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GEOREF RECORD

Numerical computation of individual far-field arrivals excited by an acoustic source in a borehole

Andrew L. Kurkjian
Numerical computation of individual far-field arrivals excited by an acoustic source in a borehole
Geophysics (May 1985) 50 (5): 852-866

Abstract

In this paper, I model the acoustic logging problem and numerically compute individual arrivals at far-field receivers. The ability to compute individual arrivals is useful for examining the sensitivities of each arrival to various factors of interest, as opposed to examining the full waveform as a whole. While the numerical computation of the mode arrivals (Peterson, 1974) and the numerical computation of the first head waves (Tsang and Rader, 1979) have been previously reported, the numerical computation of the entire set of head-wave arrivals is new and is the major contribution of this paper.Following Roever et al. (1974) and others, the full wave field is represented as a sum of contributions from both poles and branchcuts in the complex wavenumber plane. The pole contributions correspond to mode arrivals while the branch cuts are associated with body waves (i.e., head waves). Both the pole and branch cut contributions are computed numerically and results are presented for the cases of a slow and a fast formation. The shear event in the slow formation is found to be relatively small, consistent with observations in measured data. Contrary to existing knowledge, the shear event in the fast formation is also relatively small. The apparent strong shear arrival in the full waveforms is due primarily to the trapped mode pole in the vicinity of cutoff.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 50
Serial Issue: 5
Title: Numerical computation of individual far-field arrivals excited by an acoustic source in a borehole
Author(s): Kurkjian, Andrew L.
Affiliation: Schlumberger-Doll Res., Ridgefield, CT, United States
Pages: 852-866
Published: 198505
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 17
Accession Number: 1985-079347
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 1985
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