Journal Published Online: 24 March 2014
Volume 37, Issue 3

Signal Processing Challenges When Processing DST and CST Seismic Data Containing TIRs



Downhole Seismic Testing (DST) and Crosshole Seismic Testing (CST) are important geotechnical testing techniques which provide for low strain (<10–5) in situ compression (Vp) and shear (Vs) wave velocity estimates. The Vs and Vp interval velocities are determined by obtaining relative arrival times of source waves as they travel through the stratigraphy and are recorded by one or more vertically (DST) and/or horizontally (CST) offset seismic sensors. The relative arrival times are typically obtained by cross-correlating the recorded source waves or identifying reference features within the seismic trace such as a peak, trough, crossover point, or first break. A very common and yet poorly understood problem encountered in DST and CST is the analysis of seismograms that contain Total Internal Reflections (TIRs). TIRs arise when the incident angle exceeds the critical angle; as a result of which reflection coefficients become complex, which in turn leads to distortions in the reflected source wave. This paper addresses the issue of TIRs and the signal processing challenges when processing seismic data containing TIRs.

Author Information

Baziw, Erick
Baziw Consulting Engineers Ltd., Vancouver, B.C., CA
Verbeek, Gerald
Baziw Consulting Engineers Ltd., Vancouver, B.C., CA
Pages: 20
Price: $25.00
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Stock #: GTJ20130122
ISSN: 0149-6115
DOI: 10.1520/GTJ20130122