持水率对热式流量计测量影响的理论分析

恒功率热式流量计由于良好的低流量检测特性成为低产液油井流量检测的一种选择方案,但油水两相流持水率对其测量的影响妨碍了它实际的应用。针对这一问题,介绍了热式流量计的测量原理,建立油水两相流持水率和流体主要物性参数的关系,应用Matlab数值模拟软件分析不同持水率条件下热式流量计测量结果与油水两相流流量的关系。数值模拟和实际实验结果表明,相同流速下,热式流量计输出电压随着持水率的增加而单调减小。实际应用时,热式流量计的测量结果必须结合持水率才能给出正确的流量解释。

Theoretical Analysis on Effect of Water Holdup on Thermal Flowmeter Measurement

Constant power thermal flowmeter has become an option for flow detection of low-yielding oil wells due to its great characteristics of low-flow detection.However,the water holdup influence of the oil-water two-phase flow on its measurement has hampered its application.To solve this problem,this paper introduces the measurement principle of thermal flowmeter,establishes the relationship between the water-holdup of oil-water two-phase flow and the main physical properties of the fluid,and uses MATLAB to numerically simulate the relationship between the measurement results of thermal flowmeter and flow rate of oil-water two-phase flow in different water holdup.The results from numerical simulation and experiment show that the output voltage of thermal flowmeter decreases monotonously with the increase of w ater holdup under the condition of same flow rate.T herefore,in order to obtain the actual flow rate,the results of the thermal flow meter must be corrected by the water holdup.