Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Bakulin, Andrey; Liu, Yangjun; Zdraveva, Olga; Lyons, Kevin

doi:10.1190/1.3525359

Cited by 25 publications

(11 citation statements)

References 5 publications

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“…For example, in complex geologic settings including fold-and-thrust belts and subsalt plays, sedimentary formations are often described by transversely isotropic models with a vertical (VTI) or tilted (TTI) symmetry axis (Douma et al, 2009;Neal et al, 2009;Bakulin et al, 2010a). To ensure stable estimation of the symmetry-direction P-wave velocity V P0 and anisotropy parameters ε and δ, the orientation of the symmetry axis is commonly assumed to be known from structural information (Audebert et al, 2006;Bakulin et al, 2010b).…”

mentioning

confidence: 99%

Ray-based gridded tomography for tilted transversely isotropic media

Wang

Tsvankin

2013

GEOPHYSICS

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Reflection tomography in the migrated domain can help reconstruct heterogeneous, anisotropic velocity fields needed for accurate depth imaging of complex geologic structures. The presence of anisotropy, however, increases the uncertainty in velocity analysis and typically requires a priori constraints on the model parameters. Here, we develop a 2D P-wave tomographic algorithm for heterogeneous transversely isotropic media with a tilted symmetry axis (TTI) and investigate the conditions necessary for stable estimation of the symmetry-direction velocity V P0 and the anisotropy parameters ε and δ. The model is divided into rectangular cells, and the parameters V P0 , ε, δ, and the tilt ν of the symmetry axis are defined at the grid points. To increase the stability of the inversion, the symmetry axis is set orthogonal to the imaged reflectors, with the tilt interpolated inside each layer. The iterative migration velocity analysis involves efficient linearized parameter updating designed to minimize the residual moveout in image gathers for all available reflection events. The moveout equation in the depth-migrated domain includes a nonhyperbolic term that describes long-offset data, which are particularly sensitive to ε. Synthetic tests for models with a "quasi-factorized" TTI syncline (i.e., ε and δ are constant inside the anisotropic layer) and a TTI thrust sheet demonstrate that stable parameter estimation requires either strong smoothness constraints or additional information from walkaway VSP (vertical seismic profiling) traveltimes. If the model is quasifactorized with a linear spatial variation of V P0 , it may be possible to obtain the interval TTI parameters just from long-spread reflection data.

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confidence: 99%

Ray-based gridded tomography for tilted transversely isotropic media

Wang

Tsvankin

2013

GEOPHYSICS

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“…In Figure 2 we show the location of 18 wells in the Green Canyon (GC) area of the GoM. We are focusing on a study area that was investigated by Bakulin et al (2010b). We also show the corresponding tomographic P-wave velocity cube associated with the subsurface at the region.…”

Section: Gulf Of Mexico Check-shot Data Setmentioning

confidence: 99%

Anisotropic velocity model building using rock physics: Comparison of compaction trends and check‐shot‐derived anisotropy in the Gulf of Mexico

Bachrach

Liu²,

Woodward³

et al. 2011

SEG Technical Program Expanded Abstracts 2011

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Anisotropic velocity models are poorly constrained by surface seismic data. Rock-physics anisotropic modelling of shale compaction and digenesis provides information that can constrain anisotropic velocity model building. In this study we compare rock-physics-based anisotropic velocity models to an extensive data set where 18 Gulf of Mexico (GoM) wells were analyzed using checkshot data. 3D anisotropy estimates derived by interpolation and extrapolation of the checkshot data set are compared to 3D anisotropy estimates derived from rock-physics modelling. We show that regional anisotropy trends are consistent with compaction driven anisotropy as predicted by the rockphysics model. We also show that not all anisotropy observed in the region can be explained by compaction model and that check-shot data carries additional information.

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“…In 2010, the Thomsen parameters ε and δ were estimated at 11 public domain wells by jointly using well and surfaceseismic data in a 1D layer-stripping modeling and inversion scheme. The new calibrated ε and δ profiles were obtained by averaging and smoothing 5 of these 11 profiles in an attempt to remove high-frequency features that could not be accurately propagated in the subsurface over such a large area (Bakulin et al, 2010a). The profiles were then used together with a V P0 field from the second tomography iteration of the old VTI model and a structural framework consisting of the water bottom and two major horizons to construct a TTI model using a multistep process described in details by Zdraveva et al (2010).…”

Section: Large Scale Tti Model Building Using a Geological Framework:mentioning

confidence: 99%

Anisotropic model building in complex media: Comparing three successful strategies in deep water Gulf of Mexico

Zdraveva¹,

Cogan²,

Hubbard³

et al. 2011

SEG Technical Program Expanded Abstracts 2011

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Following the introduction of wide-azimuth towedstreamer data as an exploration imaging prerequisite in the deep-water Gulf of Mexico in 2006, anisotropic imaging with vertical or tilted transversely isotropic (VTI or TTI) models has become the dominant practice in the industry. Today, it is widely recognized that incorporating anisotropy in imaging increases our ability both to focus the seismic data and to accurately position the reflectors for drilling decisions. We show three successful anisotropic model building strategies applied on wide-azimuth (WAZ) data from the Walker Ridge and Green Canyon areas of the deep-water Gulf of Mexico. We demonstrate the benefits of incorporating geology information and data from boreholes into all stages of velocity model building.

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Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Cited by 25 publications

References 5 publications

Ray-based gridded tomography for tilted transversely isotropic media

Ray-based gridded tomography for tilted transversely isotropic media

Anisotropic velocity model building using rock physics: Comparison of compaction trends and check‐shot‐derived anisotropy in the Gulf of Mexico

Anisotropic model building in complex media: Comparing three successful strategies in deep water Gulf of Mexico

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