Hydraulic Oilfield Lift Pump
AssigneeNational Oilwell Varco, L.P.
InventorsGerry L. Lorimer, Denis J. Blaquiere
Life of this patent
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Abstract
A vertically orientated hydraulically driven oilfield lift pump unit having a simplified hydraulic system. The system uses a pair of single acting hydraulic cylinders in tandem with a pair of double acting hydraulic cylinders interacting with hydraulic accumulators to provide an energy efficient, robust hydraulic system design with a minimum number of components.
Claims19
A vertically orientated reciprocating oil well pumping unit comprising:
- at least one double acting hydraulic cylinder, mechanically coupled to at least one single acting hydraulic cylinder such that they extend and retract simultaneously to operate the pumping unit,
- the cap end of the double acting hydraulic cylinder in close-coupled fluid communication with a fluid end of a hydraulic accumulator, the accumulator having a precharge pressure at least exceeding a loading pressure in the cap end of the hydraulic cylinder when it is fully extended in use and under load;
- a hydraulic control valve having a first inlet/outlet port in fluid communication with the cap end of the single acting hydraulic cylinder and the valve having a second outlet/inlet port in fluid communication with the rod end of the double acting hydraulic cylinder, whereby,
- when the hydraulic control valve is operated to retract the cylinders, hydraulic pressure is applied to the rod end of the double acting hydraulic cylinder forcing it and the coupled single acting hydraulic cylinder to retract simultaneously, thereby causing the fluid from the cap end of the double acting cylinder to flow back into the accumulator, and,
- causing the fluid from the cap end of the single acting cylinder to flow back through the return port of the hydraulic control valve into a hydraulic reservoir.
A vertically orientated reciprocating oil well pumping unit comprising:
- at least one double acting hydraulic cylinder, mechanically coupled to at least one single acting hydraulic cylinder such that they extend and retract simultaneously to operate the pumping unit,
- a cap end of the double acting hydraulic cylinder in close-coupled fluid communication with a fluid end of a hydraulic accumulator, the accumulator having a precharge pressure at least exceeding a loading pressure in the cap end of the hydraulic cylinder when it is fully extended in use and under load;
- whereby, in operation under load, the power required to extend the reciprocating oil well pumping unit is approximately equal to the power required to retract the reciprocating oil well pumping unit.
A hydraulic control valve having a first inlet/outlet port in fluid communication with the cap end of a single acting hydraulic cylinder and the valve having a second outlet/inlet port in fluid communication with the rod end of a double acting hydraulic cylinder to operate a reciprocating pump, whereby,
- fluid pressure from a hydraulic pumping unit provides hydraulic fluid under pressure such that when the four-way type hydraulic control valve is operated to retract the cylinders, hydraulic pressure is applied to the rod end of the double acting hydraulic cylinder forcing it and the coupled single acting hydraulic cylinder to retract simultaneously, thereby causing the fluid from the cap end of the double acting cylinder to flow back into the accumulator, and the fluid from the cap end of the single acting cylinder to flow back through the return port of the four-way hydraulic control valve into a hydraulic reservoir.
Dependencies are inferred from the claim text.