Hydrate-Bearing Sediment Imaging of Ghost Reflection in Vertical Cable Seismic Data Using Seismic Interferometry

Abstract

Marine vertical cable seismic (VCS) collects seismic waves by hydrophone array vertically suspended in seawater to prospect the offshore geological structure and monitor the reservoir. Due to its irregular source-receiver geometry, the primary imaging has narrow illustration coverage. Here, we proposed a cross-correlation transformation based on ghost wave interferometry. This method can transform the ghost reflections from the vertical cable seismic profile into the virtual surface seismic primaries just like those excited by the source and recorded by marine seismic towed-streamer below sea surface. After processing these virtual primaries with conventional method, we can obtain the ghost reflection imaging section with high resolution which effectively extend the illustration footprints in the subsurface. By application of this transform, virtual primaries are generated from the first-order ghost reflections of the actual VCS data. Then, migration of these virtual primaries provides a high-resolution image of hydrate-bearing sediments.

Application of deconvolution interferometry to receiver ghost reflection in vertical cable seismic survey

“…Finally, we obtain a stacked seismic section as shown in Figure 5. Despite of all the amplitudes unreliable for reservoir characterization, the phases of these amplitudes are still correct according to the nature of seismic interferometry (SI) (Wang et al., 2022). Seismic reflections in phase can bring about the constructive interference and those reflections out of phase give rise to the destructive interference.…”

“…Owing to the unique field geometry of vertical cable seismic (VCS), it is convenient to distinguish receiver ghosts from primaries by upgoing and downgoing wavefield separation. Based on seismic interferometry (SI) by cross‐correlation, the receiver ghost reflections can be converted into the virtual primary reflections in surface seismic (Wang et al., 2022). In other words, the vertical cable seismic profiles (VCSP) can be mapped into the surface seismic profiles (SSP) by SI method.…”

“…According to their characteristics, it may be caused by the hydrates and free gas. Before application of deconvolution interferometry to the receiver ghosts, it is necessary to perform wavefields separation (Wang et al., 2022) on the common receiver gathers for the sake of high‐quality imaging of the receiver ghosts in VCS.…”

“…However, vertical hydrophone array (VHA) is usually suspended in deeper sea water which is deployed in VC. As a result, receiver ghosts with sufficient traveltimes can be distinguished from primaries and imaging of receiver ghosts is feasible and convenient for better submarine illumination (Hondori et al, 2019;Wang et al, 2019;Chen et al, 2022;Wang et al, 2022).…”

“…Despite all this, ghost reflections can be used for sea surface imaging to improve the resolution of marine seismic data (Laws & Kragh, 2002;Orji et al, 2010). If the receiver is deployed at adequate depths so that receiver ghost reflections can be distinguished from primaries, ghosts imaging come true, such as ocean-bottom seismometer (Dash et al, 2009;Wang et al, 2012;Shiraishi et al, 2017) and vertical cable seismic (VCS) (Hondori et al, 2019;Wang et al, 2019;Chen et al, 2022;Wang et al, 2022).…”