The flow patterns of oil/water two-phase flow in vertical upward pipes were characterized by the analysis of symbolic time series based on the conductance fluctuating signals.The study showed that the symbolic sequence temporal irreversibility T fb and chi-square χ2 fb statistics had little change with oil-in-water flow pattern variations for water cut (K w) ranging from 61% to 91% but showed irregular sudden changes with transitional flow pattern variations for water cut 51%.When distinguishing the transitional flow pattern from oil-in-water flow pattern, the symbolic time series analysis method presented more unique characteristics and was a useful assistant diagnostic tool for the identification of oil/water two- phase flow patterns.
