致密砂岩孔隙结构对两相驱替特征及CO_(2)封存效率的影响机制  

Influence mechanism of tight sandstone pore structure on two-phase displacement characteristics and CO_(2) storage efficiency

作　　者：杨柳[1,2] 吉明秀 赵艳[1,2] 耿振坤 李思源 马雄德[1,2] 张谦 YANG Liu;JI Ming-xiu;ZHAO Yan;GENG Zhen-kun;LI Si-yuan;MA Xiong-de;ZHANG Qian(School of Water and Environment,Chang’an University,Xi’an,Shaanxi 710054,China;Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of Ministry of Education,Chang’an University,Xi’an,Shaanxi 710054,China;Petro China Changqing Oilfield Company Planning Department,Xi’an,Shaanxi 710018,China)

机构地区：[1]长安大学水利与环境学院,陕西西安710054 [2]长安大学旱区地下水文与生态效应教育部重点实验室,陕西西安710054 [3]中国石油长庆油田分公司规划计划部,陕西西安710018

出　　处：《岩土力学》2025年第4期1187-1195,1204,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.42007174);中国博士后科学基金特别资助(No.2023T160558);陕西省科学技术协会青年人才托举计划(No.20230716);长安大学中央高校基本科研业务费专项资金(No.300102293206)。

摘　　要：深部咸水含水层具有巨大的CO_(2)封存潜力,研究致密砂岩CO_(2)-水两相驱替机制对实现高效安全的CO_(2)咸水层封存具有重要意义。对两个具有不同孔隙结构特征的低渗透砂岩开展了CO_(2)-水两相驱替试验,利用核磁共振(nuclear magnetic resonance,NMR)和磁共振成像(magnetic resonance imaging,MRI)技术对气驱和吸水两个阶段气水两相的分布进行了定量及可视化研究,分析了岩芯孔径分布、非均质性及渗透率差异等对两相驱替特征的影响机制。研究表明在气驱阶段CO_(2)相优先被捕获在较大的孔隙中,大孔分布较多的岩芯表现出更高的CO_(2)饱和度;但在吸水阶段小孔占比更高、渗透率更低的岩芯内捕获的CO_(2)相不易被水驱走,表现出更高的CO_(2)封存效率;岩芯局部渗透率变化对最终的残余气分布影响显著,渗透率较低的区域具有更高的最终残余气饱和度和封存效率。研究可进一步完善CO_(2)咸水含水层封存项目中的储层优选、高效封存以及安全性评估等理论体系。Deep saline aquifers offer substantial CO_(2)storage potential,and exploring the CO_(2)-water two-phase displacement mechanisms in tight sandstone is crucial for efficient and secure CO_(2)storage in saline aquifers.CO_(2)-water two-phase displacement experiments were conducted on two low-permeability sandstones with distinct pore structures.Nuclear magnetic resonance(NMR)and magnetic resonance imaging(MRI)techniques were employed to quantitatively and visually analyze the distribution of gas and water phases during the drainage and imbibition processes.The study examined the impact of core pore size distribution,heterogeneity,and permeability variations on the two-phase displacement characteristics.The research indicates that in the drainage processes,CO_(2)is preferentially captured in larger pores,and cores with a larger proportion of large pores exhibit higher CO_(2)saturation.However,during the imbibition processes,CO_(2)captured in the cores with a higher proportion of micropores and lower permeability are less likely to be displaced by water,resulting in higher CO_(2)storage efficiency.The local permeability changes of rock cores have a significant impact on the final residual gas distribution,and areas with lower permeability have higher final residual gas saturation and storage efficiency.This study can further improve the theoretical system of reservoir selection,efficient storage,and safety assessment in CO_(2)saline aquifer storage projects.

关 键 词：咸水层CO_(2)封存 两相驱替 孔隙结构特征 局部渗透率 残余气饱和度 

分 类 号：TU457[建筑科学—岩土工程]