Analysis Of Forces On Downhole String And Pipe And Application Of Progressive Cavity Pump Well

The production technology using progressive cavity pump(PCP) has already benn applied in Yushulin Oilfield, Daqing Oilfield, but the problem of string or pipe wear during the production process in PCP well does exist, which influences the normal production. In order to solving this problem, centralizers are set downhole. Therefore, analysis of forces on downhole string and pipe is necessary to help set centralizers properly.A nonlinear transient dynamic model for downhole string and pipe in PCP well is established, which string and pipe structure, boundary conditions and every load action can all be considered and describe the motion and the strained situation of string and pipe.A finite element method is presented to solve the above model, and through the establishment of diagnosing condition for dynamic clearance element and the application of momentum theory, this kind of collision problem can be sloved then. With dynamic clearance connected with beam element, using Newmark direct integral method, a finite element method for the above model, so that a numerical calculation method for dynamic analysis of string and pipe is presented, which is very effective.Using the model and the method mentioned above, transient dynamic analysis of forces on downhole strings and pipes in 8 PCP wells in Shangjia Block, Yushulin Oilfield are done, and the theoretical criterion is provided for right setting of centralizers for these 8 wells.