Cenezoic Uplift and Caprock Seal in the Barents Sea: Fracture Modelling and Seal Risk Evaluation

Abstract

Abstract Among the possible reasons for leakage from reservoirs in the Barents Sea are spill due to tilting, expulsion caused by gas expansion and cap rock failure. All mechanisms have been related to the pronounced Cenozoic uplift of the Barents Shelf. This paper focusses on how the uplift has influenced the cap rock seal. The simulations presented comprised Late Jurassic rifting at shallow burial, post-rifting sedimentation followed by two phases of Tertiary uplift/erosion with subsequent compression and extension at different depths of burial. The two main results from these simulations are: a) that cap rock failure may occur due to the build up of deviatoric stresses during uplift, and b) that minimal strain is required to initiate fracturing during extensional or compressional tectonics. By combining the map of total erosion with the results of the fracture modelling study presented, uplift could be identified as a critical factor in structurally high areas. Fracture initiation in cap rocks is less likely in basinal areas. As a result exploration can be concentrated on the most promising areas.