| 主权项 |
1. A pumping assembly comprising:
a hydraulic pump with a housing installed at a well head, the hydraulic pump having a hydraulic ram tied to a reciprocating annular piston having a central bore, the housing including a single hydraulic chamber, the annular piston directly engaging an inner surface of the housing and having a single piston head that divides the hydraulic chamber into first and second subchambers, the hydraulic pump alternatingly applying hydraulic fluid pressure directly to a bottom of the piston head of the annular piston via the first subchamber and directly to a top of the piston head of the annular piston via the second subchamber to drive the annular piston in a continuously reciprocating motion such that when the annular piston moves in an upward direction the hydraulic ram moves toward an extended position extending from the housing, and when the annular piston moves in a downward direction, the hydraulic ram moves toward a retracted position retracted within the housing; a polish rod extending up through the central bore of the annular piston and held in position by a polish rod clamp positioned on top of the hydraulic ram, such that the polish rod moves with the hydraulic ram and such that the annular piston drives the polish rod in a continuously reciprocating motion; and a secondary tube separating the polish rod and the hydraulic ram, the secondary tube immediately surrounding the polish rod and having an outer surface directly engaged by the annular piston, the secondary tube being stationary relative to the housing. |
