Study Of Characteristics And Suppression Of High-Precision Seismic Exploration For Period-Varying Ghost And Reverberation In Paralic Zone

There are such surface conditions as lands, damps, tides and shallow waters that the surface structures are very complex. Much technical difficulty exists as to high-precision seismic exploration and data processing. The suppression of period-varing ghost and multiples is one of the most important questions to solve in the seismic exploration of paralic zone. The solution of this technique is significant to the heighten of resolution, widening of frequency-band, improvement of high cut-off frequency and attainment of high-precision seismic data.In this paper physical mechanism of three kinds of ghosts in marine and their frequency characteristics are systematically analysed. Ghosts following the primary wave turn on notch phenomenon. As to high-precision seismic acquisition, the depth of source or receiver should be reduced, which can broaden the width of efficient reflection signal. A model exploded in sea water and received in declining sea bottom has been forward modeled and the source wave frequency has taken 50Hz, 100Hz and 400Hz. Detailed time and frequency character analysis of ghost has been done from the attained mono-shot record. With the improvement of source wavelet frequency, ghost can be separated in time domain clearly. Frequency characteristics of ghost with period - varing is obtained from frequency spectrum of field data in KD-1 area. What's more, the depth of source or hydrophone can obviously affect the frequency characteristics of seismic signal.The filter frequency characteristics of reverberation namely sea-bottom multiple is also studied in this paper. When the water depthis the same, but the reflection coefficient is reduced, the strengthened and the reduced frequency is the same, but the width of frequency is broaden and the amplitude is decreased. When the reflection coefficient is the same, but the water depth is deeper, the strengthened and decreased frequency of reverberation both moves to low frequency. However, the frequency band gets narrow and the amplitude decreased. To different reflection coefficient and different water depth, the first and second reverberation shows different amplitude character. Two models exploded in sea surface and received in horizontal and declined sea bottom have been forward modeled and the wavelet frequency has taken 50Hz and 400Hz. The seismic record and frequency spectrum characteristics are also analysed.During the seismic exploration in paralic zone, with the variation of water depth, the period of ghost and reverberation are both varied. Aim at the period-varing character and the belonging to surface-free multiples of ghost and reverberation, this paper selects predictive deconvolution to suppress ghost and other multiple in time domain. The notch caused by ghost has been compensated and the frequency component has been enriched. In one word, good suppression effect has been attained.