纳米孔隙中CO_(2)-页岩油的相行为特征  

Phase behavior of CO_(2)-shale oil in nanopores

作　　者：王昱翰 雷征东[2,3,4] 刘一杉 潘秀秀 陈哲伟 张元庆 郑晓宇 刘鹏程 韩艺[1] WANG Yuhan;LEI Zhengdong;LIU Yishan;PAN Xiuxiu;CHEN Zhewei;ZHANG Yuanqing;ZHENG Xiaoyu;LIU Pengcheng;HAN Yi(China University of Geosciences,Beijing 100083,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China;State Key Laboratory of Enhanced Oil Recovery,Beijing 100083,China;State Key Laboratory of Continental Shale Oil,Daqing 163000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Exploration and Development Research Institute of PetroChina Daqing Oilfield Co.,Ltd.,Daqing 163712,China;China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]中国地质大学(北京),北京100083 [2]中国石油勘探开发研究院,北京100083 [3]提高石油采收率全国重点实验室,北京100083 [4]多资源协同陆相页岩油绿色开采全国重点实验室,黑龙江大庆163000 [5]中国科学院大学,北京100049 [6]中国石油大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712 [7]中国石油大学(北京),北京102249

出　　处：《石油勘探与开发》2025年第1期161-173,共13页Petroleum Exploration and Development

基　　金：国家自然科学基金联合基金重点支持项目“古龙页岩油开发渗流理论与提高采收率机理研究”(U22B2075)。

摘　　要：综合考虑流体分子与孔壁间的相互作用、临界性质变化、毛细管力和吸附相的影响,利用修正后的PR(Peng-Robinson)状态方程和气相-液相-吸附相三相相平衡计算方法,分析CO_(2)-页岩油体系在纳米孔隙内的相行为。研究发现:受到纳米孔隙限域效应影响,随着孔径的减小页岩孔隙内流体临界温度和临界压力下降,CO_(2)对体系临界温度的降低起抑制作用、对体系临界压力的降低起促进作用;同时随着CO_(2)物质的量分数的增大,体系临界点左移,相包络线面积减小。大庆古龙A区块页岩储层具有明显的限域效应,当孔径为10 nm时,储层流体逐渐转变为具有凝析气藏流体特征的流体;10 nm孔隙中液相的CO_(2)含量比100 nm孔隙中液相的CO_(2)含量增加了20.0%,而气相中CO_(2)含量减少了10.8%,表明限域效应增强了纳米孔隙中CO_(2)的传质,有利于CO_(2)的埋存和微观驱油。Considering the interactions between fluid molecules and pore walls,variations in critical properties,capillary forces,and the influence of the adsorbed phase,this study investigates the phase behavior of the CO_(2)-shale oil within nanopores by utilizing a modified Peng-Robinson(PR)equation of state alongside a three-phase(gas-liquid-adsorbed)equilibrium calculation method.The results reveal that nano-confinement effects of the pores lead to a decrease in both critical temperature and critical pressure of fluids as pore size diminishes.Specifically,CO_(2) acts to inhibit the reduction of the critical temperature of the system while promoting the decrease in critical pressure.Furthermore,an increase in the mole fraction of CO_(2) causes the critical point of the system to shift leftward and reduces the area of the phase envelope.In the shale reservoirs of Block A in Gulong of the Daqing Oilfield,China,pronounced confinement effects are observed.At a pore diameter of 10 nm,reservoir fluids progressively exhibit characteristics typical of condensate gas reservoirs.Notably,the CO_(2) content in liquid in 10 nm pores increases by 20.0%compared to that in 100 nm pores,while the CO_(2) content in gas decreases by 10.8%.These findings indicate that confinement effects enhance CO_(2) mass transfer within nanopores,thereby facilitating CO_(2) sequestration and improving microscopic oil recovery.

关 键 词：页岩油 纳米孔隙 纳米限域效应 相行为 PR状态方程 

分 类 号：TE122.3[石油与天然气工程—油气勘探]