Study On The Application Of Hydraulic Slotting Technology In Sijiazhuang Coal Mine

The multivariate physical parameters of 15th coal seam were studied,and the adsorption desorption characteristics of coal samples were studied by adsorption and desorption experiments under conventional laboratory conditions.At the same time,a geometric model was established,and the stress,deformation and permeability of coal around the hole drilling hole were numerically simulated,and field application was carried out.The summary of the specific research conclusions is as follows:(1)The 15th coal seam in the Shijiazhuang mine belongs to the low water,high ash and high metamorphic anthracite.The initial velocity of gas release is 34-47mmHg,and the limit adsorption coefficient is between 43-48m~3/t.The pore morphology of primary coal is mainly semi open type,and pore connectivity is worse than structural coal.The pore volume of DFT under 10nm pore size is 2 times higher than that of primary coal,and the specific surface area of micropore BET is also3.3-3.6 times of primary coal.The diffusion coefficient of 10 minutes before the construction of coal is 2-5 times that of the primary coal because of the difference of pore structure.(2)The pressure relief radius of the coal body around the borehole will increase with the increase of the radius of the borehole.According to the optimal economic principle,the radius of the actual punching hole is 0.6 m,and the permeability area with a radius of 1.34 m is formed in the coal body around the borehole.The equivalent plastic deformation of the coal body is about 0.45 at the borehole wall,and the body stress is the smallest.The permeability of the coal body is increased by 350times that of the original permeability.(3)After using hydraulic slotting gas extraction concentrationincreased about 3times;pure gas drainage amount increased from 0.23 m~3/min to 0.52 m~3/min,increased about 2.3 times,the gas drainage rate increased from 27.2%to 56.4%.It can be seen that the hydraulic acupoint penetration technique is better than the gas extraction technology of ordinary gas extraction technology.