Development and Application of Polycrystalline Diamond Compact-Roller Hybrid Bit with Independent Buffer Structure

This is the authors' abstract. We don't add key points for this paper.

Summary Improving the operational stability of underground drill bits is essential to preventing premature cutter impact damage and extending drill-bit lifespan. The polygonal effect, resulting from the discontinuous circumferential arrangement of cutting structures with a certain separation between them, is a key factor in drill-bit instability. To address this, we developed a novel polycrystalline diamond compact (PDC)-roller hybrid drill bit featuring an independent buffering structure, based on impact failure analysis. Designed for the fourth section of the Xujiahe Formation in directional drilling and tailored to the geological and drilling requirements of the φ215.9-mm well section, the hybrid drill bit was manufactured, tested in full-scale laboratory experiments, and deployed in the Xujiahe Formation. The results show that the independent buffer structure, with buffer blades positioned between the roller and fixed cutting structures, effectively mitigates the polygonal effect and enhances PDC cutter protection. The hybrid bit exhibits minimal fluctuations in weight on bit (WOB) and torque, reducing torque to one-fifth of that in PDC bits. Field tests achieved a single-run footage of 112 m, a 366.7% increase over conventional PDC bits, and a 48.8% improvement in rate of penetration (ROP). The tool face remained stable during directional drilling, with no ring-out or bearing failure observed post-operation. Significant wear on the independent blade teeth confirmed its ability to absorb and reduce impact forces, underscoring its role in stabilizing the drill bit. This design provides valuable insights for enhancing drill-bit performance in complex formations and structurally challenging wells.