Effects of local stress perturbation on secondary fault development

The complex patterns of normal faults in sedimentary basins are commonly at tributed to a complex geological history with varying directions of tectoni c extension. However, we show an example of normal faulting from a North Se a hydrocarbon reservoir where the variability in secondary fault orientatio ns can be attributed to stress perturbations that developed around the larg er faults during a single phase of extension. This is demonstrated by compa ring attributes of the stress fields computed around largest faults from de tailed 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 o f the irregular geometry (bends and intersections) of larger faults on the development of smaller faults. Methods developed in this study can be appli ed to predict likely locations and orientations of subseismic faults. (C) 2 001 Elsevier Science Ltd. All rights reserved.