Wave Imaging Technology Inc.

Look at this shot record...it's a mess. You've got over 1,000 feet of topography over the spread, scattered noise in the near surface, reverberations from topography, and irregular acquisition geometry. Trying to estimate velocity around here will not be easy if you use a conventional approach, such as vertical shift to a "processing datum" and CMP semblance. The CMP gathers may not be regularly sampled, and variations in topography and near-surface velocity may make the reflection events highly non-hyperbolic.

(click to enlarge)

In complex areas, WIT's wave equation shot record depth migration is the most flexible tool to get a good image, when you have an accurate velocity. Our algorithm handles surface topography and irregular acquisition geometry. Rather than stacking the surface data, prestack depth migration "stacks" the data after downward continuation, below all the junk on the surface.

Here's a novel concept: Why not use focusing information from the depth migration to estimate velocity? We use the "time-shift imaging condition" (See Sava and Fomel's 2006 GEOPHYSICS paper) for wave equation shot record migration, to measure image focusing at a given (x,y) as a function of time shift. This is commonly called a "time-shift gather". Our patent-pending Migration Focusing Velocity Analysis (MVFA) technique converts the optimal time shift on a time-shift gather to a error in velocity. Does the method work? Take a look at the velocity panel below, extracted over the shot location shown above:

(click to enlarge)

The velocity panel on the right gives clear indication of the velocity, even in the presence of noise, topography, and dip. The peaks on the panel can be picked like a conventional semblance panels, but they were generated from depth migration, not from surface stacking!

Migration Velocity Focusing Analysis...Velocity from Wave Equation Depth Migration
Look at this shot record...it's a mess. You've got over 1,000 feet of topography over the spread, scattered noise in the near surface, reverberations from topography, and irregular acquisition geometry. Trying to estimate velocity around here will not be easy if you use a conventional approach, such as vertical shift to a "processing datum" and CMP semblance. The CMP gathers may not be regularly sampled, and variations in topography and near-surface velocity may make the reflection events highly non-hyperbolic. (click to enlarge) In complex areas, WIT's wave equation shot record depth migration is the most flexible tool to get a good image, when you have an accurate velocity. Our algorithm handles surface topography and irregular acquisition geometry. Rather than stacking the surface data, prestack depth migration "stacks" the data after downward continuation, below all the junk on the surface. Here's a novel concept: Why not use focusing information from the depth migration to estimate velocity? We use the "time-shift imaging condition" (See Sava and Fomel's 2006 GEOPHYSICS paper) for wave equation shot record migration, to measure image focusing at a given (x,y) as a function of time shift. This is commonly called a "time-shift gather". Our patent-pending Migration Focusing Velocity Analysis (MVFA) technique converts the optimal time shift on a time-shift gather to a error in velocity. Does the method work? Take a look at the velocity panel below, extracted over the shot location shown above: (click to enlarge) The velocity panel on the right gives clear indication of the velocity, even in the presence of noise, topography, and dip. The peaks on the panel can be picked like a conventional semblance panels, but they were generated from depth migration, not from surface stacking!
Interested in reading more about WIT's MVFA technology? Click below to download two SEG abstracts presented at the 2008 meeting in Las Vegas: Velocity model building with Wave Equation Migration Velocity Focusing Analysis - By Brown, Higginbotham, and Clapp (SVIP 2, 09:15) Wave Equation Migration Velocity Focusing Analysis - By Higginbotham, Brown, and Clapp (SVIP 2, 09:40)
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