川东北灯影组克劳德管富集层及其储集特征分析  

A Cloudina-rich Bed from the Dengying Formation,Northeastern Sichuan Basin,and Its Reservoir Characteristics

作　　者：张敬轩 罗翠[4] 王夏 张磊[1,2,3] 刘倩 李星霖[1,2,3] 张木辉 潘松圻[6] ZHANG JingXuan;LUO Cui;WANG Xia;ZHANG Lei;LIU Qian;LI XingLin;ZHANG MuHui;PAN SongQi(Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;Key Laboratory of Sedimentary Basin and Oil and Gas Resources,Ministry of Natural Resources,Chengdu 610081,China;State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Paleontology,Chinese Academy of Sciences,Nanjing 210008,China;School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China;CNPC Shenzhen New Energy Research Institute Co.,Ltd.,Shenzhen,Guangdong 518054,China)

机构地区：[1]成都理工大学沉积地质研究院,成都610059 [2]成都理工大学油气藏地质及开发工程全国重点实验室,成都610059 [3]自然资源部沉积盆地与油气资源重点实验室,成都610081 [4]中国科学院南京地质古生物研究所现代古生物学和地层学国家重点实验室,南京210008 [5]中国地质大学(武汉)地球科学学院,武汉430074 [6]中国石油深圳新能源研究院,广东深圳518054

出　　处：《沉积学报》2024年第4期1185-1199,共15页Acta Sedimentologica Sinica

基　　金：中国石油勘探开发研究院科学研究与技术开发项目(2021YJCQ03)。

摘　　要：【目的】近年来,继安岳气田的发现和绵阳—长宁裂陷的提出,四川盆地埃迪卡拉系—下寒武统得到了重点关注。这些油气藏的储集层主要发育在灯二段和灯四段的微生物岩和富岩溶孔隙白云岩中。通过讨论埃迪卡拉纪末期首次出现的动物骨骼化石克劳德管(Cloudina)对当时白云岩储层的潜在影响,可拓展区域油气勘探开发思路。【方法】基于四川盆地东部鹿页1井岩心资料,通过偏光显微镜、阴极发光、扫描电子显微镜观察和micro-CT分析,对灯四段顶部的岩矿特征、孔隙类型、成岩类型、成岩序列、孔隙演化进行了初步研究。【结果】川东巫溪地区灯影组顶部生物碎屑微晶白云岩中存在较丰富的管状动物化石,依据其形态特征可鉴定为Cloudina,其基质中存在大量微生物组构。识别出的孔隙类型有管状化石壳体构成的生物孔,以及基质中的粒间孔、沥青孔、晶间溶孔和晶内溶孔;识别出的主要成岩作用有多期的溶蚀作用、胶结作用以及充填作用。从重建的孔隙形态与分布来看,管状化石对生物碎屑微晶白云岩的孔隙度贡献显著,化石富集层的孔隙度至少为0.7%,而基质孔隙度仅为0.1%~0.4%。【结论】富集成层的Cloudina是灯四段局部层位中除微生物礁丘以外的另一个重要孔隙来源。这说明埃迪卡拉纪末期动物矿化骨骼的出现不仅是生物演化上的创新,也为油气储层的类型带来了深刻的改变。[Objective]The discovery of the Anyue gas field and the Mianyang-Changning intratonic sag has attract⁃ed considerable attention to the strata near the Ediacaran-Cambrian boundary in the Sichuan Basin.The reservoirs of these oil and gas fields occur mainly in the microbial and karst porous rich dolomite of the second and the fourth mem⁃ber of Dengying Formation.This study discusses the impact of Cloudina skeletal remains,one of the earliest metazo⁃an mineral skeletons,on the terminal Ediacaran carbonate reservoirs,in order to expand regional oil and gas explora⁃tion strategies.[Methods]Drilling core material from the topmost Dengying Formation of the well Luye 1,northeast⁃ern Sichuan Basin,was examined for sedimentology,diagenesis,pore types,and porosity evolution,using a combi⁃nation of methods including optical microscopy,cathodoluminescence,scanning electron microscopy,and micro-CT analysis.[Results and Discussions]Abundant tubular animal fossils,diagnosed as Cloudina,were aggregated in a layer of bioclastic micrite dolomite.These fossils are preserved in a micritic to microsparitic matrix,with their body axes oriented along the bedding plane.Micritic clots and filaments of probably microbial origin were found all around.The recognized pore types include biogenic pores formed by tubular fossils,intergranular pores,inter-and intracrys⁃talline dissolution pores,and bitumen pores.The main diagenetic processes include dissolution,cementation,and filling at different periods.The high-resolution micro-CT scan shows that the porosity of the studied material is con⁃spicuously affected by the presence/absence of the Cloudina skeleton.Only 0.1%to 0.4%of the porosity can be attributed to the dolomitic matrix,while the contribution of the tubular fossils is more than 0.7%.[Conclusion]Cloudina aggregates can contribute a considerable amount of porosity to the terminal Ediacaran dolomite,in addition to the microbial fabrics.The presence of mineralized animal skeletons at the end of the Ediacaran not only mark

关 键 词：川东北地区 埃迪卡拉系 克劳德管 孔隙 储集特征 

分 类 号：Q913.85[天文地球—古生物学与地层学]