Synchronized pump down control for a dual well unit with regenerative assist

A dual well hydraulic pumping unit for removing well fluids from a first well and a second well, comprising:

• a drive motor having a rotary drive shaft for turning in a first angular direction;
• a reservoir for a hydraulic fluid;
• a first sucker rod assembly disposed in the first well for removing the well fluids from the first well;
• a first ram connected to said first sucker rod assembly for moving in an upstroke and moving said first sucker rod assembly from a downward position to an upward position, and moving in a downstroke with said first sucker rod assembly moving from said upward position to said downward position;
• a second sucker rod assembly disposed in the second well for removing the well fluids from the second well;
• a second ram connected to said second sucker rod assembly for moving in an upstroke and moving said second sucker rod assembly from a lowered position to a raised position, and moving in a downstroke with said second sucker rod assembly moving from said raised position to said lowered position;
• a first ram pump connected to said rotary drive shaft, said first ram pump having a first ram pump suction port connected to said reservoir and a first ram pump discharge port connected to said accumulator and said first ram for transferring the hydraulic fluid into said first ram and moving said first ram from said downward position to said upward position during the upstroke of said first ram, and transferring the hydraulic fluid into said reservoir during the downstroke of said first ram pump;
• a second ram pump connected to said rotary drive shaft, said second ram pump having a second ram pump suction port connected to said reservoir and a second ram pump discharge port connected to said accumulator and said second ram for transferring the hydraulic fluid into said second ram and moving said second ram from said lowered position to said raised position during the upstroke of said second ram, and transferring the hydraulic fluid into said reservoir during the downstroke of said second ram pump;
• and
• at least one control unit adapted for controlling flow rates of the hydraulic fluid through said first ram pump and said second ram pump, and adapting said first ram pump for pumping the hydraulic fluid into said first ram during the upstroke of said first ram, and during the downstroke of said first ram passing the hydraulic from said first ram into said reservoir and turning said rotary shaft in said first angular direction to power said second ram pump in response to pressures within said first ram provided by the weight of said first sucker rod assembly in combination with said drive motor, and adapting said second ram pump for pumping the hydraulic fluid into said second ram during the downstroke of said first ram and the upstroke of said second ram, and turning said rotary shaft in said first angular direction to power said second ram pump in response to pressure within said second ram provided by the weight of said second sucker rod assembly in combination with said drive motor;
• and
• wherein should pump down be encountered in one of the first and second wells, defining a pumped down well, said at least one control unit will provide pump down control by changing at least one of a stroke length and a stroke rate of the pumped down well and synchronizing the pumped down well and the other of the first and second well such that they have substantially the same period time cycle, such that the pumped down well and the other well reverse directions at approximately the same time.

A method for operating a pumping unit, comprising the steps of:

• providing a first hydraulic ram and a first sucker rod assembly, the first sucker rod assembly and the first hydraulic ram are located at a first well and configured for lifting well fluids from within the first well, and a second hydraulic ram and a second sucker rod assembly, the second sucker rod assembly and the second hydraulic ram are located at a second well and configured for lifting well fluids from within the second well;
• further providing at least one control unit, a drive motor, a first ram pump, a second ram pump, a reservoir for a hydraulic fluid, wherein the control unit, the drive motor, the reservoir, the first ram pump, and the second ram pump are configured for moving the hydraulic fluid between the reservoir, the first hydraulic ram and the second hydraulic ram for lifting and lowering respective ones of the first and second sucker rod assemblies;
• releasing the hydraulic fluid from the first hydraulic ram into the first ram pump and to the reservoir, and thereby providing mechanical power in combination with the drive motor for turning a rotary shaft which powers the second ram pump to move the hydraulic fluid into the second hydraulic ram;
• releasing the hydraulic fluid from the second hydraulic ram into the first ram pump and to the reservoir, and thereby providing mechanical power in combination with the drive motor for turning the rotary shaft which powers the second ram pump to move the hydraulic fluid into the second hydraulic ram;
• controlling the flow of the hydraulic fluid from the first hydraulic ram, through the first ram pump and into the reservoir, and the flow of the hydraulic fluid from the second hydraulic ram, through the second ram pump and into the reservoir;
• and
• wherein first potential energy is recovered from the first sucker rod assembly when disposed in a lifted position and used to operate the second ram pump for assisting in an upstroke of the second hydraulic ram, and second potential energy is recovered from the second sucker rod assembly when disposed in a lifted position and used to operate the first ram pump for assisting in an upstroke of the first hydraulic ram;
• determining whether pump down conditions are being encountered in one of the first and second wells, which when encountered defines a pumped down well;
• and
• when pump down is detected, providing pump down control with the at least one control unit by changing at least one of a stroke length and a stroke rate of the pumped down well and synchronizing the pumped down well and the other well of the first and second wells such that they have substantially the same period time cycle, such that the pumped down well and the other well reverse directions at approximately the same time.