CREWES Project, University of Calgary

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CREWES Project, University of Calgary
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Latest company Consortium for Research in Elastic Wave Exploration Seismology

CREWES Project, University of Calgary, which stands for Consortium for Research in Elastic Wave Exploration Seismology, was established in 1989 by Professor Robert Stewart as part of his mandate as holder of the chair in Exploration Geophysics at the University of Calgary. Professor Stewart’s co-directors at that time were professors Don Lawton and Jim Brown. Since that time, CREWES has grown to become one of the most respected of the exploration geophysics consortia, whose 30 sponsors include all of the major integrated oil and gas companies, as well as all of the major geophysical contractors.[1]


Citation for the SEG Distinguished Achievement Award

Contributed by Leon Thomsen[2]

In 1989, “exploration seismology” was almost exclusively understood to mean “isotropic acoustic seismology.” There were a few folks with a renewed interest in shear waves, but the advantages of 3D imaging were quickly permeating the entire industry, and were being implemented mainly with the classic P-wave ideas. And, lots of oil was being found.

Against this background, the new occupant of the CSEG Chair in Exploration Seismology at the University of Calgary decided to build a research program around elastic waves instead. Rob Stewart, with greater prescience than most of us, went even further, to concentrate on converted waves, those strange wave types that convert themselves, from P to S (or PPS etc.) at elastic interfaces, because of the boundary conditions there. Because of such conversions, these waves are more complicated than are pure modes (either P or S), and were almost universally regarded, at the time, as curiosities rather than as useful phenomena. No matter; Stewart, and his colleagues Don Lawton and Jim Brown, defined the new Consortium for Research in Elastic Wave Exploration Seismology around these waves, and began to lay the foundations of basic understanding which would, in time, transform them into a crucial tool of modern exploration. They attracted talented students and colleagues to the new CREWES program; it has subsequently become the leading academic consortium in Canada, and one of the most well respected anywhere.

The names are too numerous to list, but the outstanding graduates include Scott Cheadle, David Eaton, Mark Harrison, Rob Vestrum, Helen Isaac, Michael Slawinski, and Rob Ferguson; and he faculty has now expanded to include Larry Lines, Gary Margrave, Larry Bentley, and adjunct John Bancroft.

With this much heft in the program, the focus has broadened appropriately, so that it is now a well-rounded one, stretching far beyond converted waves. The program includes new acquisition field methods and instruments, and physical modeling in the laboratory. It includes VSP and crosswell analysis, as well as surface seismics. And of course, it includes 3D and even 4D methods.

But, it is the original and continuing emphasis on converted waves that makes CREWES unique. They have developed a complete processing flow for converted waves, which now includes anisotropic rotations, statics solutions, velocity analysis, depth-variant mapping, P-S DMO, migration, and inversion. And, as it has become clear that multicomponent seismology is much less useful without including the effects of anisotropy, that topic has become woven into the acquisition design and processing flow. All these results, of course, have long been available to their sponsors; a subset is available to everyone who dials up http://www.crewes.org.

What makes all of this important is that, in recent years (long after the founding of CREWES) it has become possible to actually measure such waves in the marine environment, where most of the action is today. Of course, this development uses ocean-bottom seismometers; it has been the subject of another recent SEG award, and has opened up the world’s oceans to elastic wave exploration. It turns out that converted waves are crucial for imaging subsea reservoirs when P-wave images are obscured by overburden gas clouds (e.g., Valhall), or mud volcanoes (e.g., Azeri).

This alone validates Stewart’s early judgment. But, the list of useful applications for converted waves is much longer, including the characterization of fractured reservoirs (Cedar Hill), the detection of lithologic traps (Blackfoot), and the imaging of “P-transparent reservoirs” (Alba), which simply have poor P-reflectivity. All such reservoirs require vector technology that was developed long prior to its need being widely appreciated, much of it developed by the happy crew at CREWES. That is indeed a Distinguished Achievement.

References

  1. Consortium for Research in Elastic Wave Exploration Seismology.[1]
  2. Rutt Bridges (2004). ”2003 Awards Citations.” The Leading Edge, 23(2), 175-184. http://dx.doi.org/10.1190/tle23020175.1.


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CREWES Project, University of Calgary
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