三维采空区煤层气渗流空间分布特征及应用

Spatial Distribution and Application of Coalbed Gas Seepage in Three-dimensional Goaf

为研究采空区煤层气空间分布及渗流规律,研制了三维采空区煤层气渗流模拟试验系统。向系统的主体装置内铺设相似材料,利用加载系统向相似材料上部均匀加载,利用底板升降系统模拟煤层开挖,采用供气系统由下向形成的采空区内注入甲烷,通过布置在相似材料内的取气系统采集并检测三维采空区内的甲烷浓度。试验结果表明:采空区自下而上分为源流区、抑流区、汇流区和无流区。源流区内煤层气浓度最高,抑流区抑制采空区煤层气渗流且其浓度急剧下降,汇流区内煤层气浓度逐渐上升,但整体低于源流区内煤层气浓度,无流区内无煤层气存在。通过在山西省废弃矿井晋圣矿开展老采空区地面煤层气抽采试验,结果表明地面钻井底部位于源流区时抽采效果较理想。

To study spatial distribution and seepage laws of methane in gob, a three-dimensional simulation testing system for methane seepage in gob was newly developed. Laying similar simulation materials into the main body of the system, uniformly loading the upper part of similar materials using loading system, the bottom plate lifting system was used to simulate the coal seam excavation, and methane was injected into the downward goaf formed by the gas supply system. The methane concentration in the three-dimensional goaf was detected by the gas extraction system arranged in similar materials. The test results show that the goaf is divided into the source flow area, the flow suppression area, the confluence area and the no-flow area from the bottom up; the coal bed gas concentration in the source flow area is the highest, flow suppression zone inhibits coalbed gas seepage in goaf and its concentration drops sharply, the coalbed gas concentration gradually rises in the confluence zone, however, the overall concentration of CBM is lower than that of source flow area, and there is no CBM in no-flow area. By carrying out the test of surface coalbed gas extraction in the old goaf area at Jinsheng Mine, an abandoned mine in Shanxi Province, the results show that the results are satisfactory when the ground drilling bottom is located in the source flow area.