Seismic surface-wave tomography from cross-correlations of ambient noise at the Valhall oil field

A. Mordret, M. Landès, N.M. Shapiro, Satish C. Singh, Philippe Roux, Olav I. Barkved

Publikation: KonferencebidragAbstract ved konference

Resumé

Here we present cross-correlation analysis of 6 hours of noise data recorded by a network of 3D multi-component ocean bottom cable at the Valhall Life of Field. The 2413 sensors were spaced at 50 m along 10 km long line and line spacing was 300 m. At 0.4- 2 Hz frequencies, the best signal-to-noise ratio was obtained for vertical-vertical (VV) cross-correlations that clearly show Scholte waves. At higher frequencies (3-30 Hz), the seismic noise is mainly produced by the exploitation platform at the center of the network and the highest signal-to-noise ratio was obtained on transverse-transverse (TT) cross-correlations, which was dominated by Love's waves. Because of the localized noise source at these high frequencies, we selected a profile of stations suitably aligned relative to the platform and computed TT cross-correlations between all pairs of stations. We then extracted dispersion curves and inverted them to construct a 2D shear-velocity profile down to 20 m depth. We find that upper strata of the sediments have velocities of 200- 400 m/s and vary laterally, which is extremely important for S-wave statics. At low frequencies, we computed VV cross-correlations for all possible station pairs. We then measured Scholte wave group velocity dispersion curves and inverted them to build group velocity maps of the Valhall area. Similar to previously published models from full waveform inversion of an active seismic dataset, our results show a coherent pattern dominated by paleo-channels at the seabed above the Valhall field. Our results show that a detailed 3D S-wave velocity could be determined using noise data collected by permanent ocean bottom cables.
OriginalsprogEngelsk
SiderS41B-2192
StatusUdgivet - dec. 2011
Udgivet eksterntJa
BegivenhedAGU Fall Meeting 2011 - San Fransisco, USA
Varighed: 5 dec. 20119 dec. 2011

Konference

KonferenceAGU Fall Meeting 2011
BySan Fransisco, USA
Periode5/12/119/12/11

Programområde

  • Programområde 3: Energiressourcer

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