GAS DIFFUSIVITY IN POROUS MEDIA: DETERMINATION BY MERCURY INTRUSION POROSIMETRY AND CORRELATION TO POROSITY AND PERMEABILITY

摘要

Much effort has been extended on diffusivity measurement because diffusion can dominate mass transport in porous media of low hydraulic conductivity. The main purpose of this work is to derive the gas diffusivities of building materials, rocks and sediments using the average pore size measured by mercury intrusion porosimetry (MIP). MIP has been utilized for decades to obtain the poresize distribution of porous media. We performed triplicate MIP tests on concrete and Berea sandstone to evaluate the repeatability of MIP data. Gas diffusivity results are consistent with literature data using the gas diffusion methods. Our results show that the relationship between gas diffusivity and porosity is analogous to Archie's law and that two groups of rocks are differentiated according to the cementation factor m value in an Archie's-type relationship. It also appears that gas diffusivity exhibits an increasing trend with an increase of permeability, and two different exponential relationships exist between permeability and porosity for these two groups of rocks.