祁连山冻土区天然气水合物烃类气体组分的特征和成因

Hydrocarbon gas composition and origin of core gas from the gas hydrate reservoir in Qilian Mountain permafrost

祁连山冻土区天然气水合物DK-2科学钻探试验孔水合物储集层岩心气样的烃类气体组分和C同位素分析测试结果表明,祁连山冻土区天然气水合物烃类气体组分复杂,除甲烷外,还含有较高的乙烷和丙烷;δ13C1均大于-50‰,R值普遍小于100,显示出明显的热解气特征。结合钻探区的地质背景和岩性特征,初步判断气体大多来源于深部迁移上来的油型气,并有部分原地煤成气的混合。

Hydrocarbon gas composition and carbon isotope of core gas from the hydrate reservoir in DK-2 hole, one of the scientific dfilling holes of gas hydrate in Qilian Mountain permafrost, were determined and analyzed. The results indicate that gas hydrate from Qilian Mountain permafrost has complex hydrocarbon gas composition, with relatively high ethane and propane besides the dominant methane. All the g^3C1 values are higher than -50%o, and molecular ratios （R） are generally lower than 100, obviously suggesting ther- mogenic gas characteristics. According to the geological background and lithologic characteristics of the drilling area, the authors pre- liminarily estimate that gas comes from the near-by highly matured or over-matured coal-related gas and the deeper thermogenic gas which has migrated upward from the depth.