This paper describes an experimental study of water wetting in large diameter horizontal oil-water
two-phase flows. Four types of oil, one model oil and three crude oils, have been used in conjunction
with a 1 wt% NaCl brine as working fluids. Flow pattern visualization, wall conductance probes,
corrosion monitoring and wall fluid sampling were successfully applied in this investigation. Based on
the overlapping information from these four techniques, three types of phase wetting regimes (stable
water wetting, intermittent wetting and stable oil wetting) were observed. Comprehensive phase wetting
maps were constructed where and the boundaries between these water wetting regimes are identified. It
was found that the oil type has a significant effect on the transition from stable oil wetting to intermittent
wetting and that much of the influence can be ascribed to the physical properties of the oil: density,
viscosity and surface/interfacial tension. No corrosion was detected in the stable oil wetting regime,
while the corrosion rate in the full water wetting regime was typically twice that observed for the
intermittent wetting.