| 摘要 |
A downhole reciprocating piston pump is driven pneumatically from a surface facility for producing formation fluid from a well bore. The pump is cycled automatically without the use of electrical controls or components. A piston is received within a pump chamber thereby defining a power chamber and a production chamber, with the piston being movable between a retracted position and an extended position. High pressure air accumulated in a power fluid reservoir is admitted into the power chamber through a delivery port to extend the piston in a production stroke, and is vented from the power chamber through a relief conduit retraction of the piston. The delivery port is opened and closed and the vent port is closed and opened by first and second shuttle valves which are actuated by the piston as it nears the limit of its stroke in extension and retraction, respectively, thereby pressurizing and relieving the power chamber automatically.
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