鄂尔多斯盆地延长组7段3亚段异常高有机质沉积富集因素  

Sedimentary enrichment factors of extraordinarily high organic matter in the sub-member 3 of Member 7 of Yanchang Formation,Ordos Basin

作　　者：刘翰林 邹才能[1] 邱振[1] 潘松圻[1] 张文正[3] 荆振华 郝记华 尹帅 吴松涛[1] 李士祥[3] 郭秋雷 Liu Hanlin;Zou Caineng;Qiu Zhen;Pan Songqi;Zhang Wenzheng;Jing Zhenhua;Hao Jihua;Yin Shuai;Wu Songtao;Li Shixiang;Guo Qiulei(PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China;PetroChina Changqing Oilfield Company,Shaanxi Xi'an 710021,China;University of Science and Technology of China,Anhui Hefei 230026,China;School of Earth Sciences and Engineering,Xi'an Shiyou University,Shaanxi Xi'an 710065,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]北京大学地球与空间科学学院,北京100871 [3]中国石油长庆油田公司,陕西西安710021 [4]中国科学技术大学,安徽合肥230026 [5]西安石油大学地球科学与工程学院,陕西西安710065

出　　处：《石油学报》2022年第11期1520-1541,共22页Acta Petrolei 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“中国典型盆地页岩油气重点层系有机质富集机理研究与主控因素分析”(2021YJCQ02)和“烃源岩形成演化与生物勃发事件响应机理研究”(2021YJCQ03)资助。

摘　　要：鄂尔多斯盆地三叠系延长组7段页岩油资源丰富,其中延长组7段3亚段(长7_(3)亚段)沉积了一套异常高有机质的黑色泥页岩,总有机碳(TOC)含量高达35.8%,是目前中国陆上"进源找油"的重要战略性接替资源。基于全盆TOC含量统计,对异常高有机质样品(TOC≥6%)开展了元素地球化学特征分析,并结合矿物岩石学以及微体(超微)生物化石的埋藏学特征,探讨了异常高有机质沉积的富集机理及主控因素。研究结果显示:长7_(3)亚段异常高有机质富集段发育在温暖潮湿气候条件下的陆相淡水—微咸水环境,光照充足、水系发育、具有适量的陆源碎屑输入,草莓状黄铁矿形貌及粒径分布特征指示了底水以"贫氧"条件为主,营养元素含量、磷酸盐化石及金藻休眠孢囊化石埋藏特征等证据均指示沉积期湖盆处于超富营养状态。鄂尔多斯盆地长7_(3)亚段在高初级生产力水平背景下,动荡的"贫氧—氧化"底水环境和稳定的"贫氧"底水环境均可以形成异常高有机质沉积(TOC≥6%)的规模富集。The Member 7 of Triassic Yanchang Formation in Ordos Basin is rich in shale oil resources.Among them,the sub-member 3 of Member 7 of Yanchang Formation(Chang 7_(3))has deposited a set of black shale with extraordinary high organic matter content and TOC content of 35.8%.It is an important strategic substitute for"exploring petroleum inside source kitchen"onshore in China.Based on the statistical analysis of TOC content in the whole basin,the element geochemical characteristics of samples with extraordinary high organic matter content(TOC≥6%)were analyzed,and the main controlling factors and enrichment mechanism of extraordinary high organic matter deposition were discussed in combination with mineral petrology and burial characteristics of micro(ultra-micro)fossils.The research results showed that the extraordinary high content of organic matter in the Chang 7_(3) developed in a terrestrial freshwater-brackish water environment under warm and humid climate conditions,with sufficient sunlight,well-developed water systems,moderate input of terrigenous detritus.The morphology of pyrite framboids and particle size distribution characteristics indicated that the bottom water was mainly in the"dysoxic"condition,and the nutrient element content,and the burial characteristics of phosphate fossils and dormant cyst fossils of Chrysophyceae indicated that the lake basin was in a hyper-eutrophic state during the depositional period.Under the condition of high primary productivity of Chang 7_(3) in Ordos Basin,the scale enrichment of extraordinary high organic matter deposition(TOC≥6%)can be formed in both the turbulent"dysoxic-oxic"bottom water environment and the stable"dysoxic"bottom water environment.

关 键 词：异常高有机质 沉积环境 草莓状黄铁矿 微体生物化石 有机质富集主控因素 鄂尔多斯盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]