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Title: Computational aspects of Gaussian beam migration

Abstract

The computational efficiency of Gaussian beam migration depends on the solution of two problems: (1) computation of complex-valued beam times and amplitudes in Cartesian (x,z) coordinates, and (2) limiting computations to only those (x,z) coordinates within a region where beam amplitudes are significant. The first problem can be reduced to a particular instance of a class of closest-point problems in computational geometry, for which efficient solutions, such as the Delaunay triangulation, are well known. Delaunay triangulation of sampled points along a ray enables the efficient location of that point on the raypath that is closest to any point (x,z) at which beam times and amplitudes are required. Although Delaunay triangulation provides an efficient solution to this closest point problem, a simpler solution, also presented in this paper, may be sufficient and more easily extended for use in 3-D Gaussian beam migration. The second problem is easily solved by decomposing the subsurface image into a coarse grid of square cells. Within each cell, simple and efficient loops over (x,z) coordinates may be used. Because the region in which beam amplitudes are significant may be difficult to represent with simple loops over (x,z) coordinates, I use recursion to move from cell tomore » cell, until entire region defined by the beam has been covered. Benchmark tests of a computer program implementing these solutions suggest that the cost of Gaussian hewn migration is comparable to that of migration via explicit depth extrapolation in the frequency-space domain. For the data sizes and computer programs tested here, the explicit method was faster. However, as data size was increased, the computation time for Gaussian beam migration grew more slowly than that for the explicit method.« less

Authors:
Publication Date:
Research Org.:
Colorado School of Mines, Golden, CO (United States). Center for Wave Phenomena
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
7200248
Report Number(s):
DOE/ER/14079-17; CWP-127
ON: DE92018641
DOE Contract Number:  
FG02-89ER14079
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 58 GEOSCIENCES; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; SEISMIC WAVES; IMAGE PROCESSING; ALGORITHMS; BENCHMARKS; EXTRAPOLATION; GAUSS FUNCTION; MIGRATION; WAVE PROPAGATION; FUNCTIONS; MATHEMATICAL LOGIC; NUMERICAL SOLUTION; PROCESSING; 422000* - Engineering- Mining & Underground Engineering- (1980-); 580000 - Geosciences; 990200 - Mathematics & Computers

Citation Formats

Hale, D. Computational aspects of Gaussian beam migration. United States: N. p., 1992. Web. doi:10.2172/7200248.
Hale, D. Computational aspects of Gaussian beam migration. United States. https://doi.org/10.2172/7200248
Hale, D. 1992. "Computational aspects of Gaussian beam migration". United States. https://doi.org/10.2172/7200248. https://www.osti.gov/servlets/purl/7200248.
@article{osti_7200248,
title = {Computational aspects of Gaussian beam migration},
author = {Hale, D},
abstractNote = {The computational efficiency of Gaussian beam migration depends on the solution of two problems: (1) computation of complex-valued beam times and amplitudes in Cartesian (x,z) coordinates, and (2) limiting computations to only those (x,z) coordinates within a region where beam amplitudes are significant. The first problem can be reduced to a particular instance of a class of closest-point problems in computational geometry, for which efficient solutions, such as the Delaunay triangulation, are well known. Delaunay triangulation of sampled points along a ray enables the efficient location of that point on the raypath that is closest to any point (x,z) at which beam times and amplitudes are required. Although Delaunay triangulation provides an efficient solution to this closest point problem, a simpler solution, also presented in this paper, may be sufficient and more easily extended for use in 3-D Gaussian beam migration. The second problem is easily solved by decomposing the subsurface image into a coarse grid of square cells. Within each cell, simple and efficient loops over (x,z) coordinates may be used. Because the region in which beam amplitudes are significant may be difficult to represent with simple loops over (x,z) coordinates, I use recursion to move from cell to cell, until entire region defined by the beam has been covered. Benchmark tests of a computer program implementing these solutions suggest that the cost of Gaussian hewn migration is comparable to that of migration via explicit depth extrapolation in the frequency-space domain. For the data sizes and computer programs tested here, the explicit method was faster. However, as data size was increased, the computation time for Gaussian beam migration grew more slowly than that for the explicit method.},
doi = {10.2172/7200248},
url = {https://www.osti.gov/biblio/7200248}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1992},
month = {Wed Jan 01 00:00:00 EST 1992}
}