B12 Flow Regimes of Heavy Oils under Water Displacement E.S. Vittoratos* (BP Exploration (Alaska) Inc.) C.C. West (BP Exploration (Alaska) Inc.) & C.J. Black (BP Sunbury) SUMMARY We have examined the production data from heavy oil reservoirs produced by waterflooding. Previous observations from a waterflooded heavy oil reservoir on the North Slope of Alaska have indicated sequential flow regimes characterized by steps in the Water Oil Ratio (WOR) vs Cumulative Recovery curve. The most prominent feature is a period with a constant WOR near one of variable duration but often persisting for many years; this is followed by a large