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Results
Velocity model building by wavefield-continuation imaging in the deepwater Gulf of Mexico
Fliedner, Moritz M. (Stanford University) | Crawley, Sean (Stanford University) | Bevc, Dimitri (Stanford University) | Popovici, Alexander M. (Stanford University) | Biondi, Biondo (Stanford University)
Wavefield-continuation-based migration algorithms that downward extrapolate the 3D prestack wavefield (commonly known as โwave-equation migrationโ) have been recently shown to produce better imaging results than Kirchhoff migration in many synthetic and real data cases (Popovici, 2000). Wavefield-continuation methods are potentially more accurate and robust because they are based on the full wave equation and not on an asymptotic solution based on ray theory. In addition, wavefield-continuation methods handle multipathing naturally in contrast to Kirchhoff methods, focusing and defocusing effects of velocity variations are correctly modeled, antialiasing is handled implicitly, and amplitudes are consistent with the wave equation.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.95)
3D Residual Velocity Analysis And Update Toolkit For Offset-domain Prestack Depth Migration
Liu, Wei (3DGeo Development Inc.) | Bevc, Dimitri (3DGeo Development Inc.) | Popovici, Alexander M. (3DGeo Development Inc.) | Biondi, Biondo (Stanford University)
Summary We present a 3-D migration velocity analysis system and procedure for updating depth-interval velocities based on common image gathers in the offset domain. The redundant structural information contained in migrated common image gathers is extracted by residual moveout analysis. Residual velocity associated with each subsurface image point is determined from semblance scans of common image gathers over a range of values. For improved reliability, residuals are tied to and smoothed along geologic horizons. With the same form of input residual information, the toolkit provides the flexibility of using vertical, normal-ray, or tomographic update to improve the initial velocity model according to the level of complexity in the structures. Special considerations are given to residual migration moveout for dipping layers, automated residual picking for large volume data, and residual smoothing along geologic horizons for improved stability. Synthetic and marine data examples are provided to demonstrate the migration velocity analysis method.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
3D Migration Velocity Analysis For Common Image Gathers In the Reflection Angle Domain
Liu, Wei (3DGeo Development Inc.) | Popovici, Alexander M. (3DGeo Development Inc.) | Bevc, Dimitri (3DGeo Development Inc.) | Biondi, Biondo (Stanford University)
Summary We present a migration velocity analysis system for updating velocities based on common image gathers in the reflection angle domain. Such angle-domain common image gathers can be obtained from either wave equationbased or Kirchhoff integral-based prestack depth migration. Residual velocity associated with each subsurface image point is determined from semblance scans of common image gathers over a plausible range of values followed by automated picking. The extracted residuals can be tied to and smoothed along geologic horizons to improve an initial velocity model through vertical, normal-ray, or tomographic update. A marine data set and two synthetic examples are given to illustrate residual velocity analysis of common image gathers in the reflection angle domain. Introduction There is an increasing demand for advanced imaging techniques capable of providing improved knowledge of the subsurface detail in areas with complex geologic structure.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
Internet-Based Seismic Processing: The Future of Geophysical Computing
Bevc, Dimitri (3DGeo Development Inc.) | Feodorov, Ovidiu (3DGeo Development Inc.) | Popovici, Alexander M. (3DGeo Development Inc.) | Biondi, Biondo (Stanford University)
Summary There have been many significant paradigm shifts in geophysics, and we are in the middle of another one with the industry-wide impact of e-commerce. The adoption of rapidly evolving Internet/Intranet infrastructure and platform independent programming languages is allowing companies to take advantage of the exibility and technology-leverage inherent in this new information paradigm. While the brave new world of the Internet and associated information technology explosion offer unprecedented opportunities, there are many implementation and data-security issues that warrant attention. The challenges are all surmountable by intelligent design which leverages existing technology. The upside for the geophysicist/user is a set of globally accessible processing and interpretation tools available on demand, as needed, without the burden of software upgrades, equipment purchases, and hardware administration.