Using flowpaths and vector fields in object-based modeling

Object-based computer models are special types of 3D geologic block models in which idealized facies elements (objects) with well-defined geometries and stratigraphic relationships are distributed in three dimensions. Standard computer systems generate channels with sinuosity superimposed on straight trends. Depositional basins are complex features, however, so actual geologic deposits should be modeled with large-featured curvature of trends. Such curvature may be specified with a flowpath. defined to be a set of connected line segments that indicates the general direction that channels must follow in the area being modeled. Flowpaths are used to create a vector field: a 2D map-array of azimuths. An azimuth vector is located at each stack of blocks in the model. The array of vectors specifies the local direction of flow everywhere in the zone being modeled, and hence the orientation of the bodies being formed. Channels are developed by moving through the vector field in a series of short steps, with the direction of each step provided in part by the local azimuth of the vector field. Randomly modifying the azimuth provides variation in the channel's path. The resulting series of (X,Y) points defines the path of the channel. which is then used to assign facies. (C) 2001 Elsevier Science Ltd. All rights reserved.