Analysis of directional seismic signal based on phased-array vibrator system

When ambient noise is strong, seismic data signal-to-noise ratio (SNR) might still be low even if combination vibrators are used. To solve this problem we proposed to apply a phased-array vibrator system (PAVS), which can form a directional seismic wave. In theory, 3-unit PAVS can make SNR of reflected waves increasing 6.53 similar to 9.54 dB than single vibrator, and 1.76 similar to 4.77dB than combination sources. In practice, field experiments were done with different sources in the same test field. The results show that a significant SNR improvement can be seen in reflected signals of PAVS than single source according to single shot records and horizontal stacking time sections. Of course, we also noticed that there is a little difference in time domain signals between seismic signals of PAVS and combination source. Furthermore, power spectrums of reflected wave signals are analyzed and we get some quantitative results: PAVS make SNR of reflected waves increasing 0.75 similar to 8.15 dB and 0.93 similar to 3.17 dB at different traces respectively than single and combination sources. Mean SNR increases are 3.65dB and 2.02dB. It shows that the results from experiments are consistent with theoretical analysis. To evaluate PAVS and its effect on seismic signals, time sections from different sources were shown. It can be seen that directional illumination technology of PAVS is effective and superior to boost SNR of seismic signals than other routine sources.