Experimental Study On Water Holdup Measurement Of Oil-Water Two-Phase Flow Based On Microwave Transmission Method

The oil-water two-phase flow has a wide range of applications in petroleum industry. The water holdup is a key parameter of the oil-water two-phase flow for production, dehydration and transportation. However, it is difficult to measure the water holdup owing to the inherent complexity of the two-phase flow. So the on-line and accurate measurement of the water holdup of oil-water two-phase flow is an imminent demand for petroleum industry.The microwave transmission method is selected to measure the water holdup of the oil-water two-phase flow based on a lot of water holdup measurement literatures and the comparison of different measure methods. The microwave measurement technology has a wide rang of application prospect due to its real-time performance, reliability, and simple implementation. This work focuses on the water holdup measurement of the oil-water two-phase flow with high/medium water holdup using the microwave transmission method. A transducer that suited for measuring the oil-water two-phase flow with high/medium water holdup is designed according to the principle of the microwave transmission. Frequency selective amplifier with high selectivity and phase sensitive detector with large dynamic range is designed to convert the weak AC signal into DC signal that the data acquisition card required. Experiment was carried out using the developed measurement system to measure the water holdup within 20-75%, and the experimental result was satisfactory. The main works of this paper include:1. A transducer for measuring the water holdup of oil-water two-phase flow is designed. In order to reduce edge effect, minor aperture horn antenna is used in the transducer. The reflection interference is greatly minimized by directly mounting the antenna to the pipe. This transducer is suited to measure the oil-water two-phase flow with high/medium water holdup owing to the high gain and short range of the antenna.2. Based on the microwave transmission method, a set of measurement system is designed to measure the water holdup of the oil-water two-phase flow. The best working frequency of this system is 9.4 GHz, which is selected by theoretical analysis. The microwave circuit unit is composed of microwave signal resource, low noise amplifier and microwave detector. Frequency selective amplifier is used to eliminate noise. Phase sensitive detector is designed to convert the weak AC signal into DC signal that is necessary for the data acquisition card.3. The static experiment was carried out using the developed measurement system to measure the water holdup within 20-75%. In this work, the oil-water two-phase flow is investigated in two sections with different water holdup (20-60% and 60-70%), while the traditional study is limited to continuous water holdup. The static experiments were carried out in the horizontal pipe and the vertical pipe, and the initial experimental results show that the absolute measurement error is less than 4%.