CN1048076C - Hydraulic pump unit - Google Patents

Abstract

A hydraulic pump assembly equipped with a self-adjusting balance system comprising a combination of a flywheel, a high slip ratio electric motor and a reversible hydraulic pump which acts as a hydraulic motor during the downward motion of the assembly to accelerate the flywheel and accumulate energy in the form of kinetic energy in the downward rod string. The speed loss of the high slip ratio electric machine during the upward movement, and the flywheel feeds back the accumulated function to compensate the power of the electric machine to the amount needed by the upward movement. The interaction between the weight of the flywheel, the motor and the sucker rod string automatically adjusts the range of speed variation. The up and down speeds may be adjusted manually or automatically by electronically commanded stepper motors.

Description

Hydraulic pump unit

The present invention relates to a hydraulic pump unit for an oil well using a functional energy storage system to compensate the up and down motion mass of a sucker rod string.

Hydraulic pumping arrangements are often used in oil wells due to their operational advantages over prior art mechanical pumping arrangements. The smooth and direct movement of the hydraulic piston is immediately transmitted to the sucker rod string without the use of gears and conveyor belts. Due to the low weight of the hydraulic pump unit, the unit can be mounted directly on the wellhead flange, and in this way the heavy foundation requirements required for mechanical pump units are avoided. The stroke length and speed can be easily adjusted without time-consuming pulley replacement, and the absence of gear reducers, rolling bearings and belt drives contributes to reduced maintenance costs. It should also be noted that the initial investment in a hydraulic pumping arrangement is usually substantially lower than that in a mechanical pumping arrangement.

Despite the above-mentioned advantages of the hydraulic pump unit and its apparent simplicity in its practical configuration, the unit still presents operational problems which lead to frequent operational failures and increased maintenance costs.

First of all, it is necessary to point out the horizontal problem of the moving mass. In the mechanical device, this problem is solved by simply rotating the counterweight.

In operation, virtually all hydraulic pump units are actually balanced using one of the following systems.

1. Use hydraulic accumulators with floating pistons or elastic bladders, both pre-filled with high-pressure nitrogen. This system is inconvenient due to the need to frequently recalibrate the nitrogen pressure. In addition, due to the small pressure differential between the oil and nitrogen, the floating piston is prone to seizure, and the life of the elastomeric bladder is not long enough for use in oilfield conditions.

2. Pulleys of different configurations, cables or guide chains, moving mechanical guide sliders used as counterweights are also used to balance the hydraulic pump unit, but the introduction of all these elements will greatly increase the cost of maintenance.

It is therefore an object of the present invention to provide a hydraulic pump arrangement for driving a sucker rod string for use in an oil well, using a functional energy storage system to compensate for the up and down travel of the sucker rod string exercise weight. Thereby, various inconveniences of the above-mentioned prior art are overcome.

A hydraulic pump device for driving a sucker rod string provided by the present invention includes: two hydraulic cylinders each having a piston rod, and the piston rods are rigidly connected to a synchronization device to ensure their synchronization and Uniform movement, the sucker rod string is set at the center of the synchronous device; a high-slip motor, a flywheel is connected to one side of the motor, and a The reversible hydraulic pump that generates energy is then connected to the other side of the motor, and during the downward movement of the sucker rod string, the reversible hydraulic pump acts as a hydraulic motor, accelerating the flywheel speed, and When the sucker rod string moves downward, the energy of pumping the sucker rod string is stored in the form of kinetic energy; the speed regulating hydraulic valve used to adjust the upward speed and downward speed of the sucker rod string can be used The speed adjustment hydraulic valve is adjusted manually or by a stepping motor, and is adjusted by means of the stepping motor to drive the speed adjusting hydraulic valve. The processed instructions perform speed regulation according to changing conditions in the oil well; two independent flow regulating valves, which are arranged between a solenoid-controlled directional valve and a speed regulating hydraulic cylinder, in order to regulate The acceleration and deceleration of the movement of the sucker rod string at the pivot point.

In order to understand the purpose and characteristics of the present invention, the present invention is described in accordance with the accompanying drawings and the following detailed description. in:

Fig. 1 shows the state that the hydraulic pump device of the present invention is in a rest position;

Figure 2 shows the position of the control system of the hydraulic pump device of the present invention during the upward movement of the sucker rod string;

Fig. 3 shows that the control system of the hydraulic pump device of the present invention is in the reverse position shown in Fig. 2;

Fig. 4 shows the relationship curve between the total power required during the upward movement of the sucker rod string, the power of the electric motor of the hydraulic pump and the difference between the two and the rotating speed of the electric motor;

Fig. 5 shows the relationship curve between the output power of the hydraulic pump as a motor, the power required by the flywheel and the difference between them and the motor speed.

