WO2010015460A1

WO2010015460A1 - Method for operating a multi-pulse piston pump, multi-pulse piston pump, and the production thereof

Info

Publication number: WO2010015460A1
Application number: PCT/EP2009/058046
Authority: WO
Inventors: Dieter Bosse
Original assignee: Bentec Gmbh Drilling & Oilfield Systems
Priority date: 2008-08-06
Filing date: 2009-06-26
Publication date: 2010-02-11
Also published as: DE102008036528A1

Abstract

The invention relates to a method for operating a multi-pulse piston pump (10), particularly a flushing pump for use in well drill holes (12), comprising at least two pistons (24), each being guided in a cylinder (22), and one drive acting upon the piston (24) for conveying a fluid medium, and a piston pump (10) that can be operated according to the method, or that operates according to the same, wherein at least two linear motors (20) act as the drive, and each linear motor (20) acts upon at least one piston (24), and the linear motors (20) are coordinated by means of a controller (42) for controlling the pulsations.

Description

description

Method for operating a multi-pulse piston pump, multi-pulse piston pump and production of such

The invention relates to a method for operating a multi-pulse piston pump, in particular a flushing pump for use in flushing deep wells, according to the preamble of claim 1. Furthermore, the invention relates to a multi-pulse piston pump according to the preamble of claim 7 and a method for producing such a multi-pulse piston pump.

Piston pumps are well known and, like compressors, are fluid power machines. However, while compressors (compressors) are used to compress gases, in particular liquid media are promoted with such pumps. WO 2008/074428 describes a compressor in which a linear motor drives a compression piston.

Piston pumps are used, among other things, as flushing pumps. They then serve to introduce a liquid medium acting as a rinsing fluid into a drill string and / or a borehole. Rinsing serves to remove loose or dissolved material, such as overburden or cuttings, to cool and / or lubricate a boring tool used in the boring, or else to drive such a boring tool. In addition, by pressing the flushing liquid into the borehole, pressure equalization can be achieved for the rock surrounding the borehole or other base material, in particular gases and liquids contained therein. By means of the piston pump, in particular at low borehole depths, a higher mass flow is achieved at lower borehole depths. gerem pressure and at lower wells a lower mass flow at higher pressure generated. Mass flows generated by such piston pumps can be in the range of over 3,000 L / min, at a pressure of more than 500 bar.

The piston pumps known in the prior art generate pressure and a mass flow by means of movement of a piston in an associated cylinder; Retraction of the piston in the associated cylinder results in an increase of a working space volume, which allows an inflow of the liquid medium. In an opposite movement of the piston, the working space volume is reduced and thus expelled the medium. In order to drive the piston, a rotary movement of a drive shaft, for example by means of a connecting rod and crosshead, in known piston pumps is converted into a translatory, oscillating piston movement. For the rotational movement of the drive shaft about its longitudinal axis, e.g. used with the drive shaft coupled electric motor. The coupling is usually done by means of a transmission.

Such transmissions, as well as the implementation of the rotational movement in the translational, oscillating piston moving ung necessary components, e.g. Conrods, crosshead, etc., are space demanding and / or difficult and result in a large design of the pump and / or contribute significantly to a weight of the pump. Due to the large number of moveable parts installed, which, of course, even with sufficient

Lubrication subject to wear, additional costs incurred in the manufacture of the parts and / or the pump, during their maintenance, repair or the like. In addition, manufacturing, maintenance, repair, etc. are time consuming and labor intensive. Furthermore, condition in contact with each other, moving parts friction losses, which adversely affect the overall efficiency.

Known piston pumps also move the liquid medium usually with uneven pressure and an uneven mass flow. The resulting effect is called pulsation. For example, if the direction of movement of the piston in the cylinder is reversed, these pulsations can be significant. In some cases, such pulsations can be reduced in today rinsing pumps by means of three piston-cylinder arrangements, which work offset by 1/3 phase, and often additional external pressure equalizers, so-called pulsation damper, are used for further reduction. However, even with such a combination residual pulsation is not negligible and results in an increase of operating noise, loading the material, such as e.g. Pistons, cylinders, pipelines, and the like.

In particular, for special applications, such as the so-called "measuring while drilling" (MWD), in which the material to be drilled is subjected to controlled test pulses for analysis, strong pulsations by the piston pump are undesirable because they disturb the MWD measurements and thus For accurate and reliable results, the pulsations of the pump must therefore be filtered out of the measured values or subtracted from them by means of complex arithmetic operations, which results, among other things, in increased costs and work.

