Landmark Graphics Corporation

Halliburton Energy Services, Inc.

Shengwen Jin

Fan Xia

Yiqing Ren

Fan Jiang

Mingqiu Luo

Shiyong Xu

Richard Ottolini

Methods and systems are presented in this disclosure for semblance-based anisotropy parameter estimation using isotropic depth-migrated common image gathers. Far-offset image gathers can be generated from seismic data associated with a subterranean formation migrated based on an isotropic depth migration that uses an isotropic velocity model. Based on the far-offset image gathers, a plurality of semblance values can be calculated as a function of an anisotropy parameter of the subterranean formation for the different depths and the surface locations. Effective values of the anisotropy parameter of the subterranean formation can be then chosen that result in maxima of the plurality of semblance values for the different depths and the surface locations. Anisotropy model of the subterranean formation can be obtained based on the effective values of the anisotropy parameter.

Semblance-based anisotropy parameter estimation using isotropic depth-migrated common image gathers

Systems and methods for simulating an effect of multiple seismic sources concurrently on a geologic formation are provided. Data is read from a seismic source file that describes at least two seismic source types. The concurrent propagation of acoustic energy from the at least two seismic sources types through the geologic formation is modeled. A seismic output file is then generated.

Methods and systems for seismic modeling using multiple seismic source types

Disclosed are systems and methods for numerically simulating seismic-wave propagation in tilted transversely isotropic (TTI) media, using an adaptive Lebedev staggered grid. In various embodiments, the adaptive grid includes multiple horizontal zones having different associated grid spacings, which may be determined based on a vertical wave-velocity model. The numerical simulation may involve iteratively solving a set of finite-difference equations including finite-difference coefficients that vary spatially depending on the grid spacing. Additional embodiments and features are described.

Seismic elastic wave simulation for tilted transversely isotropic media using adaptive lebedev staggered grid

An example method for tomographic migration velocity analysis may include collecting seismographic traces from a subterranean formation and using an initial velocity model to generate common image gathers and a depth image volume based, at least in part, on the seismographic traces. A structure tensor may be computed with the depth image volume for automated structural dip and azimuth estimation. A semblance may be generated using said plurality of common image gathers and said structure tensor. Image depth residuals may be automatically picked from said semblance. A ray tracing computation may be performed on said initial velocity models using said structure tensor. An updated velocity model may be generated with a tomographic inversion computation, wherein said tomographic inversion computation uses said plurality of image depth residuals and said ray tracing computation.

Structure tensor constrained tomographic velocity analysis

Systems and methods for imaging seismic data using hybrid one-way wave-equation-migration in tilted transverse isotropic media and/or hybrid two-way reverse-time-migration in tilted transverse isotropic media.

Systems and methods for imaging seismic data

Seismic imaging systems and methods that employ sensitivity kernel-based migration velocity analysis in 3D anisotropic media may demonstrate increased stability and accuracy. Survey data analysts employing the disclosed systems and methods are expected to provide better images of the subsurface and be better able to identify reservoirs and deposits for commercial exploitation. Certain embodiments migrate seismic survey data with an anisotropic velocity model to obtain common angle image gathers. These gathers are processed to obtain depth residuals along one or more horizons. Angle-domain sensitivity kernels are used to convert the depth residuals into velocity errors, which are then used to refine the velocity model. A user is then able to view a representation of the subsurface structure determined in part from the refined velocity model. Multiple iterations may be needed for the velocity model to converge. The velocity model may be a layered to have constant velocity values between formation boundaries.

Sensitivity kernal-based migration velocity analysis in 3D anisotropic media

In various disclosed seismic imaging systems and methods, a fast target-oriented illumination calculation technique is employed to obtain a data volume or 'matrix' of approximate illumination values. These illumination values enable an image matrix of 'true reflectivity' values to be found. The illumination values are derived from Green's functions which, rather than being calculated and re-calculated on a shot-by-shot basis, are calculated in multi-shot groups and combined with a rolling-sum to greatly reduce the computational overhead. As a consequence, the disclosed systems and methods can provide target region illuminations more quickly and/or with higher quality than those systems relying on conventional 3D wave-equation illumination.

Seismic imaging systems and methods employing a fast target-oriented illumination calculation

In at least some embodiments, the system obtains shot gathers for a survey region and migrates the shot gather data with an initial velocity model to obtain angle-domain common image gathers. The system processes the common image gathers to determine depth residuals and corresponding angle-dependent time deviations throughout a seismic survey region. The system solves a set of tomographic equations which employ ray theory to establish a relationship between a travel time deviation and the depth residual of a reflector in the depth-offset ray parameter (z,p) domain. The resulting updates are applied to the velocity model and can be used to re-migrate the shot gather data. The system generates a representation of the survey region that can be displayed to a user.

Seismic imaging systems and methods employing tomographic migration-velocity analysis using common angle image gathers

A migration method using hybrid one-way and full-way (HOF) wave equation propagation. The HOF method extrapolates seismic wavefields in less complex media with a one-way wave equation propagator and extrapolates seismic wavefields in extremely complex media with a full-way wave equation propagator. For prestack depth migration, the HOF extrapolates source-side and receiver-side wavefields independently. Frequency-space domain and time-space domain imaging conditions are applied to the one-way and the full-way extrapolated wavefields, respectively. A suitable amplitude matching factor is introduced to combine the one-way and full-way images. The HOF method is a cost-effective migration that produces superior image quality with less noises and less computational resources.

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Sugar Land, TX, United States of America

Shengwen Jin