大兴安岭西缘贺斯格乌拉凹陷白垩系烃源岩生烃潜力与天然气成因  

Hydrocarbon generation potential and gas genesis of Cretaceous source rocks in Hesigewula Sag,western margin of Great Khingan

作　　者：孙砚泽 李世臻 刘卫彬 刘岩[1] 柯昌炜 徐耀辉[1] SUN Yanze;LI Shizhen;LIU Weibin;LIU Yan;KE Changwei;XU Yaohui(Key Laboratory of Ministry of Education of Oil and Gas Resources and Exploration Technology(Yangtze University),Wuhan 430100,Hubei,China;Oil and Gas Resources Survey,China Geological Survey,Beijing 100083,China)

机构地区：[1]油气资源与勘探技术教育部重点实验室(长江大学),湖北武汉430100 [2]中国地质调查局油气资源调查中心,北京100083

出　　处：《地质通报》2021年第9期1484-1492,共9页Geological Bulletin of China

基　　金：中国地质调查局项目《大兴安岭西缘断陷白垩系烃源岩生烃潜力评价及热演化史》(编号:DD20160202);中海石油(中国)有限公司天津分公司项目(编号:CCL2020TJT0NST1956)。

摘　　要：大兴安岭西缘贺斯格乌拉凹陷为新发现凹陷,其潜在烃源岩的生烃潜力及天然气成因尚未有过系统研究。对该凹陷3口参数井及部分煤田探井白垩系160块岩心样品进行有机岩石学、有机地球化学等分析,结合构造、沉积特征,系统分析了该凹陷白垩系泥岩生烃潜力,探讨了贺地1井天然气的成因类型。贺斯格乌拉凹陷下白垩统暗色泥岩有机质丰度较高,腾格尔组一段一般泥岩TOC平均为2.20%,腾格尔组二段TOC平均为3.67%;以Ⅱ_(1)—Ⅱ_(2)型有机质为主;成熟度较低,目前处于未熟-低熟阶段。贺地1井天然气甲烷碳同位素较轻,含量为-70.5‰~-68.2‰,结合甲烷氢同位素特征,认为该井天然气为生物成因气,二氧化碳还原与乙酸发酵混合生成。因所采岩心样品普遍浅于1000 m,推测凹陷深部(大于2000 m)已进入到生油高峰期,具有一定的油气勘探潜力。The Hesigewula Sag on the western margin of the Great Khingan is a newly-discovered sag where the hydrocarbon generation potential of its potential source rocks has not been systematically studied.Based on the analysis of organic petrology and organic geochemistry of 160 core samples from three parameter wells and some coalfield exploration wells in the Hesigewula Sag,and combined with tectonic and sedimentary characteristics,the hydrocarbon generation potential of Cretaceous mudstone in the Hesigewula Sag is systematically analyzed.The genetic types of natural gas in Well Hedi 1 are also discussed.The total organic carbon of Lower Cretaceous dark mudstone in Hesigewula Sag is high.The average TOC of K_(1)bt_(1) mudstone is 2.20%and the K_(1)bt_(2) is 3.67%.The type of the organic matter is Ⅱ_(1)-Ⅱ_(2).The degree of thermal evolution is relatively low,and it is at the stage of immature-low maturity.The carbon isotope of methane in Well Hedi 1 is relatively light,with contents ranging from-70.5‰to-68.2‰.Combined with the hydrogen isotope characteristics of methane,it is considered that the natural gas in Well Hedi 1 is biogenic gas,which is produced by the mixture of carbon dioxide reduction and acetic acid fermentation.Because the core samples are generally collected less than 1000 meters at depth,it is presumed that the deep part of the depression(more than 2000 meters)has entered the peak period of oil generation,which has a certain exploration potential.

关 键 词：大兴安岭西缘 贺斯格乌拉凹陷 白垩系 烃源岩 生烃潜力 天然气 

分 类 号：P534.53[天文地球—古生物学与地层学] P618.13[天文地球—地质学]