A recent FPC study indicated up to 600 trillion feet of natural gas in place in the Rocky Mountains in low permeability Cretaceous and Tertiary, nonmarine sandstones. This type of reservoir rock has been studied in the surface and subsurface in the Piceance Basin area of northwestern Colorado. The sandstone geometry and orientation are characterized in this paper. A random intersection" technique is developed that utilizes the geological information to generate a spectrum of reservoir models that may be used to simulate the performance of hydraulically and nuclear fractured wells. An example reservoir model for a nuclear fractured well is compared to a reservoir model for a nonfractured well. In general, the point bar sandstones can be simulated by radial models and the channel sandstones by linear models. In a sequence of channel sandstones with Piceance Basin geometry, an average well will be connected to about 180/0 of the in-place reservoir volume in a 320- acre area. Connected reservoir volumes of greater than 70% in a 320-acre area are calculated for fractured wells, with actual values depending upon fracture extent and pervasiveness. The percent of connected reservoir volume decreases as well spacing increases.