Time-frequency coherency analysis of three-component crosshole seismic data for arrival detection
- Univ. of Mining and Metallurgy, Krakow (Poland). Dept. of Geophysics
- Tohoku Univ., Sendai (Japan). Faculty of Engineering
Seismic measurements are used for precise evaluation of subsurface structure. Such precision is essential in a wide range of geophysical problems, including hydrocarbon exploration, geothermal reservoir characterization, or detection of discontinuities in coal beds. A processing method for three-component wide-band crosshole seismic data is presented. It is based on the observed phenomena of a decrease in the coherency between the coda waves recorded by closely spaced sensors or exited by closely spaced seismic sources. The authors transfer signals to the time-frequency domain and compute the instantaneous coherency at each moment of time between signals propagated on adjacent raypaths. /As a result, the authors obtain the distribution of the high-coherency time-frequency areas connected with coherent components of the signal. They can then see different modes of the recorded seismic signal and identify them as direct P- and S-waves, reflected waves, and converted tube waves. A reliable method of evaluation of the onset`s time for different modes of the seismic signal is also proposed. The technique has good resolution and allows separation of even very closely spaced wavefield components.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 316254
- Journal Information:
- Geophysics, Vol. 63, Issue 6; Other Information: PBD: Nov-Dec 1998
- Country of Publication:
- United States
- Language:
- English
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