USING GEOMETRIC SIMULATION TO EVALUATE THE SPANNING OF PERMEABLE ZONES IN HIERARCHICAL SEDIMENTARY DEPOSITS

Permeable zones within sedimentary deposits can create preferential flow pathways. Such pathways are said to span a domain if they are continuously connected from one boundary to another. The study of spanning as a function of proportion is the subject of percolation theory. Previous studies have compared spanning in infinite domains having random placement of attributes and in finite domains with spatial structure. As yet, this comparison has not been made in considering the hierarchy of stratal architecture, which is often found in sedimentary deposits. To advance such comparative studies a new simulation model is created to represent the hierarchical stratal architecture of sedimentary deposits. The stratal architecture is organized into four hierarchical levels. Each level has different scales of stratal unit types, from large-scale compound bars at level IV, down to small-scale texture, which includes sands, sandy gravels, and open framework gravels at level I. The unit types of each hierarchical level are simulated using geometric simulation. This involves representing geometric shapes of unit types at each hierarchical level with piecewise planar elements, each defined by a set of length, width, and angle parameters. Values for these parameters are then drawn from appropriate statistical distributions quantified from field data. The focus is on the spanning of open framework gravels which have highest permeability. The proportions and geometric parameters (length & width) of unit types at each hierarchical level will be varied systematically to generate multiple realizations. The realizations will be evaluated for spanning and compared with realizations where open framework gravels are randomly distributed.