The use of piston pumps with more than three piston-cylinder arrangements, for example so-called quadruplex or quintuplex pumps, does not achieve a completely satisfactory refinement. The pulsation and thus also require a costly optimization of the MWD process.

The invention is therefore based on the object of specifying a particularly suitable method for operating a piston pump as well as a piston pump which can be operated or operated according to the method and which has the above-mentioned features. Disadvantages avoided or at least reduced. Preferably, the pulsation control should increase the validity of MWD measurements or reduce the effort in the post-processing of MWD measurements to filter out effects caused by pulsation.

With regard to the method for operating a multi-pulse piston pump, this object is achieved by the features of claim 1. It is for operating a particular as a rinsing pump for use in flushing deep wells certain multi-pulse piston pump with at least two guided in each case a cylinder piston and a Acting on the piston drive to promote a liquid medium, provided that at least two linear motors act as a drive and each linear motor acts on at least one piston and that the linear motors are coordinated for pulsation control by means of a control unit. Preferably, the linear motors are gearless coupled with one or two pistons.

With regard to the corresponding device, the object is achieved with a multi-pulse piston pump with the features of claim 7. For this purpose, a piston pump of the type described above has at least two linear motors acting as a drive, each of which acts on at least one piston, and a control unit for coordinating the linear actuators for pulsation control. The advantage of the invention on the one hand in the possible with the use of linear motors as a drive omission of a common drive axle, a necessary for the drive transmission, a reduction of moving parts and concomitantly a reduction of friction losses and an increase in efficiency. This allows a total of a partial reduction, a lighter and more compact design and thus a total cost reduction in terms of purchase, maintenance, operation, transport, etc. By the translational motion of the linear motors directly into the translational movement of or

Piston is implemented, it requires no conversion of a rotational movement, z. As a motor shaft or a pump shaft, in the translational piston movement, z. B. by means of a transmission, by means of connecting rods, crossheads and the like. This reduces an energy loss otherwise associated with such a conversion and simplifies the construction of the pump. Due to the reduced number of moving parts also reduces wear, labor costs in production, maintenance and repair and consumption of lubricants and / or the like. On the other hand, the modified drive concept opens up a possibility for reducing the pulsation already by increasing the number of cylinders used and the pistons driven for this purpose, while the space requirement remains roughly constant. Each linear motor can be combined with at least one, in particular two moving pistons and the associated cylinders or to form a module and the number of modules in a piston pump is limited only by the available space. Even if, in the most unfavorable case, comparison with previous piston pumps intended for use as a flushing pump, it is assumed that a piston pump with three modules arranged next to one another in each case occupies essentially the same footprint as a three-pulse piston pump. Pump of conventional design, a piston pump with linear motors readily in another level, so quasi in the vertical direction can be supplemented by additional modules. The footprint requirement does not increase thereby. The pulsation of a mass flow generated by the piston pump decreases proportionally with the number of modules.

By virtue of the piston pump having a control unit for coordinating the linear motors for pulsation control, in a simplest embodiment at least one synchronization of the linear motors can be ensured, so that under otherwise ideal conditions, ie without external interferences, the pulsation of a mass flow output by the piston pump is minimized. This contributes to the protection of the material and thus reduces costs and labor. In addition, suitability of the piston pump for use with pulsation sensitive methods such as MWD is improved.

The multi-pulse piston pump is designed in particular as 2n-pulsed, for example six-, twelve- or 24-pulse, where "n" denotes a number of modules, each with a linear motor and "2n" results from the fact that each module has two pistons and Cylinder comprises, so that there are two mass flow pulses by staggered suction and ejection of the medium for a movement cycle of the linear motor.

Advantageous embodiments of the invention are the subject of the dependent claims. The relationships used here point to the further development of the subject matter of the main claim by the features of the respective subclaim; they should not be construed as a waiver of obtaining independent, objective protection for the feature combinations of the dependent claims. Furthermore, with regard to an interpretation of the claims, a closer specification of a feature in a subordinate to assume that such a restriction in the respective preceding claims is not present.

