四川盆地大足地区上奥陶统五峰组—下志留统龙马溪组页岩气储层特征与分布规律  

Shale gas reservoirs of the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation,Dazu area,Sichuan Basin:Characteristics and distribution

作　　者：张海杰 牟泳澄 韩贵生 蒲俊伟 罗彤彤 ZHANG Haijie;MU Yongcheng;HAN Guisheng;PU Junwei;LUO Tongtong(Chongqing Shale Gas Exploration and Development Co.Ltd.,Chongqing 401121,China;Geological Exploration&Development Research Institute,CNPC Chuanqing Drilling Engineering Company Limited,Chengdu,Sichuan 610051,China;Sichuan Hengyi Petroleum Technology Service Company Limited,Chengdu,Sichuan 610051,China)

机构地区：[1]重庆页岩气勘探开发有限责任公司,重庆401121 [2]中国石油集团川庆钻探工程有限公司地质勘探开发研究院,四川成都610051 [3]四川恒溢石油技术服务有限公司,四川成都610051

出　　处：《天然气勘探与开发》2024年第4期28-37,共10页Natural Gas Exploration and Development

摘　　要：上奥陶统五峰组—下志留统龙马溪组深层(3500~4500 m)页岩气已成为四川盆地海相页岩气勘探的主领域。位于川中隆起南缘的大足地区构造平缓,断裂不发育,但页岩储层纵横向非均质性强,开发井生产效果与现有储层评价结果存在较大差异。为此,利用测井、岩心分析化验资料,结合大足地区古地貌研究成果,对该区五峰组—龙马溪组页岩开展精细地层对比,建立了适用于“大面积、连续型”甜点区的储层评价方法,明确页岩储层的纵横向展布规律。研究成果表明:(1)五峰组—龙一1亚段沉积厚度受3个古地貌单元控制,整体呈现出南厚北薄的特征,五峰组—龙一_(1)^(1)小层的沉积中心位于古地貌单元Ⅲ北部;(2)储层展布规律与地层展布规律具有差异性,古地貌单元Ⅱ中五峰组—龙一_(1)^(1)小层Ⅰ类储层总厚度高于古地貌单元Ⅰ和Ⅲ;(3)古地貌单元Ⅱ是大足地区最有利开发区域,古地貌单元Ⅰ具备产能接替区开发潜力。研究成果丰富了大足地区晚奥陶世—早志留世富有机质页岩厚度与优质页岩气储层展布规律认识,为川中隆起南缘近剥蚀区五峰组—龙马溪组页岩气效益开发提供了新的储层评价方法与勘探目标优选思路。Deep shale from the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation(Wufeng-Longmaxi formations),with burial depth ranging from 3,500 m to 4,500 m,has emerged as the main domain for marine shale gas exploration in Sichuan Basin.Dazu area,southern margin of central Sichuan uplift(central basin),is characterized by gentle structures without any faults.But shale reservoirs in this area exhibit strong heterogeneity both vertically and horizontally,leading to great difference between production performance and available reservoir evaluation.So,a fine stratigraphic correlation was performed on the deep shale based on data of well logging and core analysis together with paleogeomorphologic research.A method of reservoir evaluation was built up for massive and continuous sweet spots.Both vertical and horizontal distribution was made clear for the shale reservoirs.Results indicate that(i)the sedimentary thickness from Wufeng Formation to the first submember of the first member of Longmaxi Formation(Long_(1)^(1)submember)is controlled by three paleogeomorphologic units,indicating thicker in the south than in the north.And the depocenter also from Wufeng Formation to Long_(1)^(1)submember is located in the north of unit III;(ii)reservoir distribution differs from stratigraphic extension.And the total thickness of Class I reservoirs from Wufeng Formation to Long_(1)^(1)submember within unit II is larger than that within units I and III;and(iii)unit II is the most favorable belt in Dazu area,while unit I with development potential as another belt of productivity replacement.The above results have enriched understandings on both organic-rich shale thickness and distribution of quality reservoirs in Dazu area from Late Ordovician to Early Silurian,and provide a new tool for reservoir evaluation and ideas to optimize exploration targets for the efficient shale-gas development in Wufeng-Longmaxi formations,southern margin of central Sichuan uplift.

关 键 词：四川盆地 大足地区 深层页岩气 五峰组—龙马溪组 古地貌单元 评价方法 Ⅰ类储层 储层展布规律 

分 类 号：P618.13[天文地球—矿床学]