Flow Of Produced Fluid In Polymer Flooding Well With Pumping Rod Moving Axially--Theory, Calculation And Applications

For the case of deep oil well, pumping rod is eccentric in oil tube during the oil recovery. The flow of the fluid produced by means of polymer-driving in a well is the flow of Non-newtonian fluid in eccentric annuli with the inner cylinder moving axially.The flow of Non-newtonian fluid in eccentric annuli with the inner cyinder moving axially and it's application in preventing pumping rod and oil tube from eccentric wear in a polymer-driving well are studied in this paper.Second order fluid and power-law fluid are used to describe the Non-newtonian rheological property of the produced fluid in a polymer-driving well; the governing equations, boundary and initial equations of second order fluid and power-law fluid in eccentric annuli with the inner cylinder reciprocating axially are established separately in bipolar coordinates system; formulas of stability parameter and stress distribution on the outwall of the inner cylinder of the unsteady flow of power-law fluid in eccentric annuli with the inner cylinder reciprocating axially are established; formula of the stress distribution on the outwall of the inner cylinder of the flow of second order fluid in eccentric annuli with the inner cylinder moving axially is established.Taking HPAM solutions as an example , the unsteady flow of power-law fluid in eccentric annuli with the inner cylinder reciprocating axially is calculated; the distribution of velocity, flow rate and stability parameter is obtained ; taking HEC solutions as another example , the flow of second order fluid in eccentric annuli with the inner cylinder moving axially is calculated too; the distribution of velocity and stress is obtained ;the effect of eccentricity and axial movement on stress distribution on the outwall of the inner cylinder is analysed.Through the laboratory flow experiments with aqueous solution of varied consistency of HPAM ,the average flow rates calculated with the theoretical formulae are compared with those meassured in the experiments , and it shows that the numerical method of the unsteady flow of power-law fluid in eccentric annuli with the inner cylinder reciprocating axially in the paper is correct.The theoretical and computational results show that an important reason resulting in eccentric wear of the inner cylinder and the pumping rod lies in the nonuniformity of the stress distribution on the outwall of the inner cylinder which yields excentralization effect of the pumping rod when swabbing fluid flows in eccentric annuli with the pumping rod moving axially in a well. Control techniques about the eccentric wear of the pumping rod and oil tube in a rod-pumped well are applied in the Fist Oil Production Factory of Daqing Oil Field in order to overcome the eccentric wear of the pumping rod and oil tube caused by the eccentric effect of the pumping rod, and these measures obtained preferable effects.