Feasibility Study On Crude Oil Lifting Technology Of Air Ejector

With a simple structure,lacking in motion parts and almost unlikely to be damaged,ejector has achieved more and more extensive application in oil & natural gas exploitation,chemical industry,light industry,refrigeration and other industrial technology areas.During crude oil lifting,ejector is employed increasingly wide and gradually takes the place of traditional sucker-rod pump for the reason that it proves to exhibit more prominent advantages than the latter and appears more adaptable.Current researches on working fluid of ejector mostly focus on water,oil and steam,while air is rarely mentioned.In order to determine the geometrical model of oil-extracting air ejector,the gas dynamic function method proposed by Sokolov in USSR was modified based on definition of each parameter,and then the basic ejector equation in terms of actual gas was deduced,which can not only be applied to ideal gas under low pressure but also actual gas under high pressure.The comparative study of cases shows that the results from two methods coincide under low pressure,while under high pressure occurs where obvious difference,indicating that the modified design not only covers Sokolov's contrivance,but also compensates for his limitation so that it can apply to all ranges of ejector design from low pressure to high.Meanwhile,C # language was used in the development of the design program of air ejector,and the geometric dimension of the air ejector model was calculated,which greatly simplified the ejector design.The numerical simulations of the velocity and pressure fields of air ejector show that the simulation results are very close to the theoretical calculations,which proves the reliability of the numerical simulation method.On the basis of above,through numerical simulation analysis was made of the influence of nozzle distance,diameter and length of mixing chamber as well as length of diffuser of the ejector on its performance.It shows that there exists an optimal value for either nozzle distance or mixing chamber diameter,and the performance will be undermined when the value is greater than or less than that.Overlong mixing chamber and diffuser will cause additional loss along the course;while when they are not long enough,the former will lead to insufficiency of mixing process,and the latter sudden change of the section size and thus additional loss.Orthogonal experiment was designed of three levels of nozzle distance,area ratio and mixing chamber length-diameter ratio of air ejector,numerical simulation was conducted on nine orthogonal experiment models,and the extreme difference and variance of the results were analyzed to determine the optimal combination of nozzle distance,area ratio and length-diameter ratio of mixing chamber.Founded on the optimal structure,the influence of working parameters such as inlet pressure of work air,inlet pressure of injection liquid and outlet pressure on ejector performance was analyzed in a simulative manner,providing a better guidance of field operation.In the end,investigation and survey was conducted on the data of 8 oil wells on the spot,and comparison was made between simulation results of the optimal performance structure under design conditions and the field investigation data.The results show that the fail-safe nature of the air ejector,the liquid ejector flow rate and the lifting height all meet the requirement of field production,and its crude oil lifting process proves to be feasible.