Disturbance study of seismic vibrator reaction mass and piston.

Abstract

The seismic vibrator has become a main energy source for land seismic exploration. For a seismic vibrator, a piston is installed in the vertical direction in the reaction mass, and the reaction mass moves up and down along the piston. Because of vibrator dynamic disturbances in the reaction mass and baseplate system, the vibrator output force is contaminated by harmonic distortion. This distorted output force results in poor quality of seismic data. This paper studies the dynamics and disturbances of the piston as well as the reaction mass. The results show that the reaction mass disturbance is mainly caused by the horizontal oil flow inlet going to the reaction mass chamber. Precisely speaking, the ideal vertical motion of the reaction mass is disturbed by a combination of a reaction mass rotational motion along the piston and a bending motion of the piston. Changing the oil flow inlet from the horizontal direction to the vertical direction significantly reduces these disturbances. In the disturbance test of the vertical oil flow inlet, the disturbance of the reaction mass in XOZ and YOZ is reduced by 73.943% and 54.232%, respectively, and the disturbance of the vibrator is obviously weakened. The motion of the reaction mass is close to the ideal vertical direction. This change of the oil flow inlet direction further improves the accuracy and reliability of the vibrator output force.