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Titel |
Poisson's ratio model derived from P- and S-wave reflection seismic data at the CO2CRC Otway Project pilot site, Australia |
VerfasserIn |
Thies Beilecke, Charlotte M. Krawczyk, David C. Tanner, Jennifer Ziesch, Research Group PROTECT |
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 |
250091428
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Publikation (Nr.) |
EGU/EGU2014-5721.pdf |
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Zusammenfassung |
Compressional wave (P-wave) reflection seismic field measurements are a standard tool for
subsurface exploration. 2-D seismic measurements are often used for overview
measurements, but also as near-surface supplement to fill gaps that often exist in 3-D seismic
data sets. Such supplementing 2-D measurements are typically simple with respect to field
layout. This is an opportunity for the use of shear waves (S-waves).
Within the last years, S-waves have become more and more important. One reason is that P-
and S-waves are differently sensitive to fluids and pore fill so that the additional S-wave
information can be used to enhance lithological studies. Another reason is that
S-waves have the advantage of higher spatial resolution. Within the same signal
bandwidth they typically have about half the wavelength of P-waves. In near-surface
unconsolidated sediments they can even enhance the structural resolution by one order of
magnitude.
We make use of these capabilities within the PROTECT project. In addition to already
existing 2-D P-wave data, we carried out a near surface 2-D S-wave field survey at the
CO2CRC Otway Project pilot site, close to Warrnambool, Australia in November
2013. The combined analysis of P-wave and S-wave data is used to construct a
Poisson’s Ratio 2-D model down to roughly 600 m depth. The Poisson’s ratio values
along a 1 km long profile at the site are surprisingly high, ranging from 0.47 in
the carbonate-dominated near surface to 0.4 at depth. In the literature, average lab
measurements of 0.22 for unfissured carbonates and 0.37 for fissured examples have been
reported. The high values that we found may indicate areas of rather unconsolidated
or fractured material, or enhanced fluid contents, and will be subject of further
studies.
This work is integrated in a larger workflow towards prediction of CO2 leakage and
monitoring strategies for subsurface storage in general.
Acknowledgement: This work was sponsored in part by the Australian Commonwealth
Government through the Cooperative Research Centre for Greenhouse Gas Technologies
(CO2CRC). PROTECT is funded through the Geotechnologien research programme in
Germany (grant 03G0797). |
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