Abstract

Production-scale variability in Mississippian reservoirs of the U.S. midcontinent is poorly understood, largely due to distant spacing of subsurface wells and the lack of outcrops that provide a 3-D distribution of potential reservoir facies. This study utilizes exposures of Upper Mississippian (Meramecian to Chesterian in age) lithofacies in a quarry to develop a 1st-order 3-D facies model at a production or enhanced-production scale (<40 ac [<16.2 ha]).

By utilizing photogrammetry to stitch and georeference high-resolution aerial photos, 3-D representations of outcropping walls and pavement were created at a submeter resolution and serve as valuable tools for the visualization of bed and facies relationships in 3-D space. Drone-based aerial and orthogonal photography was used to capture images and create 3-D models of inaccessible outcrop areas. These models were then imported as base surfaces to geostatistical reservoir modeling software (Petrel), in which they were integrated with petrographic and sequence-stratigraphic data to model facies and porosity relationships. Various algorithms and variogram lengths were tested and compared to high-resolution outcrop data to determine the most appropriate workflow for future subsurface modeling. The Petrel-based facies and porosity models illustrate the lateral and vertical variability that exists in outcrop while providing detailed approximations of subsurface reservoir heterogeneity.