Work

Study on the phase behavior and mass transfer laws of CO2-shale oil in shale oil reservoirs

Year: 2025

Type: article

Abstract: Injecting CO 2 into shale oil reservoirs has the dual purpose of enhancing oil recovery rate and geological storage of CO 2 . The phase behavior and mass transfer laws of the CO 2 -shale oil are crucial for achieving highly efficient production shale oil and gas. Based on an improved vapor-liquid equilibrium (VLE) model in nanopores, which achieves a relative error of less than 3.16%, this study investigates the phase behavior and CO 2 –oil mass transfer laws of two representative shale oils under CO 2 injection. Research results show that after CO 2 injection, the saturation pressure tends first to increase and then reduce. The CO 2 dissolution results in a significant reduction in the molecular weight and viscosity of Wolfcamp shale oil. During the multi-contact shale oil with CO 2 injection, both density and the interfacial tension (IFT) reduce at the forward contact edge, indicating forward-contact miscibility. Furthermore, the nanoconfinement effect reduces the density difference between the liquid and gas phases, leading to a reduction in the IFT, which is beneficial for gas-oil miscibility. The study results can provide a theoretical basis for understanding compositional variations in shale oils under CO 2 injection, offering promising improvements in miscibility and recovery efficiency.

Source: Petroleum Research

DOI: 10.1016/j.ptlrs.2025.11.005

Authors: FuLin Yang, YingYing Chen

Institution: Beibu Gulf University

Language: English

Topic: Enhanced Oil Recovery Techniques

Subfield: Ocean Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: diamond

Funders: Natural Science Foundation of Guangxi Zhuang Autonomous Region, National Natural Science Foundation of China, Natural Science Foundation of Guangxi Province, Foundation for Innovative Research Groups of the National Natural Science Foundation of China

Awards: G3426056909, G4718411151