Chaotic Time Series Analysis Of Oil/Water Two Phase Flow Patterns

The conductance fluctuating signals of oil/water two-phase flow in vertical upward pipe of water cut (k_w) ranging from 61% to 91% and total flowrate (Q_t) ranging from 10(m~3/day) to 60(m~3/day) were analyzed in the paper. From this studywe concluded several results as follows:1. The paper discussed several algorithms for calculating the maximal Lyapunov exponent and validated their applicability by numerical calculation. The maximal Lyapunov exponent of oil/water two-phase flow fluctuating signals was larger than zero and it showed oil/water two-phase flow was a chaotic system.2. The optimal time delay of phase space reconstruction was calculated by the first minimum method of mutual information. The method and programs were proved reliable by calculating the Mackey-Glass Equation and Lorenz strange attractors. It established foundation for extracting the correlation dimension and Kolmogorov entropy from the chaotic time series.3. For the oil-in-water pattern of 61%≤K_w <91%, the correlation dimensions ofchaotic attractor were range from 2.63 to 3.46 and Kolmogorov entropy from 0.05 to 0.488. The correlation dimension and Kolmogorov entropy had a good corresponding relationship with K_w and Q_t . The correlation dimension andKolmogorov entropy increased as Q_t increased when k_w was definite value.They showed irregular sudden changes to transitional flow pattern of water cut of 51%,and the correlation dimensions were rang from 2.9 to 4.21 and Kolmogorov entropywas rang from 0.06 to 0.392. The study showed that the correlation dimension and Kolmogorov entropy are sensitive indicators for oil/water two-phase flow pattern variations.