It is preferably provided that, for pulsation control by means of the coordination of the linear motors, a phase relationship related to a relative position of the movable part of the linear motors, that is to say of the so-called rotor, is influenced. The relative position of the movable part of the linear motors is referred to here and below as the relative position of the linear motors whose installation position is of course not changed by a control. The advantage of this embodiment of the invention can be explained comparatively simply on the basis of a trivial situation which, however, is highly relevant in practice for a particular case. If a piston pump of the type underlying the approach according to the invention has four two-pulse modules, a minimum displacement of the movements of the individual linear motors of 45 ° is required for a minimum pulsation. This results in a remaining pulsation of the order of less than 3% (explained below). If one of the modules fails, the result is a total mass flow output by the piston pump, now operated with only three two-pulse modules, with a pulsation of more than 26%. This can result in material stresses that require immediate shutdown of the piston pump. When used as a scavenge pump in deep drilling operation, the shutdown of the purge pump usually requires the setting of the drilling operation. By adjusting the phase position, however, the pulsation can be reduced to less than 5% even with only three modules. The required phase position is 60 ° for a minimum pulsation. The mass flow previously contributed by the failed module can even be compensated by increasing the speed of the oscillating motion of the linear motors in the remaining modules. Overall, therefore, both the piston pump remain in operation as well as the deep drilling continued. The defective module, which is coupled with its outlet line via locking elements, such as valves or the like, to a rinsing liquid line, can be serviced separately and optionally repaired after actuation of the locking elements. As soon as the module starts up again, it is possible to return to the original phase position and, if necessary, to reduce the speed of the linear motors which continue to be operated during maintenance.

For such a possibility of operation of the piston pump is the

Control unit for the coordination of the linear motors fed to the plurality of linear motors parked number of position signals, which encode each information in operation with respect to the position of the respective linear motor. Such position signals can be recorded on the respective linear motor by position sensors or the like, or by determining a position of the part of the linear motor acting as a rotor relative to its engine bed functioning as a stator. Another possibility is to use a drive signal for positioning the linear motor. Then a sensorless position determination is possible. For the determination of an intended phase position, the control unit is informed by each module of a signal indicating its operational readiness. On the basis of the number of such signals, the control unit can determine the at least initially required phase position. For example, with four each two-pulse modules, a multiplication of four and two results in a parameter which, with respect to a complete cycle of motion of 360 °, results in a phase angle of 45 ° (36078) between every two modules. Such an operating signal can also be derived directly from the position signal, for example in such a way that only meaningful or only continuously changing position information is evaluated as operational readiness. Apart from the fact that problems can arise during a movement of a linear motor, a mass flow generated by a module by means of the possibly undisturbed movement of the linear motor encompassed therefrom can vary and thus lead to undesired pulsations. In this regard, it is provided that a movement of the at least one associated piston associated with a movement of a linear motor causes a measurable pressure or mass flow in a line downstream of the cylinder in the conveying direction of the medium and a phase position of the mass flows is influenced by means of the coordination of the linear motors , The advantage of this embodiment of the invention can also be explained on the basis of the scenario already used. This time it is assumed that all the modules, as far as the operation of the linear motors, etc. are concerned, are running properly, yet no or very little mass flow is produced by one of the modules. In that regard, the scenario again corresponds to a situation with a failed module. That the mass flow expected by such a module can be compensated by adjusting the phase position has already been explained. The same applies if the actual lower mass flow corresponds to only part of the expected mass flow. Such a situation can only be detected if the mass flow delivered by each module or a pressure correlated therewith is detected and fed to the control unit for processing. On the basis of the measured values, the control unit then coordinates the linear motors in order to influence the phase position of the mass flows and thus overall for pulsation control.

According to a preferred embodiment, it is provided that an additional control of a total mass flow to be delivered by the piston pump is less than or less than the coordination of the linear motors. is gert. For this purpose, a desired value which encodes the desired total mass flow is preset in a manner known per se, which is compared by the control with a moment value of the total mass flow, which is obtainable, for example, by summing all the measured values of the mass flows produced by each individual module. For any corrections, it is advisable to influence the speed of movement of the linear motors, a pump pre-pressure, etc.

A residual pulsation, that is to say a pulsation of mass flow and / or pressure remaining after the coordination, is preferably 10% or less, in particular substantially 0.8% to 3%. This is particularly gentle on the material and thus results in a cost reduction. In addition, this is a particular suitability for the MWD process given, as reduce interference severely.

