气举反循环钻进技术在煤矿瓦斯抽排井中的应用

针对大直径工程井施工,采用正循环先导孔钻进,分级扩孔成井方法,井壁与钻具环状间隙大,泥浆上返速度低,排渣困难,岩悬屑重复破碎,钻头泥包严重,钻进(扩孔)效率低及护壁对泥浆性能要求高,泥浆维护成本大等问题,研究了一套大直径工程井气举反循环钻进工艺及配套钻具。通过工程实例,介绍了大直径气举反循环钻具、机具配套、钻进工艺等。同一项目中的对比试验表明,利用气举反循环工艺与常规正循环工艺进行的机械钻速提高74.3%,碎岩效率提高了2.56倍,井身质量得到保证,为今后大直径工程井高效、低耗、安全施工提供了经验。

Application of Air-lift Reverse Circulation Drilling Technology in Coalmine Gas Drainage Wells

In allusion to large diameter engineering well construction, using normal circulation pilot borehole drilling, graded reaming well completion have problems of annular space belween wall and drilling tools will be large, mud return velocity low, difficuh to re- move debris, hangiug rock cuttings repeatedly crashing, bit bailing in serious condition, drilling （reaming） inefficiency, wall protection requires high nand perfornmnce, and mud maintenance eost high, thus have developed a set uf large diameter engineering well air-lift reverse circulation drilling technology, and matching drilling tools. Through project cases, introduced large diameter air-lift reverse cir- culation drilling tools, equipment matching and drilling technology etc. Comparative trials in same project have shown that compared to the conventional, normal circulation technology, the penetration rate of air-lift reverse eirculation drilling technology has improved 74.3%, rock breaking efficiency increased 2.56 times, well quality ensured as well. Thus the practices provided experiences for large di- ameter engineering well high efficiency, low consumption and safe construction henceforth.