Seismic Low-Frequency Shadow beneath Gas Hydrate in the Shenhu Area Based on the Stereoscopic Observation System

Abstract

Spectral analysis shows a low-frequency shadow under the BSR interface. Traditional low-frequency shadow analysis is based on stacked data. In order to understand the BSR low-frequency shadow more clearly, a frequency division analysis on stereoscopic observation seismic data based on the adaptive optimal-kernel (AOK) frequency analysis method is presented. It includes ocean-bottom seismometer (OBS) data (common receiver point data including vertical and horizontal components), vertical cable data (common receiver point data) and horizontal cable data (stacked section of different offsets). The OBS data frequency analysis gets a conclusion that vertical component has a significant effect on the low-frequency shadow, but the horizontal component did not. The vertical cable data shows that the low frequency band of vertical cable is wider than OBS. And then the horizontal cable data frequency analysis points out that the bigger the angle of incidence is, the more obvious the low-frequency shadow will be. The low-frequency shadow feature is shown in the stereoscopic observation field and the visual effect on common reception point data is better. The lateral reservoir distribution characteristics are predicted from low-frequency shadow feature analysis of the hydrate BSR based on stereoscopic observation.