摘要
通过对南祁连盆地哈拉湖坳陷天然气水合物科学钻探试验QH-1孔、QH-2孔不同层段内岩心顶空气中各烃类气体含量及甲烷碳同位素值的统计,对比研究了岩心中烃类气体组分含量随不同深度的变化特征,剖析了组分含量与岩性、裂隙或破碎带之间的对应关系,探讨烃类气体的成因,指出了烃类气体对岩性、裂隙或破碎带、天然气水合物异常的地质指示意义。结果显示:顶空气高含量区间段对泥岩有一定的指示作用,岩心中一定深度范围内多处钻遇石膏晶体,石膏出露层段与顶空气高含量区间段较为吻合,烃类气体可能主要以吸附(游离)的方式被封存在泥岩中,石膏起到了一定的封堵作用;裂隙或破碎带内岩心顶空气组分含量相对较高,显示裂隙或破碎带对烃类气体的聚集有一定控制作用;与南祁连盆地木里地区相比,钻探区虽然达到了天然气水合物稳定带条件,但未能钻获到天然气水合物,推测气体浓度较低为原因之一;钻孔岩心顶空气中甲烷气体主要以热解成因为主,并含部分混合成因气。
Through the analysis of the gas components and the methane carbon isotope at different depths in headspace gases from the gas hydrate scientific drilling holes ( QH-1 and QH-2) in the Harhu Depression. southern Qilian Basin,the relationship between the components content of hydrocarbon gas and the depth of the holes is compared.The correspondence between the components content of hydrocarbon gas and the lithology?fissure and fracture zones is analyzed.The genesis of hydrocarbon gas is also discussed.The geological significance of hydrocarbon gas to lithology,fissure.fracture zone and gas hydrate anomaly is pointed out.The results show that the high-content interval of the headspace gas has an indicative effect on mudstone ?also the gypsum layer in the core is in accord with the high-level air con tent zone.It is speculated that hydrocarbon gases are trapped in mudstone in the form of adsorption ( free), and the plaster prevents the gas from escaping;Relatively high gas content in the fissure or fracture zone indicates that it has a certain control effect on the accumulation of hydrocarbon gases;Compared with the Muli,although the drilling area reached the gas hydrate stability zone conditions. but because of low hydrocarbon gas concentration, there is no drilling encountered gas hydrate;Methane carbon isotopes suggest that the hydrocarbon gas in headspace gases is genetically mainly composed of thermogenic gas, with some of mixed origin.
作者
范东稳
卢振权
刘晖
肖睿
王伟超
李永红
唐世琪
Fan Dong-wen;Lu Zhen-quan;Liu Hui;Xiao Rui;Wang Wei-chao;Li Yong-hong;Tang Shi-qi(School of Energy Resources,China University of Geosciences,Beijing 100083,China;Oil & Gas Survey,China Geological Survey,Beijing 100029,China;Qinghai No.105 Coal Geological Exploration Team,Xining 810007,China;Institute of Geophysical & Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang 065000,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2019年第4期526-538,共13页
Natural Gas Geoscience
基金
中国地质调查局项目"祁连山冻土区天然气水合物调查"(编号:DD20160223)资助
关键词
南祁连盆地
哈拉湖坳陷
顶空气组成
碳同位素
天然气水合物
Southern Qilian Basin
Harhu Depression
Headspace gas composition
Carbon isotope
Gas hydrate
