中上扬子地区陡山沱组沉积特征及其油气地质意义  

Sedimentary characteristics of Doushantuo Formation in middle-upper Yangtze region and its significance for oil and gas geology

作　　者：陈科 卢妍欣 李飞 宋腾 CHEN Ke;LU Yanxin;LI Fei;SONG Teng(Oil&Gas Survey Center,China Geological Survey,Beijing,100083,China)

机构地区：[1]中国地质调查局油气资源调查中心,北京100083

出　　处：《中国地质调查》2024年第5期92-103,共12页Geological Survey of China

基　　金：国家自然科学基金地质联合基金项目“古特提斯洋俯冲方向和过程对三江造山带构造格架的控制(编号:U2344213)”资助。

摘　　要：近期鄂西地区震旦系陡山沱组勘查获得页岩气工业气流。陡山沱组富有机质页岩主要分布于上扬子德阳—安岳断陷槽及中扬子鄂西断陷槽,探明其沉积特征和油气地质条件是进一步开展页岩气与常规油气勘探开发的重要依据。通过研究中上扬子两个断陷槽内陡山沱组露头、钻井和地球物理资料,对比分析两者的沉积特征和沉积环境,结果显示:①中上扬子地区陡山沱组沉积时期古地理格局在地形上具有西高东低的特征;②陡山沱组沉积早期,上扬子地区仍然存在大面积古陆,其厚度较薄或缺失,中晚期才接受大量沉积,而中扬子地区此时为台地、瀉湖、陆棚和盆地的沉积环境,地层发育较完整,富有机质页岩沉积厚度较大;③陡山沱组是在整体拉张环境下形成的产物,中上扬子地区断陷槽均形成台内断陷盆地,上扬子地区德阳—安岳断陷槽形成时间较晚,陡山沱组主要沉积碳酸盐岩,中扬子地区鄂西断陷槽形成较早,槽内沉积页岩夹碳酸盐岩;④鄂西断陷槽内厚层陡山沱组富有机质页岩,保存较好的构造单元中有望获得页岩气勘查新突破,并可以作为灯影组常规天然气烃源岩,在生储盖匹配地区有望形成常规油气藏。研究成果可以为震旦纪—寒武纪裂陷槽油气调查工作提供参考。Industrial gas flow of shale gas was recently achieved in Doushantuo Formation of Sinian in the western Hubei Province.The organic-rich shale of Doushantuo Formation was predominantly found in Deyang-Anyue rift of the upper Yangtze region and the western Hubei rift of the middle Yangtze region,and its sedimentary characteristics and petroleum geological conditions were critical for further exploration and development of shale gas and oil resources.A comparative analysis of the sedimentary characteristics and environment of these two rifts was conducted through the analysis of the outcrops,drilling,and geophysical data of Doushantuo Formation.The results are as follows.①The paleogeographic pattern exhibited a terrain that was higher in the west and lower in the east in the middle-upper Yangtze region during the deposition of Doushantuo Formation.②A significant area of ancient land persisted in the upper Yangtze region during the early deposition stage of Doushantuo Formation,with a relatively thin layer or missing layer,which has mass deposition in the middle-later stage.While the middle Yangtze region features sedimentary environment such as platform,lagoon,continental shelf,and basin,with well-developed strata,substantial sediment thickness,and development of organic-rich shales.③Doushantuo Formation is a product of an extensional environment,and the aulacogen in the middle-upper Yangtze region all formed graben basin with in the platform.The formation of Deyang-Anyue fault depression in the upper Yangtze region occurred late,and Doushantuo Formation primarily deposited in carbonate rock.Conversely,the western Hubei rift of the middle Yangtze region formed earlier,with shale and carbonate intercalations depositing.④In the western Hubei Province,Doushantuo Formation depositing in the rift trough contains abundant organic matter.The well-preserved structural units are anticipated to lead to breakthroughs in shale gas exploration,which could potentially serve as the natural gas source rock of Dengying Forma

关 键 词：陡山沱组 扬子克拉通 震旦纪 沉积特征 页岩气 

分 类 号：P584[天文地球—岩石学]