Evaluation Of The Residual Hydrocarbon Characteristics Of The Shale Of The First Member Of Qing1 Formation From Well Jiye-1 In Changling Sag

The shale of Qingshankou Formation is widely distributed in the south of Songliao basin.However,the research of calibration and evaluation for its residual hydrocarbon series is still poor.In this paper,the first member of Qingshankou Formation of well jiye-1 in Changling depression is taken as the research object.On the basis of the existing geological,geophysical and geochemical data,the organic geochemical profile of the first member of Qingshankou Formation in Changling depression is established by using the research methods of organic petrology and molecular organic geochemistry,and the calibration,classification and evaluation of the high abundance residual hydrocarbon series and the residual hydrocarbon geochemistry are carried out in depth.The aim of the paper is to provide scientific basis and guidance for the exploration of shale oil and gas resources in Qingshankou Formation in this area.Based on the systematic collection of core samples of the first member of Qing1formation in well Jiye1,the analysis of total organic carbon,free hydrocarbon content?S₁?,hydrocarbon generation potential?S₁+S₂?and chloroform asphalt"a"shows that the kerogen types of the first member of Qing1 formation in well jiyeyou1 are mainly of type?₁and?₂,with type?in the upper part,type?in the part,and type?in the lower part Type 2 is the main type,part of which is type?1.Considering the type of organic matter,shale oil resources have a good prospect,and the upper part of Qing1 member is better than the lower part.The geochemical model of logging data of Qing1 member of jiye-1 well is established,and the shale classification evaluation is carried out.The results show that the mudstone of Qing1 member of jiye-1 well is mainly composed of class II source rock,accounting for 53.34%,part of which is class I source rock,accounting for 26.65%,and less of class III source rock,accounting for 15.31%,and the source rocks of each class are mostly interbedded.Through the molecular geochemical analysis of the residual hydrocarbon in the shale of well Jiyeyou 1,it is found that there are significant differences in the molecular composition between the upper and lower groups of Qinger and Qing1.The characteristics of biomarkers show that the primary water environment of the shale in the first member of Qingling formation is the weak reduction environment of freshwater lake facies,while the primary water environment of the shale in the second member of Qingling formation is also the weak oxidation environment.The rearrangement compounds of the lower Qing1 member are the most developed,while those of the upper Qing1 member are the least.The three forms of the above-mentioned compounds show that the sedimentary environment and source input of shale in the three intervals are different.According to the molecular comparison between the oil-bearing sandstones in the upper and lower formation of the Qing 1 member and the residual hydrocarbons in the mudstones in the adjacent layers,it is found that the residual hydrocarbons in the upper and lower formation of the Qing1 member are not related to each other.From the molecular composition of sesquiterpenoids,tricyclic terpanes,pentacyclic triterpenoids and steranes,it is shown that the oil-bearing sandstone crude oil in the lower formation comes from the hydrocarbon generated from the shale of the lower formation.It can be seen that the upper and lower shale of the Qing1 member of well jiye-1 are self-contained systems,which are two independent oil-gas shale systems.The method of continuous extraction of shale residual hydrocarbon was established,and the law of migration and accumulation of shale residual hydrocarbon was revealed.According to the distribution of the free residual hydrocarbon content obtained from the continuous extraction experiment of the shale in the first member of Qing1 formation of well jiye-1,the free residual hydrocarbon content changes significantly with the depth.The hydrocarbon generated from the upper and lower shale of the lower formation of Qing1 member migrated to the two thin sand layers.The content of movable hydrocarbon in the lower formation is high in the thin sand layer of the third member.