Recent offshore exploratory success has focused industry interest on porous Lower Cretaceous carbonates of the James Limestone in the eastern Gulf of Mexico. The current offshore play targets the interior James platform trend in the Viosca Knoll and Mobile areas, south of Mississippi and Alabama, where water depths are 30-60 m (98-197 ft). James reservoirs in this area consist mainly of patch reef debris halos and interior platform grainstone facies at drilling depths of 4358-4632 m (14,300-15,200 ft). These facies comprise a belt parallel to, but up to 25 km (15.5 mi) behind (updip from), the James shelf margin. Diagenetic alteration, including dolomitization and dissolution of original calcite grains and cement, cause porosities of 8-19% and permeabilities in the range of 20-30 md. To date, seven fields have been discovered. Individual wells in these fields have been completed at rates ranging from 10-39 MMCFGD and have produced as much as 15.9 bcf in less than 3 yr. The new play represents an extension into the offshore of scattered, older production in the James that occurs from east Texas to southern Mississippi. When combined with the onshore part of the play, the new success in the James suggests that significant regional potential still exists in many areas of the northern and northeastern Gulf.

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