深井/超深井双作用强侧切开窗钻头研究

针对深井/超深井套管开窗侧钻中套管壁厚且强度高、岩石可钻性差、钻头切削齿极易先期钝化导致的开窗效率低/开窗失败的问题，创新性地设计了一种双作用强侧切开窗钻头。设计中考虑了开窗钻头钻进的稳定性及载荷分布的均匀性，钻头冠部设计为内锥双圆弧面和柱面，采用"等切削、等功率与等磨损"布齿理念和"螺旋高低交错"布齿规律，既能满足高效侧切金属又能快速切削岩石的设计目标；通过专有加工工艺技术的研究，完成了该新型开窗钻头的加工制造，并进行了现场应用。现场实际应用结果表明，与传统磨铣式铣锥开窗相比，研制的双作用强侧切开窗钻头由于采用了优化的布齿设计，钻头轮廓剖面扁平、切削面较短、横纵比较小，在窗口处有较强侧切力，切削套管产生的铁屑为大片状，效率提高了2.6倍以上，节省了窗口形成的施工时间和施工成本，能很好地适应深井/超深井硬地层的开窗侧钻作业。

Research on a Strong Double-action Lateral-cutting Drill Bit for Forming Windows in Deep/Ultra-deep Wells

In view of the low window-opening rates/failures in window-opening caused by the thick and strong casings used in deep/ultra-deep wells, poor formation drillability, and the tendency of cutters to wear out prematurely, we have innovatively designed a strong double-action lateral-cutting drill bit for forming windows. In this design, we considered the stability of the drill bit during the window-opening drilling and the uniformity of load distribution. The crown of the drill bit was thus designed with a depressed cone-double-arc surface and a columnar surface. The design was based on the concept of having " equal cutting, power and wear" in the cutters, and a layout with cutters arranged in a spiral and vertically staggered pattern; the resulting drill bit is capable of cutting laterally through metals in a highly effective manner and drilling through rock at high speeds. The processing and fabrication of this novel window-opening drill bit were completed via research on proprietary processing techniques, and field tests on this drill bit have also been performed. The results of these tests have shown that the novel drill bit developed in this work has 2.6 times the window-opening efficiency of conventional grinder-type milling cones for window-opening, due to its optimized cutter layout, flat contour profile, shorter cutting surface, lower aspect ratio, stronger lateral cutting forces at the window, and the fact that it produces large sheet-shaped iron shavings when it cuts through the tubular casings of a wellbore. Hence, the use of this novel drill bit reduces the time required to open windows as well as the associated costs, and this drill bit is highly suitable for window-opening and lateral drilling operations in the hard strata of deep/ultra-deep wells.