Lateral velocity anomalies

Rocca, F.; Toldi, John L.

doi:10.1190/1.1893720

Cited by 3 publications

(1 citation statement)

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“…F or certain models, this calculation can be greatly simplified by use of an approximation to w[t(m)] which is linear in m. A linear operator based on this approximation was first proposed by Lynn (1980) and more fully developed by Loinger (1983). Rocca and Toldi (1983) showed how this linear theory could be used in an inversion procedure. The linear theory calculates the change in stacking slowness that is due to a change in the interval-slowness model from a reference model.…”

Section: Optimizationmentioning

confidence: 99%

Velocity analysis without picking

Toldi

1989

GEOPHYSICS

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Conventionally, interval velocities are derived from picked stacking velocities. The velocity-analysis algorithm proposed in this paper is also based on stacking velocities; however, it eliminates the conventional picking stage by always considering stacking velocities from the point of view of an interval-velocity model. This view leads to a model-based, automatic velocityanalysis algorithm.The algorithm seeks to find an interval-velocity model such that the stacking velocities calculated from that model give the most powerful stack. An additional penalty is incurred for models that differ in smoothness from an initial interval-velocity model. The search for the best model is conducted by means of a conjugategradient method.The connection between the interval-velocity model and the stacking velocities plays an important role in the algorithm proposed in this paper. In the simplest case, stacking velocity is assumed to be equal to rms velocity. For the more general case, a linear theory is developed, connecting interval velocity and stacking velocity through the intermediary of traveltime. When applied to a field data set, the method produces an interval-velocity model that explains the lateral variation in both stacking velocity and traveltime.

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Section: Optimizationmentioning

confidence: 99%

Velocity analysis without picking

Toldi

1989

GEOPHYSICS

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Tomographic imaging by reflected and refracted arrivals at the North Sea

et al. 1999

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We discuss some processing steps of a marine 3-D data set from the Oseberg field, North Sea. We compare the prestack depth‐migrated images obtained by the velocity fields provided by different tools: velocity spectra, reflection tomography, and joint tomographic inversion of reflected and refracted arrivals. The last ones are definitely better. We also produced a synthetic example by modeling the estimated earth structure and the actual recording geometry, and we reached similar conclusions. The correlation between reflected and refracted signals may be unclear for later arrivals because of their reciprocal interference and multiple reflections. We adopt a technique based on a surgical mute in the τ-p domain, which allows coupling the signals coming from the same elastic interface.

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9. Earth Modeling in Depth

2001

Seismic Data Analysis

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Lateral velocity anomalies

Cited by 3 publications

References 0 publications

Velocity analysis without picking

Velocity analysis without picking

Tomographic imaging by reflected and refracted arrivals at the North Sea

9. Earth Modeling in Depth

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