Measurement and prediction of effective diffusivities through spreading and nonspreading oils in unsaturated porous media

The difference in phase continuity between spreading and nonspreading oils at low saturations was examined by measuring the oil phase effective diffus ivity. Results indicated that for the sand and water saturations studied, t he spreading oil (1-octanol) remained continuous at saturations as low as a pproximately 0.035 (the lowest ail saturation measured), while the nonsprea ding oil (n-dodecane) became discontinuous at a saturation of approximately 0.055. 1-Octanol also showed higher effective diffusivities than the n-dod ecane throughout the saturation range examined, indicating that the spreadi ng oil was more highly connected. Two separate models, one for spreading an d another for nonspreading oils, were used to describe the behavior of the oils in the unsaturated porous medium. Each model gave a reasonable predict ion of the experimental data and was able to describe the difference in con tinuity between nonspreading and spreading oils.