渤中凹陷西次洼古近系东营组异常高孔带特征及成因机制  

Characteristics and genetic mechanisms of anomalous high-porosity zones of the Paleogene Dongying Formation in western sub-sag of the Bozhong Sag

作　　者：朱文奇 昝春景 张莹 王涛 史朝文 巴李霞 陈亮[2] 季汉成[2] ZHU Wenqi;ZAN Chunjing;ZHANG Ying;WANG Tao;SHI Zhaowen;BA Lixia;CHEN Liang;JI Hancheng(CNOOC Research Institute Co.,Ltd.,Beijing 100028,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028 [2]中国石油大学(北京)地球科学学院,北京102249

出　　处：《岩性油气藏》2025年第2期70-80,共11页Lithologic Reservoirs

基　　金：中国石油天然气集团有限公司创新基金项目“吉木萨尔凹陷芦草沟组碳酸盐岩滩坝型储层成因与分布”(编号:2021D002-0102);中国石油大学(北京)科研基金项目“陆相混合沉积地球化学特征与甜点发育规律”(编号:2462023BJR011)联合资助。

摘　　要：通过钻井和测井资料分析,结合薄片鉴定、扫描电镜和X射线衍射等岩心分析测试资料,对渤中凹陷西次洼古近系东营组储层特征、异常高孔带的分布规律及其成因机理进行了分析。研究结果表明:①渤中凹陷西次洼古近系东营组储层岩性主要为长石砂岩、岩屑质长石砂岩和长石质岩屑砂岩,储层储集空间以次生溶孔为主,原生粒间孔次之。②研究区异常高孔带主要发育在2400~3400m的深度区,孔隙类型主要为粒间溶蚀孔、颗粒溶蚀孔和微裂缝。③研究区东营组储层物性主要受原始沉积环境的控制,辫状河三角洲内前缘亚相储层分选性好、粒径中等、胶结物含量低,具有优良的储集性能。④研究区东营组成岩阶段为中成岩A期,因有机质热演化程度较高(0.5%≤Ro≤1.0%),碳酸盐胶结物、长石和岩屑等不稳定组分被溶蚀而形成了大量溶蚀次生孔隙;硫酸盐的热氧化还原反应(TSR反应)生成的H2S也形成了少量次生孔隙,有效改善了储层的物性。辫状河三角洲内前缘和浅水三角洲内前缘沉积微相中TSR反应区和胶结—溶蚀相分布区为研究区有利储层发育区。Based on the analysis of drilling and logging data,combined with core analysis and test data such as thin section identification,scanning electron microscopy and X-ray diffraction,the reservoir characteristics,distribution law and genesis mechanism of the Paleogene Dongying Formation in western sub-sag of the Bozhong Sag were analyzed.The results show that:(1)The lithology of the Paleogene Dongying Formation in western sub-sag of the Bozhong Sag is mainly feldspathic sandstone,lithic feldspathic feldspathic sandstone and feldspathic lithic sandstone,and the reservoir space is dominated by secondary karst pores,followed by primary intergranular pores.(2)The abnormally high porosity zone in the study area is mainly developed in the depth range of 2400-3400 m,and the pore types are mainly intergranular dissolution pores,particle dissolution pores and microcracks.(3)The physical properties of the reservoirs in the Dongying Formation in the study area are mainly controlled by the original sedimentary environment,and the subfacies reservoirs in the front edge of the braided river delta have good sortability,medium particle size,low cementation content,and excellent reservoir performance.(4)The Dongying Formation in the study area are in the mesodiagenetic stage A,which forms a large number of dissolved secondary pores due to the high degree of thermal evolution of organic matter(0.5%≤R_(o)≤1.0%),the increase of organic acid content,and the dissolution of unstable components such as carbonate cement,feldspar and cuttings.Among them,the H2S generated by the thermal redox reaction(TSR reaction)of sulfate also caused the formation of a small number of secondary pores,and these factors improved the physical properties of the reservoir to varying degrees.Combined with diagenetic facies analysis,the TSR reaction zone and cementation-dissolution facies distribution area in the sedimentary microfacies at the inner front of the braided river delta and the inner front of the shallow water delta are favorable reservoir develop

关 键 词：异常高孔带 次生溶孔 沉积环境 辫状河三角洲内前缘 TSR反应 东营组 古近系 西次洼 渤中凹陷 

分 类 号：TE122.2[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]