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Noise-based Seismic Tomography at the Valhall Oil Field with Using Scholte and Love Waves
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 77th EAGE Conference and Exhibition - Workshops, Jun 2015, Volume 2015, p.1 - 5
Abstract
We present here Scholte and Love wave phase velocity tomography at the Valhall Oil Field using ambient noise recorded by a network of 3D multi-component ocean bottom cable. We have cross-correlated 6.5 hours of continuous recording of noise between vertical-vertical (ZZ), radial-radial (RR), and transverse-transverse (TT) components. After applying an F-K filter, we were able to extract the first overtone of Scholte waves at Valhall from the RR cross-correlations. We then used the filtered overtone waveforms to measure inter-station frequency-dependent phase time delays and constructed 2D phase-velocity maps with the Eikonal tomography method.
Furthermore, we compute average dispersion curves for Scholte and Love waves by combining information from more than 10 millions of individual cross-correlations. We use the Neighbourhood algorithm to invert jointly these dispersion curves and to obtain an average 1D anisotropic model of the Valhall overburden down to depths of ~1 km. We find a significant radial anisotropy at depths below 600 m. This average 1D model is used as a reference model for the 3D inversion.