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Reverse Time Migration of Seismic Forward-Prospecting Data in Tunnels Based on Beamforming Methods
Abstract For tunneling in complex geological conditions, effective and accurate advanced prospecting techniques are required to detect unexpected geological heterogeneities in front of the tunnel face. Reverse time migration (RTM) method is a promising method to image the geological changes based on seismic forward-prospecting data acquired in tunnels. However, conventional tunnel-based RTM images suffer interference of “trailing” artifacts. Beamforming method can obtain a focused wave front through the stack of wavefield, resulting in improved data quality and RTM results. In this study, we incorporate the beamforming method in RTM imaging procedure, and propose a “sweep and stack” mode RTM method as well as its calculation scheme. Three tunnel-based models with different kinds of geological interfaces are designed to generate synthetic seismic records. Wavefield extrapolation is achieved by an acoustic staggered-grid finite-difference algorithm and zero-lag cross-correlation imaging condition is applied to present RTM results. Analysis and comparison of conventional RTM results and “sweep and stack” mode record-side beamforming RTM results illustrate that, both methods can successfully identify the geological interface ahead of the tunnel face, while record-side beamforming RTM images present more concentrated energy arcs with higher amplitude, which is preferred for geology interpretations. Moreover, the synthetic test in a noisy environment demonstrates that record-side beamforming RTM has better anti-noise capability than the conventional RTM approach. A field test in a highway tunnel construction site is performed to show the good application effects of “sweep and stack” mode RTM in practical seismic detections.
Reverse Time Migration of Seismic Forward-Prospecting Data in Tunnels Based on Beamforming Methods
Abstract For tunneling in complex geological conditions, effective and accurate advanced prospecting techniques are required to detect unexpected geological heterogeneities in front of the tunnel face. Reverse time migration (RTM) method is a promising method to image the geological changes based on seismic forward-prospecting data acquired in tunnels. However, conventional tunnel-based RTM images suffer interference of “trailing” artifacts. Beamforming method can obtain a focused wave front through the stack of wavefield, resulting in improved data quality and RTM results. In this study, we incorporate the beamforming method in RTM imaging procedure, and propose a “sweep and stack” mode RTM method as well as its calculation scheme. Three tunnel-based models with different kinds of geological interfaces are designed to generate synthetic seismic records. Wavefield extrapolation is achieved by an acoustic staggered-grid finite-difference algorithm and zero-lag cross-correlation imaging condition is applied to present RTM results. Analysis and comparison of conventional RTM results and “sweep and stack” mode record-side beamforming RTM results illustrate that, both methods can successfully identify the geological interface ahead of the tunnel face, while record-side beamforming RTM images present more concentrated energy arcs with higher amplitude, which is preferred for geology interpretations. Moreover, the synthetic test in a noisy environment demonstrates that record-side beamforming RTM has better anti-noise capability than the conventional RTM approach. A field test in a highway tunnel construction site is performed to show the good application effects of “sweep and stack” mode RTM in practical seismic detections.
Reverse Time Migration of Seismic Forward-Prospecting Data in Tunnels Based on Beamforming Methods
Li, Shucai (author) / Ren, Yuxiao (author) / Liu, Lanbo (author) / Xu, Xinji (author) / Liu, Bin (author) / Zhang, Qingsong (author)
2019
Article (Journal)
Electronic Resource
English
BKL:
38.58
Geomechanik
/
56.20
Ingenieurgeologie, Bodenmechanik
/
38.58$jGeomechanik
/
56.20$jIngenieurgeologie$jBodenmechanik
RVK:
ELIB41
Reverse Time Migration of Seismic Forward-Prospecting Data in Tunnels Based on Beamforming Methods
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