Sedimentary Features And Hydrocarbon Generation Conditions Of Jurassic Of Yangye Formation In The Southeastern Depression,Tarim Basin

Southeast of Tarim Basin is a new area of exploration.Thick Coal-bearing strata developed during the Rift lacustrine period in Jurassic.The boundary of sag is mainly decided by the distribution of Jurassic strata.Gas show had already been discovered in well Ruocan 1 in Kangsu group and Yangye group in Jurassic,which proved the exploration potential of the sag.This paper will study southeast of Tarim Basin by drilling,logging and geochemical data,which concluded that geochemical characteristics,distribution and evolution characteristics of hydrocarbon source rocks and hydrocarbon generation potential.Through the understanding of hydrocarbon source rocks in the study area,it will provide the basis for deep oil and gas exploration.According to field geological section outcrops and drilling core observation,then,combined with geological information,analysis of trace elements and constant elements.We can identify hydrocarbon source rock of Yangye group is in weak oxidation-reduction environment which is under the condition of terrestrial freshwater lake deposition.It was semi deep lake-deep lake in the Jurassic sedimentary environment.Conclusion by structural evolution and sedimentary evolution,Lake Invasion culminated,and shallow lake facies distribution area expanded in the middle Jurassic Yang Ye formation sedimentary period.It forms MingFeng and Washixia sag,which are in northeast.Shallow lake facies distribution zone also have under-compensation sedimentary formation and semi deep lake facies dark mudstone is mainly southeast of Jurassic dark mudstone source rocks.Hydrocarbon source rocks of organic geochemical study shows that,from the organic matter abundance Yangye group of hydrocarbon source rock of the organic carbon content are greater than 2%.Yangye group belongs to the good hydrocarbon source rock.The kerogen type is III.The field of oil sands and oil seepage prove the existence of the southeast tower high-quality hydrocarbon source rocks.Yangye group hydrocarbon generation potential of source rocks is relatively large.The stage belongs to the mature stage of evolution of hydrocarbon generation evolution.If it is under the condition of reaching a certain depth,it can produce oil and gas.It also suggests that hydrocarbon source rocks in Yangye group can be used as main source rocks in this area.The hydrocarbon source rock development of hydrocarbon generation has created the good deposition conditions such as Middle Jurassic period of semi deep lake-deep lake sedimentary environment,terrestrial freshwater mudstone,and warmer humid climate conditions.Southeast depression of Tarim in Jurassic Yangye group is the main hydrocarbon source rock series.It is also favorable source rocks for hydrocarbon exploration in the future.