The Mississippi Salt Basin is a Mesozoic interior salt basin lying in the northeastern Gulf of Mexico. Original salt thickness in the basin was 3,000' to 5,000' over an estimated 20,000 square miles. The Mississippi Salt Basin, approximately 27,000' deep, is very clastic rich and the reservoirs are chiefly Jurassic and Cretaceous sands and a Jurassic carbonate. The source rock fix most of' the salt basin is the Jurassic Smackover carbonate and five regional seals have been identified.

Salt distribution can be separated into various structural styles depending on location within the basin (increasing overburden and salt thickness in a basinal direction). The primary forces acting on the salt in this basin are differential loading and buoyancy with minimal effect from gravity sliding and extension. The early loading effect of the clastic Norphlet and the size of the salt basin has helped differentiate this basin from the interior East Texas and North Louisiana salt basins. The Norphlet and the finite amount of original salt has created the present salt structural styles.

The different structural styles have had varying effects on the source rock and regional seals, therefore localizing hydrocarbon accumulations. Most of the large accumulations known to date are associated with the basin-bounding fault/graben system. The salt ridges and shallow piercement (salt dome) areas have very little oil or gas accumulations. The salt ridges high enough to disrupt Jurassic seals have varying fetch (drainage) depending on the shape of the salt structure. This yields little production on the ridges; however, interridge Jurassic/Cretaceous structures with more fetch may contain undiscovered oil and gas. The salt dome area has had some recent drilling success but late movement and a downbuilding history provides very little fetch. The interdomal inversion features are again the traps to pursue in this area and there is established Jurassic and Cretaceous production. The key for structural interpretation and successful economic ventures in the Mississippi Salt Basin is predicting salt movement and timing, estimating available salt volume (for height and shape of structure) and establishing the effects these have had on fetch, migration and regional seals.

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