准噶尔盆地陆梁油气田原油的生物降解特征及其成藏意义

准噶尔盆地陆梁油气田原油的生物降解现象具有较强的规律性,白垩系吐谷鲁群原油既表现了轻微-中等的生物降解(饱和烃分布不完整)特征,又表现了严重的生物降解(存在25-降藿烷)特征;侏罗系西山窑组X1段原油同时表现了无生物降解(饱和烃分布完整)和严重生物降解的特征,而X4段原油无任何生物降解.轻微-中等生物降解原油的凝固点和含蜡量明显降低而密度有所增大.严重生物降解原油的生物标记物分布特征表明,Ts,C29重排藿烷和伽马蜡烷具有较强的抗生物降解能力,C27规则甾烷抗生物降解的能力强于C28规则甾烷.根据原油的生物降解特征,推测白垩系和侏罗系油藏都是异地油藏破坏后再运移聚集的结果.

Biodegradation characteristics of the oil from the Luliang oil field of Junggar Basin, China

The biodegradation of the oil takes on a regular pattern in the Luliang oil field. The oil of the Tugulu Group takes on characters of either light-medium biodegradation or sever biodegradation in Cretaceous (the distribution of saturated hydrocarbon is not integate and there is C_~25 -hopance). The oil of Member X1 takes on characters of no biodegradation (the distribution of saturated hydrocarbon is integrate) or severe biodegradation in the Jurassic Xishanyao Formation and the oil of Member X4 does not take on any biodegradation. The condensation points and wax content of the light-medium biodegradation oil obviously decrease and the density increases. The biomarkers of the severe biodegradation oil indicate that Ts and C_~29 have a strong ability for anti-biodegradation. The anti-biodegradation of C_~27 regular sterane is stronger than C_~28 regular sterane.