AVO anybody?

It may be that there are a lot of places Amplitude Vs. Offset logic applies. It's just that I have not seen any in the dozens of gather sets I have had access to.

The ostrich icon represents how I feel about the state of seismic research. I started trying to sell my non linear approach to seismic inversion over ten years ago, only to have the concept laughed at. Where is your mathematical proof? (they asked). 

Today,  In the North Sea ,  the general consensus is that the most serious noise problem comes from long multiples emanating from the chalk horizon, that current time-series inversions are as good as we can do, that current sections portray true bed lithology and that the best exploration tool is AVO. 

I disrespectfully disagree with all these preconceptions and hope to convince you of my points via the following PowerPoint show. Clicking on the bird will take you there, but first let me spell out a few points (for the benefit of the search spiders).

In a logical world, the picture to the right should be all I need to make  the first three points. It comes from a final report I submitted to Nexen Inc. after around 7 months of pro-bono North Sea work, using my ADAPS system. Clicking on the red pointer will take you to that PowerPoint. A complete gather set is shown here, from inside to out. At the onset of my study, I was given the usual "inside, middle and outside" stacks to evaluate. Much work had been done within the company on these variations (which, to my mind, was wasted). This gather set comes from a more recent shooting than what I worked with, but it covers the same geography. While I spend time in the PowerPoint analyzing what we see here I ask that you just keep thinking "inside, middle and outside" while you study this wiggle trace layout. To my aged eye there is no evidence of multiples here, although we always keep the possibility open.

I say we are looking at horizontally traveling wave guide energy. The important thing to note here is the fact that various energy bands are radiating once critical angles are reached. The energy seeming to move upwards is really horizontal refractions that are over-corrected.  

Once past the cloning point (where the reflection becomes a wave guide (refraction), no vertical energy passes through the barrier. This picture shows that very clearly, and you can see the exaggerated effect on the outside traces.  If you stare at the details long enough, you will begin to see emanated energy radiating back toward the inside. Pay attention to this, since it is noise. I say it masquerades as long multiples.  If you spend less than ten minutes studying this you are missing the points.  In the show I present other examples of wave guide (trap) occurrences.   In this case the culprit bed is the chalk complex. In others the presence of gas is the probable cause, and AVO hits are probably accidental (at least having nothing to do with offset theory).