Figure 1 shows the hydraulic pump arrangement in a rest position. The piston rods of the two hydraulic cylinders 1 are rigidly connected by means of a synchronization device 2, in this way a synchronous and uniform movement of the two piston rods is guaranteed. The polished rod of the sucker rod string is installed in the center of the synchronizer 2 . An electric motor 4 is shown in the lower part of FIG. 1 , which is connected at one end to a flywheel 5 and at the other end to a reversible hydraulic pump 6 , as well as an auxiliary pump 7 .

For a better understanding of the operation of the assembly consisting of the flywheel 5, the motor 4 and the reversible pump 6, it should be noted that the motor 4 is a high slip motor as specified by NEMA (National Motor Manufacturers Association) D. The hydraulic pump 6 itself is a pump of the reversible swash plate type. This means that if the swash plate 10 is tilted to the right, the pump 6 moves hydraulic oil from the oil sump into the hydraulic cylinder 1, and if the swash plate 10 is tilted to the left, the hydraulic pump 6 starts a hydraulic pressure. The role of the motor, the hydraulic oil is sent back from the oil cylinder 1 to the oil pool. As shown in Figure 1, the position of the swash plate is vertical, that is, it is neither tilted to the left nor to the right, so that no hydraulic oil moves in this position, and the hydraulic cylinder 1 is in a static state. It must be pointed out that the assembly of the flywheel 5, the electric motor 4 and the hydraulic pump 6 forms a solid whole which uses only two bearings on the electric motor 4 and in this way promotes perfect alignment of the assembly.

The positioning of the swash plate 10 is accomplished by means of a connecting rod 25 which in turn is acted upon by the movement of the rod 24 of the piston 23 positioned centrally in the adjusting cylinder 22 as shown in FIG. 1 .

Connected face-to-face with the reversible pump 6 is the auxiliary pump 7, which continuously pumps hydraulic oil from the oil sump 8, the suction pipe 9 and the pressure delivery pipe 15 into the electromagnetic directional control valve 20 in order to adjust the swash plate 10 go. In the position shown in FIG. 1 , the directional control valve 20 is in its intermediate position and in this way closes the outlet of the pipe 19 . In this position, the pressure regulating valve 16 discharges oil from the auxiliary pump 7 to the discharge line 17 and then back into the oil sump 8 .

Figure 2 shows the position of the control system during the upstroke of the sucker rod string. By means of an electrical signal from a limit switch not shown in FIG. 2, the magnetic winding on the left side of the solenoid directional control valve 20 moves the valve spool to the position shown in FIG. In this way, the hydraulic oil from the auxiliary pump 7 can be transferred to the adjusting cylinder 22 and move the piston 23 in the direction indicated by the arrow. Oil on the opposite side of the piston 23 can flow through the tube 18 to the sump. Thus, the connecting rod 25 tilts the swash plate 10 of the pump 6 to the right, so that the pump can deliver the hydraulic oil to the lower end of the hydraulic cylinder 1 through the suction pipe 11, the pressure feed pipe 12 and the pipe 14, and in this way start pumping. Upward movement of the oil rod string. When the hydraulic cylinder 1 reaches the upper reversal point, the second electric signal moves the spool of the electromagnetic directional control valve 20 to the position shown in FIG. 3 . Thus, hydraulic oil from the auxiliary pump 7 moves the piston 23 to the position indicated by the arrow in Figure 3 and the connecting rod 25 tilts the swash plate 10 to the left so that the reversible pump 6 now acts as a hydraulic motor. With the aid of the synchronizer 2, the weight of the sucker rod string pushes the hydraulic oil contained in the hydraulic cylinder 1, through the pipes 14 and 12, to the hydraulic pump 6, which now functions as a hydraulic motor, the intermediate acceleration motor 4 and the flywheel 5 turn. When the hydraulic cylinder 1 reaches the lower reversal point, the cycle starts again with the situation shown in FIG. 2 . The adjustment of up and down speeds is accomplished as much as the adjustment of acceleration and deceleration by means of the numbered components shown in FIG. 1 . As can be seen from Figure 1, the hydraulic oil that moves the piston 23 must pass through one of the two flow regulating valves 21, in this way the speed of movement of the swash plate 10 is regulated during the transition of the pump 6 from the pump function to the motor function , while determining the reverse speed of hydraulic cylinder 1.

