DE1298884B - Rodless piston deep pump for use in oil wells - Google Patents

Description

The invention relates to a rodless piston deep pump for Use in petroleum wells with at least one pump powered by an electric motor back and forth under the action of relocatable, multi-pole alternating magnetic fields moved rotor is driven directly.

There are known piston pumps of this type, in which the electrical Field at the end of the stroke, reversing the connections of two phases, the direction of movement changes. These piston deep pumps mainly cause difficulties in reversing the direction of rotation, because very high starting currents are necessary, which lead to excessive heating of the Lead windings.

The object of the invention is to provide the above-mentioned in piston deep pumps To eliminate the need for high starting currents.

This object is achieved in that each time the direction of movement is reversed of the rotor in the period required for start-up and acceleration, a hydraulic one Drive is switched on, which takes advantage of the pressure of the pumped liquid column is effective. With this combination of a hydraulic drive at the beginning the electric drive for the rest of the stroke achieves that the electric motor works at a constant speed and with a constant driving force, whereby the unfavorable loads during the reversal of movement are avoided.

When using two piston pumps operated by a rotor a valve control is advantageously provided in such a way that in each case at start-up and acceleration a piston pump acts as a hydraulic drive, while the other runs empty.

To control the electric drive is in the electric supply lines of the electric motor switched on a switching device, which is under control by the rotor movement is switched off or off during start-up and acceleration of the rotor. the motor supply voltage from a minimum value to the can grow to its full value. This causes power interruption by mechanical Avoid contacts that wear out quickly at very high frequencies would. The arrangement can also be made so that as a switching device in the case of alternating voltage serving as the supply voltage, all conductors of the supply line contain a saturable choke except for one, the bias of which is up to Saturation is switched off at the reversal point of the direction of movement of the rotor and after Acceleration of the runner is switched on.

A Transformers are used, whose primary winding on the one hand with the ungrounded point of symmetry the electrical supply line of the electric motor driving the pump and on the other hand is connected to ground and its secondary winding via a rectifier feeds the saturable choke and that the conductor which is not a saturable choke contains, in addition to two induction coils, their magnetic cores depending on from the movement of the rotor when reaching the respective reversal point in the first Induction coil immersed or pulled out and pulled out of the second or immersed, is connected to ground. The magnetic cores can be synchronized on one with the rotor of the electric motor that drives the pump be attached, the two when feeding the electric motor via a three-phase system carries electrical contact elements that are guided by a saturable choke Conductors are connected and on the other hand for polarity reversal of the motor windings with polarity reversal contacts cooperate, which in turn in a known manner on two phase windings of the electric motor.

If two piston pumps are driven at the same time, the one above and the other below the electric motor in the course of the pump line arranged. Even if both pumps are arranged above the electric motor, one obtains a cheap solution.

Each piston is expediently in the opposite end position assigned a pressure valve in the pump wall, each due to the effect one attached to the associated piston and extending in the direction of piston movement Arms also after reversing the direction of the piston for a determined by the length of the arm Time interval remains open.

This means that in the event of a voltage recovery after an intentional or accidental one Mains voltage interruption, the start of the pump is independent of the position, at which the run interruption took place, controls a on the feed line of the electric motor connected relay connected to the piston chamber via its armature Valve arrangement that is closed when the supply voltage is applied, but when Suspension of the supply voltage due to the armature movement of the relay that then takes place is opened so that the piston is released and lowered by its own weight will. As a result, the drive of the electric pump always starts in the lower one End position.

The invention is described below with reference to schematic drawings explained in more detail using several exemplary embodiments. It shows F i g. 1 the general Design of an electric pump according to the invention with two stators plane air gap, F i g. 2 the arrangement of the pumps and valves for the electro-hydraulic Drive and F i g. 3 the electrical circuit for reversing the working direction.

In the embodiment according to FIG. 1 that is not yet the start-up system the pump shows at each reversal of the run, the electric motor M is between two piston pumps P and P 'arranged with alternating working stroke, one of which is the working stroke on the ascent and the other on the descent.