The linear motor can have a power in a range of 100 kW to 5,000 kW, in particular more than 200 kW. Particularly preferably, the linear motor has a power between 440 kW to 3,000 kW. With two or more linear motors, these preferably all have the same power. However, according to the approach according to the invention, a coordination of linear motors of which at least one has a different performance possible. For example, for the or each motor with the differing power, pulsation control may require operation at an increased or decreased speed. For example, in a piston pump with three modules in which the linear motors included are all operated at the same speed, a remaining pulsation can be reduced by adding a module with a linear motor running at three times the speed of the three modules a suitable shift to phase position of the li near motors, so that the (low) pulses of the faster-running module result exactly when the mass flow generated by the three modules assumes a local minimum.

Preferably, the or each linear motor is assigned to its cooling, a heat exchanger. The heat exchanger is provided for heat transfer between the linear motor and the pumped by the piston pump medium, in particular the rinsing liquid. This ensures a simple and convenient cooling of the linear motor. For example, the heat exchanger may be located on, under, beside or around the linear motor and in contact therewith to ensure efficient heat transfer.

For a production of the described multi-pulse piston pump is provided that the at least two linear motors are each coupled to at least one piston and a control and / or regulating device for coordinating the at least two linear motors with at least one sensor and the linear motors data technology is connected.

An embodiment of the invention will be explained in more detail with reference to the drawings. Corresponding objects or elements are provided in all figures with the same reference numerals.

The or each embodiment is not to be understood as limiting the invention. Rather, numerous modifications and variations are possible in the context of the present disclosure, in particular those variants, elements and combinations described, for example, by combination or modification of individual in conjunction with those described in the general or specific description part and in the features and elements or method steps contained in the claims and / or the drawing for the expert in terms of solving the problem can be removed.

Show it

1 shows a multi-pulse piston pump, the multi-pulse due to at least two modules, each with a linear motor,

2 a control signal as it comes to control the linear motors into consideration,

3 shows a graph of a mass flow profile generated by a two-pulse module,

4 shows a coordination of a plurality of modules and the linear motors included therein a plurality of drive signals with a regular phase position for controlling a pulsation of a piston pump generated in operation Gesamtmassenstromverlaufs and the resulting mass flow curves and the resulting total mass flow curve with minimal extent pulsation,

FIG 5 shows irregularities generated by several modules

Mass flow curves and a resulting total mass flow curve with increased pulsation,

FIG. 6 shows mass flow characteristics and the resulting total mass flow profile, as determined after coordination of the linear engines to compensate for the underlying in Figure 5 irregularities and

7 shows a functional unit as a means for coordinating the linear motors and insofar as means for carrying out the method according to the invention and its embodiments.

FIG. 1 schematically shows in simplified form a piston pump, generally designated 10, which is e.g. for flushing boreholes 12 may be provided and is then referred to as a flushing pump. The piston pump 10 is constructed from modular single units and each module 14, 16, 18 includes a linear motor 20 which is provided for moving at least one guided in a cylinder 22 piston 24. An internal volume of the cylinder 22 is in a manner known per se for a liquid medium, e.g. the rinsing liquid, accessible and with appropriate movement of the piston 24, the medium is ejected as a mass flow 26 through an outlet line 28. The linear motor 20 performs for this purpose on a motor bed 30 an oscillating movement. In FIG. 2, a drive signal 32 is shown schematically in simplified form.

In a minimal configuration, the piston pump 10 comprises exactly one module 14. With regard to a pulsation control aimed at with the approach according to the invention and a coordination of individual linear motors 20 required for this, a piston pump 10 according to the invention comprises at least two modules 14, 16, eg two, three, four or more modules 14-18. Each module 14-18 comprises a linear motor 20 and at least one guided in a cylinder piston 24. In a preferred embodiment, as shown provided that each module 14-18 two cylinders 22, each having a piston 24 and two outlet lines 28 are assigned. In operation, the oscillating Movement of the linear motor 20 that one of the piston 24 is moved into the respective cylinder, while results in the opposite piston 24, a reverse direction of movement. While medium 22 contained therein is ejected under pressure by means of that cylinder 22, medium is first sucked into this cylinder 22 in order then to be ejected in the next movement section. For a full cycle of movement of a linear motor 20, this results in a pressure generated by this in both cylinders 22 or a mass flow 26 which can be forwarded via the or each outlet line 28, the amplitude of which approximately follows the graph 34 shown in FIG. After pressure and mass flow coincide here at least substantially, at least condition each other, reference will briefly be made below to the generated mass flow 26 in the following. With more than one module 14-18 and / or more than one cylinder / piston 22, 24, a total mass flow 36 results from the individual mass flows 26.

