羌塘盆地侏罗系曲色组烃源岩特征及生烃潜力

Source Rock Characteristics and Hydrocarbon Generation Potential of Jurassic Quse Formation in Qiangtang Basin

应用有机地球化学分析方法,对羌塘盆地侏罗系曲色组烃源岩进行评价。勘探早期对烃源岩有机地球化学研究的基本地球化学指标包括有机质丰度、有机质类型、有机质成熟度三个指标。通过分析,曲色组烃源岩有机质丰度较高,油页岩有机碳平均质量分数为5.208%,总体表现为好烃源岩特征。有机质组成以镜质组和腐泥组为主,H/C原子比介于0.59~0.89之间,O/C原子比介于0.10~0.14之间,干酪根类型指数TI介于-56.245~49.22之间,油页岩总体表现为Ⅱ型少部分Ⅲ型。岩石热解峰温(Tmax)介于424~502℃之间,主体进入成熟演化阶段,部分达到过成熟阶段,具有良好的生烃潜力及勘探前景,可以作为后续羌塘油气勘探的目标层系。

The source rocks of Jurassic Quse Formation in Qiangtang Basin were evaluated by organic geochemical analysis.The basic geochemical indexes of organic geochemistry of source rocks in the early stage of exploration include abundance of organic matter,type of organic matter and maturity of organic matter.According to the analysis,the source rocks of Quse Formation have high organic matter abundance,and the average mass fraction of organic carbon of oil shale is 5.208%,which shows good characteristics of source rocks.The composition of organic matter is dominated by vitriinite and sapropelite,with H/C atom ratio ranging from 0.59 to 0.89,O/C atom ratio ranging from 0.10 to 0.14,and kerogen type index TI ranging from-56.245 to 49.22.The overall performance of oil shale is type II and a small part of type III.The pyrolysis peak temperature(Tmax)of rocks is between 424-502℃,the main body enters the mature evolution stage,and some reaches the over-mature stage,which has good hydrocarbon generation potential and exploration prospect,and can be used as the target layer for subsequent oil and gas exploration in Qiangtang.