The electric motor is an asynchronous motor with a squirrel cage winding and is provided with a housing 1 in which there are two stators S1 and S2. In the housing there is also a rotor A, which is arranged between the two stators and which is alternately moved vertically back and forth under the action of the displaceable multipolar alternating magnetic fields formed between the two flat air gaps.

The rotor A operates through the piston rods or drive rods 7 the movement of the piston 8, whereby it is displaced in the opposite direction in the housing located fluid causes the cooling of the motor winding. Sucks on the upstroke the piston 8 of the lower pump P at the bottom on and suppressed the fluid located on the top via the lines 9 and 12 into the delivery line 11, while the piston 8 of the upper pump P 'is the one on its top Fluid pushes to the bottom of the piston. On the downstroke, the upper piston sucks over the Line 13 and displaces the fluid located on its underside into the line 12, while the lower piston is the fluid sucked in during the previous upstroke displaced to its top.

In the embodiment according to FIG. 2 is the electro-hydraulic one Control system indicated, which using the displaced oil column hydraulic pressure exerted on the pistons, the starting when the movement is reversed on End of stroke allowed.

In this figure, a variant is shown in which the two pumps P and P ' are arranged in a single cylinder 17 , which is located above the electric motor and at both ends two pressure valves 18 and 18' and two suction valves 19 and 19 'and for In the middle, two openings 20 and 20 'without a valve, which are closed or opened directly by the piston by overlapping or by release.

Inside the cylinder are located on the from the electric motor M driven common piston rod 21 has two pistons 22 and 22 ', respectively with an arm 23 and 23 'are provided to keep the associated pressure valve open during the start-up period under hydraulic drive and the function of a cam exercising in a straight line.

The electric pump works as follows with hydraulic drive: During the downstroke under the drive of the electric motor, the piston 22 pressing on the oil in the cylinder keeps the suction valve 19 closed (which opens when it is sucked under the pressure of its spring against the interior) and forces the pressure valve 18 (which opens to the outside and which is held in the closed position by its spring when sucking in) to open and displaces the oil in the cylinder via this valve. When the end of the working stroke is reached, the electric current is passed through the in FIG. 3 shown device for the reverse connection interrupted and the movement of the piston 1 braked under the pressure of the displaced oil column.

At the end of the downstroke, the oil displacement stops, and so does the valve 18 begins to close under the pressure of its spring and the displaced oil column, however, is held open by the arm 23 so that the oil column continues to its Can exert pressure on the piston.

During the downward stroke, the other piston 22 'performed the suction stroke with the valve 19' open under the pressure of the petroleum of the layer, the oil having penetrated into the vacuum space of the cylinder formed by the displacement of the piston when the pressure valve 18 'was closed. Shortly before reaching the end of the downward stroke, the piston 22 'is somewhat free of the opening 20' and creates a free connection with the outside, so that only the pressure of the layer acts on this piston, while the pressure of the displaced oil column acts on the piston 22 rests, whereby the initiation of the reversal of the motion of the whole movable train under hydraulic drive is determined. At the moment when the moving train reaches its normal speed, the arm 23 (regulated in a corresponding manner) ceases to hold the pressure valve 18 open. The piston 22 closes the opening 20 during its upward movement and the switching device in the circuit re-establishes the current flow in the corresponding direction, in such a way that the pump changes over from hydraulic drive to electric drive.

With a continued upward stroke under the drive of the electric motor M, the piston 22 'displaces the oil of the cylinder through the valve 18', while the piston 22 executes the suction stroke with the pressure valve 18 closed and the suction valve 19 open under the pressure of the layered oil , the oil in the penetrates the vacuum space left by the piston. At the end of the upstroke, under the action of the pressure valve 18 'actuated by the arm 23' and the opening of the opening 20 by the piston 22, the moving train is decelerated and its reverse movement is initiated under the same conditions as during the downstroke.

