恩施来凤—鹤峰地区龙马溪组与大隆组页岩孔隙特征及其控制因素

The Pore Characteristics and Its Controlling Factors of the Organic-rich Shale in Longmaxi and Dalong Formation from Laifeng-Hefeng Area of Enshi

页岩孔隙结构控制着页岩气存储机制及其渗流行为。采用场发射扫描电子显微镜、低压氮气吸附技术对恩施来凤—鹤峰地区上二叠统大隆组和上奥陶统—下志留统龙马溪组富有机质页岩的孔隙结构进行研究。结果表明:研究区大隆组和龙马溪组富有机质页岩孔隙主要可以分为4个类别,即有机质中的孔隙、矿物颗粒间的孔隙、矿物颗粒和有机物之间的孔隙以及微裂隙;页岩样品比表面积均值为10.01 m^2/g,为致密砂岩气储层比表面积的5倍以上,样品孔容均值为13.69 cm^3/g;页岩孔隙类型以一端封闭盲孔为主,同时具有一定量平行板状孔和墨水瓶状孔。页岩孔隙发育特征受控于TOC含量与粘土矿物含量。

Shale pore structure controls the storage mechanism and seepage behavior of shale gas. The authors study the pore structure of the organic-rich shale, the Dalong Formation of Upper Permian and the Longmaxl Formation ot upper Ordovician-Lower Silurian in Enshi Laifeng-Hefeng area adopted, by field emission scanning electron microscope and low- pressure nitrogen gas adsorption techniques. The results show that the pole of the organic-rich shale in this study area can be divided into 4 tpyes： pore in organic matter, pore between mineral particles, pore between mineral particles and organic matter, and microfracture. The mean specific surface area of shale samples is 10.01 m^2/g, which is more than 5 times that of tight sandstone gas reservoir. And the mean pore volume of samples is 13.69 cm^3/g. The main type of shale pore is blind hole closed at one end with a certain amount of parallel plate-shaped hole and ink bottle-shaped hole. And the feature of shale pore development is controlled by the content of TOC and clay mineral.