The upward and downward speeds are proportional to the inclination angle of the swash plate 10, which can be adjusted by the adjustment bolt 29, which can be adjusted manually by the adjustment knob 27, or electrically by the stepping motor 26 and deceleration. Gear 28 to adjust. The stepping motor 26 enables the up and down speed to be regulated by receiving electric pulses from the microcomputer, and in this way the working conditions of the hydraulic pump device can be adapted to the condition changes of the oil well. In this way, a so-called "intelligence pump" can be easily implemented.

The pressure regulating valve 13 plays the role of protecting the sucker rod string from overload, and limits the liquid pressure within any regulating range.

The system described above also solves the task of balancing the hydraulic pump arrangement. The so-called balance includes the meaning of recovering the energy of the sucker rod string during its downward movement.

The present invention uses a flywheel-motor-hydraulic pump assembly to accomplish energy recovery in the manner described below. Taking the typical conditions of an oil well as an example, the total energy required during the ascent of the sucker rod string is shown by the curve (A) of Figure 4, the electric motor of the hydraulic pump unit rotating at 1800 rpm at the beginning, the electric motor Only the power shown in curve (B) of FIG. 4 . The difference between the power required in the motor and the power available in the motor is provided by the kinetic energy accumulated in the flywheel. As can be seen from Figure 4, the rotational speed of the assembly drops from 1800 rpm to 1500 rpm during the upward movement. The high slip motor used in the present invention allows for this speed variation. Due to the reduction in the rotational speed, the flywheel can emit the power shown in the curve (C) of Fig. 4 and compensate the power required by the hydraulic pump.

During the downward movement of the sucker rod string, the hydraulic oil from the hydraulic cylinder makes the hydraulic pump work as a hydraulic motor, producing the power shown in curve (D) of Figure 5, again accelerating the flywheel. In order to achieve an initial speed of 1800 rpm, the flywheel requires a power shown by curve (F) of FIG. 5 . The difference between the total power required (F) and the power recovered from the sucker rod (D) is shown by curve (E) of Figure 5 and is provided by the electric motor.

The speed range is self-adjusting during the up and down movements according to the specific conditions of the well until the synchronous speed of the motor is reached.

The balancing system of the present invention uses the recovery of kinetic energy of the flywheel rather than the recovery of static energy accumulated by the pressurized gas.

The system is self-regulating and completely maintenance-free.

Claims (4)

1. hydraulic pumping unit that is used to drive rod string is characterized in that it comprises:

Two oil hydraulic cylinders that respectively have a piston rod, described piston rod are rigidly connected on the synchronizer to guarantee that it is synchronous and evenly to move that described rod string is arranged on the center of described synchronizer;

A high slip motor, a flywheel is connected a side of described motor, a reversible oil hydraulic pump that is used for balance or reclaims the energy that is produced by the rod string downward movement then is connected the opposite side of described motor, during described rod string downward movement, described reversible oil hydraulic pump plays a part an oil hydraulic motor, quicken flywheel speed, and when described rod string moves downward, the energy of the taking out described beam hanger post form with kinetic energy is stored;

In order to the speed uplink of regulating described rod string and the speed regulation hydrovalve of downstream rate, can regulate described speed regulation hydrovalve by manual or stepping motor, regulating so that drive described speed regulation hydrovalve by described stepping motor, receiving the condition execution speed that changes in according to oil well based on the instruction after the data of load and position transducer are handled that sends from computer at described stepping motor and regulate;

Two flow control valves independently, it is configured between the directional control valve and speed regulation oil hydraulic cylinder of an Electromagnetic Control, so that be adjusted in the acceleration and the retardation of the above rod string motion of two rollback points of hydraulic pumping unit.

2. hydraulic pumping unit as claimed in claim 1, it is characterized in that, described flywheel, described motor and described reversible oil hydraulic pump are connected in the rotating shaft of described motor, and the bearing that only uses motor it rotates to lead, thereby guarantee intact alignment between described flywheel, described motor and the described reversible oil hydraulic pump.

3. hydraulic pumping unit as claimed in claim 1 is characterized in that, described oil hydraulic pump is a kind of reversible rotating sloping disk type oil hydraulic pump, and its wobbler is connected to described speed regulation oil hydraulic cylinder by a linkage.

4. hydraulic pumping unit as claimed in claim 1, it is characterized in that, be provided with a service pump in abutting connection with described oil hydraulic pump, described oil hydraulic pump and described service pump collaborative work are under the right bank state at described wobbler, and described oil hydraulic pump is carried out the function of pump, be under the left bank state at described wobbler, described oil hydraulic pump is carried out the function of oil hydraulic motor, and is under the plumbness at described wobbler, and described oil hydraulic cylinder then remains static.

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