The vibration harmonic response analysis of drillstring in compound drilling

Abstract

The harmonic response analysis model of drillstring is established to improve borehole quality. The harmonic response laws of drillstring is discussed. Harmonic response analysis is made intensively for longitudinal vibration, including non-failure case and failure case. Position of the maximum response displacement of drillstring and the maximum response stress at corresponding position are obtained through harmonic response analysis. Absorber control measure is simulated to lower vibration amplitude of drillstring. New suggestions are put forward from the view of controlling drillstring vibration by comparing and classifying features of vibration control measures comprehensively. In course of designing drilling parameter, it is required to avoid or reduce drillstring resonance under low-order inherent frequency as much as possible and adopt targeted comprehensive control measures timely. The research result is of much significance to improve wellbore quality.