Study On Testing Technology Of Complex Dielectric Constant Of Aqueous Crude Oil

The measurement of the moisture content of crude oil is an important parameter for monitoring the characteristics of oil reservoirs and evaluating the effect of enhanced exploitation,and is also an important parameter for oil well production.At the base of real-time online and accurate measurement of crude oil moisture content,collecting dynamic information of underground reservoirs and production status of each production layer,and comprehensively analyzing the dynamic information is to get the distribution of oil and water and further to achieve targeted fracturing and water plugging of underground reservoirs.Based on the theory of electromagnetic field,this article presents a dual antenna structure model based on dielectric loss principle to measure the complex dielectric of water-containing crude oil by studying the equivalent dielectric constant model of water-bearing crude oil.According to that,the voltage on the receiving antenna at different proportions of water in crude oil is obtained,at the same time,the antenna type,antenna length,antenna radius,spacing between the two antennas and the wrapping medium in the RF sensor are optimized.The COMSOL multi-physics simulation software was used to analyze the displacement current of the receiving antenna in different proportions of water-containing crude oil,which verifies the correctness of the theoretical derivation.Through based on the RF method,the signal processing circuit for equivalent complex dielectric of water-containing crude oil testing system was designed and combined with the sensor to prove the testing theory and simulation model of the complex permittivity of crude oil by RF method in the condition of indoor simulation and outdoor high temperature and pressure testing system.In addition,temperature compensation technology is adopted during outdoor high temperature and high pressure experiments.After that,the equivalent complex permittivity in different ratios of water-containing crude oil is inversed by the voltage value on the receiving antenna.The experimental results show that the absolute error of the indoor simulation and outdoor high temperature and pressure testing results is within ±0.15,which meets the requirements of the field for measurement results.After the industrialization of the water-containing crude oil complex permittivity test system,it can be further developed into a two-phase flow or multi-phase flow tester,which contributes to the modern management of the oil field.