Determining Hydrocarbon Distribution Using Resistivity, Tuscaloosa Marine Shale, Southwestern Mississippi
High energy prices created by increased global demand and ongoing international disputes have once again sparked a new wave of exploration within the United States. The need for local production is strong and the onshore shale reservoirs of the United States appear to be a prime target. The Tuscaloosa Marine Shale is one such shale reservoir that has been rapidly gaining interest throughout the petroleum industry and the availability of published data concerning the reservoir is insufficient to meet industry needs. The purpose of this study was to investigate the reservoir within southwestern Mississippi to document its structure, stratigraphy, and hydrocarbon distribution. The Tuscaloosa Marine Shale was mapped throughout southwestern Mississippi using electric logs and Petra mapping software. A resistive, hydrocarbon-bearing section is located at the base of the shale and generally thickens with depth throughout the area. The areas of thickest high resistivity are located within the southern portion of Wilkinson County where thicknesses reach 210 feet. This is due to the higher temperatures and pressures associated with the greater depths, allowing the organic-rich rock to mature and produce more hydrocarbons. This also implies that the rocks within the updip portions of the trend are still immature with respect to their hydrocarbon generation potential. Mudlogs indicate that gas volume and pressure increase with depth throughout the study area. The greater pressures along with the presence of gas will help bring the oil trapped within the tight formation to the surface during production and greatly increase the chances of achieving commercial production. The only caveat is that the resistive section lies directly above the Lower Tuscaloosa sands within these areas which could lead to potential hydraulic fracturing risks. While the depths of the trend appear to be the dominant driving factor controlling hydrocarbon distribution throughout southwestern Mississippi, the paleogeography appears to have provided the perfect scenario for the development of this unconventional resource.
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