EP1644590A1

EP1644590A1 - Well, and method for regenerating a well

Info

Publication number: EP1644590A1
Application number: EP03817507A
Authority: EP
Inventors: Magdalena Rotthäuser
Original assignee: Exploration Drilling International GmbH
Current assignee: EDI EXPLORATION DRILLING INTERNATIONAL GMBH
Priority date: 2003-07-16
Filing date: 2003-07-16
Publication date: 2006-04-12
Also published as: US20060157237A1; AU2003257469A1; WO2005007980A1; DE10394249D2

Abstract

The invention relates to a well (1) for obtaining, monitoring, and/or lowering groundwater, comprising a stand pipe (2) that is provided with at least one filtering tube area (3), and at least one pump (6) located in the stand pipe (3). In order to create a well that can be regenerated in a simple and inexpensive manner, a device (9) for spraying the filtering tube area (3) and/or the well region located next to the filtering tube area (3) is associated with the filtering tube area (3) while the spraying device (9) is connected to at least one pressure pipe (10) so as to supply the spraying device (10) with a medium that is to be sprayed.

Description

Well and process for regenerating a well

The invention relates to a well for the extraction, observation and / or lowering of groundwater, with a standpipe having at least one filter pipe area, and with at least one pump arranged in the standpipe. Furthermore, the present invention relates to a method for regenerating a well provided for the extraction, observation and / or lowering of ground water.

Wells of the type mentioned at the outset have long been known in practice. To produce a well-known well, a borehole is first sunk into the area of the water-bearing layer. Then the standpipe is inserted together with the lower filter tube or filter tube area. Filter gravel is then introduced into the annular space between the filter tube area and the surrounding mountains. The height of the filter gravel layer depends on the length of the filter tube area or the thickness of the water-bearing layer. The annular space between the standpipe and the surrounding mountains is then filled with a hydraulic binder, which is usually a water-cement mixture. This hydraulic binder should essentially ensure that there is a firm and stable position of the standpipe in the borehole and an attachment of the standpipe to the mountains. Finally, an underwater pump for pumping off the groundwater is installed in the standpipe. The top of the well is usually a well head, through which the pumped groundwater is used for its further use.

The known wells described at the outset have various disadvantages. A major disadvantage of the well-known wells is that they often only have a comparatively short lifespan. This results from the fact that a filter cake forms on the filter tube area after some operating time. At the same time, the fine pores and capillaries in the filter gravel are clogged by particles in the groundwater. This leads to a decrease in the amount of water obtained per unit of time with constant pumping power. To clean or regenerate the filter tube area and the filter gravel surrounding it, attempts are sometimes made to backwash. This is not only expensive in terms of equipment. Backwashing also leads to particles loosening from the filter cake, pressed into the mountains and thus hindering the inflow of water during subsequent pumping.

If a well can no longer be adequately regenerated even with backwashing, a new well has to be made, because pulling the old standpipe is not possible due to the firm connection with the surrounding mountains. At most, the previously used underwater pump can be used again for the new well.

Another disadvantage of the known wells is that, particularly in wells in areas in which agricultural use also takes place, excessive nitrate values occur in the required groundwater. In addition, other contaminants, such as salt water, can affect the groundwater. This results from the fact that when the groundwater is pumped out of the water-bearing layer in question, so-called extraneous water, ie water from other layers, is also pumped out.

The object of the present invention is therefore to provide a well of the type mentioned at the outset and a method for regenerating a well, the regeneration of the well being intended to be simple and inexpensive to carry out.

