Universal scaling of fluid permeability during volcanic welding and sediment diagenesis

Abstract

In sedimentary basins and volcanic edifices, granular materials undergo densification that results in a decrease of porosity and permeability. Understanding the link between porosity and permeability is central to predicting fluid migration in the sedimentary crust and during volcanic outgassing. Sedimentary diagenesis and volcanic welding both involve the transition of an initially granular material to a non-granular (porous to dense) rock. Scaling laws for the prediction of fluid permeability during such granular densification remain contested. Here, based on collated literature data for a range of sedimentary and volcanic rocks for which the initial material state was granular, we test theoretical scaling laws. We provide a statistical tool for predicting the evolution of the internal surface area of a system of particles during isotropic diagenesis and welding, which in turn facilitates the universal scaling of the fluid permeability of these rocks. We find agreement across a large range of measured natural permeabilities. We propose that this result will prove useful for geologists involved in modeling porosity-permeability evolution in similar settings.