Computer representation of complex 3-D velocity models

Abstract

We present a geologic modeling system that can accept the large, irregular surface and volume data typical of exploration studies. The modelling system is based on topological data structures that are used in other areas of computer-aided geometric design. The explicit representation of the model's topology in the data structures is crucial for carrying out the construction and manipulation of the model. The modelling system provides import functions to build 3-D velocity fields from isolated velocity points and to build 3-D surfaces from a collection of points on the surface. It also provides model visualisation and editing functions to merge multiple horizons and velocity definitions into a single model. We demonstrate the system capabilities with a complex salt body embedded in layered sediments and with a model of intersecting horizons and faults.