Depth-consistent reflection tomography using PP and PS seismic data

Foss, S. K.; Ursin, Bjørn; Hoop, Maarten V. de

doi:10.1190/1.2049350

“…Concerning the velocity macromodel, the estimation of depth consistent P ‐ and S ‐wave velocity models requires the identification of some key reflectors among the PP ‐ and PS ‐arrivals. This pairing is fastidious and can be extremely difficult in regions with a poor signal‐to‐noise ratio (Stopin 2001; Broto et al 2003; Foss et al 2005).…”

Section: Introductionmentioning

confidence: 99%

“…The approach is based on stereotomography and is called PP / PS ‐stereotomography. We limit ourselves to the isotropic case (even if it is well known that anisotropy can be an important phenomenum for converted waves (Stopin 2001; Foss et al 2005), with the difficult problem of the depth consistency of P ‐ and S ‐wave velocity models).…”

Section: Introductionmentioning

confidence: 99%

Two-dimensionalPP/PS-stereotomography:P- andS-waves velocities estimation from OBC data

Alerini

¹

,

Lambaré

²

,

Baina³

et al. 2007

Geophysical Journal International

View full text Add to dashboard Cite

S U M M A R YWe present the extension of stereotomography to P-and S-wave velocity estimation from PP-and PS-reflected/diffracted waves. In this new context, we greatly benefit from the use of locally coherent events by stereotomography. In particular, when applied to S-wave velocity estimation from PS-data, no pairing of PP-and PS-events is a priori required. In our procedure the P-wave velocity model is obtained first using stereotomography on PP-arrivals. Then the S-wave velocity model is obtained using PS-stereotomography on PS-arrivals fixing the Pwave velocity model. We present an application to an 'ideal' synthetic data set demonstrating the relevance of the approach, which allows us to recover depth consistent P-and S-waves velocity models even if no pairing of PP-and PS-events is introduced. Finally, results to a real data set from the Gulf of Mexico are presented demonstrating the potential of the method in a noisy data context.

show abstract

“…PP and PS images of the same reflector do not match in depth if the velocity model is incorrect (Foss et al, 2005;Tsvankin & Grechka, 2011). Therefore, in addition to flattening image gathers, I penalize depth misties between PP and PS sections.…”

Section: 6mentioning

confidence: 99%

Joint migration velocity analysis of PP- and PS-waves for VTI media

Cai

¹

,

Tsvankin

²

2012

SEG Technical Program Expanded Abstracts 2012

View full text Add to dashboard Cite

Combining PP-waves with mode-converted PS reflections in migration velocity analysis (MVA) can help build more accurate VTI (transversely isotropic with a vertical symmetry axis) velocity models. To avoid problems caused by the moveout asymmetry of PS-waves and take advantage of efficient MVA algorithms designed for pure modes, I suggest to generate pure SS-reflections from PP and PS data using the PP+PS=SS method. Then the residual moveout in both PP and SS commonimage gathers is minimized during iterative velocity updates. The model is divided into square cells, and the VTI parameters V P 0 , V S0 , , and δ are defined at each grid point. The objective function also includes the differences between the migrated depths of the same reflectors on the PP and SS sections and a regularization term.Synthetic examples confirm that 2D MVA of PP-and PS-waves may be able to resolve all four relevant parameters of VTI media if reflectors with at least two distinct dips are available. The algorithm is also applied to a 2D line from 3D OBS (ocean bottom seismic) data acquired at Volve field in the North Sea. After the anisotropic velocity model has been reconstructed, accurate depth images can be obtained by migrating the recorded PP and PS data.

show abstract

“…Several authors discuss joint tomographic inversion of PP and PS data (Stopin & Ehinger, 2001;Audebert et al, 1999;Broto et al, 2003;Foss et al, 2005). However, velocity analysis of mode convertions is hampered by the asymmetry of PS moveout (i.e.…”

mentioning

confidence: 99%

“…As discussed by Thomsen (1999) and Tsvankin & Grechka (2011), the apex of the PS moveout in common-midpoint (CMP) gathers typically is shifted from zero offset. Therefore, MVA for PS-waves (Du et al, 2012;Foss et al, 2005;Audebert et al, 1999) has to account for the "diodic" nature of PS reflections (Thomsen, 1999). For example, common-image gathers (CIGs) of PS-waves can be computed separately for positive and negative offsets in the tomographic objective function (Foss et al, 2005).…”

mentioning

confidence: 99%

Joint migration velocity analysis of PP- and PS-waves for VTI media

Cai

¹

,

Tsvankin

²

2013

View full text Add to dashboard Cite

Combining PP-waves with mode-converted PS reflections in migration velocity analysis (MVA) can help build more accurate VTI (transversely isotropic with a vertical symmetry axis) velocity models. To avoid problems caused by the moveout asymmetry of PS-waves and take advantage of efficient MVA algorithms designed for pure modes, I suggest to generate pure SS-reflections from PP and PS data using the PP+PS=SS method. Then the residual moveout in both PP and SS commonimage gathers is minimized during iterative velocity updates. The model is divided into square cells, and the VTI parameters V P 0 , V S0 , , and δ are defined at each grid point. The objective function also includes the differences between the migrated depths of the same reflectors on the PP and SS sections and a regularization term.Synthetic examples confirm that 2D MVA of PP-and PS-waves may be able to resolve all four relevant parameters of VTI media if reflectors with at least two distinct dips are available. The algorithm is also applied to a 2D line from 3D OBS (ocean bottom seismic) data acquired at Volve field in the North Sea. After the anisotropic velocity model has been reconstructed, accurate depth images can be obtained by migrating the recorded PP and PS data.

show abstract

Depth-consistent reflection tomography using PP and PS seismic data

Cited by 38 publications

References 36 publications

Two-dimensionalPP/PS-stereotomography:P- andS-waves velocities estimation from OBC data

Two-dimensionalPP/PS-stereotomography:P- andS-waves velocities estimation from OBC data

Joint migration velocity analysis of PP- and PS-waves for VTI media

Joint migration velocity analysis of PP- and PS-waves for VTI media

Contact Info

Product

Resources

About