由河南省煤田地质局自主研发的Φ219.1/168.3 mm大口径气举反循环钻具已成功应用于大直径工程井钻井施工,并取得了较好的经济效益.但该套钻具样品在生产试验时出现的一些如气道短路、漏浆漏气及岩心堵塞等常见问题.通过反复试验研究,有针对性地采取了在结构设计时,将内管接箍上端面与外管下端面之间间隙由原来8 mm缩小到1 mm以内,在加工工艺上,分别从材质、硬度、表面光洁度等方面对螺纹部分进行耐磨处理;在原来的连接座基础上增加一道防线,将空气盒中的压缩空气通过迷宫形式的特殊通道引入到钻井液密封区;对取心牙轮钻头,割心楔块材质选择硬度高、耐磨性好的材料,对PDC钻头,严格控制进入钻头排渣口岩屑粒径等一系列改进对策.改进后的一批钻具在新密和成煤矿瓦斯抽排井施工现场得到成功应用,运行效果良好,故障率大幅降低,纯钻时间得以延长,取得了非常好的经济效益.%The Henan Bureau of Coal Geological Exploration has independently developedΦ219.1/168.3mm large diameter air-lift re-verse circulation drilling tools and successfully used in large diameter engineering well operations and got better economic effects. But during the production tests some common problems of the drilling tool set samples have been happened such as airway short circuit, leakage of slurry and air, as well as core plugging etc. Through repeated experimental researches, pertinently shortened the clearance between internal pipe coupling upper end face and outer pipe lower end face from original 8mm to within 1mm during structural design;and on processing techniques, from aspects of material quality, hardness, and surface finish, respectively carried out a series of improv-ing measures including anti-wear treatment for threaded portion;on original connecting seat a new defensive line added, thus taking compressed air from air box through a labyrinth typed special channel into drilling fluid sealed zone;for coring roller bit and core cut-ting wedge selected higher hardness, better wear resistance material, for PDC bit, strictly controlled the rock fragment size through bit reject nozzle etc. A mass of improved drilling tools have been successively applied in Xinmi Hecheng coalmine gas drainage well con-struction site, the effect is excellent, failure rate greatly reduced, net drilling time extended, very good economic effect achieved.
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