Study On Dynamic Simulation Of Mix Sucker Rod String With Absorber

The sucker rod is an elastomer which is more than one kilometer long, it is acted upon by many kinds of loads during its working process. With the development of oilfield, majority of oilfields in our country has entered later development stage, the stress condition of sucker rod become more complex, and it also has serious vibration problem which bring violent impact to the pumping unit hanging-point, simultaneously, causes the sucker rod tripping and the endurance failure. In view of these problems, many institutes of oil well production have conducted deep research on the vibrated mechanism and the vibration characteristic of sucker rod string. To start with the improvement of stressful condition of sucker rod and the working condition, the inspires principle of attenuator and the characteristic of spring——increases carries the compression, the unloading restored——were utilized, many kind of sucker rod anti-vibration device had been designed. This article studied the dynamic simulation method of sucker rod with absorber, the paper makes the following progress:(1)The factors affecting the up boundary condition of longitudinal vibration of sucker rod, including the constant coefficient of spring and damping coefficient, the mechanical model and mathematical model of longitudinal vibration of mix sucker rod string were set up. The equation of inherent frequency of longitudinal vibration of mix rod string is established, the influence of first step inherent frequency with stiffness coefficient is analyzed. By simulating the harmonics hanging-point displacement and harmonics pump load, the response characteristic of longitudinal vibration of mix sucker rod string were analyzed.(2)The longitudinal vibration of mix sucker rod string was described by wave equation, the factors such as constant coefficient of absorber spring, damping coefficient, actual hanging-point displacement and pump load were considered for the study of boundary condition of longitudinal vibration of sucker rod string, the mechanical model and mathematical model of simulated dynamometer cards and vibration performance of sucker rod string with absorber spring were set up. The application method of difference has established the mix sucker rod string longitudinal vibration hanging-point dynamometer card and the pump dynamometer card simulation value simulation model.