以顺煤层超长定向钻孔组覆盖整个工作面,对矿井大盘区瓦斯进行采前预抽是区域瓦斯治理的新模式.从大盘区瓦斯抽采顺煤层超长定向钻孔施工工艺出发,介绍了顺煤层超长定向钻孔成孔的几大关键技术,包括钻孔递进式轨迹延伸技术、复合钻进轨迹控制技术、水力加压减阻钻进技术、正反扭转减阻钻进技术及复合侧钻分支技术等.还介绍了顺煤层超长定向钻孔施工的主要配套装备,包括ZDY15000LD大功率定向钻机、BLY460/13泥浆泵车、YHD3-3000泥浆脉冲测量系统、无缆大通孔钻杆、水力加压螺杆马达等.利用该技术与装备在保德矿二盘区进行了工程示范应用,应用结果表明,该套工艺技术与装备具备施工长度超过3300 m顺煤层超长定向钻孔能力.最后对瓦斯抽采效果进行了分析,结果显示超长定向钻孔抽采周期长,抽采量高,可以对大盘区瓦斯进行超前综合治理.

The gas control in large panel of underground coal mine objectively requires the length of ultra-long directional drilling along the coal seam to reach more than 3 000 m, however, restricted by the current directional drilling technology and equipment in underground coal mine, the maximum hole depth of directional sliding drilling along coal seam is less than 2 000 m. This paper starts from the point of view of directional drilling technology, the influencing factors of drilling resistance in sliding drilling process of ultra-long directional drilling are analyzed, and on the basis of theoretical analysis and statistics of actual drilling data, the variation law of sliding drilling resistance with hole depth is revealed, it concluded that the friction resistance between the drilling tool and the hole wall increases with the increase of the hole depth, which is the fundamental reason that restricts the drilling depth, based on this, the hydraulic pressure drag reduction drilling technology and the forward and reverse torsional drag reduction drilling technology are developed, it starts from improving the stress state of bottom hole drilling tool and replacing sliding friction with rolling friction, effectively alleviate the problem of supporting pressure of drilling tools in ultra-long directional drilling, the field application was carried out in the 81210 working face of the second plate area of Baode Coal Mine, the test results show that the slow linear growth zone of drilling resistance is improved from less than 1 000 m to less than 1 500 m by hydraulic pressure drilling, the forward and reverse torsional drilling reduced the sliding drilling pressure by 2 MPa to 4 MPa after 2 000 m, using a combination of hydraulic pressure and positive and reverse torsional drilling techniques, directional sliding drilling was successfully achieved to a depth of 2 700 m, effectively improve the control precision of ultra-long directional drilling trajectory and drilling length, and provided technical support for gas extraction in large panel.

煤矿井下超长孔定向钻进中孔内摩阻是限制其成孔率及成孔效率的主要因素,为适应大盘区瓦斯抽采模式的客观需求,研究实钻过程中摩阻及其影响规律.为顺煤层超长定向钻孔复合钻进减摩阻工艺参数选取提供依据,对煤矿井下顺煤层近水平复合钻进工况下钻柱的钻具运动特性及受力状态进行分析.通过一定的条件假设,建立复合钻进轴向摩擦阻力和旋转摩擦扭矩力学模型,通过数值计算,针对常用?89 mm定向钻具组合,在不同孔深及钻进工艺参数匹配下的摩阻规律特性进行分析.结果表明:机械钻速、钻具转速、钻孔深度是滑动摩擦阻力和旋转摩擦扭矩的主控影响因素,与超长定向钻孔实钻参数统计分析对比,推进阻力和旋转扭矩变化规律与模型计算结果吻合,该结果对于指导近水平钻孔复合定向钻进工艺参数选取、钻进工况判断具有重要的现实意义,同时,对于煤矿井下自动化、智能化定向钻进控制系统设计开发具有借鉴意义.

Aiming at the problems such as low efficiency and depth limit of directional drilling caused by the support pressure of drilling tools in the directional drilling of ultra-deep hole in underground coal mine, learning from the twist drilling technology in oil drilling, this paper analyzes the technological principle, the adaptability and operation feasibility of directional drilling in underground coal mine, describes its specific operation flow, and carries out field test in 5th area of Baode Coal Mine. The test results show that the resistance reduction technology of torsional pendulum drilling is applicable to directional ultra-deep hole drilling in underground coal mine, and the applicable range is 2 000 m to 3 000 m for directional ultra-deep hole drilling. The drag reduction effect is obvious in the process of solid drilling, and the change range of tool surface at hole bottom is small, which is mainly affected by the reverse torque of screw motor.

