| Progressing cavity pump (PCP) is a new type of artificial lift equipments with thecharacteristics of simple structure, great applicability, easy installation, less floor area, lessinvestment, high efficiency, etc. It has been widely used in oil production at home andabroad. At present, more oil fields have entered into the tertiary oil recovery stage and oilexploration is becoming difficult. Therefore, the application of progressing cavity pumpshows the clear upward trend. The progressing cavity pump composes of the stator ofelasticity and the metal rotor. The performance of stator rubber bushing directly affects theperformance of entire oil pumping system, and the wear of stator rubber is one of the mainreasons which lead to the failure of progressing cavity pump. The life of stator rubber isaffected by many factors in the course of working, which results in physical and chemicalproperty change of rubber, and accelerates aging and wear of the stator rubber. Theaffecting factors decrease the mechanical and volumetric efficiency of pump, shorten thelife of pump, and limit the scope of application. The selection of stator rubber material andits further improvement are crucial for improving the performance of progressing cavitypump, which plays an important role for extending the working life of progressing cavitypump in heavy oil wells, sand wells and inclined wells.Currently, in order to improve the performance of the stator rubber, researchers haveused plastic or various kinds of high performance fillers for blending with nitrile rubber.But so far, no researchers has taken the comprehensive performance requirements of statorrubber into account, such as strength, abrasive resistance and aging resistance, and also hasnot researched the optimization problem of rubber blend ratio. Therefore, the research onthe blend technology will be carried out in this thesis to optimize the stator rubber ofprogressing cavity pump by mixing fluorine rubber and nitrile rubber, and on wearmechanism to provide the theoretical basis for choosing stator rubber. The main works andcontributions of this thesis are listed as follows:Considering that the wear of stator rubber is subjected to the interactive coupling ofhigh temperature, high pressure, swelling, rotate speed and other factors, and the relationship between the various factor and wear loss cannot be precisely described bymathematical expression, the wear resistance of rubber blend with the different ratio ofNBR (Nitrile butadiene rubber) and FKM (Fluorine rubber) was investigated by theMPV-600and MLS-225testers. In this thesis, the effect of various factors on the wear losswas analyzed and the relation model was constructed. Specialized experimental apparatusfor simulating the high temperature, high pressure, gas swelling, which was similar to thatin the actual working conditions, was designed to analyze the effect of these factors on theproperties of rubber, and it would make the experiment data and results more accurate. Theexperimental data was disposed and contrasted to find out the excellent performance blendadapt to the practical oil extraction condition. The constitutive relation of blend rubbers isanalyzed by using scanning electron microscopy and infrared spectroscopy before and afterthe wear experiment in different conditions to determine the wear mechanism.During the actual working process of screw pump, the formulation of stator rubberand the blends ratio must be adjusted in accordance with the working conditions. Tocooperate the stator rubber formulation with the actual working conditions, theexperimental apparatus for the different conditions (temperature, swelling and other factors)is self-designed, and the relations between different formulations of stator rubber and thewear resistance in different condition (dry sliding, water lubrication, base oil lubrication)was analyzed using this wear tester. The full set of experimental method is proposed aboutthe effect of speed, load, temperature, swelling and other factors in the actual conditions onthe wear resistance of the stator rubber. The effectiveness and practicality of experimentalmethods are verified by the experimental data, infrared analysis and scanning photographsof wear experiment.Through the above research about the experimental method the design of testequipment, this paper construct the comprehensive experiment platform, which could fusemultiple factors into one and aim at the analysis of the stator rubber of screw pump. Theexperiment and analysis of stator rubber with different formulation and ratio could berealized in this platform according to the actual condition. Finally, the optimal formulationand ratio of rubber blend could be found adapt to the related operation condition. |
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