原油含水率指数对数电容检测模型及误差分析

Measurement Model and Error Analysis of Logarithmic Capacitance for Water Content Index of Crude Oil

为测量高含水原油的含水率并提高测量精度,基于电容法测量原理,采用三个平行极板构建了电容信号原油含水率指数与对数检测模型,对实验室高含水原油进行了测量.分析了电容法测量的边缘效应,得出了平行极板结构尺寸与边缘效应的关系.结果表明:该模型在含水率低于70%的条件下,含水率测量值与理论计算值基本相符,重复性误差约为±3%,最大误差约为±4%,分辨率为3%.边缘电容与检测模型几何参数呈正比函数关系,平行板结构与尺寸变化时无需标定,寄生电容为杂散电容附加值,边缘效应与传感器尺寸结构有关.为高含水原油的检测提供了新方法.

In order to measure the water content of high water cut crude oil and improve the measurement accuracy,based on the principle of capacitance measurement,the capacitance signal oil moisture index and logarithmic detection model are constructed by using three parallel electrode plates.The high water cut crude oil in laboratory is measured and the edge effect of capacitance method is analyzed.The relationship between the size of parallel plate structure and the edge effect is obtained.The results show:The measured value of water content is basically consistent with the theoretical calculation value when the water content is less than 70%.The repeatable error is about±3%.The maximum error is about±4%and the resolution is 3%.The edge capacitance is proportional to the geometric parameters of the detection model.The parasitic capacitance is the additional value of stray capacitance,and the edge effect is related to the size structure of the sensor.The measurement provides a new method for the detection of high water cut crude oil.