INVESTIGATING FLUID INCLUSIONS AND PATHWAY MIGRATION OF THE EAGLE FORD AND AUSTIN CHALK FORMATIONS

Natural fault and fracture networks provide permeability in low permeability rocks such as the Austin Chalk-Eagle Ford formations. These networks provide migration pathways for rising fluids such as oils and water. In formations such as the Austin Chalk, which has been described as a hybrid unconventional reservoir, vertical migration pathways allow for the migration of fluids from the Eagle Ford System to the Austin Chalk. Calcite veins are hosted within dilational zones associated with crack and seal textures from reactivated fault profiles. Local faults run vertically through the Austin Chalk and Eagle Ford system. Regional fault systems propagate a variation of surface failure, including tensile, shear, hybrid and local compressive behavior. Using stable isotope geochemistry analysis of fluid inclusions within carbonate veins, a formation depth can be estimated by looking at the homogenization of the fluid inclusions. Within the collected samples the inclusions range from locally to externally sourced waters with sporadic oil. Results illustrate two inclusion formation depths from two separate sources.