Monitoring Of Down-hole Working Conditions Of Beam Pumping Unit

Beampumpingunitisthemostwidelyusedapparatusofpumpingathomeandabroad.Thenormal operation of pumping unit is very important to ensure reliable production of oilfield.Pumping unit is not only typical rotary mechanism but also has operational characteristics ofrepeat and cycle. So there is important information to describe down-hole workingconditionsin the different motor torques. Based on the conclusion of previous mathematical model forsucker rod pumping system, an improved dynamic mechanism model is proposed and themotor torque is made to be as the main basis for monitoring down-hole working conditions.The monitoring method is preliminarily studied in the paper. Main contents concerned are asfollows:According to the kinematic analysis and load analysis of each part for the beam pumpingunit, the kinetics equations are established. After solving the equations, the motion law ofhanging point and each component could be gained, which provides the basis for thesimulationofvibrationcharacteristicsofsuckerrodstring.According to the load analysis of the sucker rod string micro-unit, the wave equation thatdescribes thevibrations ofsuckerrodstringis established.Bymeansofthehybridalgorithm,different sectional andhangingpoint dynamiccards canbeobtained. Simulationon theactualproduction data of a well shows that the computed dynamometer card is consistent with theactualdynamometercard.To reduce the modeling complexity of the sucker rod pumping system, a modified modelbased on dynamic mechanism modeling is proposed. Principle of kinetic energyconservationis adopted to perform on traditional computational method of the inertia moment so that theexistent model can be simplified. The dependence on the physical dimension of the groundequipment can be reduced. The motor torque of corresponding working condition can be obtained by changing bottom boundary condition. Simulation results show that the proposedmodeliseffective.The feature extraction method based on wavelet packet energy and detailed analysis ofmain-band energy is applied to analysis motor toque, and then various eigenvector areobtained. The greycorrelation identification method is used in fault classification. Simulationdata shows that it can be achieved to monitor down-hole working conditions by ways ofanalyzing motor torque. Besides, the program needs to be verified and improved by usingfielddatainthefuture.