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TU Delft proves that seismic noise measurements work in practice

Delft University of Technology

Background noise from the earth can provide a wealth of information about the earth's crust, which for example can then be used when searching for new oil fields. Researchers from TU Delft have tested this relatively new discovery in a desert in the Middle East. The seismic noise measurements have shown that the theory also works in practice. An article by PhD candidate Deyan Draganov about this research subject has been published in Geophysical Research Letters.

When acoustic noise travels through a medium, such as the earth's crust, it compiles information. Ground microphones, in conjunction with a few simple mathematical processes (cross-correlation), can extract a meaningful signal from the earth's seismic noise. This relatively new method is called 'seismic interferometry'. For researchers, the great advantage of using existing seismic noise is that signals only need to be registered and not produced (with for example vibrating plates, explosives or microwaves).

Theory

Geophysicists Kees Wapenaar and Evert Slob of TU Delft, and Roel Snieder of the Colorado School of Mines, have recently generalised the underlying theory of seismic interferometry and demonstrated that the seismic noise can now be applied to a much wider scale of physical applications than was previously thought. Among the applications to which the theory can be applied is the process of searching for new oil and gas fields.

Practice

The TU Delft researchers, in partnership with Shell, have now tested their method. The noise measurements - recorded in a desert in the Middle East - have shown that the theory also works in practice. An article by PhD candidate Deyan Draganov about this research subject has been published in Geophysical Research Letters (22nd February).

Expert

Draganov has been involved in the development of seismic interferometry from the beginning and has made especially important contributions towards proving that the method is suitable for extracting reflection-data from the seismic noise (other researchers in this field focus primarily on surface area sound waves). Draganov, who will graduate later this year, is now regarded by the geophysical world as one of the experts in this field of research. His work is also regarded as particularly important for the LOFAR-project, but Shell is also extremely interested in applying this method to the search for new oil and gas fields.

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Note for editors

Draganov, D., K. Wapenaar, W. Mulder, J. Singer, and A. Verdel (2007), Retrieval of reflections from seismic background-noise measurements, Geophys. Res. Lett., 34, L04305, doi:10.1029/2006GL028735.

Ir. Deyan Draganov, +31 15 278 3103, d.s.draganov@tudelft.nl
Roy Meijer, Science Information Officer +31 15 278 1751, r.e.t.meijer@tudelft.nl

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