In FIG. 1, pumps 38 for generating a pre-pressure (when using the piston pump 10 as a rinsing pump for generating a rinsing pressure) are shown. The pressurized medium with the form of the piston pump 10, namely the individual cylinders 22, respectively. The illustrated number of pumps 38 corresponds to the illustrated number of modules 14-18. It can also be provided for more than one module 14-18 only one pump 38. Furthermore, an optional heat exchanger 40 is shown, which may be included for cooling in each case a linear motor 20 of each one module 14-18. In operation, the heat exchanger 40 is flowed through by either a cooling liquid or a part of the pumped by the piston pump 10 medium.

Since the linear motor 20 "pumps" during a forward movement (first half of the period of the drive signal 32), namely via a The two cylinders 22, as well as during a backward movement (second half of the period of the drive signal 32), namely via the cylinder 22 opposite the initially active cylinder 22, result in two pressure or mass flow maxima during a full cycle of movement. The graph 34 can accordingly be regarded as characteristic for the operation of a respective module 14-18 and will be referred to below as an output signal or profile of the mass flow 26 (in short: mass flow profile 34). It is easy to imagine that such pressure and mass flow differences are perceived as PuI- sation.

The control of the at least two linear motors 20 takes place by means of a control unit 42. In uncoordinated operation, each linear motor 20 is driven separately and is supplied with a control signal 32 from the control unit 42. In this case, the control unit 42 ensures a phase shift of the respective drive signals 32 in accordance with the multiplicity of the modules 14-18, that is to say in accordance with the multiplicity of linear motors 20 encompassed by the piston pump 10. This should ensure a uniform distribution of the mass produced by the individual cylinders 22. currents 26 can be achieved. Even if the control unit 42 is shown as a single element in the figure, it can be a distributed control unit, namely a central control unit and in each case a local control unit associated with each linear motor 20. The central control unit outputs the respective drive signal 32 to each local control unit. Each local control unit assumes a position control, so that regardless of load and other external influences, a match of the respective position of the linear motor 20 with the respective instantaneous value of the drive signal 32 is ensured. With the output of the at least two control signals 32 to at least two linear motors 20, possibly their local control unit, the control unit 42 (or the central control unit) with the specification of the phase differences with regard to the movement cycles of the linear motors 20 encompassed by the piston pump already have a coordination for pulsation control.

In the illustrations in FIG. 4, a plurality of activation signals 32 (here four activation signals 32 for correspondingly four modules 14-18 and the linear motors 20 included therein) are provided for each of the module 14-18 controlled mass flow paths 34 and finally a graph of a curve of the resulting total mass flow 36, hereinafter referred to as total mass flow curve 44, shown. The total mass flow curve 44 results as the sum of the individual mass flow curves 34, which is easily explained by the fact that the mass flows 26 emitted by each individual module 14-18 enter a common line downstream of the individual outlet lines 28 and from there, e.g. the borehole 12 are fed to the flushing. It can readily be seen by comparison of the lower illustration in FIG. 4 and the illustration in FIG. 2 that a reduction of the pulsation can be achieved by using a plurality of modules 14-18 in addition to an increase in the total mass flow 36 by suitable coordination of the linear motors 20. This will be clarified below by numerical values.

The coordination described so far is essentially a control of the individual linear motors 20, even if possibly local control units perform a position control with respect to an exact match of the actual position of the respective linear motor 20 with the predetermined by the drive signal 32 target position. The advantage of a piston pump 10 with respect to their sequence of motion coordinated linear motors 20 is basically the size and the achievable weight reduction, by eliminating eg gear and like. The control basically simulates the previous drive of a plurality of pistons via a common drive axle and achieves a significant reduction of the pulsation with a corresponding plurality of modules 14-18. However, the method of operation of the piston pump 10 can still be improved to the extent that external influences are not taken into account. This can be achieved, for example, by recording a measured value with respect to the mass flow 26 emitted by each module 14-18 on an output side of each module 14-18, that is to say in the region of the outlet line 28 with a sensor, not shown. The sensor can be a pressure or a flow sensor. A sensor system is not shown, shown are only input signals 46 for the control unit 42, the latter of such sensors, such as a flow sensor or a example, the motor bed 30 associated position sensor when the position of the linear motor 20 is not an instantaneous value of the drive signal 32 is assumed , be forwarded.

