Study Of Measuring Technique On The Water Content Of The Crude Oil

The water content of crude oil is a key parameter in petroleum industry. The water content directly affects the crude oil exploitation, dehydration, transportation, measure, sale, smelting etc. The inaccurate measure of the water content will affect directly oil well and oil layer dynamic analysis, destroy the electrical field in the electric dehydrator, lower the dewatering effect, result in energy waste. However, it is difficult to measure the water content owing to the inherent complexity of the oil-water two-phase flow. So the on-line and accurate measurement of the water content of crude oil is an imminent demand for petroleum industry.The measurement object of the research in this paper is the crude oil with water content. Through studying the domestic and international related documents, the existing several test methods of water content of crude oil are summarized and compared. The basic principle, application, merits and shortcomings are analyzed. According to the feature of high viscosity and high water content of our country's crude oil, the method of applying the phase difference of electromagnetic wave is selected to measure the water content in this paper. Because of the different dielectric property between oil and water, the phase constants are quite different when electromagnetic wave travels in them. The coaxial transmission line is taken as the sensor and oil/water mixture flow in the coaxial line. The water content can be measured through test the phase difference of the electromagnetic wave between two sides of the sensor. The circuits of producing and magnifying 80MHz signal and testing the phase difference are designed. The data sample and transport is realized by the single chip .And the PC processes the data and shows the results. At the same time, the temperature measurement circuit is designed to reduce the effect to results brought by the change of temperature.The experiments for measuring the water content from 0 to100% are accomplished. And the results are given taken 10% as a gap. The experiments prove the method of applying the phase difference of electromagnetic wave to measure water content in crude oil is feasible. And the system designed according to the method can realize the continuous measurement. The linearity and accuracy is better when the water content ranges from 70% to 100%.