松软煤层压风钻进及下筛管地面模拟实验

Ground Simulation Experiment of Forced Air Drilling and Lower Screen Pipes in Soft Coal Seam

为了实现松软煤层长钻孔高效钻进及全孔下筛管,通过开展地面模拟实验和理论分析,对松软煤层风力排渣过程中不同风量、压力条件下煤屑在钻孔环状间隙内的变化规律和煤屑运动方式进行分析。结果表明:在环状间隙内,孔底至孔口的压力差随着钻孔深度的增加而增大,对于一定深度的钻孔,在环状间隙内单位长度下的压力损失基本为定值;在供风流量和给进速度一定的情况下,单位长度的压力损失基本为一恒定值,随着钻进深度的增加,压力损失不断累加;压缩空气自空压机输出至第一根钻杆间的压力损失较大,约占总损失的55%左右,压缩空气在钻杆内孔的压力损失约占30%。本文研究成果对松软煤层快速钻进及全孔下筛管具有借鉴意义。

In order to achieve the efficient drilling of long boreholes in soft coal seams and full length screen pipes, the variation and movement of coal dust in the annular gap of the boreholes under different air volumes and pressures are analyzed by ground simulation experiments and theoretical analysis, in the process of pneumatic slag removal. The results show that: in the annular gap, the pressure difference from the bottom to the orifice increases with the the drilling depth;the pressure loss per unit length in the annular gap is basically a constant value within a certain depth. When the air supply flow and feed speed are constant, the pressure loss per unit length is basically a constant value;but with the increase of the drilling depth, the pressure loss continues to accumulate. The pressure loss of the compressed air from the air compressor to the first drilling pipe is about 55% of the total loss, and the pressure loss in the inner hole of the drilling pipe is about 30%. Above research achievements could be a reference for the realization of the rapid drilling and the full length screen pipes in soft coal seams.