Hydraulic unit for mechanical pumping (hump) for oil lifting

Abstract

A equipment including a Cylinder and a Main Piston, a Pressure Accumulator with auxiliary Nitrogen tubes for the upward movement of the Main Piston, an Hydraulic Unit including an Hydraulic Fluid Deposit and a Heat Exchanger, an Electric or Thermal motor for making the Hydraulic bomb to work which is responsible of the downward movement of the Main Piston, responsible for the descending movement of the Main Piston, Diverter Valves, Closing Valves and Position, Temperature and Pressure Detectors. The ascent speed can be high, while the descent speed will be normal for this equipment but controlled. All this is coordinated by a program incorporated into the PLC.

1 . A hydraulic unit for a mechanical pump for oil lifting comprising:
 a cylinder,   a piston ( 32 ),   a polished rod cubassembly (CPPS),   a hydraulic pressure accumulator subassembly (PAS),   a pressure generator subassembly (PGS), and   a programmable logic controller (PLC) subassembly.   
     
     
         2 . The hydraulic unit according to  claim 1 , wherein the cylinder, piston and polished piston rod subassembly comprises a cylinder ( 34 ) having attached at an upper end to a head ( 30 ) with an inlet/outlet port and at an lower end to a lower seal holder ( 36 ) with an inlet/outlet port (O 2 ), inside which the piston ( 32 ) joined to the polished rod ( 33 ) a lower chamber ( 35 ) and an upper chamber ( 31 ). 
     
     
         3 . The hydraulic unit according to  claim 1 , wherein the hydraulic pressure accumulator subassembly (PAS) comprises a hydraulic pressure accumulator ( 13 ) including a tank, containing a liquid part and a gaseous part, with a hermetic gas separator element, which is pressurized with nitrogen coming from the cylinders suitable to work at high pressures ( 14 ), being the liquid part inside the tank, connected to the hydraulic circuit, which feeds the lower chamber ( 35 ). 
     
     
         4 . The hydraulic unit according to  claim 1 , wherein the pressure generating subassembly (PGS) comprises an oil tank with filling mouth and air filter ( 1 ), a heat exchanger ( 5 ), a hydraulic pump ( 6 ) driven by a motor ( 7 ) that sends pressurized hydraulic fluid through Valves commanded by the programmable logic controller to the upper chamber ( 31 ) of the polished rod subassembly or to the oil tank ( 1 ). 
     
     
         5 . The hydraulic unit according to  claim 1 , wherein the PLC Subassembly includes a program linked to the signals of thermometers, pressure gauges and level or position sensors that generate orders to valves and contactors. 
     
     
         6 . The hydraulic unit according to  claim 3 , wherein the (CPPS) includes the cylinder ( 34 ), joined at an upper end to a head ( 30 ) and at a lower end to a lower seal holder ( 36 ), inside which the piston ( 32 ) is joined to the polished Rod ( 33 ) generating a lower Chamber ( 35 ) when pressurized by the pressure accumulator ( 13 ) of the (PAS), generates the upward movement of the piston ( 32 ). 
     
     
         7 . The hydraulic unit according to  claim 1 , wherein at a end of an upward movement of the (CPPS), an upper chamber ( 31 ) is pressurized by a hydraulic pump ( 6 ) of the (PGS) and forcing the piston ( 32 ) to start a downward movement displacing fluid from a chamber ( 35 ) and sending it to a pressure accumulator ( 13 ) restoring an initial pressure. 
     
     
         8 . The hydraulic unit according to  claim 7 , wherein the piston ( 32 ) pulls the polished rod ( 33 ), a rod string and athe API 11AX piston of the depth pump. 
     
     
         9 . The hydraulic unit according to  claim 1 , in the subassembly (CPPS) a force that generates an upward movement of the piston ( 32 ), the polished rod, a rod string, a API 11AX piston and an oil in the tubing, is produced by a pressure of the hydraulic fluid from the pressure accumulator ( 13 ), on a lower face of the piston ( 32 ). 
     
