Rough Surface Effect on CO₂ Displacement at the Nanoscale

Abstract

CO 2 injection has great potential for enhancing shale oil recovery. Understanding the CO 2 displacement in nanometer pores of shale is critical for developing effective CO 2 injection techniques. In this work, we applied direct numerical simulation to study the effect of the rough surface on CO 2 displacement in nanometer pores of shale. By quantifying CO 2 displacement in rough nanochannels, we aimed to understand how surface roughness and morphology affect displacement progress. We found that the rough surface results in shrinkage of the CO 2 displacement path, slowing overall displacement rate. Additionally, the pinch-point effect in a rough nanochannel impedes the smooth progression of the interface contact line, causing periodic velocity fluctuation that further hinders CO 2 displacement. We also simulated the CO 2 displacement in rough nanoporous media, finding that the rough surface leads to a substantial decrease in CO 2 displacement efficiency, especially under low pressure gradient conditions. Our simulation results indicate that the rough surface of a shale nanometer pore has a nonnegligible effect on CO 2 displacement.