藏北羌塘盆地石炭系烃源岩的发现及其油气地质意义

    Chen W B, Fu X G, Tan F W, Feng X L. The discovery of the Carboniferous source rock in Qiangtang Basin of Tibet and its geological significance

    • 摘要: 羌塘盆地的油气大多源于侏罗系,所以长期以来烃源岩的研究主要以侏罗系为重点。古生代烃源岩露头在羌塘盆地分布较少,因而其生烃能力一直未引起足够的重视。依据剖面露头样品的实验测试资料,通过 Rock-Eval岩石评价、显微镜下观察、镜质体反射率、烃源岩可溶有机质特征等分析方法 , 对羌塘盆地双湖地区新发现的石炭系烃源岩地球化学特征进行综合研究。结果表明,羌塘盆地石炭系烃源岩有机质丰度较高,烃源岩的有机质类型较好,主要为Ⅱ1型,并且烃源岩形成于具一定盐度的较强还原环境,其有机质以海相低等水生生物为主。烃源岩的热演化程度总体较高,达到过成熟阶段。石炭系烃源岩的发现填补了羌塘盆地古生代烃源岩领域研究的空白,为油气勘探指出了新地层和新领域,对整个羌塘盆地油气资源评价具有重要意义。

       

      Abstract: The Jurassic source rocks have long been regarded as the research priority because most oil and gas shows in Qiangtang basin were found from the Jurassic source rocks. The Carboniferous source rocks's capability of hydrocarbon generation has not been given sufficient consideration because its strata assume scattered distribution in Qiangtang basin. According to the data obtained from the surface samples, the authors used analytical methods of Rock-Eval, microscope observation, vitrinite reflectance and biomarkers to analyze the organic geochemical characteristics of the Carboniferous source rocks in Qiangtang basin. The results reveal that the organic matter abundance of source rocks is higher in Carboniferous, and organic matter is mainly of Ⅱ1 type, and the overall thermal evolution has reached the high degree of the over-mature stage. The discovery of Carboniferous source rocks has filled for the first time the gap in the study of Paleozoic source rocks in Qiangtang basin, and indicated the new formation and new areas of oil and gas exploration,thus having great significance for the assessment of oil and gas resources in the whole Qiangtang basin.

       

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