HIGH-SPEED MEASUREMENTS OF 3-PHASE FLOW USING SYNCHROTRON X-RAYS

Accurate monitoring of flow instabilities, which can occur when nonaqu eous phase liquids (NAPLs) flow through porous media, is an important component of predicting the transport and fate of these compounds in t he subsurface. In particular, flow situations in which three mobile ph ases (such as water, NAPL, and air) exist in the porous media are inhe rently complex. Unfortunately, the relatively low source intensities a nd the nontunable source energies make traditional dual gamma techniqu es unsuitable to study flow instabilities which can change within seco nds, We present an alternate technique, which uses synchrotron X rays from the Cornell High Energy Synchrotron Source (CHESS) to measure thr ee-phase fluid saturations on the time scale of seconds. Using the har monic content resulting from X ray diffraction, we obtained a high-int ensity X ray beam consisting of distinct tunable energies. Three-phase saturations were measured on 5-s timescales during fingering of light NAPL into regions of dry and water wet sandy soil. In the water wet s oil the oil finger was less saturated, slower, and wider than the same finger in the dry soil. The results yield insights into the nature of three-phase preferential flow.