Research On Oil Shale Characteristics And Formation Environment Of Paleogene In Huadian Basin

Huadian basin is a Cenozoic depression basin which contains oil shale, located in the north extension of the Tan-Lu fault zone branches Dunhua-Mishan fault zone,and formed in the Paleogene Eocene,oil shale is in the Cenozoic Paleogene Huadian Foemation.The oil content of oil shale in Huadian basin is relatively higher,the average oil content is up to 10%,maximum 24.8%,the oil shale color is brown, taupe,gray-black,the most common original structure is horizontal bedding and massive bedding,also contains ostracods and other animal and plant fossil.By X-ray diffraction,scanning electron microscopy and inorganic geochemistry test and analysis,the average content of mainly mineral components in oil shale is 44%of clay minerals,33.43%of quartz,12%of calcite,4.57%of pyrite,3.86%of feldspar.The highest clay minerals is Montmorillonite,which average content is 30.79%.There is significant difference between rich ore and lean ore in mineral composition:the clay minerals of rich ore is obviously lower than that of lean ore,rich content for an average of 37.6 percent,while the average lean ore content of 47.56%;montmorillonite of rich ore is generally lower than the lean ore,rich content of the average 28.20%,32.22%for the lean ore;rich ore contains less quartz than the poor ore,rich quartz average content was 35.4%, 32.33%for the lean ore;rich calcite mineral is much more in rich ore,whose calcite mineral average content is 19.4 percent,only 7.89%for lean ore.In the trace element content,compared to the Fushun Basin,oil shale in Huadian basin,the content of Ba,Cs,Mo,Pb,Rb,Sr,Ta is relatively higher,In particular,Ba,Rb and Sr content shows significantly high trends;Co,Cr,Nb, Ni,V,Zn content is relatively lower,in which the content of Cr and Zn show obviously lower than Fushun basin.By the standardization of the North American shale,inHuadian basin oil shale Cr shows a strong negative anomaly and it in the Similar rocks shows loss;however,Sr shows positive anomalies,when compared with similar rocks shows slight enrichment;the rest of trace elements are closed to the North American shale.In Huadian basin oil shale,the total rare earth elements(ΣREE) is in the range of 87.52～355.98μg/g,the average ofΣREE is 164.52μg/g,which is very closed to the average value of North American shale;total amount of light rare earth elements(ΣLREE) is in 78.52～315.47μg/g range,the average value is 149.01μg / g;total weight of rare earth elements(EHREE) is in 8.69～40.51μg / g range,the average value is of 15.50μg/g.ΣLREE/ΣHREE is about 9.61,indicating that LREE is more enrichment than HREE and it belongs to moderately enriched light rare earth elements.In HD3 well Oil shale,the organic carbon average value is 10.89%; chloroform bitumen "A" generally has a "two high -two low" characteristics,that is,non-hydrocarbon and asphaltene content is relatively higher,saturated hydrocarbons and aromatics content comparatively lower;the average value of pyrolysis parameters Pg is 51.43 mg / g,these all can be combined to reveal Huadian basin oil shale features with abundance of organic matter.Through the organic elemental of oil shale analysis,kerogen maceral analysis and pyrolysis analysis,we can know that the mainly type of organic matter is humic mud and sapropel,followed by humic sapropel type;on the basis of vitrinite reflectance is less than 0.5%and the largest peak pyrolysis temperature is between 428℃～446℃that can analysis of the study area oil shale is immature-to mature thermal evolution.Hydrocarbon generation potential volume which is one of Pyrolysis Parameters of oil shale is a good linear correlation with oil content,on the basis of correlation analysis can be drawn for the following relationship:Ta= 0.1002Pg+0.0911;organic carbon content and oil content shows a linear positive correlation relationship,the relationship is Ta=0.4588TOC-10.1263.ΔLogR method is used by Exxon(Exxon) and Esso(Esso) to assess quantitative value of organic carbon in the rocks.This method has been successfully used in many parts of the world.Through.the relationship between organic carbon and oil content,ΔLogR can quantitativly evaluate oil content of oil shale.The relationship between oil content andΔLogR is Ta =4.17ΔlogR-5.95.According grain size analysis,lithological features and sedimentary structures etc,can identify mainly two types sedimentary facies of Lacustrine and Fan-delta in Huadian formation in the Paleogene Huadian basin,they can divided into six kinds of sedimentary subfacies and 13 sedimentary microfacies, semi-deep lake-deep lake subfacies is most conducive to develop oil shale.According the trace elements such as the value of B,the ratio of strontium-barium and boron gallium ratio method can indicate the formation of Huadian oil shale deposited in freshwater environment,which has partial water salinization.Through the trace elements V/(V+Ni) and rare earth elements Ce / Ce~* and Ceanom can manifest that Huadian oil shale can be formed in the lake basin of fresh water and restore the environment...