Research On The Relationship Between The Parameters Of The Current Seam Borehole And The Effect Of Gas Drainage

Gas is the biggest threat to safe production in coal mine of our country.It has been currently recognized that gas drainage is the fundamental measures against gas disasters.The main factor influencing the effect of gas drainage is related to the process parameters of borehole.Firstly,on the basis of the occurrence law of coal seam gas and the theory of gas flow,this paper established the gas spread-seepage equation in the coal body around the borehole and the numerical model by using Comsol Multiphysics according to the features of the fluid flowing in porous media,Secondly,the paper studied the quantitative relationship between the different borehole diameters and the effective drainage radius at different drainaging time by numerical simulation,and also studied the relationship between the different borehole lengths and the effective drainage radius.The results showed that there was exponential relationship between the borehole diameter and effective drainage radius in a fixed drainage time.The length of borehole has a little effect on the effective drainage radius, but the effective drainage radius is a bit different at the different depth along of borehole drilling.Finally,the paper established the quantitative relationship model of effective drainage radius among borehole diameter,borehole depth and drainaging time by using nonlinear fitting of SPSS.The effective drainage radius of Fangzhuang ? mine 41121 Working Face for different diameters and lengths was measured,and the rests are consistent between the simulation and measure.