Optimization of the Vibroseis to Enhance Signal-to-Noise Ratio for Seismic Exploration

Vibroseis has evolved into an important technology in the field of terrestrial seismic exploration. The output energy of a vibrator determines the depth of seismic exploration and the signal-to-noise ratio of the collected signals. Enhancing the source’s output energy is of significant importance for improving the quality of seismic exploration data. This research designed a method of controlling the vibrator using orthogonal frequency division multiplexing (OFDM) signals. This method replaces the widely used linear frequency modulation (LFM) signals with mixed-frequency signals that have a richer frequency composition, thereby increasing the total output power by expanding the vibrator’s instantaneous bandwidth. At the receiver, this article proposes a spectral reshaping method, compressing the OFDM signal into the baseband frequency band, concentrating multiband energy, and improving data quality. Modulation signals with different carriers were used in gradient voltage vibration experiments. The results show that, compared to LFM signals, vibrators using this method exhibit higher average power and effectively reduce harmonic distortion. The effective output power of the vibroseis has increased by more than 10 dBm. Field experiments indicate that this optimization can reflect seismic reflection events more sensitively than LFM, aiding in the clearer depiction of underground structures.