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

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.