三塘湖盆地煤层与原油地球化学特征对比

CORRELATION OF GEOCHEMICAL CHARACTERISTICS BETWEEN COALS AND CRUDE OILS IN SANTANGHU BASIN

三塘湖盆地的煤系主要发育于侏罗系西山窑组和八道湾组。４ 口井３０ 余块样品测试结果表明，煤系有机质丰度及可抽提有机质的量都较高；正构烷烃具明显奇偶优势；姥植比为１－２５～８－１７；正规甾烷内组成分布具明显Ｃ２９ 优势，Ｃ３１ 藿烷含量高，伽马蜡烷含量低；干酪根碳同位素为－ ２－２７９ 和－ ２－４１３ ；镜质体反射率为０－５０～０－６２ ，正处于主要生烃期；但其地球化学特征明显异于侏罗系、二叠系含油岩芯抽提物，表明侏罗系煤系生成的烃类并未从煤系中排出，对本区油气聚集没有贡献。所以在研究煤成烃时。

Coal measures in Santanghu Basin mainly developed in Jurassic Xishanyao and Badaowan Formations.The test results of 30 samples collected in 4 wells indicate that the abundance and extractable contents of organic matter in the coal measures are both high,n alkane possesses odd even predominance;the ratio of Pr/Ph is 1.25～8.17;n-sterane has evident C 29 predominance;C 31 hopane content is high and gammacerane content is low;kerogen carbon isotopes are-2.2790/0 and -2.4130/0,the vitrinite reflectance is 0.500/0～0.620/0 which is well in hydrocarbon generation period.The other geochemical characteristics differ clearly from the extracts of Jurassic and Permian oil bearing cores.This suggests that Jurassic coal measures generated hydrocarbon is still in the coal measures,it means the coal measures made no contribution to the area's oil and gas accumulation.It thus concludes that we should pay more attention to the expulsion conditions of coal formed hydrocarbon in the study of coal formed hydrocarbon.