EFFICIENT 2D AND 3D SHOT RECORD REDATUMING¹

Abstract

KINNEGING, N.A., BUDEJICKY, V., WAPENAAR, C.P.A. and . Efficient 2D and 3D shot record redatuming. Geophysical Prospecting 37,493-530.In order to make 3D prestack depth migration feasible on modern computers it is necessary to use a target-oriented migration scheme. By limiting the output of the migration to a specific depth interval (target zone), the efficiency of the scheme is improved considerably. The first step in such a target-oriented approach is redatuming of the shot records at the surface to the upper boundary of the target zone. For this purpose, efficient non-recursive wavefield extrapolation operators should be generated. We propose a ray tracing method or the Gaussian beam method. With both methods operators can be efficiently generated for any irregular shooting geometry at the surface. As expected, the amplitude behaviour of the Gaussian beam method is better than that of the ray tracing based operators.The redatuming algorithm is performed per shot record, which makes the data handling very efficient. From the shot records at the surface 'genuine zero-offset data' are generated at the upper boundary of the target zone. Particularly in situations with a complicated overburden, the quality of target-oriented zero-offset data is much better than can be reached with a CMP stacking method at the surface. The target-oriented zero-offset data can be used as input to a full 3D zero-offset depth migration scheme, in order to obtain a depth section of the target zone.

3D primary estimation by sparse inversion using the focal domain parameterization

“…This forward model was derived to describe migration algorithms. Note that all matrices can be interpreted in a full 3D sense, as shown by Kinneging et al (1989).…”

Electromagnetic interferometry in wavenumber and space domains in a layered earth

“…Because a source is redatumed at every receiver position, the matricesR are square. Note that the grid of receivers and the grid of sources is represented in one column or one row, respectively, to avoid tensors of higher order than two (Kinneging et al, 1989). The disadvantage of this approach is that the matrices are large.…”

Marine controlled-source electromagnetic interferometry

“…Since at every receiver position a source is redatumed, the matricesR are square. Note that the grid of receivers and the grid of sources is represented in one column or one row, respectively, in order to avoid tensors of higher order than 2 (Kinneging et al, 1989). The disadvantage of this approach is that the matrices are large.…”