ABSTRACT

The seal of critically stressed faults can be compromised by deformation/stress changes induced by external solicitations. The stress relief due to excavations or reservoir pressure changes, for example, can create favorable conditions for reactivation of faults by shear or tensile modes. Among several problems, fault reactivation may result in slope detachment, the generation of a fault scarp along the ground surface, oil exudation and seismicity. This study presents a methodology for the evaluation of fault reactivation using numerical modelling. With the finite element method, it is possible simulate the effect of both, excavations and reservoir pressure changes over geological faults. Those faults are introduced in the models using zero thickness interface elements. Some 2D and 3D models are analyzed with focus on mining and petroleum engineering applications. In relation to the mining industry, fault reactivation caused by open-pit and underground mines are taken into account. Regarding the oil industry, a case of fault slip due to hydrocarbon production is also presented. The results call attention to the different causes and effects of fault reactivation and provide some clarity to the understanding of this phenomenon.