The standard petroleum industry technique of treating faults as opaque barriers in structure and unit modeling does not provide the accurate models and hardcopy maps required today for hydrocarbon exploration and production efforts. The shortcomings of these old methods is especially apparent when attempting to develop cost-effective models of small hydrocarbon reservoirs.

The process of incorporating fault surfaces into digital subsurface models is going through a period of rapid change as new techniques for incorporating fault geometry into structure and unit modeling applications have been introduced over the last few years. These methods, which are reviewed in this chapter, provide superior solutions to the problem of incorporating faults into subsurface modeling and mapping efforts than techniques which simply treat faults as opaque barriers. However, these methods represent only interim solutions.

Inevitably, full 3-D subsurface modeling in faulted environments will replace the two-dimensional programs now available. Experimental algorithms have been developed for modeling and editing structures which have multiple depth values for single (X,Y) coordinates, such as structures cut by reverse faults or structures that include over-turned folds. At the same time, geophysicists are exploring new methods for determining both structure shapes and rock properties from seismic data.