基于瓦斯流场的抽采半径确定方法

Drainage radius measurement based on gas flow field

为了准确确定煤层瓦斯抽采半径并以此为基础合理测算同一矿区不同区域瓦斯抽采参数,采用瓦斯流动相关理论建立了抽采钻孔周围煤体瓦斯压力分布数学模型,并设计出基于VB.NET的钻孔抽采半径解算程序,数值模拟研究了抽采过程中钻孔周围煤体瓦斯压力分布规律及影响因素。结果表明,抽采时间、渗透率和负压是影响瓦斯压力分布规律的主要因素。采用圆周布孔压降法实测芦岭矿8煤抽采300 d瓦斯有效半径为4.23 m,而模型解算的结果为4.43 m,两者误差较小,在工程的允许范围内。利用比例系数法可合理测算矿井其余区域抽采半径,为煤层瓦斯抽采钻孔设计提供依据,提高瓦斯抽采效率,保证矿井安全生产。

In this paper, to accurately determine the drainage radius, and reasonably estimate the drainage parameters of different regions in the same mine, the mathematical model of gas pressure in coalmass around borehole was established by the gas flow theories, the calculation program of drainage radius was designedby using VB.NET, and the distribution rules of gas pressure around borehole and the influence factors were simulated. Meanwhile, drainage radius was measured with the method of pressure-drop testing by circumference setting-borehole. The results show that the draining time, per- meabilities and subpressure are the main factors which influencing the distribution rules of gas pressure. The actual measured drainage radius of No.8 Coal Seam in Luling Mine is 4.32 m, while the calculation results is 4.43 m, which means the proportional coefficient method can calculate the drainage radius of other zones in the mine reasonably. The achievements in this paper can provide basis for gas drainage borehole design, raise gas drainage efficiency, and ensure safety mining.