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Depositional Analysis of the Jurassic Norphlet Formation within the Mississippi Interior Salt Basin: Impact on Petroleum Potential Offshore

Abstract

The Norphlet Formation is an Upper Jurassic syn-rift clastic reservoir; recent discoveries as well as impressive single well historic production rates exceeding 3,000 BOPD and 70 MMCFGPD make the Norphlet an attractive target for continuing exploration. Due to a lack of available log and core data it is not possible to perform a detailed study of the Norphlet Formation offshore at this time, however more than 300 wells, most containing standard logging suites and five wells with core have been located that penetrate the Norphlet Formation within the Mississippi Interior Salt Basin (MISB), which serves as a robust analog for reservoir quality of the Norphlet in offshore areas where data are sparse. Through the use of U-Pb detrital zircon geochronology, sandstone petrography, and geochemistry along with well log and core analysis, compositional trends are identified that control regional reservoir quality. Samples from seven wells across the MISB using U-Pb detrital zircon geochronology by LA-ICP-MS, at this time has found that sediment for the Norphlet Formation was sourced primarily from the Appalachian Mountains (265-760 Ma) and the Grenville Province (950-1250 Ma) to the northeast, which when compared to detrital zircon provenance results of sandstone to the east, indicate complex and compartmentalized paleogeography. Fifteen thin sections studied using standard petrographic and SEM-EDS techniques has determined that major variations in reservoir quality can be attributed to variations in clay coatings in compositionally similar subarkosic reservoir rocks.