Gulf of Mexico Onshore
REGIONAL GEOLOGIC STUDY AND RESERVOIR EVALUATION OF THE LOWER TUSCALOOSA FORMATION IN SOUTHWEST MISSISSIPPI AND LOUISIANA
The Lower Tuscaloosa Regional Study addresses problems related to the exploration, reservoir evaluation, and production of Lower Tuscaloosa sandstone reservoirs. Some of the major difficulties encountered by operators in the trend have been understanding and predicting the type, geometry, distribution, and stratigraphic trapping mechanism of Lower Tuscaloosa sandstone reservoirs. Differentiating pay from non-pay zones due to low resistivity contrasts and evaluating production characteristics and associated proper completion procedures, especially concerning potential water production, are also major difficulties.
Therefore, the overall objective of this study has been to provide participating companies with detailed geological, petrophysical, and engineering characterization and evaluation of productive and potentially productive reservoir sandstones on both a local (field) and regional scale. The study contains of approximately 6,000 feet of conventional core from ninety (90) project wells located in an 8,800 square mile area encompassing ten (10) counties in southwest Mississippi and six (6) parishes in Louisiana.
The cores were geologically evaluated with special emphasis placed on productive and or potentially productive reservoir sandstones.
All cores were slabbed, photographed in color, and described in detail in terms of lithology, grain size, physical and biogenic sedimentary structures, contacts, and vertical sequence in order to interpret depositional environments. Thin section petrography, scanning electron microscopy, and X-ray diffraction were utilized to characterize such sandstone reservoir properties as texture, mineralogy, clay types, and pore space. Special emphasis was placed on the types and mode of occurrence of the various diagenetic minerals (especially clays) in the pore system and their influence on reservoir properties and log response. Productive and/or potentially productive Tuscaloosa sandstone cores were also petrophysically evaluated. Porosity, permeability, and grain density were measured for all samples that were geologically analyzed and selected key samples were analyzed to obtain advanced rock property measurements.
The generated data and interpretations for the individual project wells are provided. The wells are conveniently indexed on regional base maps. A final report was prepared that summarizes the results and conclusions pertaining to exploration and development on a regional scale. Included in the final report are nine regional facies cross sections that cover the entire area.