准噶尔盆地腹部车莫古隆起南北两侧含油构造油源及烃源灶转移

The distribution of oil sources and the transformation of hydrocarbon kitchens in oil-bearing structural belts on northern and southern sides of the Chemo plaeo-uplift within central Junggar basin

车莫古隆起位于准噶尔盆地腹部,在其主要发育期,古隆起南北两侧分别存在昌吉和盆1井西两个沉积凹陷,分布有白垩系、侏罗系和古近系等多套烃源岩。目前已在古隆起所在区域的南部发现了永进油田,在其北部发现了征沙村、沙窝地和莫西庄等油田或含油气构造,油层主要分布在侏罗系和白垩系,其中沙窝地、莫西庄和征沙村3个构造主要目的层为侏罗系三工河组,永进构造目的层为侏罗系头屯河组、三工河组、西山窑组和白垩系吐谷鲁群。为了揭示研究区原油的油源特征以及车莫古隆起对油源及成藏过程的影响,比较系统地分析了研究区原油及相关层位烃源岩的地球化学特征,进行了油源对比;根据流体包裹体和烃源岩演化等方面的研究成果,分析了油气成藏特征,并结合构造地质资料讨论了车莫古隆起形成与演化对研究区油气源特征、油气藏形成过程及分布的控制作用。结果表明:研究区不同构造或同一构造不同层位的原油地球化学特征均存在一定的差异,根据饱和烃和芳烃生物标志物组成特征将研究区原油划分为五类,这五类原油在区域分布特征、油气来源及烃源灶位置等方面均存在差别。车莫古隆起的形成与演化、生油凹陷的展布特征及主要烃源岩的成熟演化历史共同决定了研究区不同油田或含油气构造烃源灶位置的分布及其转移特征。

The Chepaizi-Mosuowan plaeouplift belt is located in central Junggar basin. During its main development period, there existed two depressions, i.e., Changji depression in the south and western Well Pen 1 depression in the north, with the distribution of Cretaceous, Jurassic and Paleogene source rocks. Recently, the Yongjin oilfield was discovered in the southern part of the uphft belt, whose target bed is Jurassic Toutunhe Formation, Sangonghe Formation, Xishanyao Formation and Cretaceous Tugulu Group. In the northern part, Zhengshacun, Shawodi and Mosuowan are very favorable oil-bearing structural zones, whose target bed is Sangonghe Formation. In order to determine the oil source correlations and reveal the uphft effect on the hydrocarbon accumulation process, the authors analyzed sources of differential types of oils and, on the basis of the investigations into fluid inclusions, nitrogen compounds and the evolution of source rocks, probed into the hydrocarbon accumulation process. In combination with geological conditions, it is also found that the formation and evolution of Chemo plaeouphft control the characteristics of oil sources, reservoir distribution and accumulation process. The results indicate that geochemical characteristics of crude oils are somewhat different in different structural belts or even in different layers of the same structural belt. According to the biomarker parameters of saturated and aromatic hydrocarbons, the crude oils can be divided into five types, which are to some extent different from each other in distribution, sources and locations of hydrocarbon kitchens. The formation and evolution of Chemo plaeouplift, the distribution of the hydrocarbon depression, and the maturity evolution of main source rocks have determined the locations and transformation of hydrocarbon kitchens in different oil-bearing structural belts or oil fields.