There is a time for ultra seismic accuracy but that comes after we have located something exciting enough to look at. Since migration before stack almost destroys our ability to pick strike slip faults, and 3D work is too expensive to warrant improved spatial accuracy when the stratigraphy is not interesting, we should look at optimized 2D for a quick look. Here, such things as sonic log simulation can spot where we should pay more attention. Now is the time to change direction and play it smart. With new things we have learned, recording techniques could be optimized before going to 3D. Over the years of developing non-linear seismic resolution improvements I have come across strong evidence that suggests much of our acquisition and pre-processing is ignoring physical realities. Central to this awakening was building the ability to actually visualize seismic noise. Possibly the most serious of these discoveries is the revelation that early strong reflectors can cause a truncation of the down wave (at critical angle crossings) and that this problem is almost omnipresent. This distortion often limits usable information to the very early traces, making many current seismic practices practically laughable. Obviously, if we know this condition exists before we shoot an expensive 3D prospect we can modify our spread design, at the minimum saving a lot of money. In addition, many of today’s spreads are so long that only the very deep horizons receive the benefit of the extra traces, even when there is no critical angle problem. A little attention to the gathers is certainly called for, but this requires an exploratory shoot. Again, 2D would do that job. After an early reminder of important seismic principles, I use some previously shown pictures to introduce some supporting PowerPoints. Please give those time to load.

This old picture dates back to my first realization of the critical angle crossing problem. It is a set of gathers that lies close to a very probable hydrocarbon hot spot that my sonic log simulation showed very nicely. It illustrates two extremely important points. A. When the critical angle is crossed, all energy is diverted to horizontally traveling refractions (as proven by the NMO over-correction). This means the down wave is truncated from here on down. B. The wild nature of the energy explosion proves that this migration before stack software could not handle the refractions. On a later work I was able to show that the explosion only occurred when such software was used. It amazed me at the time that no one seemed concerned about the phenomenon. C. As I show in later, this void of down energy causes reflections to throw refractions that fill the recorded section.

This is a recent come-on that was just supporting conclusions reached before. The gray approximations are my interpretation of how far into the spread the reflection void goes. The data is from south Louisiana, but the phenomenon is similar to much of the 3D work I have had access to. I do not think the fact that the problem occurred on so many many of the these prospects is a coincidence.

And this was to introduce I do hope you visit here. This PowerPoint shows good examples of refractions hanging on interrupted reflections.

The point of including this come-0n to is to illustrate how the refraction (and other coherent noise, inlays the reflection data. Lifting it off solves what looked to be a serious statics problem.

And this blatant ad for my services is to show what can be done with 2D. It introduces