Possibly. Variations in the delivered pressure or in the ejected mass flow 26 can be compensated according to the approach according to the invention if the recorded measured values are supplied to a control implemented, for example, in the control unit 42. An approximately on the output side of a module 14-18 briefly decreasing pressure, eg due to unexpected variations in a flushing form, can be at least partially compensated by adjusting the phase angle of the linear motors 20 in other modules 14-18. This will be explained below with reference to FIGS. 5 and 6. A coordination of the motion sequences with regard to, for example, an adjustment of the phase position is not possible in the case of previous piston pumps in which a plurality of pistons are driven by means of a common drive axis. In FIG. 5, the upper illustration based on a control by activation signals 32, as shown in the upper illustration of FIG. 4, shows a mass flow profile 34 reduced for a module 14-18 (easy to recognize at the amplitude reduced by half). For example, the reduced mass flow path 34 is based on a pump or the like provided for generating the flushing admission pressure. The resulting total mass flow curve 44 is shown for a doubled time base in the lower graph of FIG. In a comparison with the total mass flow curve 44, as it results in "undisturbed" mass flow curves 34 (FIG. 4, lower diagram), one immediately recognizes the significantly increased ripple which results in an undesirable pulsation. The terms ripple and pulsation are thus used synonymously.

By coordinating the movement sequence of the linear motors 20, such effects can be at least partially compensated. For a situation corresponding to the scenario on which the illustration in FIG. 5 is based, it is sufficient to adapt the phase position of the linear motors 20 in order to significantly reduce the ripple again. 6 shows this with further details. The upper diagram shows the mass flow curves 34 as they result from a phase correction of the control signals 32 made by the control unit 42 (the correction of the phase position undertaken to coordinate the movement sequence is so small that hardly any difference from the upper illustration in FIG 5 is noticeable). The lower diagram shows the resulting total mass flow curve 44, in which the pulsation is again significantly reduced in comparison to the "disturbed" total mass flow profile 44 according to the lower illustration in FIG. If, as the ripple or pulsation of the total mass flow path 44, a quotient of the maximum value minus the mean value on the one hand and the mean value on the other hand is determined, a waviness of 57% results for the mass flow profile 34 shown in FIG. This mass flow curve 34 would result in the total mass flow curve 44 in the case of a piston pump 10 with only one module 14-18. Even with two modules 14-18, the ripple decreases to 11.3%. With four modules 14-18, the ripple is already reduced to 2.8% (see the lower illustration in FIG. If there are irregularities in the operation of one of the modules 14-18, for example as described above, in that the mass flow profile 34 of one of the modules decreases by half, the pulsation of the resulting overall mass flow curve 44 increases significantly. For the total mass flow curve 44 shown in the lower illustration of FIG. 5, a waviness of 10.6% results. By compensation by means of the control unit 42, the pulsation can be reduced by, for example, adjusting the phase position of the individual mass flow profiles 34, thus coordinating the individual linear motors 20 with regard to a reduction of the pulsation. For the assumed scenario, for example, a correction of the phase position of the mass flow pattern 34 leading and trailing the mass flow 26 is +/- 6.5 ° in order to again achieve a ripple of 3.16% (compared to 2.8%). at equal mass flows 26). Note: If here and in the following numerical values, partially with decimal places are indicated, this refers only to theoretically achievable values without consideration of losses, dead times and the like.

In addition to the adjustment of the phase position comes as a further influencing possibility of the individual mass flow curves 34 with respect to a Pulsationskontrolle the resulting total mass flow 36 and an adjustment of the speed, ie the frequency of the oscillating ing movement of the linear motors 20, into consideration. This is not shown graphically and is mentioned here mainly for reasons of completeness.

