Volume 7, No. 6/7 June/July 1996
The Consortium for Research in Elastic Wave Exploration Seismology
We would like to give a hearty welcome to new Sponsors of the CREWES Project:
Exploration Seismic Services Ltd. (Exssel): Dr. David C. Ganley will be the CREWES representative for this Calgary-based service company.
Intevep, S.A.: This company, based in Venezuela, has provided support for Maria Donati to do her M.Sc. degree. CREWES representative is Dr. Reinaldo Michelena.
Marathon Oil Company: Marathon, based in Houston, Texas, will be represented by Mr. Chuck Meeder.
We welcome you all on board the CREWES Project and look forward to seeing you at this year's Sponsors Meeting at the Kananaskis Lodge.
|Congratulations to Maria Donati, who has successfully defended her
M.Sc. thesis: "P- and S- Wave Separation using Three-component Filters". Maria
is returning to her native Venezuela, where she has worked with Intevep S.A. since 1989.
She will continue her work there as she pursues her Ph.D. long distance at the University
of Calgary. Congratulations and good luck, Maria!
We're very pleased to announce that Dr. Gary Margrave is now an Associate Director of the CREWES Project. Gary joined the Project as a Senior Research Geophysicist in April of 1995 and has made many contributions in research and teaching since his arrival. He will take over directorial responsibilities from Dr. Jim Brown. As mentioned in the March newsletter, Jim will be working with PGS Reservoir in Norway during a two year leave of absence.
Two new staff people joined the Project in July. Vladan Simin is taking over Stan Gorek's responsibilities. Stan left the CREWES Project at the end of May and we wish him all the best for the future. Vlad's primary duties will be ProMAX support and development. He graduated with a B.Sc. in Geophysics from the University of Calgary in 1992. Since then, he has worked with Exssel and Integra Geoservices as a seismic data processing geophysicist.
Colin Potter has also joined us at CREWES. He graduated with a B.Sc. in Geophysics from the University of Calgary in 1990. Colin's most recent work experience was with Exploration Innovations, where he provided client support for Photon and Landmark software. His knowledge will be put to good use here in geophysical applications software support and development.
Editor's Note: This is an abstract of Maria's M.Sc. thesis presentation, given June 26, 1996, at the University of Calgary. The complete bound thesis will be distributed at the Sponsors Meeting.
The separation of individual P- and S-wave arrivals may be considered a problem since, due to the intrinsic geophone responses, P and S waves are observed on vertical, radial, and transverse geophone components. A method of separating P and S waves in the t-p domain is presented which inverts the three geophone records for the geophone responses, thereby separating the two wave types. The P-S modal filter coefficients in both 2-D and 3-D cases are calculated from the geophone responses and completely determined by the near-surface P- and S-wave velocities.
The P-S modal filter is developed for 3C-2D and 3C-3D data sets. For the 3C-2D case we consider two types of data: one acquired with the geophone on the surface (free-surface case) and a second one with the geophones located at a liquid-solid contact. The geophone responses of the vertical and radial geophones are different for each of the cases, but the modal filter method is the same. The P-S separation is tested using synthetic and real data. The modal filter is capable of separating pure P, S, and converted reflections and appears to have low sensitivity to errors in the near-surface P- and S-wave velocities and to noise in the data.
For the 3C-3D case, the responses in 3-D for the vertical, radial and transverse geophones are reviewed. A 3-D t-p transform is developed for the 3C-3D modal filter which can be applied to data distributed over an areal coverage without assuming any geometric symmetry. The 3-D t-p transform is tested using synthetic data which includes P and converted waves without and with random noise and ground roll added. The 3-D t-p transform performs well by reconstructing the original data and also removing the noise and ground roll present in the input data.
Kangang (Ken) joined the CREWES Project in 1995 as a M.Sc. student working with Dr. Jim Brown. Prior to coming to Canada, he worked at the Petroleum University at Beijing, China. Kangang was doing research in exploration geophysics and teaching geophysics from 1986 to 1994. He obtained his B.Sc. and M.Sc. in geophysics from the East China Petroleum Institute in 1983 and 1986, respectively.
Publications and Presentations:
AVO analysis and inversion of elastic parameters, 1992, Oil Geophysical Prospecting, 27, 4.
A fast and accurate algorithm for 2D DMO using F-K method, 1991, Oil Geophysical Prospecting, 26, 3.
Kangang Fang and R. James Brown, The relationship of Thomsen anisotropic parameters to the crack density in cracked media: 1996 CSEG National Convention, Calgary, Alberta.
The CREWES Project is expanding its research capabilities through the addition of new staff, nine new graduate students in '96-'97, more computing power, and further field work and analysis. To facilitate this growth, and as the sponsorship fee has not changed since 1988, we require additional support. As recommended by our Industrial Advisory Board at the last IAB Meeting, the fees for CREWES sponsorship will increase to $30,000 per year starting in 1997. Still a terrific bargain! We have had a very strong year in 1996 and will deliver a bundle of results at our November Meeting especially from the 3C-3D survey at Blackfoot. Great plans are in store for 1997.
|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