The southwestern Junggar Basin is an attractive region for oil exploration. A major discovery of high oil production rate from a recently drilled borehole stimulated a new round of extensive petroleum exploration in this region. The potential source beds are within the Permian, Triassic, Jurassic, Cretaceous and Paleogene strata, but no effective oil-prone source rock samples have been drilled so far due to deep burial, leading to that oil source correlation remains controversial in the region. A total of 38 crude oils and the free, adsorbed and inclusion oils obtained from 18 oil-containing reservoir rocks from the southwestern and southern Junggar Basin were analyzed by GC, GC–MS and GC–IRMS for the purpose to classify oil groups, determine oil origins, and identify effective source beds in sags. Crude oils in the southwestern Junggar Basin can be classified into two end groups and an intermediate group, namely PO, JO and PJO oils, which were originated from the Permian lacustrine source beds, Jurassic terrigenous source beds and both, respectively. Ratios of C₁₉/C₂₀ tricyclic terpanes and C₂₄ tetracyclic/(C₂₄ tetracyclic+C₂₆ tricyclic) terpanes are the most sensitive parameters to distinguish these three groups of oils. These two ratios increase from PO, PJO to JO oils. JO oils can be further classified into two subgroups, i.e. J1O and J2O. J2O oils have substantially higher amounts of C₂₇ and C₂₈ steranes relative to C₂₉ steranes, higher amount of gammacerane, lower amount of C₂₉ diasteranes, and lower isomerization ratios of steranes, compared with J1O oils. J1O oils were exclusively originated from the Jurassic source beds while J2O oil were mainly originated from the Jurassic source beds mixed with minor oils generated from the Paleogene and Cretaceous lacustrine source beds.In the Chepaizi uplift, the major PO oils and extracted oils from 14 reservoir rocks were mainly originated from source beds within the Lower Wuerhe Formation of Middle Permian (P₂w). However, the remaining minor oil samples and extracted oils from the other four reservoir rocks were clearly originated from source beds in the Fengcheng Formation of Lower Permian (P₁f) on the basis of molecular parameters and δ¹³C values of individual n-alkanes, indicating the presence of effective oil-prone source beds within the Fengcheng Formation in the Shawan sag.In shallow reservoirs within the Neogene Shawan Formation (N₁s), PO, PJO and J1O oils are severely biodegraded while J2O oils have nearly no biodegradation effect because the former entered the reservoirs much earlier than the latter.

准Jung尔盆地西南部是一个吸引石油勘探的地区。最近钻探的一个高产油率的重大发现刺激了该地区新一轮的大规模石油勘探。潜在的烃源层在二叠纪，三叠纪，侏罗纪，白垩纪和古近纪地层内，但由于埋藏较深，迄今尚未钻出有效的易生油岩样品，导致该地区的烃源相关性仍然存在争议。通过GC，GC–MS和GC–IRMS分析了从西南准southern尔盆地南部和南部准18尔盆地的18个含油储层岩石中获得的总共38种原油以及游离，吸附和夹杂油，目的是对油类进行分类，确定石油成因，并确定下陷的有效烃源层。准Jung尔盆地西南部的原油可以分为两个末端组和一个中间组，即PO，JO和PJO油，它们分别来自二叠纪湖相物源床，侏罗纪陆源物床和两者。C比₁₉ / C ₂₀三环萜烯和C ₂₄四环/（C ₂₄四环+ C ₂₆三环）萜烯是区分这三类油的最敏感参数。从PO，PJO到JO油，这两个比率增加。JO油可以进一步分为两个子组，即J1O和J2O。J2O油具有显着更高的量的C ₂₇和C _28个的相对至C甾烷₂₉甾烷，更高量的伽马蜡，C的较低量₂₉与J10石油相比，其具有更高的非甾烷烃和较低的甾烷烃异构化率。J1O油完全来自侏罗纪烃源层，而J2O油则主要来自侏罗纪烃源层，并混有古近纪和白垩纪湖相烃源层中的少量油。在车牌子隆起中，主要的PO油和来自14个储层的提取油岩石主要来源于中二叠统下古乌尔河组（P ₂ w）的烃源层。然而，来自其他四个储集岩的剩余次要油样品和提取的油中下二叠（P的风城组进行了明确来源于源层_1架F）分子参数的基础上，和δ ^13个个人的C值Ñ烷烃，表明在沙湾凹陷凤城组内有有效的易生油层。在新近纪沙湾组（N ₁ s）内的浅层油藏中，PO，PJO和J1O油被严重生物降解，而J2O油几乎被生物降解。没有生物降解作用，因为前者比后者更早进入水库。