RAPID FLUID CONTENT MEASUREMENT METHOD FOR FINGERED FLOW IN AN OIL-WATER-SAND SYSTEM USING SYNCHROTRON X-RAYS

The complexity of simultaneous flow of water and non-aqueous phase liq uids is largely unappreciated because few techniques permit accurate q uantitative measurement of water and oil contents in rapidly changing now fields. High intensity X-rays were used at the Cornell High Energy Synchrotron Source (CHESS) to obtain rapid, accurate, and non-destruc tive quantitative measurements of the changing fluid contents in a por ous medium during infiltration events. Concomitant temporal pressure m easurements were obtained for each liquid phase using rapidly respondi ng tensiometers. The system was used for measuring temporal volumetric fluid content changes during a water finger infiltration into sand sa turated with a NAPL (Soltrol-220) in a two-dimensional chamber. The fl uid content distribution of a finger in the oil-water system was found to be similar to air-water systems. The hysteretic constitutive relat ionship between pressure and the content was developed from the data. The relationship was used to explain why the finger did not widen behi nd the tip, and why, upon re-infiltration, water followed the previous ly established path. These findings are relevant for cleanup of oil-co ntaminated sites because it aids in the understanding of hydrologic co ntrol which is an essential component of cost-effective in-situ remedi ation. (C) 1998 Elsevier Science B.V.