Characteristics And Prediction Of Deep Oil Shale In The Upper Cretaceous Qingshankou Formation In The Southern Songliao Basin

The Qingshankou Formation in the Songliao Basin is rich in oil shale resources.This time,a systematic study of the deep oil shale(buried depth> 500m)in the Qingshankou Formation in the southern Songliao Basin has revealed the mineralogical characteristics,organic geochemical characteristics,Industrial quality characteristics and logging response characteristics,analyzing the distribution of deep oil shale in space,optimizing the favorable areas and layers for the development of deep oil shale,predicting the resource potential of deep oil shale in the study area,is the deep oil The shale exploration and in-situ development provided the geological basis.In this paper,through core observation and test analysis,it is known that the deep oil shale in the study area is a medium-low oil content,high ash,medium volatile,and low sulfur oil shale.The type of organic matter is mainly type I,which is in the stage of low maturity and oil production.Combined with the analysis of the logging curve,it is concluded that deep oil shale has the log response characteristics of high natural gamma,high resistivity,high acoustic time difference,and low density.TOC has the best correlation with the acoustic time difference and resistivity curve.Combined with the TOC test As a result,a ? logR model of deep oil shale in the study area was established to predict the oil shale TOC in the study area.From the petrological and organic geochemical analysis of oil shale at different depths,it can be seen that with the increasing depth of oil shale,the content of the illite and montmorillonite mixed layer in clay minerals decreases,and the content of illite increases;the maturity of organic matter increases,and the rock pyrolysis As the temperature peak(Tmax)increases,the production index(PI)and oil saturation index(OSI)increase,oil shale begins to undergo hydrocarbon generation and expulsion processes,and continues to transform to shale oil.In this paper,based on core observations and logging logs and test data,it is believed that the Qingshankou Formation in the study area is dominated by lacustrine facies,which can be further divided into two subfacies(shallow lake and semi-deep lake-deep lake subfacies)and four species.Microfacies(beach bar,muddy shallow lake,semi-deep lake and deep lake microfacies).At the same time,the sequence stratigraphy analysis of the Qingshankou Formation was carried out,which was divided into three sequences.The oil shale was mainly developed in the sequence I high water level system domain.A total of 12 oil shale deposits were developed in the study area.Among them,No.3 and No.4 deposits are relatively continuous and stable,which is a favorable formation for the development of deepoil shale.From the southeast uplift area to the central depression area,the overall depth of oil shale is increasing(except for the Changchunling anticline).The number of oil shale ore layers,oil content,and cumulative thickness all increase first and then decrease.Trends,near the Fuyu uplift zone in the central depression area and the Binxian-Wangfu depression in the southeast uplift area are favorable areas for the development of deep oil shale.In this paper,the volume method is used to evaluate resources in the two exploration areas of Fuyu-Changchunling,Qianguo-Nong'an and Songnan prediction area in the southern Songliao Basin.The resource evaluation results show that the deep oil shale resources in the study area are 48683 million tons,accounting for 48.0% of the total oil shale resources of the Qingshankou Formation in the area,equivalent to 2811 million tons of oil shale oil resources.The deep oil shale resources in the study area have high potential and have good prospects for exploration and development.