瓦斯抽采钻孔钻屑气固耦合运移压力损耗分析

Analysis on pressure loss of drilling cuttings movement caused by gas-solid coupling in gas extraction borehole

基于气固两相流体力学理论,对瓦斯抽采钻孔内钻屑运移气固两相流压损、钻杆腔体接头处局部压损、钻孔收缩和"钻穴"引起的压损进行分析,结合工程案例,对钻进系统的风压损耗进行计算和分析。结果表明,钻进系统的风压损耗主要为气固两相流的摩擦压损,开放型钻穴对钻进系统的压损影响较小,填充型钻穴会带来较大的压力损耗。结合煤层地质条件和钻孔施工工艺参数,应用文中方法计算钻进系统风压损耗,为优化压风系统提供科学依据。

Based on gas-solid two-phase fluid dynamics theory, the drilling cuttings movement pressure loss caused by gas-solid flow in borehole, the partial pressure loss generated by air flow through the joint diameter reducing po-sition, borehole shrinkage position and drilling cave area of the gas extraction borehole were analyzed.Combining with engineering case, the air pressure loss of drilling system was calculated and analyzed.The results showed that the friction pressure loss of gas-solid flow is the main components of air pressure loss in drilling system.Opened-type drilling cave has fewer impacts on air pressure loss of drilling system, but filled-type drilling cave can form great pressure loss.According to the geological conditions of coal seam and drilling design parameters, the method was applied to calculate the air pressure loss of drilling system.It can provide the scientific basis for optimizing the compressed air system.