Evaluation of the vibration accelerations of drill bit for the well rotative-vibration drilling using the cavitation hydrovibrator

Abstract

Cavitation hydrovibrator is one of the promising devices to intensify drilling of geological prospecting and production wells. Cavitation hydrovibrator transforms the stationary flow of drilling mud into a discrete-pulsed flow of increased power. The mud oscillating flow in hydrovibrator is converted into high-frequency (1,000 Hz - 20,000 Hz) vibrations of the drill bit. A method for determining the longitudinal vibrations of a drill string with bit has been developed. The method is based on the results of experimental studies of the dynamic interaction between longitudinal oscillations of the drilling string with rock massive by mathematical modeling this process with use of finite-element discretisation of drilling string. An obtained satisfactory convergence of the computed vibration accelerations of the drill bit and experimental data confirms the adequacy of the developed mathematical model and the ability with its help to determine the rational operational modes of the hydrovibrator.