中文摘要：

准噶尔盆地南缘天然气分布较为广泛,在3排背斜带均有分布。该区天然气在组分上以烃类为主,其中甲烷占主导;普遍含有氮气和二氧化碳。准噶尔盆地南缘天然气均为典型热成因气,主要为源自中、下侏罗统成熟—过成熟煤系烃源岩的煤成气,其中第一排背斜带和第二排背斜带天然气均为典型高—过成熟阶段煤成气,第三排背斜带独山子背斜下古近统和呼图壁背斜所有气样也是该类型,第三排背斜带其余煤成气样为典型成熟阶段煤成气。准噶尔盆地南缘煤成气普遍具有碳同位素部分倒转的特征,其主要由于同型不同源（侏罗系不同层位）气的混合,也有部分由于细菌氧化作用（古牧地背斜）或油型气和煤成气的混合（齐古和安集海）。该区油型气样品较少,目前发现的2个油型气样品位于卡因迪克油田白垩系和独山子油气田古近系,分别为成熟和高—过成熟阶段油型气,来自白垩系和二叠系腐泥型烃源岩。齐古背斜二叠系和三叠系中煤成气主要是由断裂下盘埋深较大的下侏罗统八道湾组煤系烃源岩所生成,而侏罗系中煤成气则主要来自中侏罗统西山窑组和下侏罗统三工河组烃源岩,其埋深相对较浅,成熟度相对较低,因此生成的天然气碳同位素值和甲烷含量均相对较小。

英文摘要：

Natural gas distributes widely in all the three anticline belts in the south margin of Junggar basin.It is mainly composed of hydrocarbons,in which methane is dominated,often with nitrogen and carbon dioxide.The gas is typically thermogenic,and mainly coal-derived from Middle-Lower Jurassic mature-over mature coal-measure source rocks.The natural gas in the first and second anticline belts,and part of the third anticline belt（Dushanzi anticline of Lower Paleogene and Hutubi anticline） is typical high-over mature coal-derived,while that in the other part of the third anticline belt is typical mature coal-derived.The coal-derived gas in the south margin of Junggar basin shows partially reversal of carbon isotopes,mainly due to the mixing of the same type gas with different sources（different strata of Jurassic）,and partially due to the bacterial oxidation（in the Gumudi anticline） or the mixing with oil-associated gas（in the Qigu and Anjihai anticlines）.The oil-associated gas of this area is only in the Cretaceous Kayindike oil field and Paleogene Dushanzi oil gas field,and sourced from mature Cretaceous sapropelic source rocks and high-over mature Permian sapropelic source rocks respectively.The Qigu coal-derived gas of the Permian and Triassic is mainly derived from the Lower Jurassic Badaowan Formation coal-measure source rocks deep-seated in the footwall of the fault.while that of the Jurassic is mainly derived from the Middle Jurassic Xishanyao Formation and Lower Jurassic Sangonghe Formation source rocks buried shallower with relatively lower maturity and therefore has relatively lower carbon isotope value and methane content.