青海木里三露天天然气水合物气源岩有机地球化学特征

通过采集青海木里三露天天然气水合物钻孔岩心样品，对该区天然气水合物赋存层段的中侏罗统和上三叠统烃(气)源岩的有机地球化学特征进行了分析。结果显示：研究区中侏罗统和上三叠统烃(气)源岩有机质丰度较高，TOC含量多在0.6%以上，即整体上为中等、好、很好烃源岩；有机质类型两套地层均主要以Ⅱ₂型、Ⅲ型为主；两套地层 样品镜质体反射率多数介于0.7%～1.3%之间，只有少部分样品镜质体反射率低于0.7%，故有机质演化整体处于成熟阶段，或处于凝析油阶段，还没有达到湿气和干气阶段，可能只为该区天然气水合物提供一定量的气源条件，其主力气源岩可能来自更深部层系；研究区上三叠统烃(气)源岩有机质成熟度整体不高甚至低于中侏罗统，可能受断层逆推作用而出露地表的影响。

Organic Geochemical Characteristics of Gas Source Rocks in the Sanlutian Mine of the Muli Mining Area,Qinghai

The organic geochemical indicators were analyzed emphatically on the hydrocarbon (gas) source rocks of the Middle Jurassic and the Upper Triassic in gas hydrate occurrence interval in Sanlutian area of Muli,Qinghai. Results showed that the organic matter contents are at high levels in hydrocarbon (gas) source rocks of the Middle Jurassic and the Upper Triassic in the study area. Most TOC contents are more than 0.6%, that is medium, good and very good source rocks.The main organic matter is typed II₂ and Ⅲ. The vitrinite reflectance of most samples are between 0 .7% to 1.3% and only a small part of the vitrinite reflectances are less than 0.7%. So the organic matter in most samples are at mature levels, or at condensate levels, not reach the level of wet to dry gas.This kind of gas source rocks may not produce large amounts of hydrocarbon gases to meet the prerequisite formation conditions for gas hydrate in the study area.The maturity of organic matter in the Upper Triassic is not high, even lower than that in the Middle Jurassic in the study area, which is probably caused by ground or shallow occurrence of the Upper Triassic reversed by faults.