COMPUTING GeoVolumes FOR GROUNDWATER SYSTEMS USING GIS

Recent developments in GIS have allowed for representation of three-dimensional features using vector-based objects called multipatches. These objects can be stored in a relational geodatabase along with other features of a groundwater system. Because the geometry of subsurface geologic units may take on a variety of patterns, the methods for computing multipatches may differ depending on the extent and geometry of overlying or underlying geologic units. In this study we develop geoprocessing models that are suitable for computing multipatch features under various geometric configurations. The models are applied to the groundwater system in the Piceance Creek Basin of western Colorado. Multipatches are computed for shale-oil rich and lean zones in the Green River Formation, in addition to aquifers and aquitards in the overlying and underlying formations. Because volumetric statistics are not explicitly stored with the multipatch features, parallel geoprocessing models are developed for estimating retort volumes and groundwater volumes. The geoprocessing models presented in this study are designed to be easily implemented when representing and quantifying three-dimensional features, and can be applied to other groundwater systems using an industry standard GIS.