As part of the characterization efforts for the Bell Creek oil field, 81 core samples of the Muddy and Mowry Formations from 21 wells were selected from the U.S. Geological Survey Core Research Center in Denver, Colorado, and analyzed by the EERC's Applied Geology Laboratory. The samples were characterized in detail for several rock properties, such as compositional mineralogy, bulk mineralogy, grain size, porosity, permeability, pore volume, clay type, bulk chemistry, diagenetic features, and biological characteristics. The goal of this characterization activity is to obtain a better understanding of the petrographic and petrophysical properties of the Mowry and Muddy Formations in and around Bell Creek oil field.