水力割刀切割失效实例分析及硬质合金刀头选型优化

Analysis on cutting failure case of hydraulic cutter and optimization of cemented carbide cutter-bit

摘要:

岩心钻探工程中，套管护壁技术能保障孔壁稳定，但竣工后因地层遇水膨胀、岩石剥落等问题，常导致套管无法起拔，造成资源浪费与经济损失。水力割刀作为套管回收与孔内事故处理的核心工具，其切割效能取决于硬质合金刀头性能与加工件的匹配度及工况适应性。本文结合山东莱芜夹钻事故处理以及广西百色套管起拔两个现场实际案例，通过对比YG类、YT类、YW类硬质合金刀头的切割效果，系统分析刀头性能与锰钢钻杆、常规套管的匹配规律。同时，结合切割过程中刀头崩刃、铁屑卡滞等失效现象及对应实物，分析了刀头材质选型偏差、出刀速度控制不当、刀头修磨状态不合理三大失效原因。本研究提出以YW2（适配锰钢钻杆）、YT5（适配高强度套管）硬质合金刀头为优先选型的方案，并展望立方氮化硼（CBN）刀头的应用前景。本研究可以为水力割刀刀头科学选型与切割工艺优化提供实践依据，并且对提升钻探工程管材回收率具有重要指导意义。

Abstract:

In core drilling projects， casing wall protection technology can ensure the stability of the hole wall. However， after completion， due to problems such as water expansion of the stratum and rock spalling， the casing often cannot be pulled out， resulting in resource waste and economic losses. As a core tool for casing recovery and in-hole accident handling， the cutting efficiency of the hydraulic cutter depends on the matching degree between the performance of the carbide cutter-bit and workpieces as well as its adaptability to working conditions. Combined with two field cases， namely the stuck-drilling accident treatment in Laiwu of Shandong and casing pulling operation in Baise of Guangxi， this paper systematically investigates the matching rules between cutter-bit properties and manganese-steel drill pipes as well as conventional casings by comparing cutting performance of YG-series， YT-series and YW-series cemented carbide bits. In view of typical failure modes including bit chipping and iron-chip jamming observed on actual failed components， three primary failure causes are summarized， that is improper material selection of cutter-bits， inappropriate cutter extending speed， and unreasonable cutter grinding status. YW2 for manganese-steel drill pipes and YT5 for high-strength casings are proposed as the priority selection schemes. The application prospect of cubic boron nitride （CBN） bits is also discussed. This study provides practical references for rational bit selection and cutting-process optimization of hydraulic cutters， and possesses important guiding significance for improving pipe recovery rate in drilling engineering.