特长套铣筒在埋钻事故中的应用

Application of Extra Long Casing Section Mill in Drill Burying Accidents

以往用煤田钻探常用的套铣筒处理一起普通的埋钻事故耗时费力，又容易滋生次生事故。在使用特长套铣筒处理钻孔中的埋钻事故，可以大大缩短处理事故的时间，减少了工人的劳动强度，收到事半功倍的效果。特长套铣筒采用石油专用的带丝扣套管，每根套管长度12m左有，套管之间用管箍连接，总长度一般在80-100m，套铣简的下端接套铣筒钻头。套铣筒的规格根据孔内事故钻具的最大外径确定，通常比事故钻具最大外径大两个级差，而又比孔径小两个级差。套铣筒钻头的规格应该比事故钻头的规格小一级或等于事故钻头的外径，钻头合金宜采用孕镶粉未合金或其它抗耐磨合金。山西某煤矿送料孔钻探到497m时埋钻，用普通方法处理上部272m钻具用时24d，改用特长套铣筒处理剩余225m钻具仅用时10d，体现了高效率的特点，为大孔径勘探孔埋钻事故的处理，找到了一条比较快速的处理方法。

In the past, using frequently-used casing section mill to deal with a common drill burying accident in coalfield drilling can be a long and hard work and secondary accident tend to happen. While the using of extra long casing section mill can greatly shorter processing time and labor intensity, thus half the work with doubled results. The extra long casing section mill uses special oil screw- thread casing, every casing length about 12m, casings are linked by hoops, total length usually 80-100m, lower end linked mill bit Specification of casing section mill is determined according to maximum outer diameter of down-hole accident processing tools, corn monly two graded differences larger than that, and two graded differences smaller than borehole diameter. Specification of casing sec tion mill bit should be one grade smaller than accident processing bit or equal to outer diameter of accident processing bit; bit allo,. should use impregnated powder alloy or other wear resistant alloy. Down to 497m, a drill burying accident happened during the drillin~ of a feeding hole in a Shanxi coahnine, using the common method to process upper 272m tools cost 24 days, converted to extra long cas ing section mill to process remaining 225m cost only 10 days, thus embodied the high efficiency, and a fast-speed way to process larg, diameter exploration borehole drill burying accident has found.