     
         10 . The hydraulic unit according to  claim 1 , wherein the subassembly (PAS) includes a pressure accumulator ( 13 ) and a battery of nitrogen tubes ( 14 ), will generate a flow and hydraulic pressure to produce an upward movement of the piston ( 32 ) that pulls the polished rod ( 33 ), a rod string and a API-11AX piston. 
     
     
         11 . The hydraulic unit according to  claim 1 , wherein the program incorporated to the PLC Subassembly, when pressing the start will verify a pressure of a manometer ( 10 ), if the pressure is not within a tolerance foreseen for a working pressure issues it indicated in the specification; the process stops when the manometer ( 10 ) sends the signal within tolerance to the PLC subassembly. 
     
     
         12 . The hydraulic unit according to  claim 1 , wherein the PLC subassembly allows a pressurized fluid to exit from the pressure accumulator ( 13 ) which enters a chamber ( 35 ) causing the Piston ( 32 ) to rise, wherein the process continues until the piston ( 32 ) makes contact with a proximity detector ( 23 ) and a program of the PLC subassembly closes valves ( 26 ) and ( 27 ); the program includes the use of the proximity detector ( 23 ) in cooperation with a pressure gauge ( 29 ) to define the time that the valves ( 26 ) and ( 27 ) should be closed, as the speed of athe API 11AX piston approaches to values close to zero; a decrease of a stretching determined by a decrease of the pressure in the manometer ( 29 ) will allow to increase a stroke of the API 11AX piston; the valves ( 26 ) and ( 27 ) wait for the manometer ( 29 ) to reach an the opening pressure in an ascent and when reaches the opening pressure sends a signal to the PLC subassembly that reopens the valves ( 26 ) and ( 27 ); the piston ( 32 ) begins to ascend and when contacting the proximity detector ( 24 ), the program will give the orders to initiate a descent. 
     
     
         13 . The hydraulic unit according to  claim 12 , wherein the PLC subassembly program, when the piston ( 32 ) reaches the proximity detector ( 24 ), drives the motor ( 7 ) and the pump ( 6 ) sending the pressurized fluid through the valves commanded by the PLC program, to an inlet/outlet orifice (O 1 ) towards the a chamber ( 31 ) thus starting a downward stroke of the piston ( 32 ); the descent continues until contacts the proximity detector ( 232 ) and the program closes the valves ( 26 ) and ( 27 ); the PLC, whose programming includes the use of the proximity betector ( 22 ) in cooperation with the manometer ( 29 ), to define athe time that the valves ( 26 ) and ( 27 ) should be closed allowing the stretching of the rod string in the downward stroke, as a speed of the API 11AX piston approaches values close to zero, returns to a real values; increases of the stretch will generate an increase of the stroke of the API 11AX piston; the valves ( 26 ) and ( 27 ) wait for the manometer ( 29 ) to reach an the opening pressure in descent and send a signal to the PLC to reopen both valves ( 26 ) and ( 27 ), wherein when the piston ( 32 ) reaches the proximity detector ( 21 ), the program give an order to start the ascent. 
     
     
         14 . The hydraulic unit according to  claim 8 , wherein at the end of the upward movement, the upper chamber ( 31 ) of the (CPPS) is pressurized by the hydraulic pump ( 6 ) of the (PGS), and forcing the piston ( 32 ) to start the downward movement, displacing fluid from the chamber ( 35 ), and sending the fluid to the pressure accumulator ( 13 ), the pressure accumulator restores the initial pressure; the speed of descent of the piston ( 32 ) is regulated by controlling the minimum force to which the polished rod ( 33 ) avoiding curls in the rod string during the whole descent; to control a minimum force the hydraulic unit includes pressure gauge ( 28 ) and the pressure Gauge ( 29 ) that-determines during the whole descent the pressures to which both faces of the piston ( 32 ) are subjected, the PLC program receives information during the whole descent the pressures to which both faces of the piston ( 32 ) are subjected, and multiply it by respective areas and send orders of partial openings or closings to the valves ( 26 ) and ( 27 ).