Note that this is different from homogeneous , which is the quality of uniformity of composition. You can think of anisotropy as a directional not just spatial variation in homogeneity. In the illustration, I may have cheated a bit. The lower-left image shows a material that is homogeneous but anisotropic.
So although the material has uniform composition, at least at this scale, it has an orientation. It's not exactly a new thing — it was an emerging trend 10 years ago when Larry Lines at U of C reviewed Milo Backus's famous 'challenges' Lines A huge table containing the elastic parameters of almost 60 samples.
And this is from a corporate scientist at Amoco. Think of flat-lying shales with gravity dominating the stress field.
Seismic anisotropy - Wikipedia
Clearly, this will also affect AVO analysis. There's more jargon.
If the rocks are dipping, we call it tilted transverse isotropy , or TTI. This causes azimuthal compass directional travel-time variations. Accounting for them is not easy though, and trying can do more harm than good. If you have handy rules of thumb of ways of conceptualizing anisotropy, I'd love to hear about them. Some time soon I want to write about thin-layer anisotropy , which is where this post was going until I got sidetracked Lines, L Addressing Milo's challenges with 25 years of seismic advances.
Thomsen, L Weak elastic anisotropy. Geophysics 51 10 , — On Friday, I reported on Chevron's take on the unsolved problems in petroleum geoscience. It was largely about technology. He had five points:.
The Calgary crowd that harvested the list of unsolved problems at our unsession in May touched on many of these points, and identified many others that went unmentioned in this session. In the past, seismic imaging and wave propagation were almost exclusively driven by isotropic ideas. In the final talk of the technical program, Leon Thomsen asserted that the industry has been doing AVO wrong for 30 years, and doing geomechanics wrong for 5 years.
Three take-aways:. Anisotropic rock physics is uncontestable, but the challenge remains to find correlations with things we actually measure. Thomas Young's sketch of 2-slit diffraction, which he showed to the Royal Society in Diffractions are fascinating physical phenomena that occur when the conditions of wave propagation change dramatically. They are a sort of grey zone between reflection and scattering, and can be used to resolve fractures in the subsufrace. Problem is, we must subtract reflections — which we deliberately optimized for — from the wavefield to get diffractions.
Evgeny Landa , from Opera Geophysical, was terse, 'we must first study noise, in this case the noise is the reflections We must study the enemy before we kill it. The Santos, Campos, and Espirito Basins off the coast of Brazil contain prolific oil discoveries and, through the application of plate tectonics, explorers have been able to extend the play concepts to offshore western Africa.
John Dribus , Geological Advisor at Schlumberger, described a number of discoveries as 'kissing cousins' on either side of the Atlantic, using fundamental concepts of continental margin systems and plate tectonics read more here. He spoke passionately about big ideas, and acknowledged collaboration as a necessity: 'if we don't share our knowledge we re-invent the wheel, and we can't do that any longer'.
Although the workshop format isn't all that different from the relentless PowerPoint of the technical talks, it did have an entirely different feeling. Was it the ample discussion time, or the fact that the trade show, now packed neatly in plywood boxes, boosted the signal:noise?
Foundations of Anisotropy for Exploration Seismics, Volume 22
The text contains exercises and problems, and solutions are provided for the exercises. Review The author presents the physical concepts, mathematical details and methodology for optimizing results of reservoir modeling, under conditions of isotropy and anisotropy. The book incorporates significant new developments in isotropic and anisotropic reflection processing, while organizing them to improve the interpretation?
First Break , Vol. Curves for Anisotropy. JK Rowling. Click on below image to change. Click on image to Zoom. Upadhyay S. Average Rating. Description Seismic Reflection Processing coherently presents the physical concepts, mathematical details and methodology for optimizing results of reservoir modelling, under conditions of isotropy and anisotropy. Upadhyay , S.
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