EVOLUTION OF GIANT SALT PILLOWS IN THE DESTIN DOME AREA, EASTERN GULF OF MEXICO: IMPLICATIONS FOR PETROLEUM EXPLORATION AND GEOLOGIC CO2 STORAGE

The Destin Dome Area contains giant salt pillows and associated salt-cored anticlines that are hydrocarbon exploration targets and potential CO₂ sinks. Publically available seismic and well data were used to develop 3D models of the salt pillows, basin subsidence, and the associated petroleum systems. The largest salt pillow forms the core of Destin Dome, which is a broad, open structure with dip generally less than 4°. Smaller pillows occur in the east-central Destin Dome Area basinward of the Destin Dome pillow. Strata above these pillows form four-way structural closures, although the crests of some structures are breached by normal faults. The age of the anticlines varies greatly. For example, one anticline is truncated by a Jurassic angular unconformity, whereas Destin Dome involves Miocene strata.

Models of total effective subsidence document diachonous salt pillow development, with loci of pillow formation migrating northward and eastward through time. Pillow Formation began during the Early Cretaceous with accumulation of salt in an arcuate ridge composed of elongate salt pillows. By the Late Cretaceous, pillow formation was restricted to the northwestern part of the ridge. Destin Dome structure did not grow significantly until the Late Cretaceous.

Thermally mature source rocks are restricted to the Jurassic Smackover Formation, which reached maturity and expelled most hydrocarbons during the Early Cretaceous. Several salt-cored anticlines have yet to be tested. Jurassic eolianite is productive in stratigraphic traps in Destin Dome that were apparently charged prior to formation of the structure. Younger strata in the dome have to date been subeconomic. Analysis of CO₂ storage potential indicates that the same sandstone units that hosted pilot programs onshore are present in the dome, as are the same sealing strata. Crestal faulting is a significant geologic risk factor and thus is an important consideration for screening candidate storage sites.