A Comparison of Facies Modelling Strategies in Fan-delta Reservoir Analogues, Sant Llorenç del Munt, Eocene, NE Spain

Abstract

The Eocene aged, Sant Llorenç del Munt fan-delta complex is a well exposed, transgressive–regressive fan-delta, which crops out in NE Spain. Outcrop data were used to test a variety of modelling strategies in which well conditioning, stratigraphic subdivision, modelling algorithm and trends were all varied. The results of these modelling exercises were compared against themselves and against a close-to-deterministically built Base Case reconstruction using a series of static measures including the distribution of fan-delta front reservoir facies, directional connectivity and reservoir-to-well connectivity. The results highlight how well conditioning improves the reproduction of the stratigraphic architecture in the different modelling approaches. That stratigraphic subdivisions including the maximum flooding surface to separate independent grids for modelling the transgressive and regressive sequence sets can actually be detrimental unless additional constrains are included. That an algorithm combining a linear trend and a Gaussian field is the most suitable algorithm for reproducing this type of architecture, but requires defining a three-dimensional trend. And finally, the need for using trends to properly reproduce the architecture when well data are sparse. These results provide guidelines for modelling analogue fan-delta reservoirs in the subsurface.