Using Full Waveform Inversion to Update Anisotropy - A North Sea Case Study

Silva, N. da; Ratcliffe, Andrew; Conroy, Graham; Vinje, Vetle; Body, Geoff

doi:10.3997/2214-4609.20141087

Cited by 2 publications

(1 citation statement)

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“…Moreover, Cheng et al (2014) apply a hierarchical approach on real data by updating the vertical velocity; first, keeping the anisotropy parameters unchanged and switching to joint inversion when vertical velocity inversion is approaching convergence. On the other hand, da Silva et al (2014) propose a simultaneous inversion in which they update the vertical and horizontal velocities simultaneously. Behind all these inversion strategies lies a need for understanding the resolvability, resolution limits, and trade-off between the parameters.…”

Section: Introductionmentioning

confidence: 99%

A new parameterization for waveform inversion in acoustic orthorhombic media

Masmoudi

Alkhalifah

2016

GEOPHYSICS

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Orthorhombic anisotropic model inversion is extra challenging because of the multiple parameter nature of the inversion problem. The high number of parameters required to describe the medium exerts considerable trade-off and additional nonlinearity to a full-waveform inversion (FWI) application. Choosing a suitable set of parameters to describe the model and designing an effective inversion strategy can help in mitigating this problem. Using the Born approximation, which is the central ingredient of the FWI update process, we have derived radiation patterns for the different acoustic orthorhombic parameterizations. Analyzing the angular dependence of scattering (radiation patterns) of the parameters of different parameterizations starting with the often used Thomsen-Tsvankin parameterization, we have assessed the potential trade-off between the parameters and the resolution in describing the data and inverting for the parameters. The analysis led us to introduce new parameters [Formula: see text], [Formula: see text], and [Formula: see text], which have azimuthally dependent radiation patterns, but keep the scattering potential of the transversely isotropic parameters stationary with azimuth (azimuth independent). The novel parameters [Formula: see text], [Formula: see text], and [Formula: see text] are dimensionless and represent a measure of deviation between the vertical planes in orthorhombic anisotropy. Therefore, these deviation parameters offer a new parameterization style for an acoustic orthorhombic medium described by six parameters: three vertical transversely isotropic (VTI) parameters, two deviation parameters, and one parameter describing the anisotropy in the horizontal symmetry plane. The main feature of any parameterization based on the deviation parameters, is the azimuthal independency of the modeled data with respect to the VTI parameters, which allowed us to propose practical inversion strategies based on our experience with the VTI parameters. This feature of the new parameterization style holds for even the long-wavelength components of the model constrained by traveltimes.

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Section: Introductionmentioning

confidence: 99%

A new parameterization for waveform inversion in acoustic orthorhombic media

Masmoudi

Alkhalifah

2016

GEOPHYSICS

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Full-waveform inversion as a game changer: Are we there yet?

et al. 2016

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Full-waveform inversion (FWI) has the potential to be a game changer for the seismic industry since it produces accurate velocity models at a resolution that cannot be matched by conventional traveltime tomography, with the additional advantage that it runs on basically raw data. Today, these two features should be better exploited to maximize the business value that FWI can deliver to an oil and gas operator. Provided that we acquire adequate data sets, FWI can be run starting from a smooth velocity model so that traveltime tomography is completely bypassed. As very little processing is required, FWI can be executed in parallel with the main preprocessing efforts, with the results of shortening considerably the overall project turnaround. For imaging purposes, FWI can be limited to the low-frequency range (∼ 10 Hz) but if run in the high-frequency range (∼ 30 Hz), FWI velocities have such a resolution that they can be used directly for interpretation. In particular, applications in the field of pore-pressure prediction and shallow hazard have great potential. In the current implementation, the main limitations are linked to data quality and computational power, but both these issues can be adequately addressed.

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Using Full Waveform Inversion to Update Anisotropy - A North Sea Case Study

Cited by 2 publications

References 0 publications

A new parameterization for waveform inversion in acoustic orthorhombic media

A new parameterization for waveform inversion in acoustic orthorhombic media

Full-waveform inversion as a game changer: Are we there yet?

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