Development of a Smart Polycrystalline Diamond Compact Cutter Featuring In-Situ Temperature and Stress Sensing

Summary

Intelligent drilling and completion systems have become the critical frontier in modern oil and gas engineering, and intelligent drill bits represent a key research direction. However, acquiring high-fidelity, real-time operational data at the microscopic cutting level remains a significant engineering challenge. To address downhole sensing limitations, a first-of-its-kind polycrystalline diamond compact (PDC) smart cutter (SCutter), integrating two temperature sensors and a preloaded lead zirconate titanate (PZT) piezoelectric force-sensing element, was developed. The external cutting force acting on the cutting face generates a time-varying internal stress field within the cutter body. The resultant compressive force produced by this internal stress field on the PZT interface is converted into an electrical response, thereby enabling the SCutter to sense internal stress variations and estimate the external cutting force through whole-cutter calibration. The PZT element has a calculated maximum axial compressive load capacity of 13.62 kN. In the dynamic internal stress sensing experiment, signals were acquired at 50 Hz, and the SCutter voltage response yielded a Pearson correlation coefficient of r=0.943 with the resultant voltage response of an external triaxial force sensor. The mean relative tracking error between the SCutter response and the scaled resultant response of the external triaxial force sensor across five cutting depths was 8.39%. These results confirm that the SCutter voltage response induced by internal stress is highly consistent with the external reference response in terms of time-domain characteristics, load envelopes, and variation trends. This pioneering study breaks conventional measurement limitations, providing a fundamental in-situ data foundation for PDC cutter online health evaluation, formation lithology identification, and closed-loop control of intelligent drilling systems.