低渗透致密砂岩储层孔隙结构对渗吸特征的影响  

Influence of pore structures on the characteristic of spontaneous imbibition in low-permeability tight sandstone reservoir

作　　者：李晓骁 任晓娟[1,2,3] 罗向荣 LI Xiaoxiao;REN Xiaojuan;LUO Xiangrong(College of Petroleum Engineering,Xi’an Shiyou University,Xi’an City,Shaanxi Province,710065,China;Shaanxi KeyLaboratory of Advanced Stimulation Technology for Oil ＆ Gas Reservoirs,Xi’an City,Shaanxi Province,710065,China;Engineering Research Center of Development and Management for Low to Extra-Low Permeability Oil ＆ GasReservoirs in West China,Ministry of Education,Xi’an City,Shaanxi Province,710065,China)

机构地区：[1]西安石油大学石油工程学院,陕西西安710065 [2]陕西省油气田特种增产技术重点实验室,陕西西安710065 [3]西部低渗-特低渗油藏开发与治理教育部工程研究中心,陕西西安710065

出　　处：《油气地质与采收率》2018年第4期115-120,126,共7页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项"鄂尔多斯盆地大型低渗透岩性地层油气藏开发示范工程"(2016ZX05050006);西安石油大学研究生创新与实践能力培养项目(YCS17212042)

摘　　要：为深入研究低渗透致密储层中不同孔隙结构的渗吸机理及对渗吸过程的影响,以邦德系数、无因次时间下的自吸驱油效率为评价指标,通过压汞、扫描电镜和核磁共振等多种实验手段,在对鄂尔多斯盆地东部X区长6段低渗透致密砂岩储层孔隙结构分类的基础上,研究不同孔隙结构对渗吸特征和自吸驱油效率的影响。结果表明:低渗透致密砂岩储层可以分为中大孔型和微孔缝型2种孔隙组合。不同孔隙结构组合的岩心中,中大孔喉的比例决定自吸驱油效果,残余油主要滞留在微孔喉中。中大孔型岩心中大孔喉比例高,地层水和表面活性剂中自吸驱油效率高,自吸过程受到毛管力作用较弱,表面活性剂改善驱油效果和渗吸方式明显;微孔缝型岩心中大孔喉比例小,毛管阻力影响大,地层水和表面活性剂中自吸驱油效率低。表面活性剂可以明显改变渗吸方式,提高自吸驱油效率,但仍有一部分残余油滞留束缚在微小孔喉中。In order to explore spontaneous imbibition mechanism of different pore structures and its influence on the imbibition process in the low-permeability tight reservoir,the pore structure of the low-permeability tight sandstone reservoirs in Chang6 member in X study area of eastern Ordos Basin was classified. On this basis,the influence of various pore structures on the imbibition characteristics and efficiency of oil displacement was researched through mercury intrusion,SEM and NMR and other analysis methods taking Bond index and imbibition efficiency in dimensionless time as the evaluation index. The experiment results show that there are two types of pore combination：mid-large pore and micro-pore and fracture. The proportion of the mid-large pore throat decides oil displacement effect of the imbibition in cores having different pore structure combinations,and the residual oil mainly remains in the micro-pore throat. The core having mid-large pore is characterized by high proportion of large pore throat,higher oil displacement efficiency of the imbibition in formation water and surfactant,weak effect from capillary pressure during the imbibition process and an evident change in oil displacement efficiency and the way of imbibition by surfactant. The core with micro-pore and fracture is characterized by low proportion of large pore throat,strong effect from capillary pressure and relatively poor imbibition efficiency in formation water and surfactant. Though the surfactant can significantly change the way of imbibition and improve oil displacement efficien？ cy,a part of the residual oil still remains in the micro-pore throat.

关 键 词：低渗透致密 砂岩储层 孔隙结构 自吸 邦德 系数 核磁共振 表面活性剂 鄂尔多斯盆地 

分 类 号：TE311[石油与天然气工程—油气田开发工程]