oa Multi-phase Flow Properties of Fault Rocks – Implications Prediction of Across-fault Flow During Production

Here we present new data on the relative permeability and capillary pressure of fault rocks as well as the stress dependency of relative permeability. The high capillary pressures and low relative permeability of some well lithified cataclastic faults helps explains why some Rotliegend reservoirs in the Southern North Sea are so severely compartmentalised by faults. The low capillary pressure and high relative permeabilities of poorly lithified phyllosilicate-framework fault rocks may explain why it is often possible to obtain good history matches of production data from faulted Brent-type reservoirs without incorporating the multiphase flow properties of fault rocks into simulation models. The multi-phase flow properties of some samples are highly stress dependent even during elastic deformation. These new data suggest that it may be necessary to take into account the stress-dependence of fault rock flow properties when modelling across-fault fluid flow in compartmentalised petroleum reservoirs.