By combining the hydraulic drive at the beginning with the electric one Drive for the rest of the stroke is achieved that the electric motor with constant Speed works as well as with a constant driving force, with the unfavorable Effects of the reversal of motion are completely eliminated when running asynchronous motors occur with reciprocating rectilinear movement; through the action of the Movable pull on the fixed springs at the end of the travel can be done by hydraulic Drive, if necessary, by compression in the braking period and then completed by relaxation in the start-up period in the opposite direction will.

In the construction according to FIG. 2 the upper cylinder of the pumps is separated from the housing of the electric motor using two separate pressure seals. One of the pressure seals is 24 on the electric motor and the other 25 on the pump. In this way, the pressure to be maintained in the housing of the electric motor is the pressure of the oil layer, ie is approximately atmospheric pressure, which facilitates the formation of the pressure seal and the sealing of the housing.

Compared to the embodiment according to FIG. 2 a, in which the two Above the electric motor M arranged pumps P and P 'with the pump chambers have their valves at their cylinder ends and require two pressure seals exposed to the pressure of the oil column, a construction can be used the in the F i g. 2 b is shown. In this construction are the two pump chambers with their valves in the middle of the cylinder of the pumps and are separated by a common wall through which the drive rod for the upper Piston passes through and which requires a single seal operating under high pressure.

For the control of the interruption and restart of the electrical Current in the action of the electric motor during the reversal of movement is a switching device provided in the illustrated embodiment of the electrical circuit diagram according to FIG. 3 saturable chokes used.

In this scheme, k means the automatic breaker of the device; u, v and w are three Head of the secondary winding of the transformer T to feed the electric pump, which is located on the surface and through a three-core cable is connected to the phase windings S ", S" and SW of the electric motor is. The saturable chokes R "and R", are located on the conductors v and w.

Two induction coils 26 are located in the housing of the electric pump and 26 ', which are equipped with magnetic cores 27 and 27' and are in series fed by a single-phase circuit, which acts as a branch circuit on the voltage of the conductor u lies and through the mass of the delivery line and through the primary winding a transformer-rectifier group TR is closed, its secondary circuit the excitation coils of the saturable chokes R ″ and RW by rectified current feeds.

When operated under an electric drive, the reactance is that of the Coils 26 and 26 'attracted magnetic cores 27 and 27' negligible; the transformer rectifier group TR feeds the bias coils of the reactors R ,, and R ', and saturates them such that their reactance is negligible and the electric motor with mains voltage is fed.

The magnetic cores 27 and 27 'are by the movement of the movable Device or the movable rotor A of the electric motor controlled such that the corresponding magnetic core when reaching a certain distance from the upper one or lower end of the stroke dips into the associated coil 26 (or 26 ') and thereby plunges The increase in the reactance of the coil determines the current in the supply circuit of the Group TR reduced to almost zero and the elimination of the premagnetization of the saturable chokes. R ,, and R "and thus the introduction of certain, practically den Three-phase feed of the electric motor canceling reactances in the circuit of this determined by both conductors.

After reversing the direction of travel of the movable device, the Magnetic core on reaching the specified distance from the end of the stroke from the associated Coil pulled out, and the current both in the bias circuit of the saturable Chokes R "and R, as well as in the three-phase supply circuit of the electric motor restored.

The reversal of the direction of displacement of the magnetic field of the electric motor at the end of the stroke is achieved by interchanging the conductors v and w, with the help of a toggle switch. 28, which is also caused by the movement of the runner A is operated; the switchover takes place in the interval in which the current of the circuit is interrupted so that the switching of the phases is carried out without power.

The same control means can also be used in the event in the case of the saturable chokes R ,, and R, electronic for power interruption Devices (such as transistors) have been used either on the earth's surface or are housed in the housing of the electric motor.

In the event of a power failure (intentional or accidental) is under an electric drive to avoid starting at any point with full load and restoration of voltage, d. H. a run-up that oversizing the motor would require the output line of the electrical Pump provided with a three-way valve 29 (FIG. 2), which is connected to one of the line u lying electromagnetic relay 30 is controlled with the voltage zero. If the voltage of the conductor u is interrupted, the relay 30 determines the release a spring 31 which controls the pivoting of the lever 32 from the normal operating position x of the valve, that of the connection between the electric pump and the delivery line of the crude oil, in the locking position y of the device causes the Connection between the electric pump and the outside space corresponds.

