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| An analytical method for dynamic performance of sucker-rod pumping system of directional well |
| Revised:December 22, 2006 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7511/jslx20081013 |
| KeyWord:directional well,nonlinear partial differential equation,support reaction,dynamic prediction,state space method |
| LIU Bai-xi LIU Hong-zhao YUAN Da-ning RAP Jian-hua |
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| Abstract: |
| Because of the Coulomb friction between the rod and pipe,the prediction model of dynamic characteristics of sucker-rod pumping system in directional well is a nonlinear partial differential equation,whose solution is difficult and complex.In order to simplify the model,a novel analytical method is put forward.Firstly,based on the well trajectory fitted by using the cubic spline interpolation method,the support reaction between rod string and pipe in directional well is calculated according to the finite element method for static load.Secondly,using the calculated support reaction,the Coulomb friction force between rod string and pipe is computed.Thirdly,the loads analysis of rod element is performed and dynamic equations of rod element are derived.Assembling all element dynamic equations,the system dynamic equation of rod string is obtained.Finally,the state space method is employed to solve the established system dynamic equation with time-varying coefficients.In the end,two prediction examples are given,where a comparison between the predicted and the measured dynamometer cards is made to show that the presented analytical method is correct and effective. |
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