Fluid flow properties of basin-bounding normal faults in platform carbonates, Fucino Basin, central Italy

Abstract

AbstractBoth structural and petrophysical (porosity, ϕ, and permeability, k) data show that the basin-bounding normal faults of the Fucino Basin, central Italy, have a combined barrier–conduit effect on fluid flow. The deformed carbonates comprise fault cores of both matrix- and cement-supported fault rocks (low ϕ and k) and major slip surfaces, and damage zones of fragmented and pulverized carbonates (high ϕ and k) and small faults. The host rocks are Mesozoic, platform-related boundstones with low ϕ (<1%) and low k (<1×10−4 mD). The results of ultrasonic analysis suggest that the fragmented carbonates contain pores with a high aspect ratio, whereas the fault rocks have pores with a low aspect ratio and some moldic porosity. These two separate fluid units are modelled as an elastic cracked medium (fragmented carbonates), and as a granular medium (fault core). By using well-known correlations, their permeability is then computed from known values of ϕ, pore radii and elastic moduli.