Experimental Study of Multi-Cation Diffusion in an Artificial Quartz Sandstone.

摘要

Integral diffusion coefficients were measured at 35 C in the interstitial solution of an artificial quartz sandstone. The porous medium was chemically inert,had a porosity of 29.3%,an average grain size of 200microns and a formation factor of 11.44. The relative rates of diffusion in sea water were K(+) >Na(+) >Cl(-) >Ca(++) >Mg(++) > SO4(--). Two quantitative evaluations were made on the effect of diffusion in the storage of fresh water in salt water aquifers. The first treatment was concerned with diffusion of Na(+) from the confining shales. The second treatment also took into consideration the release of Na(+) from exchange sites within the shales. The second treatment showed an increase of Na(+) concentration within the fresh water of nearly 300% as compared to the concentration given by the first treatment. It was found in the second treatment that in thin aquifers,appreciable quantities of Na(+) could occur in the fresh water in short time periods.