The article shows the issues of oil wells exploitation by sucker rod pumping units when pumping out reservoir fluid of high viscosity, in which a device with a sinker bars is required to ensure the movement of the pump plunger. This article analyzes the effect of unbalanced forces acting on a string of pumping rods during a down stroke, including the frictional forces that occur in the plunger pair. In this paper, we review the existing dependencies that allow us to estimate the value of the frictional force of the plunger against the cylinder of a sucker rod pump. The effect of the sinker bar on the change in the stroke length of the plunger pump ram has been estimated when moving up and down. It is shown that the use of the sinker bar allows to increase the efficiency of the operation of the sucker-rod pump, with considerable frictional forces in the plunger pair. Two types of "sinker bar" structures are presented: mechanical (sinker bar) and hydraulic (in a differential plunger pump). Recommendations are given for choosing the design of the sinker bar, depending on the viscosity of the pumped liquid. Calculations for the choice of structures of the sinker bar were made for pumping conditions with a viscosity of up to 500 mPa·s and a rod speed of up to 2.4 m/s. The authors proposed a criterion for choosing a sinker bar design, based on taking into account the viscous friction forces of the weighted bars at the down stroke. The performed calculations showed that the efficiency of using the hydraulic sinker bar in the differential boom pump in the production of high viscosity oil is higher than the standard sinker bar of the pump rods.
References
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