Catchment Scale 3D Geological Models from Sparse Data Sets

Bryce Kelly

The University of New South Wales, Australia

Abstract

Three dimensional models of regional geological structures and the properties of each unit are important for numerous earth science applications. Such models are essential for defining the distribution of base metal, defining hydrocarbon traps, conceptualizing the volume of groundwater contamination plumes and for creating the framework for hydrogeological water balance models. The geological models are built from sparse data sets including borehole logs, geological maps and geophysical surveys. Using RegionPlot3D in conjunction with the interpolation algorithms within Mathematica, it is possible to construct regional scale geological models that honor the sparse data and geological constraints. Each geological surface is defined over the horizontal extent of the region being investigated using the function Interpolation. The earth structures are then modeled using a set of relational and logical operators to replicate the geological history. The resulting volume elements that represent each geological unit are filled with the geological property of interest. The units are then combined into a single 3D model. The process is demonstrated on a catchment scale model that was constructed to define the hydrogeological framework for a regional groundwater investigation in an environmentally stressed aquifer in Australia.