| As the development of major oilfields of Daqing enter the high water-cut stages in succession, the scattered periphery oilfields experience the improved exploration and development to provide the indispensable replacement reservoir. But due to the limited output, the oil production mode includes the bailing production in addition to the mechanical oil production by pumping unit; the oil gathering is carried out through the regular oil discharging and drawing methods beside the pipeline transportation. Accordingly, the produced fluid features more complicated properties, which finally results in various problems restricting the normal operation, such as the increase in energy consumption of surface processing system, unstable operation of processing facilities and rise of consumption of treating agents. This paper focuses on the surface gathering and transportation, oil discharging, dehydration and other key technical problems arising in the Yushulin Oilfield, and conducts the research of theory and test to find out various factors affecting the stability of electric field of electrical-chemical dehydration in dehydrating station, prepare the appropriate dehydration process plan, design a new oil discharging pool in groups, and carry out the research on optimization of cooling gathering and transportation operation plan. The main research results are given as bellow:(1) The fluid produced from bailing well typically features the accumulation of many gelatine, a lot of mechanical admixture, high-content inorganic sulfide and zoogloea formed due to the successive growing and reproduction of bacteria; of which, various impurities more easily gather on the oil-water interface and form the thick interfacial film, which, together with the unavoidable long-term aging of oxygen exposure, can further improve the emulsion stability.(2) In addition to the appropriate water content, proper temperature conditions and dosage fitting, the key points to solve the frequent"field transverse"of electric dehydrator are to prevent the failed oil with high content of mechanical impurity and acidulated returns rich in iron from entering the dehydration system.(3) The HCMP can form large transient power with the advantage to damage the high-strength emulsion without generating the electrodispersion; the HCMP, when combined with the ultrasonic pre-dehydration technology, can remarkably reduce the consumption of demulsifying agent and improve the effect of purifying treatment for crude oil.(4) Study and specify the dehydration technology parameters for dehydration process flow suitable to the Yushulin Oilfield: for the phase-I dehydration of free water and phase-II HCMP electrical-chemical dehydration, the dehydration temperature shall be about 60℃, water content of incoming fluid not more than 30%, treatment amount 30~60m~3/h, operating pressure 0.2~0.3MPa, water content of oil after dehydration not more than 0.3%, oil content of sewage not more than 1,000mg/L.(5) Design an oil discharging pool with new structure. When compared with the original design plan, this one can remarkably decrease the investment and features such advantages as low energy consumption of productive operation, correct measurement, convenient dredging, and more stable operation of oil transportation pump.(6) Study and establish the mathematical model for optimization of oil/gas gathering and transportation system operation plan of Yushulin Oilfield in order to minimize the energy consumption of system, work out the solving strategy featuring optimization in levels, and carry out the cooling gathering and transformation for five transferring stations in the Yushulin Oilfield. The results show that in comparison with the operation before optimization, the gas consumption per ton of oil is reduced by 8.0m~3/t averagely, electric consumption per ton of oil by 2.3kW·h/t averagely, comprehensive energy consumption expense by 10.9 Yuan/t averagely, and more than 1.7 million Yuan will be saved each year.
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