Abstract: A submersible pumping system has an electric motor, a rotary hydraulic pump driven by the electric motor, and a linear hydraulic pump that is configured to move a production fluid. The rotary hydraulic pump produces a pressurized working fluid that drives the linear hydraulic pump. In another aspect, a method is disclosed for controlling the temperature of an electric motor within a submersible pumping system disposed in a wellbore. The method includes the steps of circulating motor lubricant through a hydraulically driven production pump to reduce the temperature of the motor lubricant.

Abstract: A method of operating a submersible pumping system includes the steps of placing the pumping system in a normal mode of operation and then detecting the possible presence of a gas slug in proximity to the pumping system by measuring a decrease in the load on the motor. Once the possibility of a gas slug has been detected, the method continues by placing the pumping system in a reduced speed cycle. The pumping system is kept in the reduced speed cycle until the absence of a gas slug in proximity to the pumping system is detected by evaluating two independent conditions within the pumping system.

Abstract: A submersible pumping system has an electric motor, a rotary hydraulic pump driven by the electric motor, and a linear hydraulic pump that is configured to move a production fluid. The rotary hydraulic pump produces a pressurized working fluid that drives the linear hydraulic pump. In another aspect, a method is disclosed for controlling the temperature of an electric motor within a submersible pumping system disposed in a wellbore. The method includes the steps of circulating motor lubricant through a hydraulically driven production pump to reduce the temperature of the motor lubricant.

Abstract: A method of operating a submersible pumping system includes the steps of placing the pumping system in a normal mode of operation and then detecting the possible presence of a gas slug in proximity to the pumping system by measuring a decrease in the load on the motor. Once the possibility of a gas slug has been detected, the method continues by placing the pumping system in a reduced speed cycle. The pumping system is kept in the reduced speed cycle until the absence of a gas slug in proximity to the pumping system is detected by evaluating two independent conditions within the pumping system.

Abstract: A submersible pumping system has an electric motor, a rotary hydraulic pump driven by the electric motor, and a linear hydraulic pump that is configured to move a production fluid. The rotary hydraulic pump produces a pressurized working fluid that drives the linear hydraulic pump. In another aspect, a method is disclosed for controlling the temperature of an electric motor within a submersible pumping system disposed in a wellbore. The method includes the steps of circulating motor lubricant through a hydraulically driven production pump to reduce the temperature of the motor lubricant.

Abstract: A submersible pumping system includes an electric motor and a pump driven by the electric motor. The pump includes a rotatable shaft driven by the motor, one or more piston assemblies configured for linear reciprocating motion and a mechanism for converting the rotational movement of the shaft to linear reciprocating movement in the piston assemblies. In one aspect, the mechanism for converting the rotational movement of the shaft includes a tilt disc assembly. In another aspect, the mechanism for converting the rotational movement of the shaft includes a camshaft assembly.