Molecular Dynamics Simulation Study on the Mechanism of CO2-CH4 Synergistic Enhanced Oil Recovery in Tight Oil Reservoirs

Tight oil reservoirs are currently a hot topic in petroleum exploration and development. However, due to the low porosity and low permeability of reservoirs and the lack of external energy supplementation, there is a significant mismatch between resources and production in tight oil. Mining and experimental studies have shown that CO2 and gaseous hydrocarbons have a high injectivity and effective oil displacement effect in tight oil reservoirs. Currently, research is mostly focused on a single energy supplement medium, and whether CO2 hydrocarbon mixtures can more effectively improve oil recovery needs to be further studied. The features of crude oil expansion capacity and interaction energy changes following various fluid interactions were investigated via molecular dynamics simulation techniques in response to the ambitious comprehension of the mechanistic changes underlying the CO2–CH4 synergistic effect during the development of tight oil reservoirs. The research results indicate that the expansion and diffusion abilities of crude oil are improved after being treated with pure CO2, CO2-CH4 (9:1), CO2-CH4 (7:3), and CO2-CH4 (1:1), and enhanced with increasing CO2 content in the injected fluid.