[HTT18-P12] Conjecture of sourcing wavelet conditions suitable for the simultaneous sourcing 3D seismic survey with the underwater speakers
Keywords:reflection survey, 3D seismic reflection survey, sourcing wavelet
Our research group has been developing the sourcing wavelet of an underwater speaker to make a more accurate and stable observation (Ogawa et al., 2019). The underwater speaker system uses different non-pulse waves created by MATLAB (MathWorks) as sound source and makes a sound by signal generators. Adjustment of sourcing wavelets such as Marine Vibrator (Orji et al., 2020) is one of the advantages of an underwater speaker. In this research, we create two types of wavelets that are sweep waves and random waves to estimate the optimal wavelet conditions for the underwater speaker system. Sweep waves are generally used in ocean acoustic surveys and land seismic surveys, and random waves are generated by pseudo-random numbers (e.g. Dean, 2013). These two types of wavelets were created for each of the three frequency bands and a total of six wavelets were used for a test at sea. Our results show that the random wavelet is more suitable for the underwater speaker system than the sweep wavelet because the random wave has a higher signal to noise ratio after cross-correlation. Also, the penetration depth of the random wavelet was deeper though the sound pressure was smaller than that of the sweep wavelet. Finally, the seismic profile with more 100-200 Hz band was the most accurate in seismic profiles filtered at 50-100 Hz, 100-200 Hz, and 200-300 Hz.