四川盆地侏罗系凉高山组沉积演化特征及页岩油气有利勘探区带  

Sedimentary evolution characteristics of Jurassic Lianggaoshan Formation and favorable exploration areas of shale oil and gas in the Sichuan Basin

作　　者：秦春雨 张少敏[1] 韩璐媛 周红飞[1] 吕龑 姜瀚 余凯 谢强[1] 洪海涛[1,2] 邱玉超 QIN Chunyu;ZHANG Shaomin;HAN Luyuan;ZHOU Hongfei;LYU Yan;JIANG Han;YU Kai;XIE Qiang;HONG Haitao;QIU Yuchao(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;Sichuan Key Laboratory of Shale Gas Evaluation and Exploitation,Guanghan,Sichuan 618300,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院 [2]页岩气评价与开采四川省重点实验室

出　　处：《天然气工业》2025年第1期53-67,共15页Natural Gas Industry

基　　金：中国石油西南油气田公司科技项目“四川盆地侏罗系页岩油甜点地质评价及富集规律研究”(编号:20230301-24)。

摘　　要：四川盆地侏罗系凉高山组沉积期湖盆面积广,三角洲体系砂体、湖相泥(页)岩频繁交互,形成了有利的砂页岩岩性组合,为近年来四川盆地侏罗系页岩油气的主要勘探对象。为探究多期湖盆迁移演化背景下的砂岩—页岩分布规律,指导页岩油气的勘探有利区带预测及优选,基于大量二、三维地震资料、连井地层、沉积相对比,并结合区域构造背景分析,揭示了盆地凉高山组湖盆变迁与沉积演化过程,进一步结合砂页储层分布及成藏富集条件,明确了页岩油气的勘探有利区带。研究结果表明:(1)凉高山组发育2期规模湖盆,第一期湖盆形成于凉一段最大湖侵期,面积达2.5×10^(4) km^(2),主要分布于川东北的平昌—川东的丰都地区,优质泥(页)岩(TOC>1%)厚度介于15~40 m;第二期湖盆形成于凉二段晚期,面积达1.6×10^(4) km^(2),主要位于川中的南充—川北的巴中地区,优质泥(页)岩(TOC>1%)厚度介于10~30 m。(2)湖盆萎缩期即凉二段沉积早期、凉三段沉积早期环湖三角洲砂体广泛发育,整体岩相组合表现为泥(页)岩与细砂岩、粉砂岩频繁互层,形成了页岩型、夹层型2种页岩油气储层。(3)夹层砂岩型储层物性受沉积微相控制,其中分流河道、分流河道—砂坝复合砂体物性好,纵向上主要发育于凉二段、凉三段的三角洲前缘相带,且紧邻优质页岩,成藏条件好。(4)半深湖相页岩厚度大、粉砂质纹层发育,具有生烃能力强、储集物性好、含油气好的特征,纵向上主要发育于凉一段晚期、凉二段晚期的半深湖相带。结论认为:(1)两种页岩油气资源潜力大,近期G119H井的突破证实,川中地区湖盆边缘规模发育的近源有利砂体为凉高山组夹层型页岩油气的重点勘探方向;(2)川东、川东北地区高TOC纹层状页岩稳定发育、有机质成熟度高、地层压力系数高,为页岩型页岩油气的勘探有利区。During the sedimentary period of the Jurassic Lianggaoshan Formation in the Sichuan Basin,the lake basin covered a large area,and the sand bodies and lacustrine mudstone/shale of delta system alternated frequently to form favorable sandstone-shale lithological assemblages,which have been the main exploration objectives of the Jurassic shale oil and gas in the Sichuan Basin in recent years.In order to explore the sandstone-shale distribution patterns under the background of multi-phase lake basin migration and evolution and provide guidance for the prediction and selection of favorable shale oil and gas exploration areas,this paper reveals the change and sedimentary evolution process of Lianggaoshan Formation lake basin in the Sichuan Basin,based on a large amount of 2D and 3D seismic data,as well well-tie stratigrahpic and sedimentary facies correlation,combined with regional tectonic setting analysis.Then,based on the distribution and hydrocarbon accumulation and enrichment conditions of sandstone-shale reservoirs,the favorable exploration areas of shale oil and gas are defined.The following results are obtained.First,there are two stages of large-scale lake basins developed in the Lianggaoshan Formation.The stage 1 lake basin was formed in the maximum lake transgression period of the first member of 4 Lianggaoshan Formation(Liang 1 Member),covering an area of 2.5×10^(4) km^(2),and it is mainly distributed in the area of Pingchang of the northeastern Sichuan Basin to Fengdu of the eastern Sichuan Basin,with the thickness of high-quality mudstone/shale(TOC>1%)ranging from 15 m to 40 m.The stage 2 lake basin was formed in the late stage of the second Member of Lianggaoshan Formation(Liang 24 Member),covering an area of 1.6×10^(4) km^(2),and it is mainly located in the area of Nanchong of the central Sichuan Basin to Bazhong of the northern Sichuan Basin,with the thickness of high-quality mudstone/shale(TOC>1%)ranging from 10 m to 30 m.Second,the lake basin shrank during the early sedimentation of Liang 2 Member

关 键 词：四川盆地 凉高山组 沉积中心 湖盆迁移 沉积相 页岩油气 勘探区带 

分 类 号：TE121[石油与天然气工程—油气勘探]