METHODS OF PRESSURE DAMPING UPON THE OSTIUM OF SUCKER ROD PUMPS

Abstract

In the article the methods of pressure damping in well flowline that arise in the work of the downhole sucker rod pumps due to ostium compensators of pressure with different force characteristics are proposed. As ostium compensators the known modern pneumocompensators (diaphragm and piston) and the compensators having the force characteristic with quasi- zero stiffness are considered. Diaphragm and piston and pneumatic com- pensators are in fact pneumatic springs having corresponding force char- acteristics. In a diaphragm pneumatic compensator, its force characteristic is influenced by the fact that a certain «jump» of the diaphragm takes place. This may cause undesirable effects when the diaphragm pneumatic compensator is operating. A mathematical model for a piston of pneu- matic compensator is proposed. The differential equation describing the movement of the pneumocompen- sator’s piston is solved numerically. Calculation of coefficient of a pulsa- tion of the ostium piston pneumocompensator taking into account dynam- ics of his work is carried out. The analysis of the developed mathematical model showed that pressure pulsation coefficient calculated by the known technique can have the underestimated value to 50 %. The version of essentially new scheme of the compensator having the force characteristic with the working site of quasi-zero stiffness is pre- sented. The offered compensator with quasi-zero stiffness represents the pneumo spring moving between guides of a settlement form. The form of guides pays off so that the restoring force of the compensator was to the constant and equal value determined by the average pressure upon the ostium of the well. At the same time the coefficient of a pulsation of pres- sure will be close to zero that can't achieve by means of known pneumo- compensators. The field of application of pneumatic compensators has been determined.