Permeability anisotropy in sandstone hosted normal faults

Measurements of permeability (k) from over ninety oriented core plugs sampled around two extensional faults set in aeolian and fluvial sandstone formations show anisotropy in three orientations independent of the original sedimentary fabric permeability. The degree of permeability anisotropy and the orientations of kmax vary with distance from the fault plane and show asymmetry between the hanging wall and footwall. Analysis of current porosity from core plugs and image analysis implies that variations in pore geometry associated with faulting may control permeability anisotropy around these fault zones. Integration of this new petrophysical information can improve understanding of permeability and transmissivity for reservoir modelling around fault zones. Previous research shows that changes in pore pressure, associated with fluid flow, can induce changes in the stresses acting on the rock (Teufel et al., 1991). Quantitative study of complex pore geometries along a fault zone can also provide information about the mechanical behaviour of rocks during faulting and inform predictions for fault stability.