Groupe d’études et de recherche en analyse des décisions


Geologic Heterogeneity Recognition Using Discrete Wavelet Transformation for Subsurface Flow Solute Transport Simulations

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Subsurface flow and solute transport simulations are performed using different scenarios of permeability fields generated from the sequential Gaussian simulation method (SGS), the multiple-point FILTERSIM and a new multiple-point wavelet-based simulation method (SWS). The SWS method is a multiple-point pattern-based simulation method which uses discrete wavelet transformation for the representation of geologic heterogeneity. For pattern-based simulation, patterns are generated by scanning a training image with a spatial template. The pattern classifications were performed after reducing the dimension of patterns by wavelet decomposition at the suitable scale and by taking only scaling component of wavelet decomposed patterns. The simulation is performed in a sequential manner by finding the best-matched class corresponding to the conditioning data and by randomly sampling a pattern from best-matched class. The developed method is compared with other two multi-point simulation algorithms i.e. FILTERSIM and SIMPAT. The comparative results revealed that the proposed method is computationally faster than the other methods while the simulation maps are comparable. Numerical simulations of two flow problems are performed using realizations SGS, SWS and FILTERSIM realizations. The numerical results show a superiority of SWS method on SGS and FILTERSIM methods in terms of reproduction of the reference images main features, and agreement with flow and transport results obtained on reference images.

, 27 pages