贵州凤冈地区牛蹄塘组页岩特征及含气性

Characteristics of Shale and Gas Content of Niutitang Formation in Fenggang Region of Guizhou Province

利用地化测试、扫描电镜和岩心观察等对凤冈地区牛蹄塘组页岩特征进行了研究,根据FC1井现场页岩气解吸数据,分析了页岩的含气性。结果表明:页岩有机碳含量在4%~28%,有机质热成熟度介于2.66%~2.95%,有机质类型为Ⅰ型,孔隙度和渗透率都较低;页岩内部以石英等脆性矿物为主,黏土矿物含量低,硅质是生物成因;通过扫描电镜发现页岩内部以有机质孔、粒间孔为主,发育有大量的铸模孔、溶蚀孔和微裂隙;岩心观察发现页岩的裂缝非常发育;FC1井现场解吸气含量在0.39~1.97 m3/t,总含气量在0.87~4.13 m^3/t,含气性较差;方解石破碎带含气性较好;强烈的构造运动产生的裂缝不利于页岩气的保存。

To study the characteristics of shale in Niutitang formation by using means of experimental geochemistry, SEM, core observation, according to the site analysis data, analysis of gas-bearing shale in Fenggang region. Results show that the organic carbon content of shale gas is between 4%-28%, organic maturity is between 2.66%-2.95%, the type of organic matter is I, has low porosity and permeability; the major of shale gas are brittle mineral quartz as a main, low clay mineral content, the causes of siliceous is biogenic; through the SEM, it is found that there are a lot of mold holes, dissolution pores and microfissures in the shale; the observation of the core shows that the shale is well developed; the fangcanlwell analytical gas content site is between 0.39-1.97 m^3/t; the total gas content is between 0.87-4.13 m^3/t, gas-poor; the well of containing gas in calcite fracture zone; shale gas is not conducive to the preservationare cracks intense tectonic movement.