基于“一抽两测”的钻孔有效抽采半径测定

Determination of Effective Extraction Radius of Drilling Based on “One Pump,Two Tests”

为准确测出在现行抽采工艺条件下煤层瓦斯抽采有效半径,以达到钻孔工程量最小而抽放效果最佳,在煤层瓦斯赋存及瓦斯流动理论的基础上,使用压降法测定的原理,设计“一抽两测”的布孔方式.在条件基本一致情况下,布设各类间距的抽采与检测钻孔,通过对检测孔的瓦斯与压力变化进行观测、综合分析来确定有效抽采半径,此布孔方式可排除测压孔间相互的影响,同时增加浓度测定,可通过其变化对压力变化进行验证,提高可靠性.测定结果:抽采有效半径为1.25 m,抽采影响半径2 m.

In order to accurately measure the effective radius of the coal seam gas extraction under the current extraction process conditions and achieve the minimum drilling capacity and the best pumping effect,this paper designs the“one pump,two tests”laying hole method,based on the coal seam gas storage and gas flow theory by using the pressure drop method to determine.In the situation that the conditions are basically the same,the effective extraction radius is determined by observing and synthesizing the gas pressure change of the test hole.Results show that the effective radius of extraction is 1.25 m,and the influence radius of extraction is 2 m.