Forward wave-field extrapolation operators sirnulmte propagation effects from one depth level to another. Inverse wave-field extrapolation operators dim-inrrtc> those propagation effects. Since forward wavefield extrapolation can be described in terms of spatial convolution. inverse wave-field extrapolation can be described in terms of spatial drc,on~olrrtion. A simple approximation to a stable, spatially band-limited deconvolution operator is obtained by taking the complex conjugate of the convolution operator. A one-way version of the Kirchholf integral that contains the conjugate complex Green' s function is derived. Unlike the situation with respect to the forward problem, the modification of the c~loscd surface integral into an open boundary integral involves an approximation that is identical to the approximation in the conjugate complex deconvolution approach. This approximation neglects the evanescent field and causes a second-order amplitude error. For a plane acquisition surface, the one-way Kirchhoff integral is transformed into a one-way Rayleigh integral. For media with small to moderate contrasts, the one-way Rayleigh integral with the conjugate complex Green' s function describes true amplitude inverse extrapolation of primary waves. This is illustrated with an example, in which the Green' s function has been modeled with the Gaussian beam method.
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.
We thank Dr Levin and Dr Lee for pointing out that the terminology "zero-offset single-fold redatumed sections" for our Fig. 17c is confusing. We fully agree and therefore this terminology is not used. In our paper we used the terminology " single-fold redatumed section ", meaning: a section obtained by redatuming a single shot record. Levin and Lee are right in saying that stacking many of these sections does not necessarily imply constructive addition. We did similar kinematic exercises in the early stages of our project and we came to exactly the same conclusion. acquisition surface new datum w . rvI secondary source FIG. 1. By stacking single-fold redatumed sections, secondary sources are constructed at the new datum. Each secondary source has wide-angle directivity properties if it is illuminated under many angles by the true sources.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.