Study on dynamic wear law of PDC bit under temperature effect

Abstract

Accurate prediction of the PDC bit wear trend and life is of great significance for improving oil and gas drilling efficiency and reducing oil and gas production costs. However, due to the combination of high temperature and load, the interaction between cutter wear, force, and body temperature changes dynamically in real-time, making it a challenge to accurately predict the life of bit cutters. This paper aims to explore the dynamic wear law of the PDC bit under temperature effect. Firstly, the PDC cutter wear experiment under the temperature effect is studied, and the microstructure and phase changes after exposure to high temperature are characterized. Then, the PDC cutter mathematic models of volume wear, line wear, cutting force, and cutter temperature rise are constructed. Finally, the dynamic wear law of the PDC bit is studied by numerical simulation. The results show that when the rake angle is 12.86°, it has better wear resistance and longer drilling footage. Increasing the footage per turn of the PDC bit aids in lowering the wear degree within the permitted range of weight-on-bit (WOB). With each increase in drillable grade, the depth of drilling achieved by PDC bits at the same wear height decreases by more than 50%. The final wear height of the PDC bit cutter considering the temperature effect is about twice that without considering the thermal effect. The numerical calculation method proposed in this paper can calculate parameters such as dynamic force change, dynamic temperature change and dynamic wear height of PDC bit during drilling, and has the advantages of fast calculation speed and diversified analysis types. The research results provide a theoretical basis and support for the life prediction of worn PDC bits.