Pump jack device

A pump jack comprising a double acting piston and cylinder motor of an equal displacement, through rod type, said motor being arranged for mounting above a well head and coaxial with a polished rod in said well head;

• means for connecting a piston rod of said motor to the polished rod;
• a variable displacement type hydraulic pump having a pair of output ports;
• a pair of hydraulic conduits each placing one of said output ports in communication with an opposite end of said motor and forming a closed hydraulic loop with said motor and pump;
• drive means for said pump;
• a pump control means for controlling the direction and volume of flow in said loop to thereby establish a total velocity profile during a complete pumping cycle and also to determine the length and position of the stroke of said piston rod;
• a compressible fluid counterbalance means for accumulation of energy during a down stroke of said piston rod and returning the energy to said piston rod during an up stroke of said piston rod;
• said counterbalance means including a cylinder having a piston with means connecting the piston thereof to the piston of said motor for drive therewith, said cylinder and piston forming a chamber containing a gaseous charge disposed to be compressed by the piston of said counterbalance means during the downward stroke of said polished rod;
• the cylinder of said counterbalance means being mounted coaxially above said motor and being secured thereto;
• said cylinder of said counterbalance means including an inner sleeve and an outer cylinder forming an annular chamber therebetween, said piston of said counterbalance means being disposed within said sleeve and forming a chamber within said sleeve below said piston, port means placing said chamber below said piston and said annular chamber in communication to thereby form said chamber containing said gaseous charge.

A pump jack comprising a double acting piston and cylinder motor of an equal displacement, through rod type;

• means for connecting a piston rod of said motor to a polished rod in a well head;
• a variable displacement type hydraulic pump having a pair of output ports;
• a pair of hydraulic conduits each placing one of said output ports in communication with an opposite end of said motor and forming a closed hydraulic loop with said motor and pump;
• drive means for said pump;
• and a pump control means for controlling the direction and volume of flow in said loop to thereby establish a total velocity profile during a complete pumping cycle and also to determine the length and position of the stroke of said piston rod;
• a compressible fluid counterbalance means for accumulation of energy during a down stroke of said piston rod and returning the energy to said piston rod during an up stroke of said piston rod;
• said counterbalance means including a cylinder having a piston with means connecting the piston thereof to the piston of said motor for drive therewith, said cylinder and piston forming a chamber containing a gaseous charge disposed to be compressed by the piston of said counterbalance means during the downward stroke of said polished rod;
• said control means including first means for sensing the hydraulic pressure at one end of the piston and cylinder motor;
• second means for sensing the hydraulic pressure at the opposite end of the piston and cylinder motor;
• third means for sensing the position of the piston in said motor;
• each of the sensing means producing a signal indicative of the value sensed thereby;
• a control unit for reading signals from the sensing means, determining required flow in said loop, and producing signal for output of said pump.

A pump jack comprising a double acting piston and cylinder motor of an equal displacement, through rod type;

• means for connecting a piston rod of said motor to a polished rod in a well head;
• a variable displacement type hydraulic pump having a pair of output ports;
• a pair of hydraulic conduits each placing one of said output ports in communication with an opposite end of said motor and forming a closed hydraulic loop with said motor and pump;
• drive means for said pump;
• and a pump control means for controlling the direction and volume of flow in said loop to thereby establish a total velocity profile during a complete pumping cycle and also to determine the length and position of the stroke of said piston rod;
• a compressible fluid counterbalance means for accumulation of energy during a down stroke of said piston rod and returning the energy to said piston rod during an up stroke of said piston rod;
• said counterbalance means including a cylinder having a piston with means connecting the piston thereof to the piston of said motor for drive therewith, said cylinder and piston forming a chamber containing a gaseous charge disposed to be compressed by the piston of said counterbalance means during the downward stroke of said polished rod;
• said control means including an electronic control unit;
• a first pressure transducer for sensing the hydraulic pressure in the cylinder at one end of the piston and cylinder motor and transferring signal indicative of the magnitude of the pressure to said control unit;
• a second pressure transducer for sensing the hydraulic pressure in the cylinder at the opposite end of the piston and cylinder motor and transferring a signal indicative of the magnitude of the pressure to said control unit;
• a third pressure transducer for sensing the pressure of the gaseous charge of the counterbalance means and transferring a signal indicative of the magnitude of the pressure to said control unit;
• and a positional transducer for sensing the position of the motor piston in its stroke and transferring a signal indicative of the piston position relative its total stroke capability to said control unit.

A pump jack comprising a double acting, through rod type piston and cylinder motor;

• means for connecting one piston rod of said motor to a polished rod projecting upward from a well head;
• a variable displacement type hydraulic pump;
• drive means for said pump;
• a pair of hydraulic conduits connected one each to opposite ends of said motor and to an output of said pump;
• a pump control means for controlling the directions and volume of flow in each of said conduits to thereby determine the speed, direction, acceleration, deceleration, dwell, length and position of the stroke of said piston rod, a counterbalance device including a cylinder having a piston with means connecting the piston thereof to the piston of said motor for drive therewith, said piston forming a chamber containing a gaseous charge for compression by the piston thereof during the downward stroke of said polished rod, said control means including a control unit, first and second pressure sensing means for providing to said control unit signal indicative of pressures in respective ends of said motor, a position sensing device for providing to said control unit a signal indicative of the position of the piston in said motor, said control unit providing a command signal for said pump in response to readings taken from said signals.

A pump jack comprising a double acting piston and cylinder motor;

• means for connecting a piston rod of said motor to a polished rod in a well head;
• said motor being mounted above said well head and coaxial with said polished rod;
• a variable displacement type hydraulic pump having a pair of output ports;
• a pair of hydraulic conduits each placing one of said output ports in communication with an opposite end of said motor and forming a closed hydraulic loop with said motor and pump;
• drive means for said pump;
• a pump control means for controlling the direction and volume of flow in said loop to thereby establish a total velocity profile during a complete pumping cycle and also to determine the length and position of the stroke of said piston rod;
• and a compressible fluid counterbalance means for accumulation of energy during a down stroke of said piston rod and returning the energy to said piston rod during an up stroke of said piston rod.