The Smackover trend within the United States extends approximately 1,000 mi from South Texas to western Florida. Prolific production has been obtained from this Upper Jurassic carbonate formation in East Texas, South Arkansas, North Louisiana, and eastern Mississippi. Continuing exploration currently is extending the productive areas eastward into Alabama and western Florida and promises to extend production into South Texas.

Most of the production has come from upper Smackover oolitic and pelletal limestones or their dolomitized equivalents. The three most important types of reservoir rocks are oomoldic dolomite, saccharoidal dolomite, and oolitic limestone with interoolite porosity. Reservoir porosity and permeability vary widely depending on the quality of the primary porosity, amount of secondary porosity development, and magnitude of porosity destruction.

Low-relief anticlines, with up to about 400 ft of closure, are the most important structural traps in terms of present production. These closures usually are associated with Louann Salt swells which underlie the Smackover section. Fault traps, traps associated with high relief structures, and salt piercements are of lesser importance at this time, but it is anticipated that they will provide major reserves as exploration continues.

Stratigraphic traps have become increasingly important exploration targets, particularly in the more mature areas where better well control adequately defines the potential trap. Major reserves already have been found in stratigraphic traps, and exploration for this trap type is rapidly increasing. Entrapment generally is provided by the updip termination of porous carbonate zones, commonly, but not necessarily, in conjunction with low relief structural noses or closures.

Exploration of diverse Smackover traps has resulted in prolific production over a significant part of the trend. Continued exploration promises to extend the production into sparsely drilled areas and to discover significant new reserves even in the "old" producing parts of the trend.

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