Sandia National Laboratories is conducting and directing the Multi-Well Experiment (MWX) core analysis program as part of the Western Gas Sands Program sponsored by the U.S. Department of Energy/ Morgantown Energy Technology Center. Sandia National Laboratories is responsible for sample selection, sample distribution, prioritization of analyses, distribution of data, and coordination of analyses performed by various agencies. The U.S. Geological Survey, along with Sandia, will provide interpretations of analytical results. A sedimentological model of the Mesaverde Group at the Multi-Well site is provided by J. C. Lorenz (1983). The Petrology Laboratory of Bendix Field Engineering Corporation provides routine mineralogic and petrologic analyses and preliminary interpretations of MWX core samples, as detailed in this report. These preliminary results are to be used primarily for characterization of the general mineralogy and textures of an interval so that variations in mineralogic trends can be delineated. This report is the fifteenth of sixteen to be submitted that will present the results of petrologic analyses from drill holes Mix-l, 2, and 3. Included here are mineralogic and pettrographic data from the Low Fluvial Interval of drill hole MWX-l