Fluids, Lithology. This discussion extended over 13 years, beginning with a TLERound Table Discussion entitled "Poisson was not a Geophysicist!", and ranging widely over many topics in seismic rock physics, with emphasis on the role (if any) played by Poisson's Ratio in the analysis.

Pore Pressure. This paper describes a unique "global algorithm" for predicting subsurface pore pressure using seismic data.  It commonly predicts the occurrence of "subsurface fluid compartments", i.e. extended volumes with a local hydrostatic gradient, and an elevated head.  But, all pore pressure prediction algorithms are imperfect, so it is important to apply several independent alogorithms, which preferably rely on different input datasets, e.g. Vp/Vs.

Understanding AnisotropyThis set of Lecture Notes supported the 2002 SEG/EAGE Distinguished Instructor Short Course; here is the Introduction. The Notes themselves are for sale through the SEG, as are recordings of the lectures, in VHS and DVD formats.

Polar Anisotropy. This 1986 paper established the modern era in anisotropy studies. It is the single most-cited paper in the history of Geophysics; if you Google 'Thomsen parameter', you will find over 30,000 hits.

Azimuthal Anisotropy (P-waves). Azimuthal AVO ("AVO-Az") was discovered by Thomsen in 1981, and analyzed in an internal Amoco report. With the recent expansion of wide-azimuth seismic surveys, the effect is seen to be ubiquitous; this 2006 paper offers the best confirmationthat the observed effect corresponds to real fractures in the subsurface: The effect of fractures on seismic wave propagation was explained theoretically (significantly revising earlier theory) by this 1995 paper, which predicted (not fitted) experimental data obtained separately.

Azimuthal Anisotropy (S-waves) Azimuthal anisotropy causes twomodes of shear waves to propagate at near-vertical incidence, rather than one. Here is the first explanationof (the now well-known) "Alford Rotation" solution to this phenomenon of shear-wave splitting, and the first report of the phenomenon in exploration field data. If the azimuth of the symmetry axis varies with depth, then a layer-stripping procedure is required.

Converted Waves used to be esoteric phenomena of interest only to academics. But, with the establishment of the feasiblity of 4-Component Ocean Bottom Seismic surveying, they became an essential part of the seismic toolkit. The industry learning curve has been rapid, paid for by the ablity of converted waves to image inside gas chimneys, gas clouds, etc. This 1999 paper was named "EAGE Best Presentation" for establishing the concepts of "C-waves", "registration", "gamma-effective", "vector infidelity", and "diodic velocity",

Since then, the list of seismic problems which can be profitably addressed with 4C OBS data has expanded considerably, to also include:

• exploration seismics for "P-transparent reservoirs"
• appraisal seismics (including fields with existing infrastructure) for
  • lithology determination
  • fluids determination
  • fracture detection
  • pore-pressure prediction

These ideas have helped to establish the modern paradigm of exploration geophysics. If this classic material makes you think that these ideas might help you with your particular problem, contact us.

Just as importantly, they establish the current base for further progress in exploration geophysics. If you think that your particular problem is notfully addressed by these ideas, contact us anyway; the way to make progress is through confronting particular problems, finding general solutions through the failure of the old ideas.