Building and unfaulting fault-horizon networks

Abstract

Abstract A fault-horizon network is a set of horizon and fault surfaces that is geologically consistent and topologically complete. It is the missing link between seismic interpretation and reservoir modelling. Building the fault-horizon network from a seismic interpretation can be a fast and automatic process. The fault slip vector field embedded in the network is used to construct tip points and fault branches, and as a powerful tool to validate network quality. A novel, very fast method is introduced to unfault the network, i.e. to remove fault-related strain. It allows further validation of the geological consistency of the network, and it delivers an unfaulted framework for reservoir modelling. The unfaulting method approximates the three-dimensional kinematics related to faulting with the simplest possible analytical description that can be calculated from the geometry of the fault-horizon network and its fault slip vector field. The construction of ‘fault swallows’ at branching faults decomposes discontinuous slip and strain at branch lines into continuous segments. With this decomposition, the unfaulting method can handle complex branching fault situations. The methods in this paper have been developed for normal faults in deltaic areas, but they can easily be extended to other geological settings.