论文部分内容阅读
西北地区已发现的侏罗纪煤系原油绝大多数为低密度、低硫、中含蜡，饱和烃含量一般为７０％～９０％，并且以Ｃ２１以前的低碳数正构烷烃为主，全油δ１３Ｃ值多为－２９‰～－２４‰。成熟度分析表明，绝大多数煤系原油为正常成熟原油，少数为低成熟原油，没有未成熟原油。天然气中的重烃含量高，Ｃ２以上组分平均达２０％，δ１３Ｃ１值一般为－４５‰～－３５‰，多属接近油型气的混合气。在侏罗纪煤系有机质和原油生物标志物分布中，类异戊二烯烷烃中姥鲛烷占明显优势，即具有较高的Ｐｒ／Ｐｈ值；含有较高的二环倍半萜烷，而三环萜烷含量较低、三环二萜烷含量很低；五环萜烷含量丰富，约占萜烷总量的８０％以上；煤和炭质泥岩中Ｔｓ、Ｃ２９Ｔｓ、Ｃ３０重排藿烷和伽马蜡烷含量很低，而煤系原油和泥岩中这些化合物相对较高；甾烷含量明显较低，且以Ｃ２９甾烷为主，占４０％～８０％；重排甾烷含量相对较高，也以Ｃ２９为主。总体上，煤系原油与泥岩的生物标志物特征较相似，而与煤和炭质泥岩有较大差异。煤系泥岩是西北地区侏罗纪煤系地层中的主力油源岩，煤和炭质泥岩是次要油源岩。这一结论在西北地区侏罗纪煤系含油气盆地具有普遍性。
The vast majority of Jurassic coal series found in Northwest China are mostly low-density, low-sulfur and wax-containing, with the content of saturated hydrocarbons generally ranging from 70% to 90%. Most of the oils are low-carbon n-alkanes prior to C21, The value of δ13C is mostly -29 ‰ ~ -24 ‰. Maturity analysis shows that the vast majority of coal-based crude oil is normal mature crude oil, a few are low-mature crude oil, there is no immature crude oil. The heavy hydrocarbon content in natural gas is high, the average composition of C2 is up to 20%, and the δ13C1 value is generally from -45 ‰ to -35 ‰, mostly close to the mixture of oil-type gas. In Jurassic coal-bearing organic matter and crude biomarker distribution, isoprenoid alkanes in the pristane accounted for obvious advantages, that has a higher Pr / Ph value; containing a higher bicyclic sesquiterpenes, and tris Low content of cyclosporin and low content of tricyclic diterpene; pentacyclic terpane content is rich, accounting for more than 80% of the total amount of terpane; and Ts, C29Ts, C30 rearranged hopane in coal and carbonaceous mudstone and The content of gamma-alkanes is very low, whereas those of coal-based crude oils and mudstones are relatively high; the content of steranes is obviously lower, with C29 steranes as the major component, accounting for 40% -80%; the content of rearranged steranes High, but also to C29-based. In general, biomarkers of coal-based crude oil and mudstone are similar in character, but different from coal and carbonaceous mudstone. Coal series mudstone is the main oil source rock in the Jurassic coal measures strata in northwest China, and coal and carbonaceous mudstone are secondary source rocks. This conclusion is universal in Jurassic coal measures petroliferous basins in Northwest China.