Frequency domain beamforming of ultrasound signals from inhomogeneous media using range Doppler method

2019 ◽  
Vol 146 (4) ◽  
pp. 2862-2862
Author(s):  
Marko Jakovljevic ◽  
Roger Michaelides ◽  
Ettore Biondi ◽  
Howard Zebker ◽  
Jeremy J. Dahl
Keyword(s):  
Frequency Domain ◽  
Inhomogeneous Media ◽  
Doppler Method ◽  
Ultrasound Signals

Application of a Range-Doppler Algorithm to Frequency-Domain Beamforming of Ultrasound Signals

2020 ◽  
Author(s):  
Marko Jakovljevic ◽  
Roger Michaelides ◽  
Ettore Biondi ◽  
Carl Herickhoff ◽  
Dongwoon Hyun ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Ultrasound Signals

Depth migration of imaged time sections

Geophysics ◽  
1981 ◽  
Vol 46 (5) ◽  
pp. 734-750 ◽  
Author(s):  
Kenneth L. Larner ◽  
Leslie Hatton ◽  
Bruce S. Gibson ◽  
I‐Chi Hsu
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Frequency Domain ◽  
Difference Method ◽  
Velocity Model ◽  
Inhomogeneous Media ◽  
Summation Method ◽  
Frequency Domain Method ◽  
Depth Migration ◽  
The Finite Difference Method

None of the leading approaches to the migration of seismic sections—the Kirchhoff‐summation method, the finite‐difference method, or the frequency‐domain method—readily migrates seismic reflections to their proper positions when overburden velocities vary laterally. For inhomogeneous media, the diffraction curve for a localized, buried scatterer is no longer hyperbolic and its apex is displaced laterally from the position directly above the scatterer. Hubral observed that the Kirchhoff‐summation method images seismic data at emergent “image ray” locations rather than at the desired positions vertically above scatterers. In addition, distortions in diffraction shapes lead to incorrect imaging (i.e., incomplete diffraction collapse) and, hence, to further displacement errors for dipping reflections. The finite‐difference method has been believed to continue waves downward correctly through inhomogeneous media. In conventional implementations, however, both the finite‐difference method and frequency‐domain approach commit the same error that the Kirchhoff method does. Synthetic examples demonstrate how conventional migration fails to image events completely. Hubral’s solution to this migration problem is two‐ (or three‐) dimensional mapping of imaged time sections into depth. This mapping, “depth migration,” replaces simple vertical conversion from time to depth. Such depth migration can be postponed until after efficient image‐ray modeling has been performed to (1) support the final choice of velocity model, and (2) determine whether depth migration is necessary. Comparisons between depth‐migrated and conventionally depth‐converted sections of both synthetic and field data properly show that significant lateral displacement is often required to position reflectors properly. Monte Carlo studies show that the lateral corrections can be important not only in absolute terms but also in relation to errors expected from an inaccurate velocity model.

Correction to "The analysis of slug tests in the frequency domain" (WRR 25(11), pp. 2388-2396

1990 ◽  
Vol 26 (8) ◽  
pp. 1863-1863
Author(s):  
Paul Marschall ◽  
Baldur Barczewski
Keyword(s):  
Frequency Domain ◽  
Slug Tests
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