准噶尔盆地南缘侏罗系烃源岩评价

第三次资源评价(三次资评)结果表明准噶尔盆地侏罗系石油资源量占盆地总资源量的30%以上,天然气资源量占盆地总资源量的28%,其中30. 7%的原油资源和45. 7%的天然气资源分布在准噶尔盆地的南缘,可见应深人分析南缘侏罗系主力烃源岩的特征及其生烃潜力。通过对三次资评之后勘探所积累的地质地球化学数据的系统分析,认为准噶尔盆地南缘有机质类型总体以且II₂型和III型为主,纵向上发育了一套优质烃源岩(八道湾组)和两套中等丰度的烃源岩 (三工河组和西山窑组),烃源岩的规模远远大于三次资源评价的结果。这3套烃源岩均达到了成熟一过成熟的演化阶段,在白垩纪末期进入生油高峰期,在新近纪末期进入生气高峰期,生油气关键时刻与圈闭的形成和定型匹配良好,有利于形成大型和超大型油气藏。研究成果对指导准噶尔盆地南缘油气勘探具有重要的理论和实际意义。

Evaluation on Jurassic Hydrocarbon Source Rock Developed in Southern Margin of Junggar Basin

The hydrocarbon resources from Jurassic source rocks account for more than 30% and the natural gas resources account for 28% of the total amount in the Junggar Basin according to the third resource evaluation in 2000. According to the evaluation result,about 30.7% of the oil and 45.7% of the natural gas of the Jurassic resource are from the southern margin of the Junggar Basin(SMJB).Thus,it is critical to keep on studying the characteristics and the hydrocarbon generating potentials of the Jurassic source rocks. Data compiled during the hydrocarbon exploration in the last ten years are helpful for a better characterization of the source rocks in the SMJB. Three sets of source rocks were recognized. The Badaowan Formation of the Lower Jurassic was high quality source rocks. Source rocks from the Sangonghe Formation in the Lower Jurassic and the Xishanvao Fomation in the Middle Jurassic are characterized by medium quality. The above three sets of source rocks are characterized by humic organic types which fall within type II₂ and type III source rocks. All the source rocks are mature-overmature source rocks. The source rocks were buried to the peak of oil generation at the end of Cretaceous. Neocene is the period when the source rocks were buried to the peak of gas generation. The perfeet match between the key period of hydrocarbon generation and the initiation and formation of the trap facilitate large-scale hydrocarbon migration and accumulation. The research is significant in guiding the hydrocarbon exploration in SMJB.