The main difference between a great anticlinal or fault trap and a great other kind is that the former is

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easy to find and the latter difficult. Thus, it is not likely that large traps of the anticlinal or fault types have been missed in well-drilled areas. But there is a fair chance that some great "other" kinds are still to be found.

Several techniques have been available for a long time, but none is routine. Detailed gravity-meter and torsion-balance surveys come high on my list, providing that core density values are carefully and competently measured (and now checked with a borehole gravimeter). Another important tool is the reflection seismograph, without CDP(!)--for scattered events, usually very poor.

These are only beginnings. They are of little value unless management, and searching engineers and scientists, are together in the gamble that focuses on the "big sleeper." They must look backward as well as forward. If they have made errors, they must study them to improve future practice. If they have been lucky, they must find why, to improve future practice--or continue to rest on luck.

So, try to get good case histories (not only the parts that justified pride but also the errors). Look for observations that were not thought necessary (luck was too good to require them!) but might still be made. Try to decide how that giant (e.g., East Texas) might have been found with a minimum of good luck. This requires a very careful analysis and understanding.

Recognize the simple fact that no technique can ever be regarded as sufficient for success in this venture. No routine package can be sold with a claim that if you manage your field teams and fine instruments according to directions you can have success.

However, there are certain necessary conditions--the kind of conditions you can look back on. Possibly the most important of these is "a high level of intellectual honesty, general competence, and a wish to know fact from fiction for the purpose of future productive use through the whole exploration and production group." Though the industry does seek new ideas and processes quite actively, it is not particularly noted for relinquishing mistaken ideas--especially when these ideas have been very expensive. Thus a kind of smokescreen is erected by many circumstances. The air needs to be cleared by critical reexamination of premises.

It is interesting and valuable to inquire "what measurable differences exist in an environment of a large petroleum accumulation that are due to this accumulation?" The effects may be a little subtle, but not completely absent.

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