Enhancing the low-frequency amplitude of ground force from a seismic vibrator through reduction of harmonic distortion

ABSTRACT Extending the vibroseis bandwidth toward low frequencies (below 10 Hz) can bring many benefits for land seismic exploration such as deeper signal penetration and for near-surface inversion techniques. Due to physical limitations in vibrator mechanical and hydraulic systems, the ground force output from a vibrator at low frequencies is limited. This limited ground force output is severely distorted by harmonic distortion such that the ground force in fundamental frequencies is reduced. We focused on reducing harmonic distortion through vibrator control algorithms to improve vibrator performance at low frequencies. The purpose was to show that with only vibrator control algorithms, the fundamental ground force from a vibrator can be noticeably improved at low frequencies. In addition, we demonstrated a synthetic case using the weighted-sum ground force to simulate slip-sweep acquisition. Presumably, reducing source generated harmonic distortion can help decrease the slip time in slip-sweep operations thereby increasing productivity rates.