Impact of glacially induced stress changes on fault-seal integrity offshore Norway

In this study, we use a three-dimensional numerical model of glacially related lithospheric flexure to estimate in-situ stress and pore pressure changes through time in the Norwegian sector of the northern North Sea. The model results match available borehole measurements of in-situ stress and pore pressure, which show a transition from high horizontal stresses at large distances from the coast to lower horizontal stresses in near-coastal areas and an associated rotation in stress orientation. In addition to the present-day predictions, the model results provide an estimate for the evolution of stress and pore pressure during glacial and interglacial periods. We found that the temporally changing stress field might have induced repeated reactivation of reservoir-bounding faults during the course of the Pleistocene glaciations, especially during Weichselian interglacials. As a result, hydrocarbon fields in the Norwegian offshore areas appear to have been exposed to multiple periods of fault reactivation and potential hydrocarbon leakage.