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<p>To further explore and improve the high-efficiency rock-breaking mechanism of rotary-impact drilling technology, this paper first innovatively carried out a rock drillability experiment with the micro PDC bit under static and harmonic dynamic loads and then performed scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses on the PDC cutter. A systematic study was conducted on the rock drillability, drilling efficiency and PDC bit abrasion under seven different load combinations. Subsequently, the numerical simulation calibration of mechanical property parameters of red sandstone and yellow sandstone was performed. Finally, a 3D numerical modeling, similar to the indoor experiment, is proposed to investigate the mechanism of rock breaking and rate of penetration (ROP) improvement under harmonic dynamic loading from the perspectives of the bit drilling displacement, rock damage and stress field, rock breaking specific work, average cutting force and stress field of PDC cutter. Based on the analysis undertaken, it can be concluded that the rock breaking efficiency is improved by the combined impact of static and dynamic loads on the basis of static load, while dynamic load alone plays a negative effect. Within the experimental range, the ROP of sandstones grows up to 211.18% and reduces up to 80.41%. The influence of dynamic load on the ROP of hard sandstone is higher than that of soft sandstone. On the premise of constant static load, both the frequency and amplitude of harmonic dynamic load are conducive to promoting rock damage, reducing the specific energy of rock breaking, facilitating rock fragmentation and not aggravating the fluctuation of cutting force as well. It also can be observed that under the combined loads, the range and degree of stress concentration on the PDC cutter surface are increased. The abrasion of PDC cutter in terms of material and structure, accompanied by the adhesion of rock components, resulting in a sharp performance degradation and rapid failure.</p>

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Experiment and Numerical Simulation of Rock Breaking by Micro PDC Drill Bit under Harmonic Dynamic Loading

  • 期刊论文

  • 发表日期：

    2025年8月11日

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  • Siqi Li,
  • Siqi Wang,
  • Zhuolun Li,
  • Yingcao Zhou,
  • Shaoyong Gao,
  • Wei Li

摘要

To further explore and improve the high-efficiency rock-breaking mechanism of rotary-impact drilling technology, this paper first innovatively carried out a rock drillability experiment with the micro PDC bit under static and harmonic dynamic loads and then performed scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses on the PDC cutter. A systematic study was conducted on the rock drillability, drilling efficiency and PDC bit abrasion under seven different load combinations. Subsequently, the numerical simulation calibration of mechanical property parameters of red sandstone and yellow sandstone was performed. Finally, a 3D numerical modeling, similar to the indoor experiment, is proposed to investigate the mechanism of rock breaking and rate of penetration (ROP) improvement under harmonic dynamic loading from the perspectives of the bit drilling displacement, rock damage and stress field, rock breaking specific work, average cutting force and stress field of PDC cutter. Based on the analysis undertaken, it can be concluded that the rock breaking efficiency is improved by the combined impact of static and dynamic loads on the basis of static load, while dynamic load alone plays a negative effect. Within the experimental range, the ROP of sandstones grows up to 211.18% and reduces up to 80.41%. The influence of dynamic load on the ROP of hard sandstone is higher than that of soft sandstone. On the premise of constant static load, both the frequency and amplitude of harmonic dynamic load are conducive to promoting rock damage, reducing the specific energy of rock breaking, facilitating rock fragmentation and not aggravating the fluctuation of cutting force as well. It also can be observed that under the combined loads, the range and degree of stress concentration on the PDC cutter surface are increased. The abrasion of PDC cutter in terms of material and structure, accompanied by the adhesion of rock components, resulting in a sharp performance degradation and rapid failure.