湘中拗陷泥盆-石炭系海相泥页岩地球化学特征及等温吸附性能

利用湘中地区泥盆-石炭系野外剖面泥页岩有机地球化学参数及泥页岩等温吸附特征参数,评价页岩气富集的关键地质参数特征。海相泥页岩有机地球化学参数表明,其有机碳含量高,泥盆系泥页岩有机质类型为Ⅰ—Ⅱ1型,石炭系大塘阶测水段为Ⅱ1—Ⅲ型;泥盆—石炭系有机质的成熟度高,基本都达到高成熟—过成熟阶段。泥页岩等温吸附曲线表明,泥页岩吸附容量较大。这些参数表明,湘中拗陷页岩气的基础地质条件好,具备页岩气富集成藏的地化条件,泥盆系棋梓桥组、佘田桥组及石炭系大塘阶测水段3套海相泥页岩厚度大、分布范围广、有机质丰度高。

Geochemical characteristics and isothermal adsorption properties of the Devonian-Carboniferous marine mud shale in the Xiangzhong depression, Hunan, China

This paper mainly evaluates the key geological parameter characteristics of the shale gas enrichment in the Devonian-Carboniferous marine strata by using the organic geochemical parameters and mud shale isothermal adsorption characteristic parameters from the field sections of the central area of Hunan.The organic geochemical parameters reveal that the marine mud shale has a high organic carbon content.The organic matter type of the Devonian mud shale is typeⅠ and Ⅱ1,while the organic matter type of the Ceshui segment mud shale of Datang Stage is typeⅡ1 and Ⅲ.The organic matter of the Devonian-Carboniferous mud shale has entered into a high mature-postmature stage on the whole.The isothermal adsorption curves of the mud shale show that the mud shale has a high adsorption capacity.These parameters indicate that the shale gas in the Xiangzhong depression has good basic geological conditions and has the geochemical conditions to accumulate the shale gas.The main formations that can accumulate shale gas are Devonian Qiaoziqi Formation,Shetianqiao Formation and Ceshui segment of Datang Stage,and the three formations have the marine mud shale with a large thickness,wide-spreading,and high abundance of organic matter.