Hydrocarbon Accumulation Law And Favorable Target Prediction In The Datong Basin

The Datong Basin is located in the north of the North China plate and the northeast of the Ordos Basin.This thesis mainly relies on pre-inspection and continuous production project of Emaokou Coal-gas of Zhouzhuang-Huairen in Inbei,Shanxi Province.In this study,DY-3 hole coring in Huairen Block concave was analyzed.The results show that source rocks in Yangtouya formation of Cretaceous discovered in the deep part of DY-3 hole coring in the Datong basin is semi-deep lake-deep lake sediments,with higher the organic matter content and type III kerogen of high maturity moisture,which is excellent medium source rock and provides oil source material for the basin.Based on the analysis of stratigraphic characteristics,structural distribution,lithology,characteristics of sedimentary facies,it is proposed that three stages of river-lake transformation have occurred in Datong Basin since the early Cretaceous and a set of sediments with rich organic matter of extremely thick river lake facies have been deposited which not only ensures a certain scale of source rock in the basin,but also provides a sedimentary environment to avoid oxidation of organic matter.The organic matter accumulated in the later stage was buried rapidly,and the burial environment gradually changed to the physical and chemical conditions(such as pressure,temperature and other conditions)that were conducive to the transformation of hydrocarbon.A complete system of source-reservoir-cap assemblages is formed with Cretaceous sandstone as the reservoir and Baode formation and Nihewan formation as the cap formation.At the same time,the Datong Basin has undergone multiple periods of tectonic movement,which not only created the necessary structural conditions for promoting oil-gas migration,but also provided traps for oil-gas accumulation.The western part of the basin is controlled by the Kouquan fault,forming a classic reverse traction anticline trap;in the middle part of the basin,large faults are developed,generally forming fault traps;in the eastern gentle slope zone,wide and gentle anticline traps are formed.To sum up,the Datong Basin has the basic conditions for the production,storage,cap,circle,transportation and protection of the oil-bearing basin,and good gas survey has been found in the early stage of exploration,which indicates that the Datong Basin has a good prospect for oil-gas exploration.