Obliquity-correction imaging condition for reverse time migration

Costa, Jessé C.; Neto, F. A. Silva; Alcântara, M. R. M.; Schleicher, Jörg; Novais, Amélia

doi:10.1190/1.3110589

Cited by 54 publications

(21 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the elastic RTM, physically meaningful images can be obtained by crosscorrelating the pure wave modes of the source and receiver wavefields (Yan and Sava, 2008). For shot-profile migration, different imaging conditions have been extensively compared and tested (Chattopadhyay and McMechan, 2008;Schleicher et al, 2008;Costa et al, 2009). These studies show that the crosscorrelation imaging condition with illumination compensation produces fewer migration artifacts, obtains high stability, and has amplitudes that better represent the reflectivity of the model and exhibit the correct scaling and sign.…”

Section: Elastic Imaging Conditionsmentioning

confidence: 97%

“…Yoon and Marfurt (2006) used the energy flux density vector to estimate the scattering angle between source and receiver wavefields to suppress the low wavenumber noise in an acoustic RTM. Costa et al (2009) calculated the dip-dependent weight function using the energy flux density vector to compensate for the reflector dip effect on the amplitudes of an acoustic RTM.…”

Section: Polarity Distribution Of the S-wave Componentmentioning

confidence: 99%

See 1 more Smart Citation

Polarity reversal correction for elastic reverse time migration

Zhu

2012

GEOPHYSICS

165

View full text Add to dashboard Cite

Polarity reversals in PS and SP images of elastic reverse time migration will cause destructive interference in the final stacked results, which may lead to an erroneous interpretation. We derive a polarity reversal correction based on an analysis of the polarity distribution of PS and SP images. The key aspect for a polarity reversal correction is the polarity distribution of the S-wave component. Polarity reversal correction methods can be performed according to the actual patterns of the polarity distribution in gathers. For the 2D isotropic case, a sign factor is introduced to represent the polarity distribution of the S-wave component; this sign factor can be computed using the energy flux density vector. We present a procedure to correct the polarity reversal for elastic reverse time migration in the common-shot domain. First, the sign factor is computed during the wavefield reconstruction for every imaging point. Then, the polarity reversal is corrected by multiplying the PS and SP images with the sign factor at every time step when an elastic imaging condition is applied. We also design a filter algorithm for the sign factor to improve its consistency along an event and thereby to diminish the impact of the inaccuracy of the energy flux density vector and to improve the imaging results. Numerical examples have shown that the polarity reversal correction procedure works and that the sign filter algorithm successfully eliminates the consequences of the inaccuracy of the energy flux density vector. The quality of the migration events is effectively improved.

show abstract

Section: Elastic Imaging Conditionsmentioning

confidence: 97%

Section: Polarity Distribution Of the S-wave Componentmentioning

confidence: 99%

Polarity reversal correction for elastic reverse time migration

Zhu

2012

GEOPHYSICS

165

View full text Add to dashboard Cite

show abstract

“…Especially for the P-and S-wavefields reflected or transmitted from the subsalt reflectors, separation at the image point reduces the artifacts from inaccurate separation. Accurate vector wavefield separation also gives an accurate Poynting vector for up/downgoing P-and S-waves at the image point and each time step, which helps reduce migration artifacts and greatly improves the migration image ͑Yoon and Marfurt, 2006; Costa et al, 2009͒. The final advantage is that the method does not suffer from salt-related interbed multiple artifacts introduced by strong reflectivity variations around the salt compared to standard RTM because only the target-oriented local velocity model is used in the local migration. The method also accounts for turning waves from the surface source to the image points compared to the conventional one-way wave-equation migration; however, it suffers from typical migration artifacts as a result of VSP receiver geometry with limited aperture.…”

Section: Theorymentioning

confidence: 99%

Local vertical seismic profiling (VSP) elastic reverse-time migration and migration resolution: Salt-flank imaging with transmitted P-to-S waves

2010

View full text Add to dashboard Cite

To avoid the defocusing effects of propagating waves through salt and overburden with an inaccurate overburden velocity model, we introduce a vertical seismic profiling ͑VSP͒ local elastic reverse-time-migration ͑RTM͒ method for salt-flank imaging by transmitted P-to-S waves. This method back-projects the transmitted PS waves using a local velocity model around the well until they are in phase with the back-projected PP waves at the salt boundaries. The merits of this method are that it does not require the complex overburden and salt-body velocities and it automatically accounts for source-side statics. In addition, the method accounts for kinematic and dynamic effects, including anisotropy, absorption, and all other unknown rock effects outside of this local subsalt velocity model. Numerical tests on an elastic salt model and offset 2D VSP data in the Gulf of Mexico, using a finite-difference time-domain staggered-grid RTM scheme, partly demonstrate the effectiveness of this method over interferometry PS-PP transmission migration and local acoustic RTM. Our method separates elastic wavefields to vector P-and S-wave velocity components at the trial image point and achieves better resolution than local acoustic RTM and interferometric transmission migration. The analytical formulas of migration resolution for local acoustic and elastic RTM show that the migration illumination is limited by data frequency and receiver aperture, and the spatial resolution is lower than standard poststack and prestack migration. This new method can image salt flanks as well as subsalt reflectors.

show abstract

“…The right boundary of the tunnel model does not use the absorbing boundary in order to save computations. To eliminate waveform distortion near the source, we use obliquity-correction imaging conditions (Costa et al, 2004) instead of crosscorrelation imaging.…”

Section: Migration and Velocity Model-building In Tunnel Predictionmentioning

confidence: 99%

Combined migration velocity model-building and its application in tunnel seismic prediction

et al. 2010

View full text Add to dashboard Cite

We propose a combined migration velocity analysis and imaging method based on Kirchhoff integral migration and reverse time migration, using the residual curvature analysis and layer stripping strategy to build the velocity model. This method improves the image resolution of Kirchhoff integral migration and reduces the computations of the reverse time migration. It combines the advantages of effi ciency and accuracy of the two migration methods. Its application in tunnel seismic prediction shows good results. Numerical experiments show that the imaging results of reverse time migration are better than the imaging results of Kirchhoff integral migration in many aspects of tunnel prediction. Field data show that this method has effi cient computations and can establish a reasonable velocity model and a high quality imaging section. Combination with geological information can make an accurate prediction of the front of the tunnel geological structure.

show abstract

Obliquity-correction imaging condition for reverse time migration

Cited by 54 publications

References 18 publications

Polarity reversal correction for elastic reverse time migration

Polarity reversal correction for elastic reverse time migration

Local vertical seismic profiling (VSP) elastic reverse-time migration and migration resolution: Salt-flank imaging with transmitted P-to-S waves

Combined migration velocity model-building and its application in tunnel seismic prediction

Contact Info

Product

Resources

About