Study On The Tight Oil Source Conditions Of The Fourth Member Of Shahejie Formation In The Western Depression Of Liaohe River

The fourth member of Shahejie formation(Sha 4th member)has been one of the exploration target of the tight oil exploration in western sag,Liaohe depression,Bohai Bay basin.It has a great theoretical and practical significance to study in detail on its source rocks characteristics.In this paper,making full use of drilling,logging,seismic and other laboratory analytical data,thes thesis used the combine method of macroscopic and microcosmic,geology,well logging and seismic data to make a detailed study on source rocks characteristics in Sha 4th member.Make sure the tight oil source of reservoirs are determined adopting the method of oil source correlation by using biomarker such as n-alkanes,isoprenoids,terpenes and stericles.According to core analysis,thin section identification,combining with some research measures such as scanning electron microscopy,X diffraction to analysis the source rocks petrological characteristics of Sha 4th Lember;and then investigated the source rocks geochemical characteristics such as abundance,kerogen type and maturity of the Liaohe depression by using of parametric analysis of the rock pyrolysis,kerogen microscopy analysis and element analysis;Aim at the restriction of the source rock specimen,It build the model between logging data and the TOC by using of the ALgR law,which can lay the foundation for Identifying and classifying excellent source rock;By using the relationship between tar conversion and depth,established the standard of excellent source rock in the study area and then identify and classify the excellent source rocks of Sha 4th member;Ascertain the vertical and horizontal distribution regularities of the excellent source rocks by using the fine stratigraphic correlation data.Research the relationship between the excellent source rocks and tight oil with the data of reservoir characteristics and formation testing.The results are as follows:?The tight oil in sha 4th member is mainly distributed in middle-upper part of Gaosheng layer and bottom of the third layer of Dujiatai(Du 3rd layer),which has the configuration relation of the“lower generation,upper accumulation" and "self generation,self accumulation";?The favorable facies belt of source rocks in Sha 4th member is semi-deep and deep lacustrine subfacies.The main type of source rock is carbonate/carbonate shale,felsic type shale and clay shale,carbonate/carbonate shale hydrocarbon potential,followed by clay shale;The organic matter abundance in source rock is higher as a whole,The highest organic matter abundance in Gaosheng layer,The average of the TOC is 5%,The organic matter is mainly typeI,followed by ?1,The organic matter is in the stage of low maturity to maturity;?Based on the parameter of TOC,the evaluation criteria of high quality source rocks in the study area are established,TOC=4%?2%?1%respectively as the lower limit of I-class,?-class and ?-class source rocks?In the study area,the main layers of high quality source rocks are Du 3rd layer and Gaosheng layer;?The distribution area of the high degree of overlap in tight oil distribution area and high quality source rocks,near-source accumulation.High quality source rocks provide the material basis for the formation of tight oil,The main power of tight oil accumulation is the hydrocarbon generating pressurization.