多层叠置含煤层气系统不同排采制度下的排采效应

Drainage Effects of Multiple Superimposed CBM Systems under Different Drainage Systems

在多煤层发育地区,各煤层组之间发育低渗透岩层,使得上下煤组之间形成独立的多层叠置含煤层气系统。根据相对独立含气系统理论对西山煤田南部赤峪地区的多煤层进行了含气系统的划分,并对储层压力、临界解吸压力等参数进行了分析,在此基础上采用COMET3数值模拟软件进行了单层排采、合层排采和递进排采分析。模拟结果显示:单层排采产量低,经济可采时间短,且成本较高;合层排采比单层排采产量高,经济可采时间长,但各含气系统之间由于相互干扰,贡献不一,使资源浪费;递进排采产气量和稳产时间均优于前两者。可根据产气压力来确定多层叠置含煤层气系统排采次序,首先排采产气压力最高的含气系统,当压力降至压力低的系统时再合排。

In multiple coal seams developed area, low permeable strata have existed between coal groups, thus formed independent multiple superimposed CBM systems. Based on the relatively independent CBM system theory has divided CBM systems of multiple coal seams in the Chiyu area, southern Xishan coalfield; analyzed parameters of reservoir pressure, critical desorption pressure etc. On this basis used COMET3 numerical simulation software carried out single layer drainage, multilayer drainage and progressive drainage analysis. The result has shown that the single layer drainage has low yield, short economic recoverable time, and high cost; the multilayer drainage yield is higher, economic recoverable time is longer than single layer drainage, but because of mutual interference exists between methane-bearing systems and different yields made resources waste; the progressive drainage yield and stable production time are all superior to the former two. The drainage sequence of multiple superimposed CBM systems can be based on methane pressure,firstly drain the highest methane pressure CBM system, when the pressure lowering down to the same as low pressure system, then using multilayer drainage.