Porosimetry of vesicular volcanic products by a water‐expulsion method and the relationship of pore characteristics to permeability

Abstract

Porosimetry of vesicular volcanic products was conducted by a water‐expulsion method to investigate the relationship between pore characteristics and gas permeability. The pores in a rock were categorized as total, connected, transport, dead‐end, and isolated pores. Gas flow takes place only through the transport pores but the pores that do not provide a flow path are included in both total and connected porosities. Permeability correlated weakly with total porosity, connected porosity, and transport porosity. The characteristic maximum pore‐throat radius r ch (m) was also determined. Both r ch and transport porosity correlated well with permeability k 1 (m 2 ) according to the following form of the Kozeny‐Carman relation: k 1 = 0.0022ϕ tra r ch 2 . Permeability is thus strongly dependent on pore size, and estimation of pore size is essential for understanding the permeabilities of vesicular volcanic products.