| 摘要 |
The invention provides both a novel reciprocating pump for pumping fluid from a source by forming and moving a fluid column within a tubing, and a method of using the pump. The pump, which is particularly suited for oil wells, uses the pressure generated by the fluid column to increase the downward force acting on the pump plunger during the downstroke. The pump is provided with a reciprocablefirst surface which is in contact with the fluid column, a second surface which moves with the first surface and has a smaller cross-sectional area than the first surface, valve means cooperating with the second surface for subjecting the second surface to fluid at the pressure of the fluid at the source in the vicinity of the pump during movement in one direction and to fluid at the pressure of the fluid column in the vicinity of the pump during movement in the opposite direction. The magnitude ofthe downward force can be affected by regulating one or both of the pressure of the fluid column and the pressure of the fluid in the source.
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