1887

Abstract

Summary

We derived an anisotropic eikonal tomography method for phase velocities based on a two-dimensional elliptical-anisotropic wave equation. The method is applied to Scholte-waves emitted between 0.2 and 1.3 Hz by virtual seismic sourced from stations in the Life of Field Seismic (LoFS) Ocean Bottom Cable (OBC) array installed over Ekofisk field. The virtual seismic sources are created by passive seismic interferometry of 40 hours of noise recordings from Ekofisk’s LoFS array. Azimuthal-anisotropic Scholte-wave velocities form a large circular pattern over the Ekofisk field and are result from the overburden stress-state and from sea-floor subsidence induced by decades of hydrocarbon extraction. A dispersion analysis shows that the Scholte-wave virtual seismic source exhibits a peak sensitivity between 160 and 565 m below the sea floor. These results are significant because they show that noise recordings made at Ekofisk’s LoFS array can be used to monitor azimuthal-anisotropy in the near surface.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.20141371
2014-06-16
2024-10-09
Loading full text...

Full text loading...

References

  1. Aki, K.
    [1957] Space and time spectra of stationary stochastic waves, with special reference to microtremors. Bulletin of the Earthquake Research Institute, 35, 415–456.
    [Google Scholar]
  2. Aki, K., and Richards, P. G.
    [2002] Quantitative Seismology - second edition: University Science Books.
    [Google Scholar]
  3. Bussat, S. and Kugler, S.
    [2011] Offshore ambient-noise surface-wave tomography above 0.1 hz and its applications. The Leading Edge, 30, 514–524.
    [Google Scholar]
  4. Campillo, M. and Paul, A.
    [2003] Long-range correlations in the diffuse seismic coda. Science, 299, 547–549.
    [Google Scholar]
  5. Claerbout, J. F.
    [1968] Synthesis of a layered medium from its acoustic transmission response. Geophysics, 33, 264–269.
    [Google Scholar]
  6. Dellinger, J. A. and Yu, J.
    [2009] Low-frequency virtual point-source interferometry using conventional sensors: 71st Meeting, European Associated of Geoscientists and Engineers, Expanded Abstracts, X047.
    [Google Scholar]
  7. de Ridder, S. A. L.
    [2014] Pasive seismic surface-wave interferometry for reservoir-scale imaging. PhD thesis, Stanford University.
    [Google Scholar]
  8. Draganov, D., X.Campman, X., Thorbecke, J., Verdel, A. and Wapenaar, K.
    [2009] Reflection images from ambient seismic noise. Geophysics, 74, A63–A67.
    [Google Scholar]
  9. Eriksrud, M.
    [2010] Towards the optical seismic era in reservoir monitoring. First Break, 28, no. 6, 105–111.
    [Google Scholar]
  10. Folstad, P. G., Amundsen, L. and Landrø, M.
    [2010] Monitoring of the ekofisk field. GeoExpro, 7, no. 3, 72–74.
    [Google Scholar]
  11. Lin, F.-C., Ritzwoller, M.H. and R.Snieder
    [2009] Eikonal Tomography: Surface wave tomography by phase-front tracking across a regional broad-band seismic array. Geophys. J. Int., 177, 1091–1110.
    [Google Scholar]
  12. Lin, F.C. and M.H.Ritzwoller
    [2011] Helmholtz surface wave tomography for isotropic and azimuthally anisotropic structure. Geophys. J. Int., 186.
    [Google Scholar]
  13. Longuet-Higgins, M. S.
    [1950] A theory of the origin of microseisms. Philos. Trans. R. Soc. London, Ser. A, 243, 1–35.
    [Google Scholar]
  14. Lyngnes, B., H.Landa, K.Ringen, and N.Haller
    , 2013, Life of Field Seismic at Ekofisk - Utilizing 4D seismic for evaluating well target: 75th Meeting, European Associated of Geoscientists and Engineers, Expanded Abstracts, We 12 09.
    [Google Scholar]
  15. Mordret, A., Shapiro, N. M., Singh, S., Roux, P., Montagner, J. P. and O. I.Barkved
    [2013] Azimuthal anisotropy at Valhall: The Helmholtz equation approach. Geophys. Res. Lett., vol. 40, 1–6.
    [Google Scholar]
  16. Olofsson, B., Probert, T., Kommedal, J. and Barkved, O.
    [2003] Azimuthal anisotropy from the valhall 4c 3d survey. The Leading Edge, 22, 1228–1235.
    [Google Scholar]
  17. Olofsson, B.
    [2010] Marine ambient seismic noise in the frequency range 1–10 hz. The Leading Edge, 29, 418–435.
    [Google Scholar]
  18. Sandwell, D. T.
    [1987] Biharmonic spline interpolation of GEOS-3 and SEASAT altimeter data. Geophys. Res. Let., 14, 139–142.
    [Google Scholar]
  19. Stewart, P.
    [2006] Interferometric imaging of ocean bottom noise: SEG Technical Program Expanded Abstracts, 25, 1555–1559.
    [Google Scholar]
  20. Van Dok, R., Gaiser, J. and Byerley, G.
    [2003] Near-surface shear-wave birefringence in the north sea: Ekofisk 2d/4c test. The Leading Edge, 22, 1236–1242.
    [Google Scholar]
  21. Wapenaar, K.
    [2003] Synthesis of an inhomogeneous medium from its acoustic transmission response: Geophysics, 68, 1756–1759.
    [Google Scholar]
/content/papers/10.3997/2214-4609.20141371
Loading
/content/papers/10.3997/2214-4609.20141371
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error