不同煤储层条件下煤岩微孔结构及其对煤层气开发的启示

Micropore structure of coals under different reservoir conditions and its implication for coalbed methane development

在现场宏观观测的基础上,采用显微镜下观测、镜质组反射率测试及低温氮吸附方法,对沁水盆地和淮北煤田不同矿区煤岩的变质变形作用与微孔结构特征进行了深入研究。结果表明:高变质强变形—较强变质煤储层(Ⅰ类)和中变质较强变形煤储层(Ⅲ类)有利于煤层气的富集,不利于煤层气的扩散和渗流;高变质弱变形煤储层(Ⅱ类)和中变质弱变形煤储层(Ⅳ类)较有利于煤层气的富集,也有利于煤层气的渗流;低变质强变形煤储层(Ⅴ类)有利于煤层气的富集,但不利于煤层气的解吸和渗流。由此,沁水盆地南部及淮北煤田中南部是煤层气勘探开发的有利区域。

This paper analysed micropore structure of coal samples from coalmines of Qinshui basin and Huaibei coalfield by using micro-macroscopic observation,R_o testing,and low temperature nitrogen adsorption method.Results indicate that there are five different coal reservoir types in the study areas.High grade metamorphic and relatively strong to strong deformed coal reservoir(typeⅠ) and medium grade metamorphic and relatively strong deformed coal reservoir(typeⅢ) are favourable for coalbed methane(CBM) accumulation,but disadvantageous to CBM seepage; high grade metamorphic and relatively weak deformed coal reservoir(typeⅡ) and medium grade metamorphic and relatively weak deformed coal reservoir(typeⅣ) are advantageous to CBM accumulation and seepage;low grade metamorphic and strong deformed coal reservoir(typeⅤ) is favourable for CBM accumulation,but not advantageous to CBM desorption and seepage.Consequently,southern part of Qinshui basin and south-central of Huaibei coal field are potential areas for coalbed methane exploration and development.