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| Titel |
Seismic attenuation: Laboratory measurements in fluid saturated rocks |
| VerfasserIn |
Shankar Subramaniyan, Claudio Madonna, Nicola Tisato, Erik Saenger, Beatriz Quintal |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089261
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| Publikation (Nr.) |
 EGU/EGU2014-3457.pdf |
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| Zusammenfassung |
| Seismic wave attenuation could be used as an indicator of reservoir fluids due to its
dependence on rock and fluid properties. Over the past 30 years, many laboratory
methodologies to study attenuation in rocks have been employed, such as ultrasonic
(MHz), resonant bar (kHz) and forced oscillation methods in the low frequency
range (0.01-100Hz) (Tisato & Madonna 2012; Madonna & Tisato 2013). Forced
oscillation methods have gained prominence over time as the frequency range of
measurements correspond to that of field seismic data acquired for oil/gas exploration.
These experiments measure attenuation as the phase shift between the applied stress
(sinusoidal) and measured strain. Since the magnitudes of measured phase shifts are
quite low (Q-1 ~0.01-0.1) and the amplitudes of strain applied to the rock samples
are of the order ~10-6 (i.e., similar orders of magnitude to seismic waves), it is
challenging. A comparison of such forced oscillation setups will be presented to provide
an overview of the various possibilities of design and implementation for future
setups.
In general, there is a lack of laboratory data and most of the published data
are for sandstones. Currently, attenuation measurements are being carried out on
carbonate and sandstone samples. We employ the Seismic Wave Attenuation Module
(SWAM, Madonna & Tisato 2013) to measure seismic attenuation in these samples for
different saturation degrees (90% and 100% water) and under three different confining
pressures (5, 10 and 15MPa). Preliminary results from these investigations will be
discussed.
REFERENCES
Madonna, C. & Tisato, N. 2013: A new seismic wave attenuation module to
experimentally measure low-frequency attenuation in extensional mode. Geophysical
Prospecting, doi: 10.1111/1365-2478.12015.
Tisato, N. & Madonna, C. 2012: Attenuation at low seismic frequencies in partially
saturated rocks: Measurements and description of a new apparatus. Journal of Applied
Geophysics, 86, 44-53. |
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