硬地层PDC钻头切削齿尺寸及后倾角优化设计

摘要

PDC bit,a rock-breaking tool,has been widely used in the oil drilling industry. While its result in hard formation is not good,the drilling efficiency is low and the working life is short. PDC cutter size and back rake are the very important design parameters affecting the performance of PDC bit. Considering the cutter design of PDC bit in hard formation and using the cutting depth as the index to reflect the cutting efficiency, the effects of PDC cutter size and back rake on the ROP of PDC bit were investigated through the micro-bit drilling experiment. The results showed that in hard formation with drillability higher than Ⅵ level,the larger the cutting teeth size,the lower rock-breaking efficiency. In the rock with drillability in Ⅵ - Ⅶ ,the PDC bit designed with 13. 44 mm cutter has the best cutting efficiency and the best back rake is 15°.%PDC钻头是目前石油钻井中使用较为广泛的一种破岩工具,但其在硬地层中的使用效果不佳,钻进效率低,使用寿命短.PDC钻头的切削齿尺寸、后倾角等是影响其钻进性能的重要参数,通过室内微钻头试验,综合考虑硬地层PDC钻头布齿设计中切削齿的重叠和覆盖情况,以相同钻压下微钻头在岩样表面旋转一周的切削深度作为评价其破岩效率的指标,分析了切削齿尺寸、后倾角等对硬地层PDC钻头破岩效率的影响.结果表明:在钻进可钻性超过Ⅵ级的硬地层时,切削齿尺寸越大,其破岩效率越低；钻进可钻性为Ⅵ—Ⅶ级的硬地层时,(o)13.44 mm切削齿的破岩效率最高,其最佳后倾角为15°.