A Determination Method of CO2-Oil Miscible State in the Heterogeneous Low-Permeability Reservoir

Abstract

CO 2 flooding can effectively enhance the recovery of low-permeability reservoirs and realize CO 2 storage. However, the strong heterogeneity of low permeability reservoirs makes it difficult to accurately determine the miscible state of CO2 and oil. In this study, first, a PR-EOS is modified by considering the shifts of critical properties. Second, the parachor model is coupled with the modified PR-EOS to predict the minimum miscible pressure (MMP). Third, considering the multiple contact process between CO 2 and oil, a MMP prediction model based on the microscopic heterogeneity is established. Afterwards, the model calculation results are compared with the prior experimental results of CO 2 flooding to verify its applicability and superiority. Finally, the model is applied to the actual low-permeability reservoir to determine the miscible state of CO 2 and oil.

Innovative Zoning Control Techniques for Optimizing a Megaton-Scale CCUS-EOR Project with Large-Pore-Volume CO2 Flooding

“…However, in the actual development process of reservoirs, it is impossible to achieve complete miscible between injection and production wells due to the need to maintain a certain oil recovery rate. 57 Therefore, it is necessary to study the dynamic miscibility range during CO 2 flooding and analyze its impact on CO 2 flooding efficiency and CO 2 storage efficiency. This provides guidance for determining a reasonable work system.…”