华北地区煤层气储集与产出性能

Preservation and deliverability characteristics of coalbed methane,North China

对华北地区9个典型煤田（盆地）共144件煤岩样品进行块煤光片法显微裂隙测试、低温氮比表面及孔径测试和压汞孔隙结构测试。测试结果表明，华北地区煤的显微裂隙以宽度小于5μm、长度小于300μm的裂隙为主，裂隙密度约20～200条／9cm^2，孔隙度为2．38％～10．3％，孔隙类型以孔径小于100nm的吸附孔为主，有利于煤层气储集而不利于其产出。煤层的储集性能以焦作煤田和荥巩煤田最好，平顶山煤田、大同煤田和沁水盆地南部次之，其他地区较差。煤层气产出性能以淮北煤田、淮南煤田、平顶山煤田和安鹤煤田最好，永夏煤田和大同煤田最差。焦作煤田显微裂隙不甚发育，荣巩煤田孔隙连通性差，沁水盆地煤的微孔、小孔比例过大，分别成为制约各区煤层气产出的“瓶颈”问题。

One hundred and forty four coal samples from 9 coalfields （or coal basins） in North China were examined using the microfracture analysis by fluorescence microscope, liquid nitrogen adsorption analysis and mercury-injection analysis. Microfractures in coals are dominantly less than 5μm wide and less than 300μm long, and frequency is about 20-200 strips per 9cm^2. Porosity of the coals ranges from 2.38% to 10.3%, and is mainly of adsorption-pore （pore size＇less than 100nm） which is favorable for adsorption and accumulation of gas, but unfavorable for desorption and recovery of gas. Accumulation ability is best in Jiaozuo, Xinggong, secondarily in Pingdingshan, Datong, south Qinshui, and followed by others, while deliverability is best in Huainan-Huaibei, Pingdingshan, Anhe, and worst in Yongxia and Datong. Poor- developed microfractures in Jiaozuo, poor connectivity in Xinggong, and low proportion of seepage-flow pores （pore size larger than 100nm） in Qinshui bring about ＂bottleneck problems＂ for the recovery of coalbed methane.