柴北缘侏罗系烃源岩地球化学特征及其综合评价

通过对柴达木盆地北缘侏罗系烃源岩有机质丰度及其类型的研究,以及对柴北缘烃源岩成熟度和柴北缘热演化史的分析,综合评价了烃源岩的生烃潜力。主要结论是:①柴北缘主要烃源岩下侏罗统暗色深水湖相泥岩和下侏罗统的煤岩,可分为Ⅱ、Ⅲ1和Ⅲ2型;②中、下侏罗统烃源岩大多数已超过成熟阶段。下侏罗统在E3-N2时期进入生排烃高峰期,中侏罗统则在N2进入生排烃阶段;③柴北缘下侏罗统为一套好的烃源岩,生气强度达到大中型油气田的规模。中侏罗统为一套中等的源岩层,生气强度中等,具备形成大中型气田的气源条件。

GEOCHEMICAL CHARACTERISTICS AND HYDROCARBON GENERATION CAPABILITY OF THE JURASSIC HYDROCARBON SOURCE ROCK ON THE NORTHERN EDGE OF QAIDAM BASIN

On the basis of analysis about the abundance and the types of Jurassic organic matters on the northern fringe of Qaidam Basin and research about the source rocks' maturity and the thermal evolution history, this article evaluates the hydrocarbon generation capability of the source rocks. It is concluded that the major hydrocarbon source rocks in the fringe are those that were developed in Middle-Lower Jurassic, including deepwater lacustrine mudstone and coal seam. There are three types of organic matters (II, III_1 and III_2) in those source rocks. Most of the Middle-Lower Jurassic source rocks are in the over-maturity stage. The maximum accumulative generation of the source rocks occurred in the stage of E_3 to N_2, while maximum accumulative generation of the Middle Jurassic source rocks occurred during N_2. The Lower Jurassic source rocks are excellent in terms of hydrocarbon generation intensity and show the capacity of forming big- to middle-sized oil-gas field, while the Middle Jurassic consists of a set of source rocks possessing middle generation intensity that can lead to formation of big- to middle-sized gas field.