On the generation of low frequencies with modern seismic vibrators

Abstract

Acquiring low-frequency seismic data using Vibroseis techniques has gained attention in recent years. Successful application of low-frequency Vibroseis acquisition requires evaluating each element of the data acquisition system and ensuring that each part of the system contributes to the success of the method. We focus on generating low frequencies with Vibroseis sources rather than recording and preserving them. To generate the low-frequency signals using seismic vibrators, it is better to know (1) the hydraulic and mechanical system of the vibrator; (2) the design of a low-frequency sweep that can deliver the vibrator ground force maximally; and (3) the vibrator control system that can minimize the harmonic distortion of the vibrator ground force output at low frequencies. Field tests show that hydraulic pump flow is not a limiting factor for the generation of the low frequencies for most modern seismic vibrators. In addition, with harmonic distortion reduction control, the vibrator performance at low frequencies is improved.