Investigation on displacement efficiency and enhance oil recovery performance of CO2 and CO2-chemical additive composite system flooding using LBM simulation

CO2 flooding is a promising EOR method. Chemical additives reduce oil viscosity and CO2-oil interfacial tension. In this study, we propose a multiphase and multi-component model based on the LBM to examine the effectiveness of CO2 flooding and identify the factors that influence its performance. Additionally, we present a novel approach for simulating CO2-chemical additive composite system (CCAS) flooding by modifying fluid interaction parameters and reducing oil viscosity when exposed to chemicals. A comparison was conducted between the CO2 flooding approach and the CO2-chemical additive compound systems. The results show that the force between fluid molecules has a significant impact on interfacial tension and miscibility, affecting the displacement process. The viscosity and injection speed of the displaced fluid play a crucial role in determining the initial momentum and CO2 displacement performance. Additionally, reservoir rock morphology has an impact on the velocity of fluid molecules, and affects the displacement efficiency. The CCAS flooding has the potential to increase oil recovery by 15% compared to using CO2 flooding alone. Optimizing additive concentration, injection timing, and injection rate can further improve oil displacement efficiency by 5%-10%. Valuable theoretical guidance for applying CO2 chemical additives is provided by these research findings.