Volume 7, No. 5 May 1996
The Consortium for Research in Elastic Wave Exploration Seismology
|CREWES was a strong contributor to the recent CSEG Convention, with nine
talks and one poster paper. Several papers were recognized by the Technical Committee with
the following awards, which will be presented at the June 12th CSEG technical luncheon.
Best Poster Paper:
Hans Westbroek, Robert Stewart & Don Lawton:
Best Data Processing Paper:
Don Lawton, Jennifer Leslie & Richard Kellet: Structural imaging below dipping anisotropic layers: Predictions from seismic modelling
Best Student Paper:
Rob Ferguson & Robert Stewart: Characterizing a sand channel reservoir using 2.0, 4.5 and 10 Hz 3-C seismic data, Blackfoot, Alberta (Honorable Mention: Sue Miller, Evsen Aydemir, Gary Margrave, & Don Lawton: Coupled P-P and P-SV seismic interpretation of a Glauconitic channel, Blackfoot Field, Alberta)
Congratulations on your excellent work!
Landmark Graphics Corporationis making a software donation with a commercial value of $5 million to the Department of Geology and Geophysics through CREWES and the Foothills Research Project. Landmark has supported our efforts since 1989, when we were awarded our first RT workstation as a result of a worldwide competition. Since that time, we have maintained a number of Landmark applications on a dedicated platform. This new grant gives us multiple licenses for SeisWorks and ProMAX , and thus allows us to use these programs for teaching as well as research. We will also receive licenses for a variety of other Landmark applications, including ZMap+, StratWorks, PetroWorks, Rave, TDQ, SeisCube, and more. The software will run on the new UltraSPARC workstations.
Special thanks to some of the folks at Landmark who helped make this happen: Merv Swan (Regional Vice President, Canada), Clayton Phair, Scott Lowry, Josette Van Driel, Thom Fisher (Director, Third-Party and University Relations) and Chris Dale.
Perhaps the some of the most exciting news (so far!) from the Blackfoot survey is the critical importance of Vs in determining sand/shale ratios from these data. Many literature studies of well log and core data report lower Vp/Vs values in sandstones than in shales. At Blackfoot, studies of dipole sonic log data confirm this result and show that it is a relative increase in Vs which lowers the ratio. In this area, Vp is quite insensitive to changes in the channel-fill sediments. Figure 1 is a plot of Vs versus Vp for the Glauconitic Formation using dipole sonic log data from the 8-8 well (sand channel) and the 12-16 well (shale channel). According to these data, Vs is significantly higher in sandstone than in shale, whereas Vp is similar for both. The encircled points from the 12-16 well are taken from a thin layer of sand in this well, and plot in the same region as Vs values from the sand-channel well.
Seismic modelling studies of these wells show that this change in Vp/Vs should be detectable using Vp/Vs isochron analysis of seismic data (Miller et al., 1995, CREWES Research Report 7, Chapter 42). Based on the well log data analysis, a decrease in Vp/Vs along the 3C-2D seismic line was interpreted to represent a sandstone channel which shales out along the edges. This Vp/Vs decrease was observed using both Vp/Vs isochron analysis (Miller et al., 1995) and P-P and P-S velocity inversion of 2 Hz seismic data (Ferguson & Stewart, 1996, CSEG Convention). The inversions were independent of the horizon picks used for Vp/Vs isochron analysis. A comparison of P-wave and S-wave velocity inversions shows that the Vp/Vs decrease occurs because there is an increase in S-wave velocity at this location (Figure 2) while the P-wave velocity remains constant. The circled area is higher velocity and is interpreted to be channel sands.
Fig. 1. Vs vs. Vp from dipole sonic log data.
Fig. 2. 2 Hz S-wave velocity inversion.
Please note:The Sponsors Meeting will be held from November 3 to 5, not October 27 - 29 as previously reported. This will allow us to present results from the Blackfoot 3C-3D survey, which are available for CREWES presentation after November 1, 1996. We'll send you more details as the Meeting approaches.
Bahraini security guard protects precious CREWES technology!?!
|Over the past few years, CREWES has been working with a number of international companies and universities. This provides insight into new technologies and geophysical problems worldwide. We intend to increase our international efforts. Towards this end, Drs. Rob Stewart and John Bancroft presented posters at the Middle Eastern Petroleum Conference - Geo 96 in Bahrain in April. We will also have a strong presence at the EAGE Conference in Amsterdam in June. Nine CREWES papers will be presented (see the March CREWES NEWS for details).|
Processing of the 3C-3D Blackfoot Seismic Project is almost complete and we are really excited about the results. We also have the intial products from the 3-D VSP which was recorded simultaneously, and are very encouraged. The correlations between vertical and horizontal components of the surface seismic and the VSP data are very good. This data is now available to Blackfoot Seismic Project participants. A meeting for Blackfoot participants is tentatively scheduled for July 30th, 1996, at the Metropolitan Centre in Calgary. Boyd Petrosearch will present the interpretation report and the Project will be formally wrapped up. Further results will be presented at the CREWES Sponsors Meeting, November 3-5, 1996. Participation in the Blackfoot Seismic Project is still available; contact John Boyd at Boyd Petrosearch (233-2455) for more information.
Check out the June issue of the CSEG Recorder for an overview of the Blackfoot seismic surveys!
|The CREWES Project
Dept. of Geology & Geophysics
University of Calgary
2500 University Dr. N.W.
T2N 1N4 CANADA
Dr. Robert Stewart: 220-3265
Dr. Jim Brown: 220-7484
Dr. Don Lawton: 220-5718
Siriporn Chaisri: 220-3083
Wai-Kin Chan: 220-8093
Maria Donati: 220-6444
Jocelyn Dufour: 220-8266
Ken Fang: 220-8093
Robert Ferguson: 220-3271
Helen Isaac: 220-8396
Glenn Larson: 220-3458
Xinxiang Li: 220-6749
Nicolas Martin: 220-3083
Darryl Parry: 220-3032
Chanpen Silawongsawat: 220-3083
Zandong Sun: 220-6444
Dan Vetrici: 220-3269
Shaowu Wang: 220-5027
Hans Westbroek: 220-6596