准噶尔盆地四棵树凹陷侏罗系有机质生烃差异及油气藏分布规律

准噶尔盆地四棵树凹陷位于盆地南缘西端,是重要的油气富集区。随着近些年勘探的不断突破,对烃源岩的认识不断加深。但目前对侏罗系烃源岩的生烃母质、生烃潜力尚不明确。通过对准噶尔盆地四棵树凹陷中下侏罗统烃源岩的有机质丰度、成熟度等有机地球化学指标进行综合评价,并根据天然气组分碳同位素与岩性厚度分布图探讨了不同母质生烃差异及空间分布范围;同时进行烃源岩的热演化分析与数值模拟,建立动态演化过程,从而获得平面烃源岩展布规律及有利勘探方向。研究结果显示:四棵树凹陷侏罗系烃源岩中煤岩生烃效果要优于炭质泥岩,目前储层中天然气中煤成气贡献较大;此外,平面上生气中心更靠南部,是天然气运聚的主要方向。整体上看,四棵树凹陷烃源岩仍具有较大的生烃潜力,具有较高的勘探价值。

Patterns of hydrocarbon generation and reservoir distribution in the Jurassic strata,Sikeshu Sag,Junggar Basin

The Sikeshu Sag,located in the west of the Junggar Basin,contains large oil and gas deposits. However,the patterns of source rocks and potentials of hydrocarbon generation in the Jurassic strata are still under debates. Taking into account of TOC,maturity and other organic geochemical indexes,hydrocarbon generation differences from various source rocks are speculated with the carbon isotopes and isopach map. Besides,thermal analysis and numerical modeling were conducted to establish the evolution of source rock and to evaluate the potential exploration prospects in the research area. The results show that the hydrocarbon generated from coal is much better than that of carbonaceous mudstone in the Jurassic strata of Sikeshu Sag. In addition,the gas is transported and gathered mainly in the south of the area. The source rocks in the Sikeshu Sag show high hydrocarbon potentials and explorational values.