My Geology Is Too Complex for My Grid: Grid-Free Surface-Based Geological Modelling
C. Jacquemyn, M.P. Rood, Y. Melnikova, P. Salinas, M.D. Jackson and G.J. Hampson
Event name: 80th EAGE Conference and Exhibition 2018
Session: Building and Updating of Static Geomodels I
Publication date: 11 June 2018
Info: Extended abstract, PDF ( 833.08Kb )
Price: € 20
Building spatially realistic representations of heterogeneity in reservoir models is a challenging task that is limited by predefined pillar or cornerpoint grids. Diverse rock types are ‘averaged’ within grid cells of arbitrary size and shape; continuity of baffles, barriers or high-permeability streaks is often lost; large features are over-resolved and small features are under-resolved or omitted. We present a surface-based modelling workflow using grid-free surfaces that allows creation of geological models without the limitations of predefined grids. Surface-based modelling uses a boundary-representation approach, modelling all heterogeneity of interest by its bounding surfaces, independent of any grid. Surfaces are modelled using a NURBS description. These surfaces are efficient, and allow fast creation of multiple realizations of geometrically realistic reservoir models. Surfaces are constructed by (1) extruding a cross section along a plan-view trajectory, or (2) using geostatistical models. Surface metadata is created to allow automatic assembly of these individual surfaces into full reservoir models. We demonstrate this surface-based approach using common elements such as facies belts, clinoforms, channels and concretions, which are combined into reservoir models that preserve realistic geometries. This is applied to a coastal-plain and overlying shoreface succession, analogous to an upper Brent Group reservoir, North Sea (e.g. SPE10-model).