Study On The Identification Of Two-phase Flow Patterns

In this paper, the background and current situation of two-phase flow measurement techniques were firstly reviewed, and the conductance measurement method was emphatically introduced. Then the vertical multiple electrodes array conductance sensor and the measurement system were shown and the dynamic experimental test of gas/liquid two-phase flow and oil/water two-phase flow were done based on its system in the multiphase flow simulant wells of Tianjin University and Huabei oil field.Recurrence analysis method and its application on the identification of two-phase flow patterns were placed emphasis in this paper. The influence of embedding dimension, time delay and threshold to the result of recurrence analysis method was studied, which was indicated that the analysis result was insensitive and stable to these parameters, and these parameters could be chosen arbitrarily in some ranges. The flow patterns identification was an important aspect in two-phase flow measurement. The recurrence analysis method was used to process the conductance fluctuate signal of gas/liquid two-phase flow and oil/water two-phase flow experiments, and the result shown that there were strong differences on the lines structures of recurrence plots with different flow patterns, which could reflect the flow characters of two-phase flow, and the corresponding recurrence characteristic values could be the effective indicator of two-phase flow patterns.Moreover, the experiments signals were also processed by wavelet analysis method and fractal R/S analysis method, which could explain the dynamic characters of different two-phase flow patterns in the multi-scale time-frequency domain way. The result indicated that the main energy was concentrated in the low frequency area and each flow pattern showed different character on each scale. The wavelet analysis with fractal method could describe the fractal characters of two-phase flow on each scale, and depict the total and detail movements. The dynamic characters of different flow patterns in different frequencies were clearly described by the multi-scale analysis applied to the conductance fluctuate signals, and it was a powerful tool to characterize the dynamic movement of two-phase flow from macro scale to micro scale.