3-D Characterization Of An Alluvial Aquifer System: A Case Study Using Borehole Data And Indicator Geostatistics

The three-dimensional characterization of a complex, alluvial aquifer system in the<br>West Alberta Plains was made possible by using indicator geostatistics to interpolate<br>between borehole log interpretations. Gamma-ray logs, induction logs, and lithology<br>determined from cuttings were used to assign indicators (categories) of sandstone and till<br>aquifers, and mudstone/ siltstone aquitards. The indicators in ninety well columns were<br>then used to compute variograms and create a 3-D, anisotropic variogram model. The<br>variogram model and the vertical proportions of sandstone and non-sandstone were used to<br>constrain the indicator simulation of the sandstone and non-sandstone indicators. Then,<br>using sequential gaussian simulation, the thickness of the till was simulated and added to<br>the sandstone and non-sandstone models. The resulting 3-D geologic models will be used<br>for groundwater flow and chemical transport modeling.