Finally, the control unit 42 is shown in FIG 7 with further details. As already shown (FIG. 1) and explained, the control unit 42 generates control signals 32 for controlling the individual linear motors 20 included in the piston pump (FIG. 1). The control unit can determine the number of linear motors 20 and the configuration of the individual modules 14-13. 16 (single or two-pulse) to be fixed. Based on such default values, the control unit 42 can already determine the required offset of the movement sequences of the individual linear motors 20 and generate a corresponding plurality of drive signals 32 with a suitable phase position. For this purpose, the control unit 42 has a processing unit in the manner of a microprocessor 48 or the like, which generates or determines the drive signals 32 and their phase position according to an algorithm implemented in preferably in software or firmware. The algorithm forms part of a control program 52 stored in a memory 50 of the control unit 42 and is thus included in a first functional unit 54 of the control program 52. The first functional unit 54 determines based on predetermined data for the configuration of the modules 14-18, for example, whether it is one- or two-pulse modules 14-18, and based on the number of modules 14-16 the most favorable for Pulsationskontrolle phase position of Ansteuersig- signals 32. The number of modules 14-16, that is, the number of linear motors 20, can also be based on predetermined values. If the control unit 42 determines the number of linear motors 20 on the basis of the input signals 46 (for example, if an input signal 46 is present or if the input signal 46 coding a position of the linear motor 20 changes), the need for a corresponding specification and in the case of In the event of a failure of a module 14-18, the phase angle of the drive signals 32 for the remaining modules 14-18 can be corrected immediately. If the linear motors 20 comprised by the modules 14-18 have different powers or the cylinders 22 have different volumes, this results in an expected mass flow 26 correlated with the power and the cylinder volume. Such influencing factors predetermined by configuration data or recognizable on the basis of input signals 46 can be the first Function unit 54 also in the generation of the drive signals 32 and in the determination of their phase Läge draw. For example, in three modules 14-18 with the same power and cylinder volume and a module 14-18 with reduced power and / or cylinder volume to control signals 32 with regularly distributed phase position for the first three modules 14-18 and a drive signals 32 for the fourth Module 14-18, which allows the linear motor 20 of this module 14-18 with corresponding phase offset to run three times as fast as the linear motor 20 of the other modules 14-18. The mass flow pulses generated by this module 14-18 are then exactly at local minima of the mass flow curve as it results for the first three modules 14-18. Overall, this achieves a reduction of the pulsation. The first functional unit 54 takes into account such and other constellations for the coordination of the linear motors 20 with regard to the lowest possible pulsation.

If, during operation of the piston pump 10, individual operating parameters change, for example as described in connection with FIG. 5 and FIG. 6 for a module 14-18, the mass flow 26 returns, a second functional unit 56 of the control program 52 assumes a coordination of the piston pump Modules 14-18, that is to say the linear motors 20 included in it. The decrease, which is used as an example for explanation, of one of Dule 14-18 generated mass flow 26 can be seen on the basis of the control unit 42 as state of the piston pump 10 supplied input signals 46. The coordination of the modules 14-18 thus takes place on the basis of output variables of the modules 14-18, so that this justifies the designation of the second functional unit 56. A possible

Control algorithm as it may be encompassed by the second functional unit 56 can be described in a highly simplified manner as follows: The phase position of a minimum is determined in a total mass flow profile (see lower illustration in FIG. for the total mass flow rate whose pulsation is determined; the control signals 32, which are closest to the minimum in terms of their phase position, are shifted in their phase position in predefined or specifiable steps toward the minimum; a branch is made to the step for determining the pulsation; if the pulsation decreases as a result of the shifting of the phase position, the displacement in the previous direction or with a reduced step size in the opposite direction is continued until a minimum pulsation has been reached. The coordination just described is based on an approach that can be called heuristic search. With a complete description of the system formed by the respective piston pump 10 and

Application of control theory approaches, an analytical coordination of the linear motors 20 is possible. To this extent, the second functional unit 56 is also provided for carrying out more complex adaptations than described here and then comprises specific algorithms for this purpose.

Finally, the control unit comprises a third functional unit 58 with which one of the control systems or control systems implemented by the first and / or second functional unit 54, 56 is realized with respect to the pressure or total mass flow 36 to be delivered by the piston pump 10. Such a scheme is processed a predetermined or predefinable pressure or mass flow setpoint and, for example, as the mass flow actual value, a sum of the input signals 46 which code the individual mass flows 26. A P, PI, PID control or the like can be considered as the control structure.

With suitable control of the pulsation, even external pulse generators can be dispensed with in the MWD, since controlled test pulses for the MWD can be generated by means of the method described and further explained below. As a result, not only is the MWD advantageously simplified, but there are also costs, eg. B. for the external pulser, reduced.

