页岩油储层混合细粒沉积孔喉特征及其对物性的控制作用——以准噶尔盆地吉木萨尔凹陷二叠系芦草沟组为例  

Pore throat characteristics of fine-grained mixed deposits in shale oil reservoirs and their control on reservoir physical properties:A case study of the Permian Lucaogou Formation,Jimsar Sag,Junggar Basin

作　　者：马克[1,2] 侯加根 董虎[2] 吴国强 闫林 张丽薇 Ma Ke;Hou Jiagen;Dong Hu;Wu Guoqiang;Yan Lin;Zhang Liwei(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;IRock Technologies Co.,Ltd.,Beijing 100094,China;Research Institute of Science and Technology,PetroChina,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]数岩科技股份有限公司,北京100094 [3]中国石油科学技术研究院,北京100083

出　　处：《石油与天然气地质》2022年第5期1194-1205,共12页Oil & Gas Geology

基　　金：国家重点基础研究发展计划(973计划)项目(2015CB250901)。

摘　　要：准噶尔盆地吉木萨尔凹陷二叠系芦草沟组页岩油勘探近年来取得重大突破,使得这套储层成为陆相页岩油勘探开发的重要目标。综合运用铸体薄片、微量元素、扫描电镜、微米CT、纳米CT及多种压汞实验数据,研究了芦草沟组咸化湖混合细粒沉积复杂岩性内部孔喉结构及其对储层物性的影响。研究结果表明:芦草沟组白云质粉砂岩、粉砂质白云岩及砂屑白云岩构成了甜点体的优势岩性,微纳米级孔喉系统占据了储集空间主体,孔喉半径在数百微米至数十纳米的区间内连续分布;微米至亚微米级喉道对渗透率贡献最大,主流喉道半径区间为0.25~0.63μm。微纳米级孔喉结构控制了储层的渗透性及含油性,优势岩性峰值孔喉半径大、分布范围宽,喉道半径分布区间、主流喉道半径及有效喉道体积是控制储层渗透率的关键因素。这些认识为储层油气充注预测及优势沉积相带内井位部署提供了重要的地质支撑。Major breakthroughs have been made in recent years in shale oil exploration in the Permian Lucaogou Formation of the Jimsar Sag,Junggar Basin,which has become an important target for the exploration and development of continental shale oil reservoirs.An integration of cast thin sections,trace elements,SEM(scanning electron microscopy),micron and nanometer CT imaging,PMI(pressure-controlled mercury injection)and RMI(rate-controlled mercury injection)was applied to study the pore throat structure of the fine-grained mixed(silisiclastic-carbonate)deposits in the Lucaogou Formation of saline lacustrine basin facies and its control on porosity and permeability of reservoirs.The results suggest that the dolomitic siltstone,silty dolomite and dolomicrite are of the best lithologic types in sweet spots.Micro-/nano-scale pore throat systems take a dominant position in reservoir space,with a pore throat radius ranging from hundreds of micrometers to tens of nanometers.Micro-to sub-micro-scale pore throats make the greatest contribution to permeability with the main throat radius ranging from 0.25μm to 0.63μm.The structure of micro-to nano-scale pore throats controls the permeability and oil content.The dominant lithologic types have larger peak values and wider distribution of pore throat radius.Besides,the distribution of throat radius,mainstream throat radius and volume of effective throat volume are the key factors controlling reservoir permeability.These understandings act as important geological supports for reservoir hydrocarbon charging prediction and well deployment in dominant sedimentary facies zones.

关 键 词：孔喉结构 储层质量 混合沉积 陆相页岩油 芦草沟组 吉木萨尔凹陷 准噶尔盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]