Harmonic distortion reduction on seismic vibrators

Abstract

To improve seismic resolution using vibroseis, vibrators must output the ground-force energy with minimum harmonic distortion. Four main sources within the vibrator system cause the ground force to suffer severe harmonic distortion: the nonlinear servo-valve flow-pressure character-istics, the servo-valve characteristics near null, the fluctuations in the hydraulic pressure, and the nonlinear contact-stiffness between the baseplate and the ground. Modeling was undertaken to investigate and quantify harmonic distortion from each source. As a result, three modifications have been made to reduce the harmonic distortion of the ground force: