FLUVIAL ARCHITECTURE AND FACIES DISTRIBUTION OF THE CUTLER FORMATION WITHIN FISHER MINI-BASIN, PARADOX BASIN, UTAH: RESERVOIR MODELING OF A SALT-INFLUENCED, SOURCE-PROXIMAL FLUVIAL SYSTEM USING DIGITAL OUTCROP TECHNIQUES

The Paradox Basin lies on the southwest flank of the Uncompahgre Uplift, which was a high-relief source of arkosic sediment to the basin in the Permian (Mack and Rasmussen, 1984). Outcrops of the Permian Cutler Formation proximal to the paleo-Uncompahgre (6-15km) near Moab, Utah record the transition from proximal alluvial fan deposits to braided (anastomosing) stream channels within a salt modified mini-basin. Numerous canyons provide excellent exposure of the high energy fluvial channels in multiple directions, providing insight into the three-dimensional architecture of these channels. Mapping of these architectural elements will lead to detailed models that will improve the understanding of this heterogeneous fluvial reservoir.

The exposed length of the Cutler Formation in the study area provides an analog for similar source proximal, high energy systems elsewhere in the geological record. Preliminary work in the area suggests that although subdivision of the Cutler Formation is difficult due to the chaotic nature of the preserved strata, genetically-related packages that may represent parasequences can be identified and correlated, at least at a local scale. Changes in the dominant sedimentary structures, grain size and sorting, and channel architectures are apparent as we move basinward from the most proximal outcrops and into the center of the mini-basin. Through application of differential GPS and other techniques, very accurate (10-50 cm accuracy) mapping will be done, in conjunction with measurement of detailed vertical sections and sample analysis, to better characterize and quantify the variations observed, and to aid in correlation across the study area. The data collected will be the basis for geostatistical analysis and three-dimensional static modeling of facies associations, rock properties, and reservoir characteristics of the Cutler Formation. This digital analog can be used as a predictive tool in other outcrop or subsurface settings that were deposited under similar conditions, with the goal of becoming more predictive away from control in data-limited instances.