WIT Inc. is pleased to present our 3D Shot Gather Migration tool. Run through our SeisPak^TM processing system, this industrial-strength migration code scales very efficiently in WIT's multi-core parallel computing environment. The algorithm has many efficiency-enhancing features, developed by Dr. Joe Higginbotham and tested over many years on a variety of depth imaging projects from around the world.

Algorithm specifications

• High quality PSPI imaging algorithm
• Expanding aperture option with increasing depth
• Makes one large depth step through constant velocity layers
• Increase depth step with increasing velocity
• Interpolation before applying imaging condition to avoid aliasing
• Shot consolidation improves efficiency without discarding data

Sub-salt depth imaging

WIT's 3D Shot Gather Migration is a excellent candidate for your sub-salt imaging needs. Our algorithm correctly handles the extreme lateral velocity variations often found around Gulf of Mexico salt bodies, and can image in VTI media. Our 3D Shot Gather Migration has an option to compute and compensate for variable subsurface illumination; this is almost always an important issue around and under salt.

Depth Imaging on Land

Land data often require depth imaging, and WIT's 3D Shot Gather Migration is a excellent candidate to fill your needs, especially if you're exploring in regions with large lateral velocity variations, or with topographic relief. Our code can easily image either pure shear waves or P-to-S converted waves, simply by supplying the appropriate velocity cube(s).

VSP/OBC Depth Imaging

WIT's 3D Shot Gather Migration is a highly flexible tool; sources and receivers can exist anywhere in (x,y,z) space, which makes our code applicable to both VSP and OBC geometries. Moreover, our code can easily image P-to-S converted waves, which may help discriminate lithologies, simply by supplying the appropriate velocity cube(s).

Shot Gather Migration Applied to BP 2D Velocity Benchmark Synthetic

Click on any of the small images below to view the results of WIT's Shot Gather migration performed on the BP 2D Velocity Benchmark Synthetic. This dataset, distributed as a blind velocity test, has nonetheless gained popularity as a test of migration algorithms (when the correct velocity is used, as it is here). While the overturned flanks of the "tooth" salt on the model's right side generally require reverse time migration to be imaged correctly, notice that our code does an excellent job on the rugose salt body on the model's left side. This salt body, similar to those seen in the ultradeep Gulf of Mexico, causes severe focusing and defocusing of the wavefield, and presents lateral velocity variations that challenge many wave equation migration codes.

Click on any thumbnail image above to start "slideshow"

Click on any thumbnail image above to start "slideshow"

Shot Gather Migration Applied to Hess 2D VTI Synthetic Data

Click on any of the small images below to view the results of WIT's Shot Gather migration performed on the Hess 2D VTI Synthetic dataset. These data, modeled by Hess Corp., mimic the situation interpreted to be found at the Baldpate field, an early Gulf of Mexico deepwater sub-salt field. The primary targets are the two "sands" truncating against the underside of the salt. The data are VTI, but not weakly so, as the Thomsen parameters in the large anisotropic "pod" exceed 0.25. Our VTI extension to WIT's Shot Gather Migration code yields a superior result for less than twice the cost of isotropic migration.

Click on any thumbnail image above to start "slideshow"