页岩储层压裂液渗吸期间微观孔隙原油动用特征  

Characteristics of oil production in microscopic pores of shale reservoir during fracturing fluid imbibition

作　　者：孙庆豪 王文东 苏玉亮[1,2] 徐纪龙 郭新成[1,2] 李冠群 SUN Qinghao;WANG Wendong;SU Yuliang;XU Jilong;GUO Xincheng;LI Guanqun(Key Laboratory of Unconventional Oil&Gas Development,Ministry of Education,Qingdao 266580,China;School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China)

机构地区：[1]非常规油气开发教育部重点实验室,山东青岛266580 [2]中国石油大学(华东)石油工程学院,山东青岛266580

出　　处：《中南大学学报（自然科学版）》2022年第9期3311-3322,共12页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51974348,51904324)。

摘　　要：为揭示页岩油储层压后闷井渗吸期间微观孔隙内原油的动用规律,并研究页岩组构相、渗吸方式等因素对渗吸效果的影响,针对沧东凹陷孔店组二段页岩油储层,利用纹层状组构相及块状组构相页岩,开展页岩压裂液自发渗吸及带压渗吸实验。首先,利用扫描电镜(SEM)及低温氮气吸附(LTNA)分析页岩微观孔隙结构特征;其次,利用低温氮气吸附对孔隙直径(孔径)与横向弛豫时间(T_(2))之间的转换系数进行标定,并利用核磁共振技术(NMR)揭示页岩孔径分布特征;最后,开展基于核磁共振技术的压裂液渗吸实验,分析渗吸过程中核磁共振T_(2)谱变化特性,研究不同孔径微观孔隙内的原油动用特征,并定量评价微孔、介孔和大孔的原油采出程度及其贡献度。研究结果表明:页岩渗吸过程分为快速渗吸段、过渡段以及平稳段3个阶段;页岩油采出程度主要取决于介孔,介孔对总孔原油采出程度贡献度可达50%以上;块状组构相页岩微孔及介孔中原油动用难度较大;相比于自发渗吸,带压渗吸时,大孔原油采出程度大幅增加。The propose is to reveal the production law of oil in microscopic pores during the imbibition(well shut-in)after fracturing shale oil reservoir,and study the influence of shale fabric facies,imbibition mode and other factors on imbibition effect.The shale oil reservoir of Member 2 of Kongdian Formation in Cangdong Sag was taken as study object,the laminar fabric facies and massive fabric facies shale were selected,and the fracture fluid spontaneous imbibition and forced imbibition experiments of shale were carried out.Firstly,the microscopic pore structure characteristics of shale were analyzed by scanning electron microscope(SEM)and low-temperature nitrogen adsorption(LTNA).Then,the conversion coefficient between pore diameter and transverse relaxation time(T_(2))was calibrated by low-temperature nitrogen adsorption,and the pore size distribution characteristics were revealed by nuclear magnetic resonance(NMR)technology.Finally,the imbibition experiments of fracturing fluid based on nuclear magnetic resonance technology were carried out to analyze the variation characteristics of NMR T_(2) spectra in the imbibition process,study the characteristics of oil production in the microscopic pores with different pore sizes,and quantitatively evaluate the oil recovery and contribution to shale oil production in micropores,mesopores and macropores.The results show that the process of shale imbibition can be divided into rapid imbibition stage,transitional stage and stable stage.The shale oil recovery mainly depends on the mesopores,and the contribution of mesopores to produced oil is more than 50%.It is difficult to release oil in the micropores and mesopores of massive fabric facies shale.Compared with spontaneous imbibition,the oil recovery in macropores increases greatly with forced imbibition.

关 键 词：页岩油 自发渗吸 带压渗吸 微观孔隙结构 组构相 核磁共振 

分 类 号：TE349[石油与天然气工程—油气田开发工程]