准噶尔盆地南缘侏罗系烃源岩排烃效率研究

Study on Expulsion Efficiency of Hydrocarbon for the Jurassic Source Rock in the Southern Margin of Junggar Basin

准噶尔盆地南缘下部成藏组合勘探日趋重要,其主力烃源岩生烃潜力和排烃效率的研究亟待加强。根据排烃门限理论,利用生烃潜力法建立了准噶尔盆地南缘侏罗系烃源岩的生、排烃模式,并计算了烃源岩的生烃量、排烃量和排烃效率。研究表明,准噶尔盆地南缘侏罗系泥质烃源岩和煤层的排烃门限对应的镜质组反射率均为0.7%。侏罗系烃源岩的总生烃量为3 973.84×108t,总排烃量为1 402.71×108t,其中八道湾组烃源岩排烃量占总排烃量的69.85%。准噶尔盆地南缘侏罗系烃源岩的平均排烃效率为35.30%,不同层系不同岩性烃源岩,其排烃效率明显不同,泥质烃源岩排烃效率远大于煤层。综合分析认为,准噶尔盆地南缘侏罗系烃源岩生、排烃量大,排烃效率较高,下部成藏组合以侏罗系烃源岩为主力烃源岩,具有良好的资源潜力。

The below oil-reservoir combination in the southern margin of Junggar basin is playing an important role in the hydrocarbon exploration,thus it is necessary to focus our attention on the research on hydrocarbon potential and expulsion efficiency of hydrocarbon of chief source.In this paper,based on the theory of hydrocar-bon-expulsion threshold,models of hydrocarbon generation and expulsion of the Jurassic source rocks were es-tablished and their quantity of hydrocarbon generation and expulsion,expulsion efficiency of hydrocarbon were calculated by using the hydrocarbon-generation potential method.The results showed that the vitrinite reflec-tance corresponding to hydrocarbon-expulsion threshold of both mudstone and coal seam is 0.7%.The total hy-drocarbon generation quantity and the total hydrocarbon expulsion quantity of the Jurassic source rocks are 3,973.84 ×10^8t and 1,402.71 ×10^8t respectively.Of all the hydrocarbon expulsion quantity,69.85 percenta-ges of them were expulsed by the source rocks in Badaowan Formation.The average hydrocarbon expulsion effi-ciency of Jurassic source rocks is 35.30%in the southern margin of Junggar basin.The hydrocarbon expulsion efficiency of source rock with different series of strata and different lithology is obviously different.The hydrocar-bon expulsion efficiency of mudstone is much higher than that of coal seam.In general,source rocks in the Ju-rassic have generated and expulsed large amounts of hydrocarbons,and the expulsion efficiency of hydrocarbon is quite high,indicating a promising resource prospect of the below oil-reservoir combination in the southern margin of Junggar basin.