Sam Gray has a long and distinguished record of publications addressing not only the theoretical side of wave propagation and migration theory (and other topics). But, significantly, along with these contributions, his work has also focused on the practical side of imaging. His most recent contributions have contributed to our understanding of beam migration and other true-amplitude imaging issues. He won the SEG Maurice Ewing Medal in 2017.
SEG Maurice Ewing Medal 2017
Samuel Gray’s work from an industry perspective is impressive, with major contributions in the areas of depth imaging, velocity estimation, and seismic modeling. In particular, he has pioneered and collaborated with others in the areas of turning wave imaging, antialiasing in Kirchhoff migration, true-amplitude imaging, beam migration, and wave-equation migration. Gray also excels as a great communicator. He not only has mastered conveying complicated mathematical formulas behind seismic imaging in simple, understandable language for fellow geologists and geophysicists who are not familiar with seismic imaging, he also has inspired newcomers to our industry to carry the torch to further advance imaging technology.
Biography citation for the Maurice Ewing Medal 2017
Everyone who knows Samuel Gray describes him as energetic and engaging, astute and brilliant, practical and performance-driven, and most importantly humble and wise. Sam's mentors at the University of Denver were Norm Bleistein and Jack Cohen. There he found that he could always collaborate with one of those two eminent scientists to explain the more esoteric concepts proposed by the other. That ability to synthesize and improve the understanding of complex topics by reaching out to colleagues is one of Sam's great strengths. Sam did not start his post-PhD work in exploration seismology; instead he worked for the Naval Research Lab and then as an instructor at the General Motors Institute, now known as Kettering University. But he realized he had something important to give to the field of geophysics and joined Amoco Production Research Company in Tulsa, Oklahoma. There his colleagues, collaborators, and mentors were the likes of Ken Kelly, Sven Treitel, and Dan Whitmore. It was there at the Tulsa lab, “the house that Sven built,” that Sam began to make his mark on exploration geophysics.
Sam was the focal point of Amoco's efforts to develop 3D Kirchhoff prestack depth migration (PSDM) in the late 1980s/early 1990s. There were many scientific and engineering compromises in the design and implementation of that technology; during those days many of them were not fully explored. There were many times when he could have called the work “good enough” and just delivered what would have been improved images compared to what we had. That was not good enough for Sam, who has an amazing ability to create algorithms that are not only faster than you think possible, but also more accurate. The Kirchhoff 3D PSDM implementation that Sam helped create gave Amoco a pioneering capability in industry. It ran faster than what many believed even theoretically possible and, on top of that, was essentially true amplitude. We later coined the term “warp-drive” for the computational technique that Sam and the team developed, which allowed the Amoco 3D KPSDM to run so well. When Sam joined CGG in 1999 he immediately demonstrated the depth of his theoretical knowledge and his ability to translate theory into practical algorithms and efficient computer code, just like he did for Amoco.
Sam is also a key figure in the development of beam migration methods in general and CGG's development of controlled beam migration in particular. The R&D team sought to develop a variant of beam migration that is both better and faster than Kirchhoff migration and Gaussian beam migration. As one would expect for any project with such lofty goals, the team was stuck for months. Sam cracked the secret of migrating exactly which few percent of the data to produce images of high signal-to-noise ratio at lightning speed. Sam modestly considered his contribution to be trivial, and he graciously declined to share a CGG technical award with the R&D team. But of course this reminded everyone that Sam is one of the giants in seismic imaging who allows us to see and go further on his shoulders.
Sam skillfully presents complex technical ideas in a way that is both amusing and understandable. I've always profited from Sam's advice to “never have more than one and a half ideas” in a presentation. His conference presentations always draw huge crowds, and the audience is never disappointed. It is rumored that he doesn't even need slides. Sam once was giving an imaging presentation to a large, diverse audience. After the first couple of slides, the projection system malfunctioned, and all that remained was a white screen. There was growing concern from the event organizers, but Sam seemed completely unfazed by the complications. When it became evident that the projection system was not going to return, Sam had a suggestion: “Why don't I continue the presentation and just describe what you would be seeing if the slide was actually there.” He then proceeded to give the full presentation in that fashion.
For those who have worked closely with him, Sam is particularly famous for his dry wit and sense of humor. His best witticisms are usually reserved for those who need their complacency challenged, and through the years he has had a few Yogi Berra moments. On one particular occasion, someone was glowing about how good we had become in seismic imaging and turned to Sam for corroboration. Sam thought for a moment and gently said, “You don't have to be good to be the best; you just have to be the best.” The recipient didn't quite understand what Sam meant and changed the subject. From that point on, “you don't have to be good to be the best” became the reality check for those of us trying to imitate Sam's ethos of excellence. We are reminded over and over again that being the best is not always good enough in seismic imaging. Sam's many cleverly honest quotes continually tell us that we can always improve what we do in seismic imaging.
