定向钻机及其成套装备在碎软煤层瓦斯治理中的应用

Application of directional drilling rig and its whole-set equipment in gas control of broken soft coal seam

为解决丁集煤矿碎软煤层底抽巷常规回转穿层钻孔轨迹不可控带来的补孔多、瓦斯治理效果难以保证等问题,提出利用气动定向钻进技术进行顺层瓦斯治理的新模式。针对1212(1)采面受构造影响产生大范围碎软煤层,设计四翼刮刀扩孔钻头,解决飘钻问题;对钻具进行改进,采用全螺旋结构外形,提高排渣效率;采用“三堵两注”的封孔方式,增大囊袋体积,有效避免由于钻孔塌孔导致封闭不严的问题;采用筛管完孔技术提高下筛管率。通过试验验证,在对气动定向钻进装备工艺进行改进后,成孔率大幅增加,孔深超过165 m;瓦斯抽采单孔体积分数最高达97%,平均抽采体积分数为35.3%,平均抽采纯量为3 m^(3)/min,累计抽采瓦斯734383 m^(3),理论抽采率为47.9%,达到了预期目的。

In order to solve the problems caused by the uncontrollable trajectory of conventional rotary cross-layer drilling in the bottom drainage roadway of the broken soft coal seam in Dingji Coal Mine,such as more filling holes and difficult to guarantee the effect of gas control,a new model for layered gas control by using the pneumatic directional drilling technology was proposed.Aiming at the large-scale broken soft coal seam caused by the structure in 1212(1)mining face,a reaming bit with scrapers at four wings was designed to solve the problem of hole deviations.Then,the drilling tool was improved by adopting a full spiral structure to improve the slag discharge efficiency.At the same time,the hole sealing method with three blocks and two injections was adopted to increase the volume of the bag,so as to effectively avoid loose sealing caused by the drilling collapse.In addition,the sieve tube completion technology was used to improve the lower sieve tube rate.Through the experimental verification,after the improvement of the pneumatic directional drilling equipment technology,the hole forming rate was greatly increased with the hole depth exceeding 165 m,the single hole volume fraction of gas extraction was up to 97%,the average extraction volume fraction was 35.3%,the average extraction purity was 3 m^(3)/min,the cumulative extraction gas was 734383 m^(3),and the theoretical extraction rate was 47.9%,achieving the expected purpose.