In this situation the pump in which this is without pressure in the outside space displaced, determines the weight of the runner regardless of the position in which it is located, its displacement up to the lower end of the lifting distance at which one seated on the piston rod of the piston 22 'and intended for linear movement Cam 33 the return of the lever 32 in the working position x, the renewed loading of the relay 30 and the locking of the cam 33 and accordingly that of pumps P and P 'determined at the end of the stroke.

When the voltage is restored, the relay 30 locks the cam 33; then the electric pump is located in the as with every reversal of movement Start-up position under hydraulic drive.

Instead of the three-way valve 29 described above, two can be used Use mutually controlled valves, one of which is in the delivery line of the Piping and the other interposed in the delivery line to the outside area and both by a common voltage relay or two separate voltage relays are controlled in such a way that in the event of a power failure, the valve in the Piping is closed and the valve to the outside is open and that with recurring Tension the valve to the outside closed and the valve in the piping is open.

To avoid working in the single-phase area in the event of overload, if the voltage on one of the conductors v and w is interrupted, the automatic Circuit breaker k is provided with a relay for zero voltage on all three conductors.

By using the hydraulic drive for starting the Reversal of motion, whereby the electric motor is only in the constant speed range is used, the electric motor can also be provided in the form of a synchronous motor whose rotor is supplied with direct current, which is fed by a branch Rectifier switched from the feed line of the electric motor into the circuit and from a generator controlled by the movement of the rotor.

The use of a synchronous motor as a pump drive brings about an asynchronous motor has the following advantages: while the power factor is on 1 can have an approximate value because due to the large number of pole pairs the loss value of the stator winding for the same useful power at least to the Reduced by half, the value of the power factor is in the asynchronous variant below 0.7; for the same value of the losses and correspondingly the current in the stator the power of the electric motor increases by 40 to 50% compared to the asynchronous variant; with the same dimensions of the electric motor, the Air gap in the synchronous variant must be noticeably larger, which makes the design of stators larger Length and, accordingly, facilitated by engines of great power; for engines with The energy losses and, in particular, the voltage drops are of the same power in the feed line reduced by at least half, which results in better operating conditions result.

In the case of choosing a drive with a synchronous motor, one can also take the single-phase synchronous motor, which has the following advantages: it allows the Use of a single-conductor cable, with the current flowing back through the delivery line he follows; it makes the elimination of the phase switching device possible.

For supplying the electric pump with electrical energy and for their control by a three-wire cable without influencing the controls the control of other electric pumps, you have to use a suitable three-phase transformer, which corresponds to the electrical diagram of FIG. 3 corresponds or at least for a single-phase transformer take care of the phase used for control.

To implement a zero point isolated from the control device and it is still possible to use a cable with three conductors and neutral conductors directly use the voltage of a mains three-phase current.

To feed the electric pump with electrical energy you can especially for the case of the pump working at great depth as well as for the realization if possible favorable conditions with regard to the winding insulation two above the electric pump Use single-phase transformers arranged in stages to supply the supply voltage to decrease.

On the basis of a calculation to determine the dimensions, one has at the embodiment with a cylindrical air gap and determined as an asynchronous variant, that an electric pump with a pumping frequency of 30 double strokes of 3.5 m per minute, which has a throughput of 8 wagons of crude oil in 24 hours from a depth of 1500 m realized and introduced into a column with a diameter of 120 m can, would have an efficiency of about 0.7 and a stator height of 2.60 m.

If one takes into account the two extensions (of greatly reduced Diameter) of the housing for the stroke of the movable device, then exceeds the total length of the electric motor is not 10 m.

