Zhang Miaoxin, Wu Jingchun, Cai Liyuan, Li Bo, Yu Xin, Hou Yangyang, Shi Fang, Zhang Chunlong
Key Laboratory for EOR Technology (Ministry of Education), Northeast Petroleum University, Daqing, 163318, China.
Daqing Yongzhu Petroleum Technology Development Co Ltd, Daqing, 163000, China.
Sci Rep. 2025 Jul 26;15(1):27224. doi: 10.1038/s41598-025-11778-1.
This study targeted a highly water-sensitive reservoir with high clay content (average 23.87%, mainly montmorillonite and illite), where waterflooding development induces hydration swelling of clay minerals, leading to pore-throat narrowing. The anti-swelling system and CO₂ were found to mitigate this phenomenon. The research investigated the dissolution, diffusion, and synergistic effects of CO₂ in the anti-swelling system/crude oil within the context of Carbon Capture, Utilization and Storage-Enhanced Oil Recovery (CCUS-EOR). Using the pressure decay method, core flooding experiments, microscopic visualization of oil displacement, and an improved mathematical model. We systematically investigated the influence of clay minerals on the balance between CO₂ storage and enhanced oil recovery (EOR). It was found that the diffusion coefficient of supercritical CO₂ increased rapidly and then levelled off with increasing pressure, which indicated that clay minerals hindered CO₂ diffusion. The anti-swelling system increases the effective pore connectivity by suppressing clay swelling, which increases the diffusion coefficient by 20-28%. The enhanced mathematical model combines the oil-water phase partition coefficients with the PR-EOS equation of state to accurately describe the multiphase interactions. The calculation results fit the experimental data by 92%, which is better than the traditional single-phase model. Through microscopic oil displacement experiments, core flooding tests, and quantitative analysis of full-cycle CO₂ saturation evolution. It is demonstrated that the sweep efficiency is anti-swelling system-CO₂ flooding is a higher sweep efficiency (73.95%) and achieves 58.12% oil recovery and 46.16% CO sequestration efficiency in a core with a permeability of 102.95 × 10 μm². The full-cycle CO saturation change rule was quantified, and the saturation cloud map was drawn. It is proven that the technology has the synergistic mechanism of 'stabilising pore structure-reducing oil viscosity-efficient sequestration', which combines significant oil recovery and carbon sequestration benefits, and provides theoretical and practical guidance for the low-carbon development of strong water-sensitive oilfields.
本研究针对的是一个高水敏性油藏，其粘土含量高（平均23.87%，主要为蒙脱石和伊利石），注水开发会导致粘土矿物水化膨胀，进而使孔喉变窄。研究发现，抗膨胀体系和二氧化碳可缓解这一现象。该研究在碳捕集、利用与封存强化采油（CCUS-EOR）背景下，研究了二氧化碳在抗膨胀体系/原油中的溶解、扩散及协同效应。采用压力衰减法、岩心驱替实验、微观驱油可视化以及改进的数学模型。我们系统研究了粘土矿物对二氧化碳封存与强化采油（EOR）之间平衡的影响。结果发现，超临界二氧化碳的扩散系数随压力升高先迅速增大然后趋于平稳，这表明粘土矿物阻碍了二氧化碳扩散。抗膨胀体系通过抑制粘土膨胀增加了有效孔隙连通性，使扩散系数提高了20 - 28%。改进后的数学模型将油水相分配系数与PR状态方程相结合，准确描述了多相相互作用。计算结果与实验数据的拟合度达92%，优于传统单相模型。通过微观驱油实验、岩心驱替测试以及全周期二氧化碳饱和度演化定量分析。结果表明，在渗透率为102.95×10μm²的岩心中，抗膨胀体系 - 二氧化碳驱替的波及效率更高（73.95%），采收率达到58.12%，二氧化碳封存效率达到46.16%。量化了全周期二氧化碳饱和度变化规律并绘制了饱和度云图。结果证明，该技术具有“稳定孔隙结构 - 降低原油粘度 - 高效封存”的协同机制，兼具显著的采油和碳封存效益，为强水敏性油田的低碳开发提供了理论和实践指导。
