Reason Analysis Of Influencing Factors For Wellhead Back Pressure In Circular Gathering And Transferring Process And Research On Method Of Regulation And Control

The stable yield is increasing gradually with the development of oil field. Thus, importance of blocks with low yield, low permeability and low abundance, which are called “three lows”, have gradually increased. Generally, the investment of transmission network in oil field is about one third of total investment in oilfieldsurface, and the energy consumption of oil and gas transmission is about two fifths of the whole producing energy consumption. According to the feature of the "three lows" Block, for the purpose of optimization, simplification and saving cost, and in order to saving energy and decreasing loss, the ringlike gathering-transferring process flow of monotube gets popularization and application in large area in the "Three lows" Block of Daqing peripheral area. As the over-high wellhead back pressure will cause a series of questions such as wellhead washout, packing changed frequently and pumping unit load increasing, so the wellhead back pressure of single well should below than 1.5MPa. However, in the process of pipeline operation a variety of influencing factors cause high wellhead back pressure, so it has an important meaning for stable operation of oil gathering and transportation system in oil field to analyze the reasons of high wellhead back pressure and putting forward adjusting methods.In this paper, according to the status of ringlike gathering-transferring process flow pipeline, the possible reasons for the high wellhead back pressure have been put forward, and three diagnostic methods have been proposed depending on different causes of the reasons. Transformed the cyclic gathering and transferring system and conducted research the flow pattern and pressure drop in different conditions, and based on the test data, the applicability of method of resistance coefficient and Baker model in oil and gas water mixing section are compared and analyzed, on the basic of ringlike gathering-transferring process flow pipeline, the revised Baker model is choosen to simulate the pipeline pressure drop, and the research results are applied to the analysis of the influencing factors of wellhead back pressure.Due to the comprehensive effect of various factors on the wellhead back pressure, single factor analysis and orthogonal test analysis are applied on the 6 influence factors, through which the effect sequences of influence on wellhead back pressure are as follow: pipe diameter, viscosity of oil and water mixture, return oil pressure in meteringrooms, pipeline length, water content and liquid yield. Finally, based on relevant research results, diagnosing the the problem of wellhead back pressure of Ring 3 in Room 2109 and Ring 4 in Room 2110 of the 10 th Block, proposing methods for adjustment.The research can provide considerable enlightenments for stable operation of oil gathering and transportation system in oil field.