Study Of Characteristics And Formation Mechanism Of Hydrocarbon Source Rocks Of Lucaogou Formation In Jimsar Depression

The oil and gas reservoirs in the Junggar basin have the characteristics of integrated source and reservoir.Therefore,the study of the formation mechanism of hydrocarbon source rocks is of great significance to exploration and resource prediction of oil and gas reservoirs.In this paper,the source rock of Lucaogou Formation in Jimsar Depression of Junggar Basin is taken as the object of study and makes a comprehensive use of the geological,geochemical and biomarker parameters to make a detailed evaluation of the source rocks of the Lucaogou Formation,and clear the distribution pattern of the source rocks and the main controlling factors for the formation of source rocks.According to the evaluation of the source rocks of the Lucaogou Formation in Jimsar depression,it is found that the lithologies of the source rocks of the reooagou formation are diverse,they are mainly tuff,mudstone,dolomite and siltstone.The organic matter abundance of the Lucaogou Formation is high,and the organic matter types are mainly type I and type II,and they are generally in a low maturity-mature stage with high hydrocarbon generation potential.Paleo-productivity and organic matter conservation conditions are the two major factors affecting the formation of source rocks.Palaeo-lake productivity in the Lucaogou Formation is controlled by lithology,paleoproductivity of tuffaceous rocks is large,source of organic matter is mixed source,contribution of terrestrial organic matter Larger,the overall performance of the depositional environment is a weak reducibility with high salinity.Lake paleoproductivity and preservation conditions of organic matter are the main factors controlling the formation of source rocks in the lagagou formation.The paleo productivity of Lucaogou Formation is obviously controlled by lithology,of which the paleoproductivity corresponds to the tuff,the tuff dolomite and the mudstone is high,and the silty mudstone,the muddy dolomite,the siltstone and the dolomite are less productive.The sedimentary environment has a weak reducibility,and the reducibility is obviously controlled by lithology.The reducibility of the tuff,tuff dolomite and mudstone is stronger,and the reducibility of silty mudstone,muddy dolomite,siltstone and dolomite is weak.The sedimentary environment of the Lucaogou Formation is relatively high and the stratification occurs with the increase of depth.The main controlling factors affecting the formation of hydrocarbon source rocks in the upper and lower sections of the Lucagou Formation are different.The paleoproductivity and the preservation conditions of organic matter have complementary characteristics,of which the upper part of the Lucaogou Formation is larger,the reducibility is weak,the formation of the source rock is strongly controlled by the paleoproductivity,and the control effect of the redox condition is weak;The lower paleoproductivity and strong reducibility of the lower section of the Lucaogou Formation are controlled by paleoproductivity and are controlled by the preservation conditions of organic matter.