Water layer height measurement in oil-water two-phase flows

Water layer height was measured by a single-wire capacitance probe in horizontal oil-water two-phase flows. The viscosity of oil was up to 140 mPa·s to simulate the actual flow in oil production logging. Typical water-layer-height curves with time were obtained when water was continuous. The accuracy was estimated by a quick-closing valve (QCV) system. Time traces of water layer height were completely consistent with the corresponding flow structures. The statistic parameters, such as amplitude, average, and frequency, were different from each other, which can describe the features of the flow patterns. The single-wire capacitance probe can only detect continuous water, instead of emulsified water in oil. However, the emulsified water had effect on flow structure, indirectly influencing the measurement results. On the basis of the measurements in different flows, the same principle was obeyed including air-water, and oil-water two-phase flows with oil of different viscosities. The detection ability of the probe decreased as interfacial velocity increasing or the size decreasing of the discrete phase, and flow patterns determined the measurement accuracy. The error of estimated water holdup by the probe was -35∼10% and 5∼25% for stratified and dispersed oil in water flows, respectively.