碎软煤层气动定向钻进技术在青龙煤矿的应用

Application of pneumatic directional drilling technology for soft-fragmentized coal seam in Qinglong Coal Mine

针对现有碎软煤层回转钻进技术存在成孔深度浅、钻孔轨迹不可控、钻进效率低和瓦斯抽采效果差等问题,提出采用气动定向钻进技术进行碎软煤层瓦斯抽采钻孔施工。气动定向钻进技术以井下防爆空气压缩机输出压风为钻进动力和排渣介质;利用有线随钻测量装置随钻获取钻孔轨迹参数;应用压风监控装置实时监测供风压力、温度和流量等参数,为孔内工况判断提供依据;应用压风除尘装置对孔口煤尘进行分级净化以实现煤尘高效处理。在兖矿贵州能化有限公司青龙煤矿21608运输巷南段钻场开展了现场试验,在普氏系数为0.37的碎软煤层中采用气动定向钻进技术施工定向钻孔,最大孔深为345m,单班平均有效进尺比普通回转钻孔提高了30%以上;单孔平均瓦斯抽采体积分数保持在70%左右,与普通回转钻孔相比提高了60%左右;钻场主管路平均瓦斯抽采体积分数为71.2%,平均瓦斯抽采纯量达4.0m3/min,累计抽采瓦斯11.5万m^3,有效覆盖了300m待掘巷道瓦斯抽采区域。气动定向钻进技术具有钻孔轨迹可控、成孔深度大、钻进效率高和瓦斯抽采效果好的优势,可应用于碎软煤层瓦斯区域抽采和采前预抽,为碎软煤层瓦斯治理提供了新的技术途径。

In view of problems of rotary drilling technology for soft-fragmentized coal seam,such as shallow borehole completed depth,uncontrollable borehole trajectory,low drilling efficiency and poor gas drainage effect,pneumatic directional drilling technology was put forward to carry out gas drainage borehole construction in soft-fragmentized coal seam.Compressed air output by underground explosionproof air compressor is used as drilling power and slag discharge medium.Wired measurement while drilling device is used to obtain borehole trajectory parameters.Compressed air monitoring device is applied to monitor parameters such as air supply pressure,temperature and flow rate in real time,which provide basis for judgment of working condition in borehole.In order to realize efficient coal dust treatment,compressed air dust removal device is used to purify coal dust in orifice.The field test was carried out in drilling field of southern region of 21608 roadway in Qinglong Coal Mine of Yankuang Guizhou Nenghua Co.,Ltd.The pneumatic directional drilling technology was adopted to construct directional boreholes in soft-fragmentized coal seam with firmness coefficient of 0.37.The maximum borehole depth is 345 m,and the average effective footage of single shift is more than 30%higher than that of ordinary rotary borehole.The average gas drainage volume fraction of single borehole remains at about 70%,which is about 60%higher than that of ordinary rotary borehole.The average gas drainage volume fraction of main pipeline in drilling field is 71.2%,the average gas drainage purity is up to 4.0 m^3/min,and accumulated gas drainage volume reaches 115000 m3,which effectively covers gas drainage area of 300 mroadway to be excavated.The pneumatic directional drilling technology has advantages of controllable borehole trajectory,long borehole completed depth,high drilling efficiency and good gas drainage effect.It can be applied to gas regional drainage and pre-drainage in soft-fragmentized coal seam,which provides a new technical approach for gas control in soft-fragmentized coal seam.