沁水盆地榆社-武乡区块煤系页岩气储层特征评价

Assessment of Coal Measures Shale Gas Reservoir Features in Yushe-Wuxiang Block,Qinshui Basin

通过对沁水盆地榆社-武乡区块石炭-二叠系山西组-太原组富有机质泥页岩展布特征、地球化学特征以及储层特征进行分析认为,研究区富有机质泥页岩十分发育,连续性较好。TOC含量集中分布于1.5%~2.5%,干酪根以III型为主,热演化程度为高成熟—过成熟阶段,为好-优质的烃源岩。泥页岩矿物成分以黏土矿物和石英为主,黏土矿物主要为高岭石和伊蒙混层。页岩孔隙类型以黏土矿物粒间孔和有机质孔最为发育。泥页岩具有良好的吸附性能,页岩比表面积和孔隙体积有很好的正相关关系,表明研究区页岩具有较好的储集性能。优选的山西组-太原组页岩气有利区分布于研究区的北部及中部偏南一带,有利区内泥页岩累计厚度均在50m以上,TOC含量大于2%,构造较为简单,埋深适中,有利于页岩气的勘探与开发。

Through analysis of Permo - Carboniferous Shanxi and Taiyuan formations organic rich argillutite distribution, geochemical and reservoir features in the Yushe - Wuxiang block, Qinshui Bain has considered that the organic rich argillutite in the study area is well developed with better continuity. The TOC content is concentrated between 1.5 % -2. 5 %, kerogen mainly type III, thermal evo- lution degree in high maturity to over maturity stage, thus a good - excellent source rock. The mineral composition of argillutite is main- ly clay minerals and quartz. Clay minerals have kaolinite and illite/montmorillonite mixed - layer. The most developed shale pore type is clay mineral intergranular and organic matter pores. Argillutite has good adsorptivity, shale specific surface area and pore volume is positively correlated, thus indicated argillutite in the area has better reservoir properties. Optimized shale gas favorable areas in the Shanxi and Taiyuan formations are distributed in north and middle by south parts in study area, argillutite accumulated thickness in fa- vorable areas all above 50m, TOC content over 2%, structurally simple and buried depth moderate, thus propitious to shale gas explo- ration and exploitation.