东海盆地西湖凹陷平湖斜坡始新统平湖组成岩相类型及对储层的控制  

Diagenetic Facies Types and Their Control on Reservoirs of EocenePinghu Formation in Pinghu Slope,Xihu Sag,East China Sea Basin

作　　者：郭刚 李鑫 韩雅坤 李峰 陈莹 李林致 Guo Gang;Li Xin;Han Yakun;Li Feng;Chen Ying;Li Linzhi(CNOOC Research Institute Co.,Ltd.,Beijing 100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《吉林大学学报（地球科学版）》2024年第5期1494-1505,共12页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(42202157);中国博士后科学基金项目(2021M693543)。

摘　　要：为了在深埋藏、强非均质性背景下寻找相对优质储层,本文以东海盆地西湖凹陷平湖组为例,基于直观微区观测、间接压汞表征及孔渗分析相结合的方法,在储层沉积学分析的基础上,先划分成岩相类型,进而明确不同成岩相的差异储集能力特征,评价成岩相储集能力。结果表明:平湖组沉积于河流和潮汐双向水动力条件的三角洲-潮坪体系,砂体多发育于水下分流河道、河口坝、潮道、砂坪和混合坪中,以细粒和极细粒为主,主要为长石岩屑砂岩和岩屑长石砂岩;基于成岩作用类型的强度差异将成岩相划分为3类,包括长石溶蚀相、富塑性压实相和钙质胶结相;同一成岩相类型孔渗特征和孔隙结构特征均一,而不同成岩相之间物性差异显著;以孔隙度、渗透率、最大连通孔喉半径为标准对3类成岩相进行量化参数分级评价,长石溶蚀相孔隙度>15%,渗透率>10.0×10^(-3)μm^(2),最大连通孔喉半径>5.0μm,物性条件优于富塑性压实相和钙质胶结相,优选出长石溶蚀相为最有利的储层砂体类型。In order to find relatively high-quality reservoirs under the background of deep burial and strong heterogeneity,this paper takes Pinghu Formation in Xihu sag of East China Sea basin as an example.Based on the combination of intuitive micro-area observation,indirect mercury intrusion characterization and porosity/permeability test,the types of diagenetic facies are first divided based on reservoir sedimentology analysis,and then the differential reservoir capacity characteristics of different diagenetic facies are clarified,and the reservoir capacity of diagenetic facies is evaluated.The study shows that the Pinghu Formation is deposited in a deltaic-tidal transitional system with bi-directional hydrodynamic conditions of rivers and tides.The sand bodies are primarily developed in submerged divergent channels,estuarine dams,tidal channels,sand flats,and mixed flats,which are mainly fine-grained and very fine-grained.Lithologic characteristics are mainly feldspathic sandstones and lithic feldspathic sandstones.Three types of diagenetic phases are classified based on the difference in intensity of diagenetic types,including feldspathic dissolution facies,ductile-rich compaction facies,and calcareous cementation facies.The porosity-permeability and pore structure of the same diagenetic facies type are uniform,while the physical properties vary significantly among diagenetic facies.The three types of diagenetic facies are evaluated in terms of porosity,permeability and maximum connected pore throat radius.Among them,the porosity of feldspar dissolution facies is more than 15%,the permeability is more than 10.0×10^(-3)μm^(2),the maximum connected pore throat radius is more than 5.0μm,and the physical properties are better than ductile-rich compaction facies and calcareous cementation facies.Therefore,feldspathic dissolution facies is the most favorable reservoir sand body type.

关 键 词：西湖凹陷 平湖组 深层 非均质性 成岩相 压汞 东海盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]