Topology provides important constraints on the mechanical behaviour of a geological region, its capacity for transporting fluid, heat and electricity and its history. Hence, it is important to understand the sensitivity of topology to the uncertainties inherent in any geological modelling process. This study explores the concept of topological uncertainty and describes methods for identifying, quantifying and illustrating it, and proposes its application in uncertainty analyses. A method is presented for describing the topology of three dimensional (3D) water-tight geological models as a set of adjacency relationships, expressed as a ‘topology network’. Data defining implicit geological models were perturbed in order to simulate data uncertainties and the amount of topological variation in the resulting model suite quantified, allowing probabilistic assessments of specific topological hypotheses, identification of key sources of topological uncertainty and the classification of possible model realisations based on their topology. Overall, topology was found to be highly sensitive to data uncertainty, with almost all of the several thousand perturbations of realistic geological models defining unique topologies, and uncertainty regarding faults and unconformities found to have particularly profound topological implications. Finally, a framework for describing the topology of geological models is proposed, possible uses of topology as a geodiversity metric and validation filter discussed, and methods of incorporating topological uncertainty into physical models suggested.
|Unpublished - Oct 2015