Study Of Heat Fluid Coupling During The Process Of Circulation Of Warm Liquid And Temperature Monitoring System

During the process of exploiting the crude oil, the temperature and pressure of the crude oil gradually reduce when the crude oil is pumped up along the tubing. The wax dissolved in the crude oil participates and subsequently deposits on the tubing's inner wall. As a result, the oil's flow resistance increases, and the pump efficiency declines, so some measures should be taken to remove the deposited paraffin, In the Daqing Oilfield, the method of circulation of warm liquid has offered an principal solution to remove deposited paraffin. However, its parameters are currently only controlled by the operating technicians, which has the shortages of inefficiency and tremendous energy cost. So analyze the heat and fluid coupling temperature, online monitoring the warm liquid temperature, reasonably ascertain the parameters and raise efficiency become an urgent problem to be solved.Take warm liquid, well bore, stratum as study object, a model coupling heat and fluid during the process of circulation of warm liquid is developed in this work. The liquid temperatures along the well depth are calculated against the developed coupling model. The main parameters that influence the efficiency of circulation of warm liquid are obtained. The finite element model of warm liquid temperature during the process of circulation of warm liquid is developed using Fluent software, the influence on temperature of each parameter is studied. The practicability of using the coupling model to optimize parameters is verified.The Raman optical fiber temperature monitoring system during the process of circulation of warm liquid is developed. The system is overall designed firstly, then the structure of the sensor is designed, including the optical fiber sensor being packaged according to the special working condition in the oil well, positioning and protecting devices of the sensor in oil well being designed, multiple interfaces heat transfer problem of the packaged optical fiber sensor being discussed. In the end, calibration experiment of Raman optical fiber sensor is conducted.The field test of temperature monitoring is conducted using the Raman optical fiber temperature monitoring system. The warm liquid temperatures of a test well in the Daqing Oilfield are monitored during the process of a circulation of warm liquid method named super conduction several times, the warm liquid temperature distribution law along the well depth is obtained. The warm liquid temperatures of a test well in the Daqing Oilfield are monitored during the process of other three different circulation of warm liquid methods, the four different circulation of warm liquid methods are analyzed using normalization method, parameters are changed one by one, the warm liquid temperature variation according to each parameter is obtained.Optimize the parameters of a test well. The liquid temperature in tubing-casing annulus of a test well in Daqing Oilfield is online monitored using the Raman optical fiber temperature monitoring system developed by the author. The monitoring temperatures are well suited to the values calculated by the coupling model. The maximum deviation of the temperature is 3℃, which proves that the coupling model is of high accuracy. The parameters of a test well in the Daqing Oilfield during the process of four different circulation of warm liquid methods are optimized based on the coupling model, the parameters optimizing method can also be applied to the other oil wells, the parameters optimization method proposed by the author can raise efficiency and reduce energy consumption.