Vol.3 No.4 (August 2013)
Study on the Characteristics and Origin of the Oil Shale in the Chang 7 Member, Yanchang Formation in
> In Ordos basin, which is rich in oil shale resource, oil shale is mainly found in the southern part of Chang 7 member of the Triassic Yanchang-3 Formation, with common thickness of 5 to 30 m and 40 m of maximum. In this pa- per, a statistic synthetic study on test data of both surface and borehole oil shale sample was conducted based on the field measures of oil shale sections. Research shows that oil content ranges from 4% to 9% with average of 7%, calo- rific value varies between 7 MJ/kg and 13 MJ/kg with average of 9.1 MJ/kg, ash content is between 45.6% and 90.1% with average of 69.5%, and total sulfur values are between 0.01% and 14.01% with the average of 2.82%. The oil shale in the mass is characterized as high ash, medium to high rich sulfur, and medium grade oil shale. The organic matters of oil shale, with high content and mainly of sapropelic and humic-sapropelic type, are dominantly in the mature stage and have good hydrocarbon generation potential. It is made clear by geological and geochemical study that the Chang 7 oil shale was formed in semi-deep and fresh-half salt lake with water depth more than 15 m under warm-humid climate, where it was a closed, stagnant, anoxic and strong reducing sedimentary environment. During Chang 7 deposition stage of Late Triassic, biological prosperity provided a source of organic matter for the formation of Chang 7 oil shale, the stable water stratification resulted in the strong reducing environment of the lake bottom, which was favorable for the accumulation of organic matter and its preservation and thereafter forming good type oil shale of high organic carbon content and high oil content.
张庆春 , 汪凯明 , 罗顺社 , 吴晓智 (2013) 鄂尔多斯盆地长7油层组油页岩特征及成因分析。 地球科学前沿， 3， 197-209. doi: 10.12677/AG.2013.34028
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