Enhancing CO2 Sweep Volume through PressureModulation in Heterogeneous Reservoirs: An Experimental Study

作者：Kesheng Tan, Lu Jiang, Weifeng Lyu, Xiaoming Lang, Boya Zhao, Ming Gao, Yutong Yan, Jiangfei Wei · 发表于：ACS Omega · 年份：2026 · DOI：10.1021/acsomega.6c04018 · 研究领域：CO2 Sequestration and Geologic Interactions、Hydraulic Fracturing and Reservoir Analysis、Enhanced Oil Recovery Techniques

Abstract CO2 flooding is a key technology for achieving the synergistic benefits of enhanced oil recovery (EOR) and geological CO2 storage. However, preferential CO2 channeling and poor sweep efficiency caused by interlayer reservoir heterogeneity severely restrict the large-scale application of this technology. Moreover, the mechanisms by which dynamic pressure modulation intervenes in the multiphase flow field remain insufficiently understood. In this study, a heterogeneous two-dimensional visual physical model consisting of high-, medium-, and low-permeability layers was constructed, and constant-pressure and stepped pressure-modulation flooding experiments were systematically conducted. Combined with a high-precision real-time monitoring system, the sweep dynamics under different pressure-control modes were quantitatively characterized, and the coupled response between displacement-front evolution and phase-behavior-related mass transfer was analyzed. The results show that, under the constant-pressure mode, increasing the displacement pressure can effectively suppress gravity override and improve the mobility ratio by reducing the oil–gas density difference and enhancing multicomponent mass transfer and extraction. Compared with the 15 MPa near-miscible flooding scheme, the 22 MPa miscible flooding scheme increased the ultimate recovery factor by 12.2 percentage points. The stepped pressure-increase strategy applies transient pressure perturbations, generates transverse p...