1887

Abstract

Summary

Wavefield separation is a crucial step in suppressing crosstalk artifacts and improving imaging quality in elastic reverse time migration (ERTM). In isotropic elastic media, the most popular wavefield separation technique is the Helmholtz decomposition. However, the Helmholtz decomposition produces pure-mode wavefields with incorrect amplitudes, phases, and physical units. In addition, when we implement multi-shot ERTM using pure-mode wavefields, polarity changes in the converted wave can destroy reflection events. To remedy these problems, we modify the Helmholtz decomposition and apply a scalar imaging condition to obtain scalar images of ERTM with accurate amplitudes and phases. Instead of using the P- and S-wave decoupled elastic wave equations, we produce vector P- and S-wavefields through the following two steps. First, we correct the amplitudes and phases of the pure-mode wavefield during the Helmholtz decomposition. Second, we obtain vector P- and S-wavefields using a wavefield composition method. Using the separated vector wavefields, we adopt a scalar imaging condition for ERTM. These operations enable us to produce migrated images directly with the correct amplitudes, phase, and physical units. Numerical results demonstrate that the proposed ERTM provides high-quality migrated images. The method is also feasible and sufficiently robust for imaging complex subsurface structures.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.201900825
2019-06-03
2020-04-02
Loading full text...

Full text loading...

References

  1. Aki, K. and Richards, P. G.
    [1980] Quantitative Seismology: Theory and Methods. University Science Books.
    [Google Scholar]
  2. Du, Q. Z., Gong, X. F., Zhang, M. Q., Zhu, Y. T. and Fang, G.
    [2014] 3D PS-wave imaging with elastic reverse-time migration. Geophysics, 79(5), S173–S184.
    [Google Scholar]
  3. Stewart, R. R., Gaiser, J. E., Brown, R. J. and Lawton, D. C.
    [2003] Converted-wave seismic exploration: Applications. Geophysics, 68(1), 40–57.
    [Google Scholar]
  4. Sun, R. and McMechan, G. A.
    [2001] Scalar reverse-time depth migration of prestack elastic seismic data. Geophysics, 66(5), 1519–1527.
    [Google Scholar]
  5. Sun, R., McMechan, G. A. and Chuang, H.
    [2011] Amplitude balancing in separating P- and S-waves in 2D and 3D elastic seismic data. Geophysics, 76(3), S103–S113.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201900825
Loading
/content/papers/10.3997/2214-4609.201900825
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