非平面三棱形PDC齿破岩机理研究与现场试验

Study on Rock Breaking Mechanism and Field Test of Triangular Prismatic PDC Cutters

刘建华 令文学 王恒

LIU Jianhua LING Wenxue WANG Heng

中国石化石油工程技术研究院，北京 102206

Sinopec Research Institute of Petroleum Engineering, Beijing, 102206, China

非平面三棱齿的破岩机理不清晰，导致三棱齿PDC钻头达不到预期的破岩效果。为此，采用有限元法对非平面三棱齿进行数值模拟分析，分析破岩过程中的各项切削力的变化规律，研究其破岩机理。数值模拟和刮切试验结果表明，三棱齿与平面PDC齿在破岩过程中的岩石受力状态存在明显的差异，相同条件下三棱齿切削破碎砂岩时的切向力及切向力的波动幅度均小于常规平面齿。三棱齿PDC钻头现场试验表明，其在研磨性高、冲击性强地层中的破岩效率较高，抗冲击性能较好。研究表明，三棱齿主要通过拉剪作用破坏岩石，切向力和扭矩更小，抗冲击性和耐磨性更高，能够提高破岩效率、延长钻头使用寿命。

The lack of clarity over the rock breaking mechanism of triangular prismatic cutters hinders their effective applications. In view of this, the finite element method was employed to conduct a numerical simulation analysis of triangular prismatic cutters in this study with the aim of clarifying the change rules of various cutter force during rock breaking and revealing the rock breaking mechanism. The results of numerical simulation and scraping experiments suggested that triangular prismatic cutters and planar PDC (polycrystalline diamond compact) cutters demonstrated a distinct difference in the stress on the rocks during breaking. The tangential force and its fluctuation were smaller when a triangular prismatic cutter was used to break sandstone as compared with a conventional planar cutter under the same conditions. The field test of the PDC bit with the triangular prismatic cutters proved a high efficiency in rock breaking and impact resistance in strata with high abrasiveness and strong impact. This study demonstrates that breaking rocks using tension and shear, triangular prismatic cutters can make the tangential force and torque smaller and the impact resistance and abrasion resistance higher. In that way they can enhance the rock breaking efficiency and prolong the service life of bits.

国家科技重大专项“海相碳酸盐岩超深油气井关键工程技术”（编号：2017ZX05005-005）和中国石化重大科技项目“特深层油气勘探开发工程关键技术与装备”（编号：P17049）资助

https://doi.org/10.11911/syztjs.2021040