Importance

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Abstract

The invention contemplates oil-well pumping apparatus (a) in which a traction cylinder is mounted at the well-head for direct reciprocating operation of the polish rod from which a pumping piston is suspended in a well casing, and (b) in which hydraulic-counterweight principles of copending application, Ser. No. 601,481, filed Apr. 18, 1984 are employed to reduce lift-capacity requirements which would otherwise be imposed on the prime mover. In one embodiment, wherein a single well is to be pumped, a pressurized hydraulic accumulator is connected to the traction cylinder via a power integrator which is so driven by the prime mover as to shuttle hydraulic fluid under pressure between the accumulator and the traction cylinder, to accomplish the traction cylinder action necessary to drive the polish rod and its load; in another embodiment, wherein two nearby wells are to be pumped, the hydraulic accumulator is replaced by the traction cylinder for the polish-rod assembly of the second well, and the pumping cycle of one well is in phase opposition to that of the other well, so that the minimum loads of the respective traction cylinders offset each other.

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First Claim