Biography citation for the Reginald Fessenden Award
Sam received his Ph.D. in mathematics at the University of Denver in 1978. Sam’s style was established from the get-go: cut-off shorts, wrinkled tees, long hair, tennis with a wood racket at the local park, and a bike with too few gears and a steep frame. He was a fine colleague to his fellow graduate students; a source of humor and camaraderie. During this time, he met his wife Julie and they married at the Evans Memorial Chapel on the campus of the University of Denver. Sam and Julie have two children, Christopher and Catherine.
Sam’s career in exploration geophysics began in 1982 when he joined Amoco. He was among the last in a cohort of gifted scientists hired by Amoco’s Tulsa Geophysical Research Division. Here he first became interested in the 1D seismic inverse problem, a topic made popular by earlier work of Geza Kunetz at CGG in France. After some time, he became increasingly attracted to a seismic imaging project conducted by Dan Whitmore in a group run by Ken Kelly. Here Sam’s deep mathematical insights began to bear fruit: early work with poststack Kirchhoff time migration was successively followed by Kirchhoff poststack depth migration, and these already established techniques then led him to their prestack counterparts.
Next Sam tackled a problem that had defied the efforts of the best imagers in the trade: to map not only the steepest portion of a salt dome flank, but also to obtain pictures of the salt overhang from below. He was among the first, if not the first, who managed to achieve this impressive feat by the use of turning rays, whose computer implementation he achieved by remarkably clever programming trickery. Sam’s earliest imaging work at Amoco soon found widespread application within the company because of a close collaboration with Davis Ratcliff, who was then working in Amoco’s Houston office. While Sam developed the ideas and the software, Davis became its masterful salesman; the two made quite a team.
A clever contribution of Sam’s was his solution of the operator aliasing problem in Kirchhoff migration. It arises when the migration swings events out to very steep dips; the high-frequency components become under-sampled on the migration grid, and a noisy image results. Use of sampling theory led to a migration operator that produced cleaner images. This trick is now universally applied to Kirchhoff migration.
By 1994 it became clear that Amoco’s Research Center had entered a period of decline; Sam requested a transfer to Amoco Canada in Calgary, where he continued his imaging research until Amoco was merged into BP.
Sam joined Veritas, now part of CGGVeritas, in Calgary in 1999, where he has remained ever since. He continued his work in depth imaging, velocity estimation and seismic modeling, both in classic acoustic models and in anisotropic elastic models of the Earth. He is also part of a group in the company who are intent on introducing “true-amplitude” adjustments in a ray-theoretic sense to various migration techniques, including Gaussian beam and reverse time migration. He is much in demand for expository presentations and papers, sharing his insights on the imaging aspects of seismic data processing in which he is a recognized expert. A paper he co-authored received a Best Paper award in Geophysics (1999), with two others cited for honorable mention, and he received an award for Best Paper presented at the SEG Annual Meeting in 2004. He also co-authored a paper that received a Best Paper Award in The Leading Edge this year. Sam remains active in research and development of modeling and migration methods, collaborating with colleagues both in and outside of CGGVeritas. The variety of his co-authors is an indication of the breadth of his interests and capabilities. His current title is Chief Scientist, a clear indication of his stature within the company, and more broadly within the industry.
SEG Best Paper in Geophysics Award 1999
- (2017). ”Honors and Awards.” The Leading Edge, 36(10), 806–819. http://dx.doi.org/10.1190/tle36100806.1
- Gray, S. H. and G. E. Murphy (1999), Manual seismic reflection tomography, Geophysics 64(5):1546.
- Zhu, J., L. R. Lines, and S. H. Gray (1998) Smiles and frowns in migration velocity analysis, GEOPHYSICS 63(4):1200.
- Whaley, J., 2017, Oil in the Heart of South America, https://www.geoexpro.com/articles/2017/10/oil-in-the-heart-of-south-america], accessed November 15, 2021.
- Wiens, F., 1995, Phanerozoic Tectonics and Sedimentation of The Chaco Basin, Paraguay. Its Hydrocarbon Potential: Geoconsultores, 2-27, accessed November 15, 2021; https://www.researchgate.net/publication/281348744_Phanerozoic_tectonics_and_sedimentation_in_the_Chaco_Basin_of_Paraguay_with_comments_on_hydrocarbon_potential
- Alfredo, Carlos, and Clebsch Kuhn. “The Geological Evolution of the Paraguayan Chaco.” TTU DSpace Home. Texas Tech University, August 1, 1991. https://ttu-ir.tdl.org/handle/2346/9214?show=full.