A Spatial Uncertainty Index on Subsurface Models for Drill Hole Planning

摘要

The existence, position and orientation of geological surfaces such as faults, grade shells and lithological contacts are determined by exploration drilling. To take full advantage of drilling data, drill hole planning should incorporate the reduction of spatial uncertainty associated to the location and shape of these surfaces. The goal of the present work is to define a spatial uncertainty index on geological surfaces and to develop a method to estimate this index to help plan and execute subsequent drilling campaign.This is done with simulated drilling. Analyzing the difference between two successive models of a simulated mineralized lenses 'bounding surface, the second including new drilling data, a probabilistic model for the surface deviation is determined. As the deviation is an unstationary random field, a normalization process is verified. Then, geostatistics are used to interpolate the normalized deviation. Finally, a spatial uncertainty index for geologic surfaces is proposed, estimating the local dispersion of the deviation.