南祁连盆地木里冻土区第四纪沉积物中可溶有机质的来源及其与天然气水合物的关系  

Source of soluble organic matter in Quaternary sediments in the Muli permafrost area of the South Qilian basin and its relationship to gas hydrate

作　　者：何大双 张鹏辉[1,2] 明承栋 裴发根 何梅兴[1,2] HE Dashuang;ZHANG Penghui;MING Chengdong;PEI Fagen;HE Meixing(Institute of Geophysical and Geochemical Exploration,CAGS,Langfang 065000,Hebei,China;National Research Center of Geo-exploration Technology,Langfang 065000,Hebei,China;EnerTech-Drilling&Production Co.,CNOOC,Shenzhen 518067,Guangdong,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [2]国家现代地质勘查工程技术研究中心,河北廊坊065000 [3]中海油能源发展股份有限公司工程技术分公司,广东深圳518067

出　　处：《地质通报》2020年第7期1062-1071,共10页Geological Bulletin of China

基　　金：中央财政科研项目结余资金项目《木里地区冰缘地貌与水合物分解烃逸散成因关系研究》(编号:JY201705);中国地质调查局项目《陆域冻土区天然气水合物勘查技术方法集成》(编号:DD20160224)。

摘　　要：在南祁连盆地木里坳陷钻遇中国陆域第一例天然气水合物实物样品。通过对木里冻土区钻遇水合物区域(DK井区)第四纪沉积物及邻区湖相沉积物中可溶有机质开展有机地球化学分析,发现DK井区浅地表沉积物中明显存在热解成因的可溶有机质,而邻区老人湖湖相沉积物中可溶有机质以高等植物输入为主。与区内烃源岩对比,热解成因的可溶有机质主要来源于中侏罗世烃源岩,晚三叠世尕勒得寺组烃源岩也有一定的贡献。结合该区水合物气源研究成果,DK井区沉积物中可溶有机质与形成水合物的烃类气体可能属于同源,侏罗纪、三叠纪烃源岩热演化生成的烃类能够沿断裂、砂岩裂隙等通道向上运移或渗漏至浅地表,其中甲烷、重烃气等轻质组分能够在稳定带内与地层水结合形成天然气水合物。木里地区第四纪沉积物中可溶有机质的来源解析能够为天然气水合物的勘探提供新的视角。Muli depression in the South Qilian basin is an area where the first natural gas hydrate sample was drilled in land area in China.Organic geochemical analysis was carried out on the soluble organic matter in the Quaternary sediments in gas hydrate-drilled area(DK well area)as well as the Quaternary sediments in adjacent Laoren lake area in the Muli permafrost area.The results show that pyrogenic organic matter obviously exists in shallow surface sediment in the DK well area,while the soluble organic matter in the sediments of Laoren Lake is mainly derived from higher plants.Compared with the characteristics of source rocks in this area,the pyrogenic organic matter mainly comes from the Middle Jurassic source rock,and the Upper Triassic Galerdesi source rock also has a certain contribution.Combined with the research results of hydrate gas source in the study area,the pyrogenic organic matter in Quaternary sediments in the DK well area is probably homologous to hydrocarbon gases that form hydrates.Oil and gas generated by thermal evolution of deep source rocks migrate upward or leak to shallow surface along channels such as faults and sandstone fissures.The light components of methane and heavy hydrocarbon gas can combine with formation water to form gas hydrate in the stable zone.The research on the source of soluble organic matter in the Quaternary sediments in the Muli area can provide a new perspective for the exploration of gas hydrate.

关 键 词：木里冻土区 第四纪沉积物 可溶有机质 热演化 天然气水合物 

分 类 号：P534.63[天文地球—第四纪地质学] P618.13[天文地球—古生物学与地层学]