低-特低渗透储层微观孔喉结构特征及对水驱油特征的影响--以鄂尔多斯盆地渭北油田长3油层组储层为例  

Pore throat microstructures of low-ultra-low permeability reservoirs and their influence on water displacement characteristics:Taking the Chang 3 reservoir of Weibei Oilfield in Ordos Basin as an example

作　　者：何辉 周永强[3] 龙卫江 黎明[3] 贺子箫 王肃 吴可可 朱玉双[1,2] HE Hui;ZHOU Yongqiang;LONG Weijiang;LI Ming;HE Zixiao;WANG Su;WU Keke;ZHU Yushuang(State Key Laboratory of Continental Dynamics,Northwest University,Xi’an City,Shaanxi Province,710069,China;Department of Geology,Northwest University,Xi’an City,Shaanxi Province,710069,China;Research Institute of Exploration and Development,SINOPEC Henan Oilfield Company,Zhengzhou City,Henan Province,450003,China)

机构地区：[1]西北大学大陆动力学国家重点实验室,陕西西安710069 [2]西北大学地质学系,陕西西安710069 [3]中国石化河南油田分公司勘探开发研究院,河南郑州450003

出　　处：《油气地质与采收率》2021年第4期23-34,共12页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项子课题“碎屑岩输导层结构模型中成岩演化过程与流体流动特征”(2017ZX05008-004-004-001);国家自然科学基金项目“高热与超压背景的成岩响应及流体活动对储层成岩-孔隙演化的影响”(41972129)。

摘　　要：渭北油田延长组长3油藏属于低-特低渗透油藏,针对该油藏在注水开发过程中存在储层微观孔喉结构与流体可动用性关系不清楚、渗流机理不明确等问题,利用真实砂岩微观水驱油实验,结合铸体薄片、扫描电镜、高压压汞及物性分析等测试手段,分析渭北油田延长组长3油层组储层微观孔喉结构特征、水驱油渗流特征及其影响因素。结果表明:研究区长3油层组储层的储集空间以粒间孔、粒间溶孔及粒内溶孔为主,发育片状、缩颈状喉道;孔喉结构可分为Ⅰ,Ⅱ和Ⅲ共3种类型,其对应的储层渗流特征及水驱油效率差异明显,Ⅰ和Ⅱ类孔喉结构孔道内以活塞式驱油为主,Ⅲ类孔喉结构主要为非活塞式驱油;孔隙网络中Ⅰ类孔喉结构的驱替方式主要为均匀状、网状-均匀状,Ⅱ类孔喉结构为网状驱替,Ⅲ类孔喉结构主要为指状-网状驱替;由Ⅰ—Ⅲ类孔喉结构对应的储层物性逐渐变差,小孔喉含量增多,最终驱油效率依次降低。储层物性、孔喉结构、驱替压力和注水倍数等均对水驱油渗流特征和最终驱油效率产生影响。储层物性越好,孔喉结构越好,水驱油效率也就越高,适当增加注入压力以及注水倍数,可以提高水驱油最终采收率。Chang 3 reservoir of Yanchang Formation in Weibei Oilfield is a low-ultra-low permeability reservoir.The rela⁃tionship between pore throat microstructures and fluid availability and the percolation mechanism are unclear during the water injection development of this reservoir.With regard to this problem,microscopic water flooding experiments on real sandstones were performed to investigate the pore throat microstructures,water-flooding percolation characteristics,and their influencing factors in Chang 3 reservoir of Yanchang Formation in Weibei Oilfield,using the casting thin-section anal⁃ysis,scanning electron microscopy,high-pressure mercury intrusion,physical property analysis,and other test methods.The results show that Chang 3 reservoir space in the study area is dominated by intergranular pores,intergranular dissolved pores,and intragranular dissolved pores,with flaky and necking throats.The pore throat structures can be divided into TypesⅠ,ⅡandⅢ,and their corresponding percolation characteristics in reservoirs and water displacement efficiencies are distinctly different.The water displacement in TypesⅠ-Ⅱpore throat structures mainly belongs to the piston-like,while that in TypeⅢpore throat structure is mainly the non-piston-like.In the pore networks,the water displacement pattern is mainly uniform and networked-uniform in TypeⅠpore throat structure;while networked in TypeⅡstructure;meanwhile fin⁃ger-shaped-networked in TypeⅢstructure.In addition,the physical properties of the reservoirs corresponding to TypesⅠ-Ⅲpore throat structures gradually deteriorate;the number of small pore throats increases;the ultimate oil displacement efficiency decreases successively.Reservoir physical properties,pore throat structure,displacement pressure,and water in⁃jection multiples all influence the water-flooding percolation characteristics and the ultimate displacement efficiency.The more favorable reservoir physical properties and the better pore throat structure can lead to the higher water

关 键 词：孔喉结构类型 渗流特征 水驱油 驱替压力 注水倍数 渭北油田 特低渗透油藏 

分 类 号：TE348[石油与天然气工程—油气田开发工程]