低压气体吸附法在页岩孔径表征中的应用——以渝东南地区页岩样品为例  

The Application of Low Pressure Gas Adsorption to the Characterization of Pore Size Distribution for Shales:An Example from Southeastern Chongqing Area

作　　者：李腾飞[1,2] 田辉[1] 陈吉[1,2] 程礼军[3] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院大学,北京100049 [3]重庆地质矿产研究院国土资源部页岩气资源勘查重点实验室,重庆400042

出　　处：《天然气地球科学》2015年第9期1719-1728,共10页Natural Gas Geoscience

基　　金：国家重点基础研究发展计划("973")项目(编号:2012CB214705);中国科学院战略性先导专项(编号:XDB10040300)联合资助

摘　　要：泥页岩中的孔隙以纳米级孔隙为主,其孔径分布特征对页岩气的保存与开发具有重要影响。以渝东南地区渝参7井下志留统及上奥陶统页岩为例,开展了77.4K下N2和273.15K下CO2吸附实验,利用修正的BET方程、DFT方法、Stoeckli方法等分析手段,探讨了泥页岩孔结构的组成特征及孔径分布的表征方法,初步评价了页岩中微孔、介孔和宏孔的分布特征。结果表明:1渝参7井下志留统和上奥陶统页岩中的微孔、介孔、宏孔均较发育,其相对比例大致相同;2页岩中微孔孔径的均值主要集中在1.26nm处;3基于CO2吸附的Stoeckli方法得到的微孔分布曲线与基于N2吸附的DFT介孔及部分微孔孔径分布曲线在2nm处可较好地衔接,说明联合利用N2和CO2吸附数据可获取页岩中微孔、介孔和部分大孔的连续孔径分布模式。The pores in shales are mainly of nanometer-scale,and their pore size distribution is very important for the preservation and exploitation of shale gas.This study is focused on the pore structures of Upper Ordovician-Lower Silurian black shales sampled from well YC7 in southeastern Chongqing area.Nitrogen and carbon dioxide gas adsorption were conducted at 77.4Kand 273.15 K,respectively,and the pore structures were characterized by modified BET,BJH,DFT and Stoeckli methods.The results show that：（1）All the micropores,mesopores and macropores are well developed in both Lower Silurian and Upper Ordovician shales,and their relative proportion is almost identical;（2）The mean diameter of micropore for our samples is about 1.26nm;（3）The micropore size distribution curves from the Stoeckli method using CO2 adsorption at 273.15 Kcan be well correlated with that calculated by DFT method using nitrogen adsorption at 77.4K.This indicates that a continuous pore size distribution could be achieved for micropores,mesopores and part of macropores in shales by combing together the N2 and CO2adsorption data.

关 键 词：泥页岩 N2和CO2吸附 孔径表征 

分 类 号：TE122.2[石油与天然气工程—油气勘探]