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A Born-WKBJ inversion method for acoustic reflection data

Clayton, Robert W. and Stolt, Robert H. (1981) A Born-WKBJ inversion method for acoustic reflection data. Geophysics, 46 (11). pp. 1559-1567. ISSN 0016-8033. http://resolver.caltech.edu/CaltechAUTHORS:20121010-132926440

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Abstract

Density and bulk modulus variations in an acoustic earth are separately recoverable from standard reflection surveys by utilizing the amplitude-versus-offset information present in the observed wave fields. Both earth structure and a variable background velocity can be accounted for by combining the Born and WKBJ approximations, in a "before stack" migration with two output sections, one for density variations and the other for bulk modulus variations. For the inversion, the medium is considered to be composed of a known low-spatial frequency variation (the background) plus an unknown high-spatial frequency variation in bulk modulus and density (the reflectivity). The division between the background and the reflectivity depends upon the frequency content of the source. For constant background parameters, computations are done in the Fourier domain, where the first part of the algorithm includes a frequency shift identical to that in an F-K migration. The modulus and density variations are then determined by observing in a least-squares sense amplitude versus offset wavenumber. For a spatially variable background, WKBJ Green's operators that model the direct wave in a medium with a smoothly varying background are used. A downward continuation with these operators removes the effects of variable velocity from the problem, and, consequently, the remainder of the inversion essentially proceeds as if the background were constant. If the background is strictly depth dependent, the inversion can be expressed in closed form. The method neglects multiples and surface waves and it is restricted to precritical reflections. Density is distinguishable from bulk modulus only if a sufficient range of precritical incident angles is present in the data.


Item Type:Article
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http://dx.doi.org/10.1190/1.1441162DOIUNSPECIFIED
http://geophysics.geoscienceworld.org/content/46/11/1559.abstractPublisherUNSPECIFIED
Additional Information:© 1981 Society of Exploration Geophysicists. Manuscript received by the Editor July 30, 1980; revised manuscript received April 20, 1981. We would like to thank the sponsors of the Stanford Exploration Project for their support.
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Stanford Exploration ProjectUNSPECIFIED
Record Number:CaltechAUTHORS:20121010-132926440
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20121010-132926440
Official Citation:Robert W. Clayton and Robert H. Stolt A Born-WKBJ inversion method for acoustic reflection data Geophysics, November 1981, v. 46, p. 1559-1567, doi:10.1190/1.1441162
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34828
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:10 Oct 2012 21:35
Last Modified:27 Dec 2012 02:51

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