东海盆地西湖凹陷平湖组煤系烃源岩条件及成烃模式  

Coal source rock conditions and hydrocarbon generation model of Pinghu Formation in Xihu Depression,East China Sea Basin

作　　者：蒋一鸣 刁慧 曾文倩 Jiang Yiming;Diao Hui;Zeng Wenqian(CNOOC China Limited-Shanghai,Shanghai 200335,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《地质科技通报》2020年第3期30-39,共10页Bulletin of Geological Science and Technology

基　　金：国家科技重大专项(2016ZX05027-001)。

摘　　要：西湖凹陷是中国近海最重要的煤成油气凹陷。近年来,油气勘探证实平湖组煤系烃源岩为西湖凹陷提供了丰富的油气资源。与陆上其他中生代煤成油气盆地不同,近海新生代海陆过渡相平湖组煤系烃源岩在母质来源、生烃条件和演化特征上都有其独特性。研究表明,平湖组煤和炭质泥岩具有富含树脂体、高I H指数、Ⅱ1-Ⅱ2型干酪根、广覆式分布特点;煤系烃源岩富含三环二萜异海松烷、四环二萜β-扁植烷和五环三萜奥利烷,指示了针叶类裸子植物、蕨类植物和被子植物多植被母质来源;有机质组成差异、“内热外冷”地温和差异的沉积沉降速率造成了煤和泥岩在不同构造带成烃演化具有明显不同。这种差异决定了煤成油气资源具有“油气并举、东气西油”的分布格局,烃源岩成烃演化表现为“早期有利生油,晚期持续生气”模式。Xihu Depression is the most important coal-forming oil and gas depression in the offshore of China.In recent years,oil and gas exploration has confirmed that the Pinghu Formation coal-series source rocks provide abundant oil and gas resources for Xihu Depression.Different from the Mesozoic coal-forming oil and gas basins in the Terrestrial,the offshore Cenozoic transitional phase of the Cenozoic sea-continental coal source rocks is unique in terms of parent material source,hydrocarbon generation conditions and evolution characteristics.Studies have shown that the source rocks of Pinghu Formation coal-bearing source are rich in tricyclic diiso-isoaspam,beta-flatane and pentacyclic triterpenoids,indicating conifers,ferns and angiosperms.Coal source rock and carbonaceous mudstones are rich in resin,high I H,Ⅱ1-Ⅱ2 type kerogen,and wide-spread distribution characteristics;coal source rocks are rich in tricyclic diterpene iso-seapine,tetracyclic diterpenoidβ-phytoplantans and pentacyclic triterpenoids orienes,indicating the source of multi-vegetative parent material of gymnosperms,ferns,and angiosperms;differences in organic matter composition,"internal heat and external cold"geothermal differences in sediment deposition velocity caused significant differences in the evolution of coal and mudstones in different tectonic zones.This difference determines that the coal-derived oil and gas resources have a distribution pattern of"simultaneous oil and gas and east-west oil",and the hydrocarbon-forming evolution of source rocks shows a pattern of"favorable oil production in the early stage and continued gas generation in the late stage".

关 键 词：煤系烃源岩 西湖凹陷 生烃条件 成烃模式 煤成油气 

分 类 号：P618.11[天文地球—矿床学] TE122.2[天文地球—地质学]