The Maness Shale: a comparison of the geomechanical and mineralogical properties within the Lower Eagle Ford Formation, South Texas

Abstract

The Maness Shale is a clay-rich mudrock that has been correlated to the basal Lower Eagle Ford in South Texas. Where present, the Maness may prove beneficial, acting as a fracture barrier between hydraulically fractured Eagle Ford wellbores and underlying aquifers. Geomechanical studies demonstrate that the Maness is 34% weaker than the Eagle Ford and 76% weaker than the Buda. XRD analyses found that the samples from the Maness contain an average of 10% more clay than the Eagle Ford. A regression analysis established a 91.7% correlation between Maness thickness and oil/water ratios, which are based on cumulative first year oil and water production, indicating that the Maness may be acting as a fracture barrier in the region. This analysis also found a 50% decrease in oil/water ratios between Maness thicknesses of 5 to 10 ft (1.5 to 3.1 m), suggesting that a minimum of 10 ft is needed for the Maness to effectively act as a fracture barrier.