湖北寒武系牛蹄塘组页岩气成藏条件与综合评价

Accumulation Characteristics and Comprehensive Evaluation of Shale Gas in Cambrian Niutitang Formation,Hubei

牛蹄塘组是湖北省重要的海相页岩气层系之一,对其深入研究有助于预测资源潜力并指明勘探方向.利用露头及探井资料对区内牛蹄塘组的储层特征、资源潜力等进行了研究.结果表明,牛蹄塘组依据岩性组合可以分为一段和二段,鄂西宜昌-恩施、神农架西侧深水陆棚相以及鄂东南盆地边缘相富有机质页岩厚度大,TOC含量高,以硅质类页岩为主,页岩气成藏物质基础良好.气显较好的地区集中分布在鄂西黄陵背斜东南缘,分析认为较弱的变形、有效的顶底板和适中的热演化是牛蹄塘组页岩气富集成藏的关键.除宜昌局部地区具有勘探开发前景外,秭归、鹤峰等地区仍值得探索,鄂东南及鄂西北地区由于构造变形和岩浆活动强烈,保存条件极差,基本无页岩气勘探前景.

The Lower Cambrian Niutitang Formation(∈;n)is one of the important shale gas target reservoirs in Hubei Province,China.The deep study of the∈;n helps to calculate the resource potential and indicate exploration direction.Based on outcrop profiles and wells,the characteristics of shale reservoir and resource potential of the∈1n were deeply studied.The results show that the∈;n can be divided into two sections,the first section(∈;n~1)and the second section(∈;n~2).The organic-rich shales of Yichang-Enshi and Shennongjia in West Hubei and Tongshan-Chongyang area in eastern Hubei are characterized by large thickness,high TOC and silica content,which indicates a good material foundation and shale gas resource potential.The area with high gas content is mainly distributed in the southeast slope of Huangling anticline in Yichang,West Hubei.The weak deformation,the effective roof and floor,and moderate thermal evolution are the key factors for the enrichment of Niutitang shale gas reservoir.In addition to Yichang area,Zigui and Hefeng areas are also worthy of further exploration.Due to the strong tectonic deformation and magmatic activity,there is no shale gas exploration prospect in Southeast Hubei and Northwest Hubei.