Improvements in reservoir characterization can greatly enhance reservoir performance predictions. Heterogeneity within most reservoirs, such as the Madison Group, can be better understood from integration of results from detailed core analyses. A fractured dolomite core sample from the Upper Madison Group, near Carter Creek gas field in southwest Wyoming was studied in detail to supplement the current methodology for delineating heterogeneities in core samples. Directional permeability, fracture system orientation, and other heterogeneities related to the core sample fabric were determined and quantified by studies of: impregnated thin-sections and use of computed tomography x-ray intensity, x-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Computed tomography (CT) is a fast, nondestructive, qualitative and quantitative tool for the evaluation of fracture systems and associated mineralogy. The scanning procedure employed involved assigning a density range that would highlight minerals having characteristic CT densities. This procedure helped to identify variations of fracture infilling materials. The core analyses data were integrated with the regional geology, downhole logs, and production data for final evaluation.

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