焉耆盆地煤系源岩特征、生烃机理及烃源岩倾向性研究

焉耆盆地位于南天山造山带东部,是在华力西期褶皱基底上形成的中新生代含煤沉积盆地.作为西部地区一个小型的侏罗纪含油气盆地,焉耆盆地除与周缘的塔里木、吐哈盆地有相似性外,亦有自己独特的地质条件,即:改造型盆地、煤系生烃和高地温梯度.通过研究认为,煤系源岩特征是决定生烃能力的内因,高地温梯度则是促使油气生成的外因.笔者通过现今地温的测量和岩石热导率的分析,认为焉耆盆地博湖坳陷现今地温梯度较高,其原因主要是该盆地大地热流值较高,认为地温梯度高的原因来自地内深处.从侏罗系煤系源岩的类型、特征、分布,到对其有机显微组分:镜质组、惰性组、壳质组、腐泥组的组成,开展了侏罗纪煤系烃源岩倾气倾油性评价;尤其是进行热压模拟实验,开展中下侏罗统煤岩、碳质泥岩和煤系泥岩热压模拟液态烃、气态烃产率分析.指出侏罗系煤系源岩液态产烃率以煤岩为最高、泥岩次之、碳质泥岩最差;气态产烃率则以泥岩为最高、煤岩次之、碳质泥岩最差.

Research on Characteristics and Hydrocarbon-generating Mechanism of Jurassic Coal Measures Source Rock of Yanqi Basin and Analysis on Hydrocarbon-generating Capacity and Tendency(Liquid and Gas) of Different Source Rock

Yanqi Basin, located in the east of South Tianshan orogenic belt, is a Mesozoic-Cenozoic coal-bearing basin formed on the Hercynian folded basement. As a small Jurassic petroliferous basin in western area, Yanqi basin has its own unique geological conditions besides similarity with Tarim and Turpan-Hami basin. It is a reformed basin of hydrocarbon-generating coal stratum and high geothermal gradient. Research shows that characteristics of coal measure source rocks determine hydrocarbon capacity while high geothermal gradient drive oil and gas generation. Analysis on present geothermal measurement and thermal conductivity shows that the major cause of present high geothermal gradient in Bohu depression of Yanqi basin is high terrestrial heat flow and it is believed that the origin of the high geothermal gradient is from deep underground. On the basis of types, characteristics, distribution and organic maceral including vitrinite, inertinite, exinite and sapropelinite of Jurassic coal measure source rock, evaluation of oil-gas tendency and heat-press simulation experiment, analysis on liquid and gas hydrocarbons yield of coal rock, carbonaceous mudstones and coaly mudstone of middle-lower Jurassic were carried out. The conclusion shows that liquid hydrocarbons yield are, in order, coal rock, mudstones and carbonaceous mudstones respectively and gas hydrocarbons yield are, in order, mudstones, coal rock and carbonaceous mudstones respectively.