Effects of local stress perturbation on secondary fault development

The complex patterns of normal faults in sedimentary basins are commonly attributed to a complex geological history with varying directions of tectonic extension. However, we show an example of normal faulting from a North Sea hydrocarbon reservoir where the variability in secondary fault orientations can be attributed to stress perturbations that developed around the larger faults during a single phase of extension. This is demonstrated by comparing attributes of the stress fields computed around largest faults from detailed three-dimensional (3D) geomechanical models, with fault data such as discretized fault orientation and density observed from a high quality 3D seismic reflection survey. The modeling results show the strong influence of the irregular geometry (bends and intersections) of larger faults on the development of smaller faults. Methods developed in this study can be applied to predict likely locations and orientations of subseismic faults. (C) 2001 Elsevier Science Ltd. All rights reserved.