黔北地区二叠系龙潭组页岩微观孔隙特征及其储气性

为了深入研究黔北地区海陆过渡相页岩储层微观孔隙结构特征，选取了二叠系龙潭组钻井岩心页岩样品进行氩离子抛光-场发射扫描电镜实验、氮气吸脱附实验、及相关地化和等温吸附等测试，研究页岩微观孔隙类型及孔隙结构特征，并探讨微观孔隙对页岩储气性能的影响。研究结果表明，龙潭组页岩储层的孔隙类型主要包括粒间孔、粒内孔、有机质孔、微裂缝4种，以矿物颗粒粒间孔和黏土矿物粒内孔最为发育，有机质孔发育较少，这主要是因为Ⅲ型干酪根显微组分为结构稳定的镜质组和惰质组在生烃过程中不易产生有机质孔；氮气吸附实验结果显示龙潭组页岩孔隙类型复杂，主要表现为两类：细颈广体的墨水瓶孔隙和四边开口的平行狭缝型孔隙，孔径主要介于3～5nm，以发育中孔为主，BET比表面积平均为15.846m2/g，BIH总孔体积平均为0.01258ml/g；龙潭组页岩样品吸附气含量较高（平均为2.37m3/t），页岩储层微观孔隙对吸附性能有重要的影响，其中吸附气含量与页岩的孔径呈负相关关系，与页岩的比表面积、孔体积呈较好的正相关关系，页岩的纳米级孔隙为烃类气体的赋存和运移提供了有利条件。

Characteristics of microscopic pore and gas storage on shale in Permian Longtan Formation, northern Guizhou

To deeply study micropore characteristics of marine-continental facies shale reservoir in Longtan Formation, northern Guizhou, the shale in the Permian Longtan Formation was selected for experiments including the Argon Ion milling-Field Emission Scanning Electron Microscopy, nitrogen adsorption-desorption experiment, organic geochemistry and isothermal adsorption experiment etc., to study microscopic pore types and pore structure characteristics of shale, and discussed the effect of microscopic on shale gas storage. The research result show that, pore types mainly including interparticle, intraparticle, organic matter pore and micro cracks in Longtan Formation shale reservoir, the mineral particle interparticle pore and clay mineral intraparticle pore are most developed, and little organic matter pore, this is due to huminite (vitrinite, inertinite), as the structure-stable OM, have difficulty altering their inner structure to form the organic matter pore within them; the result of nitrogen experiment shows that Longtan Formation shale pore types are complex, mainly manifested an opening four parallel slit pore and neck wide ink bottle pore, the pore diameter mainly ranged from 3 to 5nm, mostly develop mesopore, the average of BET surface area is 15.846m2/g, the average of BJH pore volume is 0.01258ml/g; the Longtan Formation shale samples adsorbed gas content is relative high(the average is 2.37m3/t), the micro porosity of shale reservoir has an important influence on the adsorption performance, it suggested that adsorbed gas is negatively correlated to the pore diameter, and positively correlated to surface area and pore volume, the nanometer pores of shale provide favorable conditions for the occurrence and migration of hydrocarbon gases.