there is a huge variation in rock grain size and different amineral compositions of different-sized sand grains. The mineral composition and microstructure of the rock both have an impact on the characteristics of the remaining oil in the reservoir. The stripping mechanism of a surfactant system on sand-conglomerate surface crude oil with varied grain size minerals was explored in this paper. Sand-conglomerate was classified and analyzed to determine their wettability and stripping oil effects. The optimization of the surfactant solution system and molecular dynamics simulation revealed the surfactant stripping mechanism on crude oil on distinct sandstone minerals. The results of the study showed that montmorillonite minerals are more readily adsorbed by surfactants. The crude oil within them is more likely to compete for adsorption and to be stripped off, and then extracted with the recovery fluid. The surfactant solution system can increase the hydrophilicity of the rock surface, make the crude oil on the rock surface shrink and gather, and enhance the transportation ability of the displacement fluid. And the emulsification seals part of the pore in the reservoir, increases the displacement pressure, and improves the overall wave volume. The results of this paper are of great significance for the efficient development of sand-conglomerate reservoirs.