Research and Field Test of High Specific Pressure Wide-Edge Cutter Bit for ROP Increase

To address the problems of difficulty in penetrating the stratum and low rate of penetration (ROP) encountered by conventional PDC drill bits in deep drilling, a design of a high specific pressure wide-edge cutter bit was proposed. A specific pressure distribution theory for a new type of PDC bits was developed. Through finite element simulation with laboratory rock-breaking experiments, the advantages of a wide-edge cutter in rock breaking were verified: The distribution of the specific weight on bit (WOB) of the wide-edge cutter was more uniform, and the single cutter’s penetration depth was significantly better than that of a conventional cutter, with a wider crushing zone. When drilling into the sandstone stratum, at a rotary speed of 30 r/min and a WOB of 200–500 N, the ROP of the wide-edge cutter was 1.46 times that of the conventional cutter. At a WOB of 600 N, the increase in rotary speed resulted in an increase amplitude of 179% in ROP(compared to 104% for the conventional cutter). When drilling into the limestone stratum, the wide-edge cutter achieved an ROP that was 154% higher than that of the conventional cutter (with a WOB of 1 600 N) at a lower WOB (1 100 N), and the stick-slip vibration intensity was lower. When drilling the strata of Wutonggou Formation with a wide-edge cutter bit in a well, the ROP reached 12.38 m/h, which was 19.34 times that of the conventional cutter bit, significantly improving the ROP. Research shows that the wide-edge cutter bit, by optimizing the distribution of specific pressure and the cutter shape design, has higher rock-breaking efficiency and potential for speed improvement in deep plastic rock strata, providing an effective solution to the problems of deep drilling.