ABSTRACT

The recent discovery of large gas-condensate reserves in the Smackover formation of East Texas has caused the industry to initiate a major exploratory effort in this area. Reserve values per well in excess of $12,000,000, and possibly as high as $50,000,000 have been the impetus for leasing, drilling and seismic activity to reach all-time highs in the search for new Jurassic reserves. There has been a relatively small amount of Smackover drilling and the most significant new finds have been downdip from the Mexia-Talco fault zone. The structures appear to be Jurassic in age, resulting from isostatic adjustment rather than salt tectonics. Smackover drilling in the Mexia-Talco fault zone has been disappointing due to the location of tests on Cretaceous age drag folds and the fact that the Jurassic throw of the faults has been sufficient to place the Smackover in juxtaposition with porous, downthrown Cotton Valley sands. A thorough examination of the drilling which has been done to date indicates the possibility of a large number of untested prospects in the fault zone as well as the twenty-five to fifty miles downdip from it. Successful development of large new reserves seems assured although Jurassic structural geology is complex and demands close co-ordination of geology and geophysics.

Figure 1. (unnumbered) Smackover fields in East Texas.

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