Yangquan Coal Industry (Group) Company Limited Xi'an Research Institute, China Coal Technology and
Engineering Group

针对寺家庄矿瓦斯抽采钻孔成孔深度浅、护孔效果差的问题,基于空气螺旋钻进工艺和筛管护孔工艺原理,完成了地层适用设备选型、钻具结构及施工工艺优化,并进行了现场试验。试验结果表明:使用该套设备施工,钻孔平均深度145 m,成孔深度较之前提高了30%,最大孔深180 m。试验护孔筛管下入率83.7%,孔底固定用悬挂装置轴向拖拽距离2~3 m,135 d后筛管有效护孔率达89%,筛管护孔工艺保障了筛管下入深度和护孔效果。加强型三翼可开闭式钻头平均穿岩51 m,钻头结构稳定,有效提高钻孔穿岩深度;相同孔深钻孔有效煤孔段(即煤岩比)与瓦斯抽采效果无相关性,钻孔深度及筛管有效护孔率是影响瓦斯抽采的主要因素。

According to a shallow completed depth of the gas drainage borehole and poor borehole protection effect problems in Sijjazhuang Mine, based on the pri nciples of the air auger drilling technique and the screen pipe borehole protection technique, the equipment selection suitable to the strata, drilling tools structure and th e construction technique optimization were completed. A site test was conducted and test results showed that with the application of the set equipment to the constructi on, the average depth of the borehole was 145 m, the borehole completed depth was improved by 30% in comparison with the previous depth and the max depth of the borehole was 180 m. The screen pipe placing rate of the borehole protection trial was 83.7%, axial dragging distance of the fixed suspended device at the bottom of the borehole was 2 ~ 3 m, the effective borehole protection rate of the screen pipe was 89% after 135 days and the screen pipe borehole protection technique could protect the screen pipe placing depth and the borehole protection effect. The average rock penetration rate of the enhanced model three wings open and close type drilling bit was 51 m and the drilling bit structure was stable and could effectively improve the rock penetration depth of the borehole. In a same borehole deep drilling, the effectiv e seam borehole section (coal and rock ratio) and the gas drainage effect would have no correlation and the borehole depth and the screen pipe effective borehole prot ection rate would be the main factors affected to the gas drainage.