Straight-Ray Datuming in 3-D Media: Fast and Flexible

Tariq Alkhalifa¹*, Henk Innemee², and Chris Benson^2
1KACST, Saudi Arabia
²Spectrum, UK
*[email protected]

Common datuming approaches, like the Kirchhoff or finite-difference methods, require rea-sonable sampling of the sources and receivers. This becomes a serious limitation for da-tuming data acquired using 3-D conventional land-acquisition layouts, because of the typi-cal sparse spacing of either the sources or receivers. To combat this, we extend Alkhalifah and Bagiani’s (2006) straight-ray datuming (SRD) to handle 3-D acquisition geometries. As in the 2-D case, 3-D SRD is based on the straight-ray assumption above-and-below the datum with Snell’s Law honored in between. This allows for the application of SRD to common-shot gathers in one operation (no need to sort the data to common receivers). Similarly, it can be applied to common-receiver gathers without the need to sort the data back to common-shot gathers. This feature allows for more flexibility in acquisition as it requires, unlike in the conventional case, either the sources or receivers to have a complete fine coverage of the area. In addition, SRD does not require a detailed description of the near-surface velocity model; information from refraction static or any other commonly used method to obtain near-surface time shift suffice. SRD, in addition to carrying out reda-tuming, can be used to map irregularly sampled spatial data at the acquisition surface into regularly sampled data at the datum. In fact, since the operation is a partial migration, it suppresses diffractions generated from inhomogeneities above the datum. The computa-tional cost of applying 3-D SRD is larger than static corrections, but because of the limited spatial extension and analytical formulation, it is far less than Kirchhoff re-datuming.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain