Petrologic investigations from wells drilled in the southern Mississippi Interior Salt basin and in the northern Gulf Coast Salt basin have revealed regionally predictable diagenetic-facies trends within the deeply buried (19,000-22,500 ft) Smackover Formation. Within deeply buried Smackover trends, calcitic facies and dolomitic facies are recognized.

The calcitic facies is areally widespread and exhibits diagenetic intensities ranging from well-preserved grainstones to pervasive neomorphism. Petrographic evidence of multistage cementation, solution compaction, replacement fabrics, and cement-occluded secondary porosity is common. The calcitic facies is characterized by low porosity and low permeability.

The dolomitic facies is less abundant, and its distribution can be related to the Jurassic paleotopography. The Wiggins uplift, a prominent basement element extending across southern Alabama and southern Mississippi,

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exerted significant control on the areal distribution of this facies. Porous and permeable intervals in the deeply buried Smackover are restricted to this facies. The most significant textural parameter of the dolomitic facies is crystal size. Finely crystalline dolostone is normally of low porosity and low permeability, whereas coarsely crystalline dolostone exhibits more-favorable reservoir properties.

The distribution of these diagenetic facies has important implications on future hydrocarbon exploration in the deeply buried Smackover Formation.

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