Nuclear Magnetic Resonance Investigation of Imbibition and CO 2 Huff-and-Puff Enhanced Oil Recovery in Shale Porous Media

作者：Xiaodong Dai, Jianguang Wei, Ying Yang, Anlun Wang, Dong Zhang, Anqi Shen, Runnan Zhou · 发表于：Energy & Fuels · 年份：2025 · DOI：10.1021/acs.energyfuels.5c04125 · 被引用次数：3 · 研究领域：Hydrocarbon exploration and reservoir analysis、Enhanced Oil Recovery Techniques、Hydraulic Fracturing and Reservoir Analysis

Efficient recovery of shale oil remains a major technical challenge due to the ultralow permeability, complex pore-fracture structure, diverse lithofacies, and inherently limited natural productivity. Conventional enhanced oil recovery (EOR) techniques often yield limited effectiveness when they are applied independently. The present study investigates a hybrid EOR strategy that combines acidic slickwater imbibition with CO 2 huff-and-puff, aiming to enhance oil recovery through synergistic physical and chemical mechanisms. Core samples from four representative shale reservoirs were tested under reservoir-representative temperature and pressure conditions. A suite of experiments, including 2D nuclear magnetic resonance (NMR), rheology tests, and minimum miscibility pressure (MMP) evaluations, were conducted to assess fluid behavior and recovery. 2D NMR results revealed that CO 2 huff-and-puff significantly enhanced oil displacement, especially from micropores and mesopores that were less responsive to water imbibition. Interfacial tension measurements confirmed that CO 2 exhibited the lowest values (∼1 mN/m), while acidified slickwater outperformed base slickwater. CO 2 dissolution further reduces the oil viscosity, enhancing fluid mobility. MMP tests showed that miscibility between CO 2 and oil was achieved only in the DMT reservoir (37.61 MPa), partially explaining the superior recovery performance. Overall, the hybrid acidic slickwater + CO 2 approach is proven effective, ...