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In this paper, firstly the Lorenz chaotic equation was taken as an example to produce a nonlinear time series, and we discussed the applicability of delay time algorithm to the presence of noise at different time series length. The study shows that the C-C algorithm of delay time is robust, and the Fraser et al's mutual information algorithm and auto-correlation function algorithm are affected by presence of noise and variations of time series length and the Libert et al's mutual information algorithm can not calculate the delay time. Based on the above studies, we characterized the gas/liquid two phase flow patterns based on the chaotic analysis of conductance fluctuating signals. The results indicate that at a low superficial water velocity, with increasing superficial gas velocity, the dynamic characteristic of bubble and churn flows becomes more complex, and the slug flow is affected by the liquid superficial velocity; whereas at high superficial water velocity, with increasing superficial gas velocity, the dynamic characteristic of gas/liquid two phase flow becomes simpler while the flow pattern changes from bubble flow to slug flow, and the dynamic characteristic of slug flow shows unsteady fluctuating phenomena due to liquid phase turbulence interaction, and the dynamic characteristic of two phase flow becomes more and more complex while the flow pattern changes from slug to churn flow. The study shows that we can characterize the flow pattern variations of gas/liquid two phase flows based on the chaotic analysis of conductance signals, it is a useful tool to understand flow pattern transition mechanism and its dynamic evolution characteristic.

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The injection polymer well logging technology has been used widely in Daqing oilfield of China. Accurately determining the changing rules of polymer velocity profiles in injection well has practical significance in understanding performance of production well. This study mainly investigates flowrate measuring problem of injection polymer well, and then pay more emphases on analyzing flow field distribution and magnetic field distribution characteristics of four electrodes electromagnetic flowmeter. We employ finite element method to analyze magnetic field distribution characteristics, and use finite volume method to analyze flow field distribution characteristics in the annular area between oil pipe and flowmeter body at different flowrate and polymer concentration. Finally we make a comparison between the velocity profile distribution curves and practical measurement response curve getting from experiments shown in Figure 1 and Figure 2 respectively. We conclude that the measurement response of electromagnetic flowmeter can be interpreted by using flow field distribution characteristics by numerical simulations.