The previously derived object is achieved according to the invention in a well of the type mentioned at the outset in that a spraying device for spraying the filter tube area and / or the well area adjacent to the filter tube area is assigned to the filter tube area and in that the spraying device has at least one pressure line for Supply of the spraying device is connected to a medium to be sprayed. The invention offers a number of advantages, some of which are significant. First of all, the invention makes it possible to increase the life of a well considerably. By means of the spraying device it is possible to loosen a filter cake located on the filter tube area and to loosen up the gravel layer surrounding the filter tube area as an adjacent well area to such an extent that particles which clog pores and capillaries in the filter gravel layer are discharged. It is crucial that it is possible via the spray device, to supply the medium in a very targeted manner only to the areas to be regenerated, so that the indentation of particles into the water-bearing layer can be at least substantially avoided. Since the spraying device is completely independent of the pump of the well, the spraying and thus regeneration of the well can also take place during pumping. Particles that become detached and other contaminations due to the spraying are prompted via the pump without clogging the surrounding mountains. In addition, it is possible with the invention to supply a wide variety of media to the spraying device through the pressure line, which ends above ground. The supplied medium can serve both for regeneration, that is to say for cleaning the filter tube area and the filter bed, and also for water treatment if gases such as ozone and / or liquid water treatment agents, in some cases also with solid matter such as water with charcoal dust the pressure line of the spraying device are supplied.

In order to be able to regenerate the filter tube area and the filter gravel layer adjacent to it as far as possible over the entire circumference, the spraying device has at least one ring channel attached to the filter tube area. This ring channel is distributed over its length with a large number of nozzles through which the medium is fed. The distance between the individual nozzles is preferably chosen such that sufficient removal of the filter cake on the filter tube area and sufficient loosening of the filter gravel layer are readily possible. It is also the case that, in the case of a comparatively long filter tube area, two or more ring channels can also be provided, which are then sufficiently far apart in the axial direction to ensure adequate regeneration of the entire lower well area.

Moreover, it goes without saying that, instead of an annular spraying means, it is of course also possible to provide a plurality of individual spraying points which are arranged distributed over the circumference of the filter tube area.

Good regeneration values, ie detachment of the filter cake at the filter tube area and loosening of the adjacent filter gravel layer, are preferably achieved by a part of the nozzles being parallel to the tube axis, preferably immediately adjacent to the wall of the filter tube area or in a point Angles are aligned. Horizontal alignment of the nozzles is also possible. However, this can lead to particles being pressed into the neighboring mountains, which can affect the groundwater supply.

In one embodiment of the invention it is provided that the nozzles are adjustable. An adjustment can be achieved, for example, by pivoting the nozzle out of a basic position when the spraying device is pressurized as a function of the pressure. In principle, it is also possible for the nozzles to rotate about an axis lying on the ring circumferential axis of the ring channel when pressure is applied.

The nozzles can basically be designed as simple openings in the ring channel. However, in order to avoid clogging of the individual nozzles by particles and thus a loosening or sintering, the nozzles at least partially each have a valve, in particular a spring-loaded check valve. As a result, the individual nozzles are closed in the non-pressurized state. The check valves only open at a predetermined minimum pressure which results when the spraying device is pressurized, in order to close again immediately after the pressurization has ended. Ultimately, this ensures permanent and trouble-free operation of the spraying device.

It has already been pointed out beforehand that the spraying device can have one or more ring channels depending on the length of the filter tube area. If only one ring channel is required, it is advisable for the spraying device to have a base plate which is connected to the ring channel and which closes off the filter tube region at the bottom. The spraying device or the annular channel thus forms the lower end of the pipe string. In this embodiment, the nozzles of the ring channel should not be directed downwards in order to prevent the floor from being rinsed out at this point.

In order to be able to ensure trouble-free continuous operation of the spraying device according to the invention, both the ring channel and the pressure line supplying the medium z should be made of plastic or stainless steel and should preferably be attached to the outside of the standpipe. The external fastening ultimately ensures that when the pump is pulled there can be no contact between the pump and the pressure line, which could damage both the pump and the pressure line.

It has already been mentioned at the beginning that wells usually end at a well head located above ground, which is also provided in the well according to the invention. According to the invention it is now provided that an outlet is provided on the well head with which the pump line of the pump communicates. This outlet has a valve designed in such a way that the water pumped by the pump is not discharged via the usual water discharge line, but exclusively via the outlet. A motor drive should be assigned to the outlet, via which the outlet is automatically opened after or during a spraying operation and the drained water is drained off without the need to dismantle the well head, remove the pump or take any other measures.

