宣城地区荷塘组页岩含气性浅析

Discussion about the gas-bearing nature of the shale of Hetang group in Xuancheng area

通过对宣页1井实钻地质资料和岩心样品地球化学分析数据,从有机地球化学和岩石矿物学角度对下扬子地区下寒武统荷塘组黑色页岩含气量偏低的原因进行了分析,并探讨宣城地区页岩气成藏基本地质条件。初步认为该区发育的荷塘组泥页岩粘土含量低,不利于页岩气吸附,热演化程度较高、区域构造条件复杂,导致页岩含气量较低。高热演化是本区内印支期—燕山期岩浆活动的结果,断裂发育是热液扰动的原因。高热演化和断裂发育并非下扬子地区页岩气勘探的制约因素,同时认为二叠系具有较大的页岩气勘探潜力。

Based on the drilling geological data and core sample geochemical data,this paper analyzed the cause of lower gas content of the black shale gas of Hetang group of lower Cambrian series in lower Yangtze region from the perspectives of organic geochemistry and petromineralogy,and also discussed the basic geological condition for the formation of shale gas in Xuancheng area.The results showed that the lower clay content in mud shale of Hetang group was adverse to the adsorption of shale gas and that the high degree of thermal evolution and complicated regional tectonic conditions had also led to the lower gas content of shale gas.In addition,the high thermal evolution was the result of magma activities in the period of Indosinian to Yanshanian and fracture was the cause of hydrotherm disruption.Finally,this paper pointed out that high thermal evolution and fracture development weren’t the constraint factors of shale gas exploration in lower Yangtze region and that Permian system had great potential for shale gas exploration.