The advantages of the electric pump according to the invention are increasing Pump depth greater, as the construction and mode of operation of the electric pump does not go through the growing depth will be affected because the driving force and accordingly the performance can be kept constant. Therefore, the same can be used for a certain depth applied electric motor can also be used for a much greater depth, assuming a pump whose flow rate is inversely proportional to the depth.

Claims (11)

Claims: 1. Rodless piston deep pump for use in petroleum wells with at least one pump driven by an electric motor with movable, multi-pole alternating magnetic fields reciprocating rotor directly is driven, characterized in that each time the direction of movement is reversed of the rotor (A) a hydraulic one in the period required for start-up and acceleration Drive is switched on, which takes advantage of the pressure of the pumped liquid column is effective. 2. Piston deep pump according to claim 1, characterized in that when using two piston pumps (P, P ') operated by a rotor (A), a valve control (18, 23; 18', 23 ') is provided in such a way that in each case at start-up and acceleration, one piston pump (e.g. P) acts as a hydraulic drive, while the other (e.g. P ') runs idle. 3. piston deep pump according to at least claim 1, characterized in that in the electrical supply lines of the electric motor (M) a switching device is switched on, which is controlled by the rotor movement switched off during start-up and acceleration of the rotor (A) or in a steady state Transition the motor supply voltage increases from a minimum value to the full value leaves. 4. piston deep pump according to claim 3, characterized in that as a switching device in the case of alternating voltage serving as the supply voltage, all conductors of the supply line except for one (u) contain a saturable choke (R ", R,") whose bias switched off until saturation at the reversal point of the direction of movement of the rotor (A) and is switched on after the rotor (A) has accelerated. 5. piston deep pump according to claim 3 or 4, characterized in that a transformer (TR) is used for direct current bias of the saturable chokes (R ", R,"), the primary winding of which on the one hand with the ungrounded symmetry point of the electrical supply line of the electric motor driving the pump ( M) and, on the other hand, is connected to ground and its secondary winding feeds the saturable chokes (R ", R,") via a rectifier, and that the conductor (u), which does not contain a saturable choke, also has two induction coils (26, 26 ') ), whose magnetic cores (27,27) are immersed or pulled out of the first induction coil (26) and pulled out or immersed in the second (26 ') depending on the movement of the rotor (A) when the respective reversal point is reached Mass lies. 6. piston deep pump according to claim 5, characterized in that the magnetic cores (27, 27 ') are attached to a synchronous with the rotor (A) of the pump (P, P') driving the electric motor (M) displaceable switching pump (28) , which carries two electrical contact elements when the electric motor (M) is fed via a three-phase system, which are connected to conductors that are each led via a saturable choke (R ", R,") and, on the other hand, interact to reverse the polarity of the motor windings with polarity reversal contacts, which in turn are inherent known way on two phase windings (S ", S,") of the electric motor (M). 7. Piston low pump according to claim 2 to 6, characterized in that at the same time Drive two piston pumps (P, P '), one (P') above and the other (P) below of the electric motor (M) is arranged in the course of the pump line. B. Piston deep pump according to claim 2 to 6, characterized in that two Piston pumps (P, P ') both above the electric motor (M) in the course of the pump line are arranged. 9. piston deep pump according to claim 7 and 8, characterized in that each piston (22, 22 ') is assigned a pressure valve (18, 18') in the pump wall in each case in the opposite end position, which is in each case by an assigned piston (22 or 22 ') attached arm (23 or 23') extending in the direction of piston movement is kept open for a time interval determined by the length of the arm, even after reversing the direction of the piston (22, 22 '). 10. piston deep pump according to claim 9, characterized in that the pump end surfaces Coil springs are assigned, each by the piston (22, 22 ') when reaching the piston end positions are pressed together. 11. piston deep pump according to claim 1 to 10, characterized in that one of the feed line (u) of the electric motor (M) connected relay (30) via its armature controls a valve arrangement (29) connected to the piston chamber, which when the Supply voltage is closed, but is opened when the supply voltage is interrupted by the armature movement of the relay (30) which then takes place, so that the pistons (22, 22 ') are released and lowered by their own weight.