沁水盆地中段煤系页岩气地球化学特征研究

Study on Coal Measures Shale Gas Geochemical Features in Qinshui Basin Middle Segment

针对沁水盆地中段页岩气勘探程度低,烃源岩发育情况及特征不清楚等问题。利用有机地球化学方法对研究区发育的主要页岩层段进行有机质类型、丰度、成熟度、生烃潜能等方面的评价;利用矿物X射线衍射试验和扫描电镜分析方法研究了泥页岩矿物组成特征。结果表明:①根据富气泥页岩的发育层位、分布范围和埋藏深度划分了四套页岩层Y1、Y2、Y3、Y4。②通过对样品的分析,得出页岩有机地化特征,页岩干酪根为Ⅲ型腐殖型,有机质含量平均为1.90%,镜质组反射率平均为2.47%,干酪根处于高成熟阶段,具有较好的生烃潜力。③泥页岩黏土矿物含量为2.4%~63%,平均为45.1%;其次为石英,含量为8.7%~62.2%,平均为40.2%;其他矿物仅少数样品测得,所占比重不大,一般在10%以下。页岩脆性指数平均值>30%。④综合评价后四套页岩层Y1、Y2、Y3、Y4中,整体Y2层段厚度大,TOC含量高,为较有利的页岩生气储层。此研究为沁水盆地页岩气勘探提供了可参考的指导方向和基础数据。

Considering the issues of low level exploration in the Qinshui Basin middle segment,source rock development status not clear etc,and using organic geochemical method has carried out assessment for organic matter type,abundance,maturity,hydrocarbon generation potential etc aspects of main shale segments developed in the study area.Through mineral X-ray diffraction test and SEM analysis have studied argillutite mineral composition features.The study has concluded:①according to gas-rich argillutite development horizon,distribution range and buried depth divided into four shale sets,namely Y1,Y2,Y3 and Y4;②through sample analysis worked out shale organic geochemical features,shale kerogen belongs to type III humics,organic matter average content 1.90%,vitrinite reflectance average 2.47%,kerogen in high-maturity stage with better hydrocarbon generation potential;③argillutite clay mineral content is 2.4%~63%,average 45.1%,the second is quartz content 8.7%~62.2%,average 40.2%,other minerals can get only from few samples,proportions not large,generally below 10%,shale brittle index average>30%;④after comprehensive assessment,the Y2 in four shale sets has large thickness as a whole,TOC content high,is rather favorable shale gas generation reservoir.The study has provided a referable guiding orientation and fundamental data for shale gas exploration in Qinshui Basin.