OJITO AMPHITHEATER; USING OUTCROP ANALOGS TO IMPROVE OUR UNDERSTANDING OF SUBSURFACE FLOW IN MORRISON FORMATION SANDSTONES

For the past two decades, subsurface heterogeneity studies have focused on modeling sedimentary structure and facies distributions using a variety of geostatistical approaches; however, due to limitations in parameterization data these approaches may not capture realistic facies geometries and subsequent fluid flow paths. Vertical variability is often observed at high resolution, as in core and geophysical well logs, however lateral heterogeneity is difficult to capture and as a result, a high amount of uncertainty exists in subsurface flow models. In an attempt to more accurately characterize aquifer sediments, an outcrop analog-based approach utilizing terrestrial lidar and high-resolution digital photography is combined with lithofacies analysis to produce a robust 3D outcrop model. The Morrison Formation's Westwater Canyon Member is a laterally extensive fluvial sandstone that crops out along the northwestern edge of Ojito Wilderness, New Mexico, USA.

In the summer of 2011, terrestrial lidar scans and digital images of approximately 15,000 m² of contiguous cliff face were acquired. The resulting 3D lidar point cloud has a density of approximately 400 points per m². The digital images are processed through a series of filters to delineate different facies and bounding surfaces. Architectural element analysis of the outcrop allows for correlation of the north and south faces, to be used for interpolating the eroded deposits between the faces. Classification and projection of digital images on terrestrial lidar measured outcrops allows us to develop highly realistic digital outcrops for parameterization of aquifer models.