鄂西宜昌地区五峰-龙马溪组古环境演化及其对页岩储层的影响  

Palaeoenvironmental evolution of Wufeng-Longmaxi Formation and its influence on shale reservoir in Yichang Area,Western Hubei

作　　者：张焱林 黄赛鹏 孙梦迪 许露露 李雄伟 温雅茹 任志军 ZHANG Yanlin;HUANG Saipeng;SUN Mengdi;XU Lulu;LI Xiongwei;WEN Yaru;REN Zhijun(College of Resources and Environment,Yangtze University,Wuhan,Hubei 430100,China;Hubei Geological Survey,Wuhan,Hubei 430034,China;Institute of Unconventional Oil&Gas,Northeast Petroleum University,Daqing,Heilongjiang 163318,China)

机构地区：[1]长江大学资源与环境学院,湖北武汉430100 [2]湖北省地质调查院,湖北武汉430034 [3]东北石油大学非常规油气研究院,黑龙江大庆163318

出　　处：《东北石油大学学报》2023年第5期1-16,I0001,共17页Journal of Northeast Petroleum University

基　　金：国家自然科学基金项目(42202155);湖北省自然资源科技项目(ZRZY2021KJ22)。

摘　　要：鄂西宜昌地区夷陵区块五峰—龙马溪组获重大页岩气发现。以研究区夷地1井为研究对象,根据总有机碳(TOC)质量分数、主微量元素、扫描电镜等测试,分析五峰—龙马溪组页岩沉积环境特征及其页岩气地质意义。结果表明:五峰组和龙马溪组下段TOC质量分数平均大于2.00%,为富有机质页岩,相对富集Si、Ca、Vr、Co、Ni、Zn、Mo、Ba和U。五峰—龙马溪组属于强滞留环境,五峰组和龙马溪组下段主要沉积于底水缺氧铁化环境,古生产力较高,是有机质富集的主要原因。鲁丹阶向埃隆阶过渡期,广西运动导致的构造剧烈抬升,底水氧化,洋流上涌较弱,导致水体贫营养化,是笔石带由LM5转变为LM6的主要原因。富有机质页岩特别是龙马溪组下段储层物性较好,含气量高。与川东南礁石坝区块相比,五峰—龙马溪组富有机质页岩厚度较薄(10~20 m),总含气量较低,TOC质量分数较高,且受黄陵刚性基底保护构造改造弱,在研究区北东靠近秦岭洋方向,具备较好的页岩气勘探潜力。该结果对鄂西宜昌地区页岩气勘探开发具有指导意义。Significant shale gas sources have been discovered in Wufeng-Longmaxi Formation in the Yiling Block of Western Hubei.This paper aims to investigate the palaeoenvironmental conditions and its shale gas geological significance of the Wufeng-Longmaxi shales from well YD1 by integrating data on total organic carbon(TOC)content,major and trace elements,and scanning electron microscope and so on.The results show that the average TOC value of the Wufeng Formation and the lower part of Longmaxi Formation are greater than 2.00%,and thus they are organic-rich shales which are rich in Si,Ca,Vr,Co,Ni,Zn,Mo,Ba and U.The Wufeng-Longmaxi shales were deposited under highly restricted conditions,which are the main reasons for the organic matter accumulation.Due to the tectonic uplift caused by the Kwangsian Orogeny in the Upper Longmaxi Formation,the palaeoenvironment was characterized by a bottom water oxic conditions,and the insufficient nutrients caused by the weak upwelling,which is the main factor for the turnover of graptolite biozones from LM5 to LM6.The organic rich shale,especially the lower part of Longmaxi Formation,has better physical properties and higher gas content.Compared with the Jiaoshiba Block in Southeastern Sichuan,although the organic-rich shale of Wufeng-Longmaxi Formation in Yiling Block is thinner(10-20 m)and the total gas content is relatively lower,the TOC content is high and the tectonic activity is weak due to the protection by the Huangling rigid basement.It still has good shale gas exploration potential in the northeastern of study area close to the Qinling Ocean.This research has direct meaning to the development of shale gas in Yichang Area,Western Hubei.

关 键 词：古环境 五峰—龙马溪组 黑色页岩 页岩气 鄂西地区 夷地1井 

分 类 号：TE122.2[石油与天然气工程—油气勘探]