Dynamic analysis of sonic vibration drilling string with the sampling tool

Abstract

Sonic vibration sampling technology is widely used due to its high sample fidelity, low disturbance to the stratum and environmental protection. The influence of the diameter variation of sonic drill string caused by the sampling tube on the axial vibration of the system is still unclear, which restricts the improvement of coring efficiency. In this study, an axial vibration model of a sonic drilling string with a sampling tool is established, which takes into account the section variation. Adopting numerical simulations, the influence of the drill string on the vibration characteristics of the system, the relationship between the excitation and the amplitude of the sampling bit, and the effect of the cross-sectional area on the bearing capacity of the drill string with the sampling tube are obtained. With the longer the sampling tube and the thicker the wall thickness, the lower the inherent frequency and the higher the bearing capacity. The results show that the discontinuity of the drill string section caused by the sampling tube inevitably affects the natural frequency and response of the drill string system. The model can provide a theoretical basis for the research of sonic vibration sampling engineering. Properly balancing parameters can improve drilling and sampling performance.

Keywords

• Sonic drilling
• Drilling sampling
• Variable cross-section
• Resonance vibration