青藏高原乌丽冻土区过成熟烃源岩原始有机质类型讨论

Discussion on Original Organic Types of Over Over-mature Source Rocks in Wuli Permafrost Zone of Qinghai-Tibeatean Plateau

为了查明青藏高原乌丽冻土区高成熟烃源岩的原始有机质类型,对采自乌丽水合物试验孔ZK1及周边钻孔的岩心样品进行了测试。测试结果显示,研究区烃源岩干酪根显微组分以镜质组为主,含量为79.68%～83.62%,惰质组含量为14.19%～18.35%,干酪根类型为Ⅲ型。从烃源岩生物标志化合物来看,Pr/nC17与Ph/nC18的值分别为0.29～1.05和0.57～1.56,C23三环萜烷/C30藿烷值为0.47～2.23,且C27/C29甾烷值为0.64～1.35,干酪根类型可能为Ⅱ1型或Ⅱ2型。考虑到研究区烃源岩处于过成熟演化阶段,通过综合分析,认为研究区烃源岩的原始有机质类型可能为混合型,部分有机质可能主要来源于水生生物。

In order to find out the original organic types of Wuli permafrost zone on QinghaiTibetan Plateau,the cores core samples are taken analyzed which are from gas-hydrate drilling hole（called referred to as ZK1）and its adjacent drilling holes are analyzed.The results show that the kerogen maceral from the ZK1and adjacent drilling holesstudy area is mainly composed of vitrinite,accounting for 79.68%—83.62%,and some inertinite with a proportion of,respectively accounting for 79.68%—83.62% and 14.19%—18.35%.Therefore,it is can be inferred that the kerogen could be of TypeⅢtype.On the baseis of biomakers,the ratios of Pr/nC17and Ph/nC18respectively get to 0.29—1.05and 0.57—1.56,while the ratios of C23tricyclic diterpane/C30hopane and C27/C29sterane respectively reach to 0.47—2.23and 0.64—1.35.It will can be seen from these data that the kerogen could be classified into fall into TypeⅡ1or TypeⅡ2type.Considering that the fact that maturity of source rocks reaches to are in over mature evolution stage,it it could be summarized a conclusion that the original organic type of the source rocks was probably belongs to mixed typea mixture,while with some organic matters mainly could be originated mainly from inferior aquatic organisms.