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

Abstract：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 uplift 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 uplift 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 plaeouplift 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.