Zhang Miaoxin, Wu Jingchun, Cai Liyuan, Li Bo, Zhao Yang, Hou Yangyang, Shi Fang, Zhang Chunlong
Key Laboratory for EOR Technology (Ministry of Education), Northeast Petroleum University, Daqing, China.
Daqing Yongzhu Petroleum Technology Development Co Ltd., Daqing, China.
PLoS One. 2025 Sep 5;20(9):e0331674. doi: 10.1371/journal.pone.0331674. eCollection 2025.
Strongly water-sensitive reservoirs with high clay content face challenges in conventional development due to clay swelling and impeded seepage. CO2 injection shows potential for enhanced oil recovery (EOR) and carbon sequestration; however, the role of clay minerals in regulating CO2-induced asphaltene deposition and sequestration remains unclear.
We conducted experiments on clay-oil interactions, nuclear magnetic resonance (NMR), measurements of crude oil properties, and long core water flooding tests to evaluate deposition, reservoir damage, and CO2 sequestration.
CONCLUSIONS/SIGNIFICANCE: Results demonstrate that clay minerals significantly promote CO2-induced asphaltene deposition, with the deposition amount in clay-containing crude oil increasing by 37% compared to clay-free systems. The interfacial tension (IFT) between crude oil and CO2 decreases from 15.68 to 12.53 mN/m at 10 MPa with increasing clay content, while crude oil viscosity reduces by up to 43.58% when CO2 injection exceeds 30 mol%. Microscale NMR analysis confirms that clay-asphaltene aggregates preferentially block large pores, reducing reservoir heterogeneity and enhancing CO2 sequestration in medium/small pores. Macroscale long-core experiments highlight the significance of high clay mineral content for geological sequestration, showing that the CO2 sequestration rate increases from 43.15% to 48.21% as clay content rises from 8.35% to 29.92%. Although deposition slightly impairs permeability, it drives CO2 into medium/small pores, thereby achieving a balance between oil recovery efficiency and long-term storage stability.
高黏土含量的强水敏油藏在常规开发中面临黏土膨胀和渗流受阻的挑战。二氧化碳注入在提高采收率（EOR）和碳封存方面显示出潜力；然而，黏土矿物在调节二氧化碳诱导的沥青质沉积和封存中的作用仍不明确。
我们进行了黏土 - 油相互作用实验、核磁共振（NMR）、原油性质测量以及长岩心水驱试验，以评估沉积、储层损害和二氧化碳封存情况。
结论/意义：结果表明，黏土矿物显著促进了二氧化碳诱导的沥青质沉积，含黏土原油中的沉积量比无黏土体系增加了37%。在10MPa下，随着黏土含量增加，原油与二氧化碳之间的界面张力（IFT）从15.68降至12.53mN/m，而当二氧化碳注入量超过30mol%时，原油黏度降低高达43.58%。微观尺度的核磁共振分析证实，黏土 - 沥青质聚集体优先堵塞大孔隙，降低储层非均质性，并增强中/小孔隙中的二氧化碳封存。宏观尺度的长岩心实验突出了高黏土矿物含量对地质封存的重要性，表明随着黏土含量从8.35%升至29.92%，二氧化碳封存率从43.15%增至48.21%。尽管沉积会轻微损害渗透率，但它会将二氧化碳驱入中/小孔隙，从而在采收率和长期储存稳定性之间实现平衡。
