渤海沙一段生物碎屑混积岩古生物特征及储层意义  

Paleobiological Characteristics and Its Reservoir Significance of Bioclastic Migmatite in First Member of Shahejie Formation in Bohai Sea

作　　者：潘文静 王清斌 杜晓峰 田德瑞 王改卫 曹洁 Pan Wenjing;Wang Qingbin;Du Xiaofeng;Tian Derui;Wang Gaiwei;Cao Jie(Bohai Petroleum Research Institute,Tianjin Branch of China National Offshore Oil Corporation Limited,Tianjin 300459,China;Engineering Technology Branch of Energy Development of China National Offshore Oil Corporation Limited,Tianjin 300452,China)

机构地区：[1]中海石油(中国)有限公司天津分公司渤海石油研究院,天津300459 [2]中海油能源发展股份有限公司工程技术分公司,天津300452

出　　处：《地球科学》2020年第10期3827-3840,共14页Earth Science

基　　金：国家科技重大专项(No.2016ZX05024-003)。

摘　　要：渤海海域古近系沙一段广泛发育湖相混积岩,其中生物碎屑混积岩物性好、产能高,是混积岩中的优质储层.对生物碎屑混积岩中的生物碎屑成分展开系统的古生物研究,明确腹足类是渤海海域沙一段生物碎屑混积岩中最主要的生物碎屑类型,共鉴定出腹足类21属27种,介形类19属74种,并且均以适宜一定盐度浅水环境生活的小型化类型为主.结合古环境研究表明,高能环境腹足类易富集,相对低能环境介形类含量上升.通过铸体薄片、扫描电镜、电子探针等分析发现,生物碎屑对混积岩储层演化具有重要影响.生物碎屑体腔孔、壳体铸模孔、遮蔽孔、差异收缩缝直接提供了储集空间;生物碎屑早期溶蚀能有效改善储层渗透能力,促进生物碎屑富集段的白云岩化作用,形成生物碎屑白云岩优质储层;生物碎屑在微生物作用下形成性质稳定的泥晶套,起到了孔隙格架支撑作用.受壳体成分及各门类生物沉积环境差异影响,腹足类为主的生物碎屑混积岩物性更好.Lacustrine migmatite is widely distributed in the first member of Shahejie Formation of Paleogene in Bohai Sea.The bioclastic migmatite is the high-quality reservoir with good physical properties and high productivity.In this paper,a systematic paleontological study of bioclastic components in bioclastic migmatites is carried out.It is confirmed that gastropods are the most important bioclastic types in the first member of the Shahejie Formation in Bohai Sea.21 genus and 27 species of gastropods and19 genus and 74 species of ostracoda are identified.They are mainly miniaturized types suitable for living in a certain salinity and shallow water environment.It is found that the gastropods are easily to accumulate in high energy environment,while the content of ostracods is relatively high in low energy environment combined with paleoenvironmental studies.The analyses of casting thin section,SEM and EPMA show that bioclasts play an important role in the evolution of migmatite reservoir.The reservoir space is directly provided by the cavity hole of the bioclastic body,the mold hole of the shell,the shielding hole and the differential contraction joint.Early dissolution of bioclasts can effectively improve the permeability of the reservoir,promote dolomitization of the bioclastic enrichment section,and form a high-quality reservoir of bioclastic dolomite.Bioclasts form a stable mud crystal set with the action of microorganism,which plays a supporting role of pore lattice.The physical properties of the bioclastic migmatite mainly composed of gastropods are better than the others,as influenced by the differences of shell composition and various kinds of biological sedimentary environment.

关 键 词：渤海海域 古近系 生物碎屑混积岩 古生物 储层 沉积 

分 类 号：P581[天文地球—岩石学]