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Well Log Clustering Analysis and Upscaling Procedure of the Tuscaloosa Marine Shale, Mississippi and Louisiana

Abstract

The Cretaceous Tuscaloosa Marine Shale is an important unconventional gas-shale reservoir located within the Interior Salt Basin in Louisiana and Mississippi. This study aims to create a detailed characterization of different facies within the Shale by integrating mineralogical, core, and wireline log data within a study area extending west to east from Rapides Parish, Louisiana, to Amite County, Mississippi, and north to south from Wilkinson County, Mississippi, to East Feliciana County, Mississippi.

The software program GAMLS, a probabilistic well log clustering analysis, is used to correlate well logs in over 70 wells throughout the region in order to understand heterogeneities in the Tuscaloosa Marine Shale, as well as to upscale organic porosity, mineralogical, and core data to the basin scale. Preliminary results have indicated that by utilizing the GAMLS well log clustering analysis, the formation can be divided into eight electro-lithofacies units (rock types). These lithofacies were correlated to variations in water saturation, mineralogy, and production results throughout the study area. Core samples were taken from each of these eight lithofacies, and the relative amounts of quartz, calcite, and clay minerals were correlated to productivity. The mineralogy and fracture density of the shale is highly heterogeneous throughout the study area, and as a result all eight lithofacies are not present in every well. A positive correlation was made between mineralogy, fracture density, and oil production. These were mapped throughout the region. Physical characteristics of each lithofacies, as well their thickness, are examined to determine target zones within the formation. These lithofacies were mapped throughout the region and correlated to depositional environment of each lithofacies.