ABSTRACT: The Sub-Salt Play Moves Onshore

BLACKHALL, RAYMOND N., Cosara Energy Company, Houston, TX; and JIM BOB JACKSON, Trace Oil and Gas, Houston, TX

Significant major reserve potential exists beneath tabular layers of salt. Recent discoveries by Phillips, Anadarko and other companies in the Gulf of Mexico have proven this statement and have demonstrated tremendous reserve potential.

Delineation of this play was made possible due to the nearly incredible advances in seismic technology and the renewed confidence in its detailed interpretation. High costs and extreme risks discouraged exploration before the industry acquired the ability to correctly image beneath salt or below the salt-sediment interface. The wide spread use of 3-D seismic offshore, due to its ever increasing reliability and the lower cost and relative ease of acquiring this data, has made the exploitation of this new reserve possible. Total exploration and development expenditures in the offshore sub-salt trends are very high.

New evidence suggests that the sub-salt play extends and exists in the Gulf Coast Onshore and perhaps in numerous other salt basins. Tabular salt deposits, residual features, tear drop shaped domes and any intruded lateral salt bodies have hydrocarbon potential beneath the salt. The occurrence of hydrocarbons beneath this type of deposit will depend on numerous other factors, but the Law of Uniformitarianism suggests that, if major reserves can be discovered offshore, this type of play has potential onshore.

Thanks to the cooperation of Veritas Geophysical Services, we are fortunate enough to be able to present what we think are several examples of these features in the onshore. Lower drilling costs and faster gas hookups onshore make this an economical alternative to expensive offshore sub-salt exploration. Increasing reliability of onshore 3-D seismic and greater resolution at ever increasing depths move this play into reality.

AAPG Search and Discovery Article #90908©2000 GCAGS, Houston, Texas