Principle Analysis And Software Design Of Steam Quality Measurement Instrument Based On Fiber Optic Sensor

The cyclic steam stimulation is the most popular process used in the exploit of heavy oil. The efficiency of energy source and the recovery factor of heavy oil relate to online measurement of the steam quality in steam injection well. The measurement of the steam quality is very difficult because steam's phase change and complex flow model. The online measurement of the steam quality is a difficult problem of world in petroleum industry, because of high temperature and high pressure of steam and narrow space of steam injection well. Although a lot of method can be used to measure steam quality of steam injection well, but the most of these methods have some problems with measured scope and accuracy. Nowadays there is no satisfied method can be used in measurement of steam injection well.According to this circumstance, main study in this paper shows as following:1. Vapor water ratio can be directly measured through the method of steam quality measurement which is based on refractive index modulation principle, then steam quality can be got by substituted with density of steam and water. The advantages of this method are anti-jamming, online continuously measurement, wide measurement scope, accurate measurement value, almost have no interference to flow. In the actual application, sequential response value of steam quality is measured under steam injection well with high temperature and high pressure.2. The method is related to many different techniques, such as fiber optic sensor, micro-electronics, automatic control, optical design, thermodynamics etc. Establishing of correct mathematics model is most important for method success. Calculation formula of steam quality and other parameters was gotten through analysis of principle of refractive index modulation and thermodynamics. By analysis, the relationship of reflection index and steam quality, the conclusion is that the method of refractive index modulation can be well adapted to actual application circumstances of steam injection well.3. An instrument based on refractive index modulation is developed for measuring steam quality. A series of response value of steam quality were gathered by experiments on laboratory, steam pipeline of boiler and steam injection well. The mathematics model is proved correctly by analysis of the response value of steam quality.4. Programming software of the instrument is a difficulty because the instrument is offline work and accomplishes scheduled measurement under steam injection well. So the steadily running and accurately measuring of the instrument is depending on correctly programming software of the instrument. Analysis and design of the software is according to the standard of software engineering. In actual application of the software, the result can be pointed out that the technical requests of engineering in oil-field are well followed by the method based on the principle of refractive index modulation and the program.