Ray-path concepts for converted-wave seismic refraction

Hearn, Steve and Meulenbroek, Alan (2011) Ray-path concepts for converted-wave seismic refraction. Exploration Geophysics, 42 2: 139-146. doi:10.1071/EG10030


Author Hearn, Steve
Meulenbroek, Alan
Title Ray-path concepts for converted-wave seismic refraction
Journal name Exploration Geophysics   Check publisher's open access policy
ISSN 0812-3985
1834-7533
Publication date 2011-01-01
Sub-type Article (original research)
DOI 10.1071/EG10030
Volume 42
Issue 2
Start page 139
End page 146
Total pages 8
Place of publication Collingwood, Australia
Publisher C S I R O Publishing
Language eng
Formatted abstract
P-wave reflection-statics solutions typically incorporate P-wave refraction data, derived from the first breaks of the production data. Similarly, converted-wave refractions, taken from inline-component recordings, can be exploited to yield S-wave receiver statics, required in the processing of converted-wave reflection data. This methodology requires extensions to well known P-wave refraction analysis methods. This paper outlines extensions of the slope-intercept method and the reciprocal method, required to analyse converted-wave refractions. We discuss the computation of S-wave time-depths and describe how the observed ratio of S-wave to P-wave time-depths can provide a useful estimate of the near-surface V P/V S ratio, which is of interest in the analysis of engineering rock strengths.

We also include discussion of several related practical issues, with particular reference to dynamite sources. When the source is buried in the refractor, the required reciprocal times cannot be directly measured from the raw travel-time data. They can, however, be easily derived via correction using measured intercept times. Often converted-wave refractions are of poorer quality than conventional P-wave refractions, such that reversed refractions may not be available over some parts of the spread. In this situation, the preferred time-depth quantity cannot be computed. However, delay-times derived from single-ended data can be substituted, particularly if lateral variations in refractor velocity are allowed for.

The concepts outlined here are used in a companion paper to correct S-wave receiver statics in a coal-scale dataset from the Bowen Basin in central Queensland.
Keyword Converted-wave
Delay-time
Reciprocal method
Seismic refraction
Slope-intercept
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
Official 2012 Collection
 
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Created: Tue, 28 Feb 2012, 02:12:21 EST by Ashleigh Paroz on behalf of School of Earth Sciences