羌塘北缘开心岭—乌丽冻土区水溶烃组分及甲烷碳、氢同位素特征研究  

Study on Features of Water Soluble Hydrocarbon Components and Carbon-hydrogen Isotopes of Methane in the Kaixinling-Wuli Permafrost Region on the Northern Margin of Qiangtang Area

作　　者：王进寿[1] 卢振权 王富春 陈静[1] 薛万文[1] 张志清[1] WANG Jinshou;LU Zhenquan;WANG Fuchun;CHEN Jing;XUE Wanwen;ZHANG Zhiqing(The Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources Laboratory,Qinghai Geological Survey Institute,Xining,Qinghai 810012,China;Oil and Gas Survey,Beijing 100083,China;Qinghai Geological Survey,Xining,Qinghai 810004,China)

机构地区：[1]青海省地质调查院青藏高原北部地质过程与矿产资源重点实验室,青海西宁810012 [2]中国地质调查局油气资源调查中心,北京100083 [3]青海省地质调查局,青海西宁810004

出　　处：《现代地质》2019年第6期1306-1313,共8页Geoscience

基　　金：中国地质调查局地质调查项目(1212010818055)

摘　　要：羌塘北缘开心岭-乌丽冻土区沿隐伏断层发育多处冷泉含水溶解烷烃,采用水溶烃组分和甲烷的稳定碳、氢同位素特征对其成因开展了分析研究。结果表明,开心岭-乌丽冻土区水溶烃组分中甲烷含量比例高达99.83%~99.96%,同时伴随有少量乙烷、丙烷,另含微量的乙烯和丙烯。开心岭一带水溶烃甲烷δ13CPDB值介于-46.5‰^-55.1‰,δDVSMOW值为-281.0‰^-342.0‰;乌丽一带水溶烃甲烷δ13CPDB值介于-47.8‰^-58.9‰,δDVSMOW值为-339.0‰^-346.0‰,指示水溶烃甲烷为有机成因,但气源较复杂,利用δ13CCH4-δDCH4、δ13C1-C1/(C2+C3)等成因图解判别,得出甲烷主要属微生物气,次之为热解成因气,混有少量原油伴生气。推断甲烷主要为有机质在微生物作用下分解的烃类气体或次生生物气,与晚二叠世那益雄组含煤烃源岩有关,气源条件暗示该地区冻土带200~500 m深度内有利于微生物成因气为主的甲烷天然气水合物形成。Several cold springs bear water soluble alkanes along the concealed faults in the Kaixinling-Wuli permafrost region on the northern margin of Qiangtang area.Based on analyses of the water soluble hydrocarbon components,stable carbon-hydrogen isotopes of methane,the genesis of the water soluble alkanes was studied.The results showed that the methane(CH4)volume fraction ratio in the water soluble hydrocarbon components reached as high as 99.83%-99.96%in the Kaixinling-Wuli permafrost region,accompanied by a small amount of ethane(C2 H6),propane(C3 H8),trace amounts of ethylene(C2 H4)and propylene(C3 H6).In water soluble hydrocarbon,methaneδ13 CPDBvalues range in-46.5‰to-55.1‰withδDVSMOWvalues of-281.0‰to-342.0‰in the Kaixinling permafrost area.In water soluble hydrocarbon,methaneδ13 CPDB values are-47.8‰to-58.9‰,andδDVSMOWvalues are-339.0‰to-346.0‰in the Wuli permafrost area.These features indicate that in water soluble hydrocarbon,methane is of organic origin,but the gas origin is relatively complex.Methane mainly belongs to microbial gas,secondarily pyrolysis gas,mixed with a small amount of oil-associated gas,discriminated by the genesis diagrams ofδ13 CCH4 vs.δDCH4 andδ13 C1 vs.C1/(C2+C3).It is inferred that methane is mainly originated from the hydrocarbon gases or sub-microbial gases,decomposed from the organic matters under the action of microorganisms,in connection with the coal-bearing hydrocarbon source rocks in Nayixiong Formation of the Late Permian.Gas condition implies that at depths from200 to 500 meters,it is conducive to form methane hydrate with microbial gas in this permafrost region.

关 键 词：水溶烃组分 甲烷碳、氢同位素 成因 天然气水合物 开心岭-乌丽冻土区 羌塘北缘 

分 类 号：P632[天文地球—地质矿产勘探] P618[天文地球—地质学]