WED3D: Semi-recursive Kirchhoff migration of the Marmousi, using first-arriv al traveltimes.

2-D and 3-D Kirchhoff wave-equation datuming
3DGeo's Kirchhoff wave-equation datuming program is designed to provide solutions for some of the most challenging imaging problems facing the industry today. Two of these challenges are imaging through complex velocity structures which give rise to complicated multivalued arrivals, and imaging under rugged topography which distorts the recorded seismic wavefield.

3DGeo's Kirchhoff wave-equation datuming program performs variable velocity upward and downward continuation of seismic data between arbitrarily shaped datums. The datuming program can be used individually or combined with 3DGeo's migration programs to provide efficient and effective imaging solutions.

Wave-equation datuming can reduce cost and facilitate imaging in a variety of challenging geological settings. By resynthesizing the data at a lower datum, it is possible to remove the complicating effects of the overlying velocity structure, which is often the major cause of imaging difficulties.

Subsalt Imaging
WED3D can be used for challenging subsalt imaging objectives, where complicated propagation through the salt layer creates difficulties for standard Kirchhoff imaging algorithms. By downward continuing the data through the salt layer, and imaging from some datum below the salt layer, a greatly improved image may be obtained. Also, the imaging problem in the lower part of the section may be simpler since sediment velocities are generally well behaved. This means that a simpler imaging algorithm (ie. time migration or poststack migration) can be used at depth once the complicated overburden has been datumed through. This can represent a substantial cost savings since simpler imaging algorithms are much less expensive than prestack depth imaging.

Semi-recursive Kirchhoff migration
The semi-recursive Kirchhoff depth migration developed by combining Kirchhoff datuming with Kirchhoff migration produces excellent images and application of the method to three dimensions offers great potential for enhanced image quality, increased accuracy, and computational efficiency. Combining steps of wave-equation datuming with Kirchhoff migration produces excellent images because the complex velocity model is subdivided and traveltimes are calculated under conditions where they accurately parameterize the wavefield (Bevc, 1995). By dividing the imaging problem in this way, the traveltimes are better behaved and multivalued arrivals are accounted for.

Easy Integration
The datuming software is modular in design and can be customized to a clients specific requirements. WED3D is available on vector supercomputers, workstations, and other architectures. If desired, 3DGeo can integrate the package into a clientęs processing environment. Any widely used seismic data format is accepted, as well as irregular geometries for both the data and the velocity model.