Mechanism Of Eccentric Wear Between Sucker Rod And Tubing For Polymer Flooding

A problem has been put forward that the rate and degree of eccentric wear between sucker rod and oil tube aggravated in polymer flooding wells than which in water flooding wells since polymer wells put into production in Daqing oil field. The main reason is that the viscosity of produced liquid increases in polymer flooding wells than water flooding wells, it makes for all the frictional resistances increased correspondingly, the result is the maximal load become larger during upstroke and the minimum load become smaller during downstroke than water flooding after polymer output from polymer flooding well, force status of the rod turn too bad, and the lengthways buckling load increased in downstroke, make the buckling numbers brought by lose stability of sucker rod also increased, eccentric wear between sucker rod and oil tube become serious, the rate of sucker rod broken be increased, operating wells obvious add a lot, so it must influence the production of polymer flooding well. While operating charge increase, and the production cost enhanced also.This paper aimed at the problem, carry through the mechanism analysis of eccentric wear between sucker rod and oil tube for polymer flooding, based on datum on-site and educed influencing factors of eccentric wear. At first, study rheological property of produced liquid in polymer flood well, presented the formula of viscosity calculation of produced liquid; Second established the force model of sucker rod and the resistance calculating model on up and down stroke, we can conclude that the rheological property of produced liquid is an important factor to influence the hanging load; Educed the coefficient of critical load equation while sucker rod flexure transformed, the conclusion is that the distributing force along the axis direction and the diameter of sucker rod are main variables to influence critical load, advanced to bring forward measures of protection eccentric wear, mainly is lower sinker rod and centralizer, and based on the above-mentioned theories, programmed the software of eccentric wear, analyzed the influencing factors, through verified by datum on-site, the rate of accordance can be reached 80% or so, it can well direct the work of oil field.