Selection And Analysis Of Multiphase Pump In Oil&gas Mixed-transportation Process

The technology of multiphase mixed-transportation is to directly pressurize the gas-liquid mixed fluid produced by the oil well without separation.It can reduce the production cost and simplify the production management,which has great economic value and practical significance.The multiphase pump is the key of the multiphase mixed-transportation system,which is also of great significance to the study of pump type,the working theory of the booster unit in the pump and the flow analysis of the flow field.In this paper,the method of combining theory,numerical simulation and actual situation is adopted.Firstly,according to the situation of the oilfield,the multiphase pump is optimized,and then study the working theory of the booster unit in multiphase pump.Finally,the numerical simulation of the flow field in multiphase pump is performed.Specific contents include:(1)Based on the basic situation of the Sha11 booster station in Changqing Oilfield,the ordinary booster station is transformed into a digital booster station with oil and gas mixed transmission function while keeping the original process flow unchanged.By analyzing the characteristics and limitations of four different types of multiphase pumps,including screw-type,rotor-type,reciprocating-type and axial-type multiphase pumps,list four multiphase pump schemes that could satisfy the requirement of Sha 11 booster station.At the last,self-designed helical axial multiphase pump is selected as the main booster equipment of Sha 11 booster station by using multi-objective decision-making method.(2)Analyze the basic booster theory and external characteristic parameters of the helical axial multiphase pump,including the cylindrical layer assumption hypothesis theory,planar infinite straight-row cascade,the speed triangle of the cascade and the dynamic characteristics of the airfoil and cascade,etc.,to obtain the expression of flow rate,head,efficiency and power of axial multiphase pump is obtained.(3)Use ANSYS CFX software to perform numerical simulation on 15 kinds of working conditions of a single booster unit in self-designed helical axial multiphase pump,including gas content of 10%,30%,50%,and flow rate of 0.6Q,0.8Q,1.0Q,1.2Q,1.4Q.The velocity distribution,pressure distribution and exit phase distribution in the impeller and guide impeller flow field are analyzed under different conditions of gas content and flow rate,and theconclusions of the analysis and external characteristic curves are obtained.Through the above research,this paper provides some basic theories and reference for the further analysis about the booster unit theory,the flow field situation and the structure optimization of complete multiphase pump.It provides a reference for the selection and application of multiphase pump in engineering.