济阳坳陷孤岛油田微生物降解原油伴生气成因特征

Genetic characteristics of associated gases from crude oil biodegradation in Gudao oilfield,Jiyang depression

王万春 李钜源 唐洪三 崔军汉 康晏

Wang Wanchun Li Juyuan Tang Hongsan Cui Junhan Kang Yan

微生物降解原油伴生天然气中,既有遭受微生物降解后残余的组分,也可能有厌氧微生物降解原油后的产物。济阳坳陷孤岛油田降解原油伴生气组分及同位素组成特征表明,孤岛油田天然气由腐泥型母质生成,主要来自沙河街组三段烃源岩。由于微生物降解原油过程中产生的碳同位素组成偏轻、氢同位素组成偏重的次生生物成因甲烷的混入,使降解原油伴生气组分组成变干,甲烷碳、氢同位素组成呈反常的负相关分布。微生物对天然气中丙烷及正丁烷组分的降解,导致一些样品具有明显偏重的丙烷和正丁烷δC值。

Associated gases from crude biodegradation possibly contain remnants from microbial degradation as well as products from the anaerobic biodegradation of crude.Studying this kind of associated gas and restoring its original properties are helpful to gas source correlation and exploration of natural gas.The components and isotopic compositions of associated gases from crude biodegradation in Gudao oilfield of Jiyang depression indicate that the natural gas in this field is generated by the sapropelic organic materials mainly in the third member of the Shahejie Formation.The interfusion of secondary biogenic methane with relatively lighter carbon and heavier hydrogen isotopic compositions that are generated from the biodegradation of oils results in the drier components and abnormal negative correlation between the carbon and hydrogen isotopic compositions of methane for the associated gases of crude biodegradation.The attack of micro organisms on propane and n-butane of the na-tural gas causes evident heavier δC values of propane and n-butane in some samples.

10.11743/ogg20070319