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

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 rch and transport porosity correlated well with permeability k(1) ( m 2) according to the following form of the Kozeny-Carman relation: k(1) = 0.0022 phi(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.