Abstract: This is a method and apparatus for controlling a downhole, hydraulically actuated pump. Two fluid flow monitoring means generate signals which are a function of the power fluid flow rate to the downhole pump and the return fluid flow rate from the well. An automatic controller causes the power fluid flow rate to be maintained essentially directly proportional to the return flow. Thus, the power fluid flow is not varied in the opposite direction of any change in return flow to maintain the return fluid flow constant, but conversely, is changed in a manner which will tend to accentuate any changes in the return fluid flow.

Abstract: This invention is a hydraulic pumping unit which uses a cyclone feed pump means to vary the speed of the above-ground pump, while still providing proper cleaning of the power fluid for the downhole pump. The ability to conveniently change the speed of the above-ground pump allows the speed of the pump to be reduced whenever well conditions make such a reduction appropriate, and this provides a very substantial reduction in the cost of power for the prime mover (typically an electric motor). In addition to the cyclone feed pump and a speed control means to vary the speed at which the prime mover drives the above-ground pump, this invention uses a flowback line connected from the cyclone overflow to the feed pump inlet.

Abstract: This is a method and apparatus for a control system for a well-fluid hydraulic pumping unit. The system senses level in the suction vessel and operates an underflow throttling valve to control both the level in the suction vessel and the flows of the cyclone separator. The system maintains the level in the horizontal suction vessel and simultaneously maintains flows to the cyclone in a range for effective cleaning of the fluid and for self-cleaning of the underflow. The cyclone and its associated hardware are sized based on the above-ground pump flow and any bleed flow from the suction vessel. The system is generally applicable to hydraulic units in which the speed of the above-ground pump is not varied over a wide range.