The functional units 54, 56, 58 are cyclically called in the control program 52 at predetermined times, so that a quasi-parallel processing takes place and is promptly, ie in real time or virtually in real time, governed by any changes in the operation of the piston pump 10. The or individual functional units 54, 56, 58, as well as the control program 52 comprising them, are examples of means for implementing the method according to the invention and its embodiments. Other means are not shown in the drawings

Sensors or actuators, e.g. the respective drive signal 32 processing, a linear motor 20 upstream drives.

Thus, the invention can be represented as follows: A method is described for operating a multi-pulse piston pump 10, in particular a flushing pump for use in flushing deep wells 12, with at least two pistons 24 guided in each case in a cylinder 22 and a drive acting on the pistons 24 Promotion of a liquid medium, as well as an operable or operating according to the method piston pump 10 indicated in which or at least two linear motors 20 as Actuate drive and each linear motor 20 acts on at least one piston 24 and the linear motors 20 are coordinated for pulsation control by means of a control unit 42.

LIST OF REFERENCE NUMBERS

10 piston pump

12 borehole

14 module

16 module

18 module

20 linear motor

22 cylinders

24 pistons

26 mass flow

28 discharge line

30 engine bed

32 drive signal

34 Mass flow profile

36 total mass flow

38 pump

40 heat exchangers

42 control unit

44 Total mass flow

46 input signal

48 microprocessor

50 memory

52 control program

54 first functional unit

56 second functional unit

58 third functional unit

Claims

claims

1. A method for operating a multi-pulse piston pump (10), in particular rinsing pump for use in flushing deep wells (12), with at least two in each case a cylinder (22) guided piston (24) and one on the piston (24) acting drive for Promotion of a liquid medium, characterized in that at least two linear motors (20) act as a drive and each linear motor (20) acts on at least one piston (24) and that the linear motors (20) for pulsation control by means of a control unit (42) are coordinated.

2. The method of claim 1, wherein by means of the coordination of the linear motors (20) to a relative position of the linear motors (20) relative to each other related phase position for Pulsationskontrolle is affected.

3. The method of claim 2, wherein the control unit (42) for coordinating the linear motors (20) to the plurality of linear motors (20) parked number of input signals (46) is supplied, which in operation in each case an information regarding the position of the respective Code linear motor (20).

4. Method according to claim 1, wherein a movement of the at least one associated piston (24) associated with a movement of a linear motor (20) has a measurable pressure or mass flow (32) in a line (28) downstream of the cylinder (22) in the conveying direction of the medium ) and wherein by means of the coordination of the linear motors (20) a phase position of the mass flows (32) is influenced.

5. The method of claim 4, wherein the control unit (42) for coordinating the linear motors (20) one of the plurality of linear motors (20) corresponding number of Signals are supplied, which in each case encode information with respect to the respective linear motor (20) caused mass flow (32).

6. The method according to any one of the preceding claims, wherein a residual pulsation is substantially 10% or less, in particular substantially 0.8% to 3%.

7. Multi-pulse piston pump (10), in particular rinsing pump for use in flushing deep wells, with at least two in each case a cylinder (22) guided piston (24) and on the piston (24) acting drive for conveying a liquid medium, characterized by at least two linear motors (20) acting as a drive, each linear motor (20) acting on at least one piston (24) and a control unit (42) for coordinating the linear motors (20) for pulsation control.

8. A multi-pulse piston pump according to claim 7, comprising means for carrying out the method according to one of claims 1 to 6.

9. A multi-pulse piston pump according to claim 7 or 8, wherein each linear motor (20) and the or each driven piston (24) forms a module (14-16) and each module (14-16) comprises at least one signal output, of which from the control unit (42) is an input signal (46) which codes a state value, namely a state value related to the position of the respective linear motor (20) or to the pressure or mass flow (26) produced by the linear motor (20).

10. Multi-pulse piston pump according to claim 9, wherein a desired phase position can be determined on the basis of the number of state values transmitted during operation.

11. Multi-pulse piston pump according to one of claims 7 to 10, with a at least one cylinder (22) coupled to the heat exchanger (40).

12. Multi-pulse piston pump according to one of claims 7 to 11, with a coordination of the linear motors (20) under or superimposed control of a dispensed pressure and / or total mass flow (36).

13. A method for producing a multi-pulse piston pump (10) according to one of claims 7 to 12, wherein at least two linear motors (20) are each coupled to at least one piston (24) and a control unit (42) for coordinating the at least two linear motors (20 ) is data-technically connected to the linear motors (20).