基于瓦斯含量的相对压力测定有效半径技术

针对现有煤层瓦斯有效抽放半径测定方法实用性差的问题，基于瓦斯压力和瓦斯含量的抛物线方程关系，推导出瓦斯压力变化与瓦斯抽采率的关系，发明了基于瓦斯含量的相对压力测定有效半径技术。利用瓦斯压力随抽放时间的变化情况确定煤层瓦斯抽放半径与抽放时间的关系，进而确定抽放钻孔间距、抽放时间等抽放参数，避免了在设计抽放钻孔过程中出现抽放空白带和钻孔的无效重叠，提高了煤层瓦斯的抽采率。

Relative pressure determination technology for effective radius found on gas content

According to the problem that existing method for determining effective drainage radius of coal seam gas is poor practicality,based on parabolic equation relation between gas content and gas pressure,the relation between gas pressure change and gas drainage efficiency was deduced,and invented the relative pressure determination technology for effective radius found on gas content. The relation between drainage radius and drainage time was determined by the change of gas pressure with drainage time,and determined borehole space，drainage time and other drainage parameters,and avoided drainage blanking zone and invalid overlap of borehole in devising drainage borehole，enhanced gas drainage efficiency.