Pore system evolution in arenaceous regoliths - Case study from the Sila Massif (southern Italy)

Porous and permeable crystalline rocks have the potential of being hydrocarbon reservoirs. In many cases, reservoir properties are created by rock-altering physico-chemical processes occurring in near-surface environment. Hydrocarbon reservoirs altered granitoids may comprise both arenaceous (clay-poor) argillaceous (clay-rich) palaeoregoliths, hence outcrop analogues from various environments required. Sila Massif, southern Italy, weathering medium to coarse grained granodioritic has been studied. The pore system, dominated microfractures, was described quantified at each stage process (altered coherent rock facies → saprock facies→ lower upper saprolite soil) relation changes chemical physical properties. transformation close an isochemical process, as demonstrated low variations bulk mass transfer coefficient (τbulk). At same time, trans-, intra- intermineral microfractures increased frequency aperture upwards through regolith profile. It main reason for reduction densities (ρb) 2.66 g/cm3 1.88 saprolite, corresponding formation up 30% porosity (φc). results suggest that a volume increase >50%, represented volumetric strain factor (ε), cause solid porous saprolite. Anisovolumetric regoliths with minimal loss, result one major processes, notwithstanding they much less understood than isovolumetric, anisochemical, regoliths. Arenaceous saprolites potentially can excellent permeability properties, open well-connected microfractures. Reservoir quality is stark contrast poor observed some where isolated dissolution voids within clay-rich matrix.