Abstract

There is a significant number of very large anticlinoria remaining to be exploited in the Permian basin. These have not been developed because they have been effectively hidden from seismologists. Many think this is related to local masking by near-surface and shallow seismic velocity problems, which does occur, but there is a far more important reason. Thermally uplifted dilational structures created by rifting are far more fractured and faulted than anyone has realized because we have lacked a proper dilational model of rifting. Diffractions off those faults and fractures are capable of destroying seismic reflectivity as has recently been found by McCarthy and Thompson (1988).

The existing seismic maps of the basin depict the structures in far less detail than most seismologists realize, A simple, predictive model of rifting can be used to assist in making interpretations where the normal reflectivity has been sharply reduced. When a seismologist knows what he should be looking for structurally, he can often interpret reflections through the diffractions.

We now have a non-seismic geophysical tool that very accurately measures true vertical depth, and that helps to improve the composite picture. When combined with the use of structural mechanics, we can map structures that are mechanically possible, which had not been done previously.

Some of the largest structures in the basin still remain to be exploited. The greater the uplift, the more difficult they are to see on the seismic sections.