In view of the problems such as high resistance, low efficiency and limited drilling depth during the sliding directional drilling under the condition of deep hole, this paper studies and forms the drag reduction technology of sliding drilling, including hydraulic pressure drilling technology and positive and negative twist drilling technology. This technology has been applied to complete a 3 353 m ultra-long directional drilling along coal seam in Baode Coal Mine. Analysis of drilling parameters shows that the technology has obvious drag reduction effect of sliding drilling, which has great significance to improve the drilling capacity, drilling efficiency and drilling trajectory control accuracy of ultra-long directional drilling in coal mine.

针对现有煤矿井下定向钻进技术与装备在钻进3000 m以上顺煤层超长距定向孔中存在的不足,提出采用ZDY15000LD大功率定向钻机和BLY460高压泥浆泵车提高装备钻进能力,通过优化钻进系统冲洗液管路和研制大通孔钻具以降低冲洗液水路压耗,合理设置泥浆脉冲无线随钻测量系统运行参数以提高超长孔工况下信号传输稳定性,利用井下冲洗液净化循环系统实现定向钻进冲洗液循环利用.创新开发了滑动钻进减阻技术、复合钻进倾角控制技术和复合钻进侧钻分支技术等超长定向孔钻进关键技术.结合神东煤炭集团保德煤矿大盘区煤层瓦斯大区域超前治理需要开展3000 m以上顺煤层超长距定向孔钻进的工程实践,创造了主孔深度3353 m的顺煤层超长贯通定向孔深度记录,实践结果表明:超长距定向孔钻进装备系统有效提高了煤矿井下深孔钻进能力,降低了钻进过程中泥浆泵压力,实现了超长孔工况下信号稳定传输,减少了定向钻进时清水用量和污水排放量;开发的超长距定向孔钻进关键技术降低了滑动定向钻进阻力,提高了滑动定向钻进深度、钻进效率和复合钻进应用比例,解决了超长孔内侧钻分支孔的难题.

针对超长工作面瓦斯区域超前治理需要,分析了施工顺煤层超长定向钻孔对关键钻进装备的技术要求,总结对比了国内外几款典型的顺煤层超长孔定向钻进关键装备性能特点.结合保德煤矿超长工作面生产需要,优选钻进装备在保德煤矿二盘区开展了工程实践,完成了3个孔径120mm、 孔深2000m以上的顺煤层超长定向钻孔,其中最大孔深达到2570m,创造了煤矿井下顺煤层定向钻孔深度的新纪录.结合钻进工艺参数及测量数据,分析了关键装备的应用效果和局限性,对进一步提高顺煤层超长定向钻孔装备能力进行了展望.

为进一步验证顶板高位大直径定向钻孔对复杂地层的适应性及其抽采效果,在淮南矿业集团顾桥矿南区进行了工业性应用试验.针对顾桥矿南区1212(3)工作面顶板局部岩层破碎、负角度延伸、断层发育等复杂情况,采取大角度穿层、扩孔及使用无线随钻测量等工艺技术,顺利完成全部7个孔深500 m以上、孔径153 mm的大直径顶板定向钻孔.试验结果表明,通过采取针对性的工艺方法,顶板高位大直径定向钻孔能在各种复杂地层中顺利钻进,可以进行工业化推广.

In order to further increase directional borehole depth along coal seam and improve drilling efficiency of ultra-long directional borehole, influencing factors of weight on bit(WOB) transmission of ultra-long directional borehole along coal seam were analyzed, including borehole trajectory, borehole depth, sediment in borehole and drilling strata. Based on engineering background of 2 570 m ultra-long directional borehole along coal seam in Baode Coal Mine, law of WOB transmission under compound directional drilling was researched. The research results show that with the increase of borehole depth, feed pressure of sliding directional drilling increases exponentially, and finally reaches rated feed pressure of drilling rig, which leads to decrease of transmission efficiency of WOB. Under condition of compound drilling, feed pressure of compound drilling keeps at a low level with the increase of borehole depth, which is far lower than rated feed pressure of drilling rig. Rotary pressure of drilling rig almost increases linearly with the increase of borehole depth, but it is lower than rated rotary pressure of drilling rig, which leads to high transmission efficiency of WOB. The higher the pump pressure and pump volume of mud pump are, the higher the slag discharge efficiency is, the lower the friction resistance of drilling tool is, and the higher the transmission efficiency of WOB is. Conversely, the lower the transmission efficiency of WOB is.

针对顾桥煤矿顶板地层条件复杂,高位定向钻孔难以有效成孔的问题,开展了顾桥煤矿顶板复杂地层中高位定向钻孔成孔试验.根据煤层顶板地层实际情况,制定了注浆加固易碎地层、扩大易碎地层孔段钻孔直径、增大易碎地层孔段钻孔倾角和选用大弯角螺杆马达等具体技术措施,成功在顾桥煤矿施工了7个孔深超过500 m、孔径Φ153 mm的顶板高位大直径定向钻孔,为高位定向钻孔在顾桥煤矿及类似条件矿区推广应用提供了技术保障.