1.采前地面垂直井抽放方法。若地面井在采前10年就开始生产,采用此法煤层气的抽出率可达50%～70%,抽出率高又不影响生产,是很值得推广的一种抽取方法。2.采空区井。此法一般是在开采前从地面打井到煤层上方3～15m左右,当采煤工作面向钻孔推进时,煤层卸压而产生裂隙,由此造成围 1. Pre-mining ground vertical well drainage method. If the surface well starts production 10 years before the mining, adopting this method the extraction rate of CBM can reach 50% ~ 70%. The high extraction rate does not affect the production, which is worth promoting. 2 goaf wells. This method is generally drilled from the ground before drilling to the top of the coal seam about 3 ~ 15m, when the coal mining work facing the drilling advance, the seam pressure relief and cracks, resulting Wai