In addition, the fountain according to the invention is assigned a feed device for feeding the liquid and / or gaseous medium to the spraying device. This feed device is connected to the pressure line at its surface end. The supply device is preferably designed such that the medium is supplied to the spraying device either under constant pressure or via pressure surges. In order not to impair the regeneration or water treatment result in this connection due to excessively high pressures or excessive pressure surges, the feed device has a pressure limiter so that certain maximum pressures cannot be exceeded. In addition, it is particularly useful for automatic operation of the spraying device that the feed device has a timer. As a result, spraying can take place over a precisely specified period of time without the need to monitor an operator. In this context, it is also favorable that the feed device is coupled to the outlet or its control in such a way that, depending on the spraying, water is automatically removed from the outlet for a predetermined time interval.

At the beginning it was pointed out that it is not possible with the known wells to adequately close the filter tube area or the filter layer regenerate. To solve this problem, it is provided in an alternative embodiment that the standpipe is arranged in an outer standpipe, that the outer standpipe is firmly connected to the surrounding mountains and that the standpipe is designed to be pullable from the outer standpipe. The result is a double-headed design of the well with an inner and an outer standpipe. While the outer standpipe is firmly connected to the Geb ge in a manner known per se, the inner standpipe, on which the lower filter pipe area is located, can easily be pulled for surface regeneration, which is not possible with conventional wells. In the embodiment according to the invention, the lower filter tube area can be cleaned for days after pulling the inner standpipe. The collapsed filter gravel is rinsed out of the borehole itself, which is kept open further via the outer standpipe. Then the inner standpipe with the cleaned or a new filter pipe area can be reinserted into the outer standpipe. The required amount of filter gravel is then introduced into the annular space between the outer and the inner standpipe. The fountain can then continue to be operated. In this context, it is particularly advantageous that the regeneration described above can easily be carried out by the user of the well himself, so that a corresponding specialist company for carrying out the regeneration is not absolutely necessary.

Moreover, it goes without saying that the spraying device described at the outset offers particular advantages, particularly in connection with the double-tube design of the fountain, since the possible drawing of the inner tube only has to be carried out very rarely. In this context, the spraying device is then fastened to the inner pipe string, namely to the filter pipe area, in the manner described above.

So that there is no impairment of the pumping through the outer standpipe, the filter pipe area of the inner standpipe string projects beyond the lower end of the outer standpipe. As a result, in the case of the double-pipe version of the well, the outer standpipe extends to the respective water-bearing layer and thus stabilizes the borehole from above to the water-bearing layer. Demge- opposite the inner pipe string with the filter pipe area protrudes into the water-bearing layer, so that the promotion can take place.

In order to facilitate both the insertion and the pulling of the inner tube into or out of the outer tube and to ensure a defined constant annular space between the inner and the outer standpipe, the necessary filter gravel in the area of the filter tube area via this annular space spacers are provided. These can be attached to the inner and / or the outer standpipe.

In connection with the spraying device described in the introduction, the pressure line should preferably be received between two spacers which have a greater extent in the radial direction than the pressure line, so that in this case the spacers have an additional protective function for the pressure line. It is understood that a plurality of corresponding spacers are provided in the axial direction over the pipe string.

At the outset, it was pointed out that a further disadvantage of the prior art is that in the known wells it often happens that the pumped water has contaminations, for example in the form of nitrates and / or salt water.

To obtain uncontaminated groundwater, the invention provides that the outer standpipe is sealed from the surrounding mountains by a hydraulic mineral binder in such a way that groundwater is obtained only from the water-bearing layer in which the filter tube area is located, and a water inflow avoided from other layers w d. The invention differs from the prior art in that the hydraulic binders used in the prior art are used only for fastening the outer standpipe in the borehole. However, in known wells there is no adequate sealing between the rock and the outer standpipe, which leads to an inflow of contaminated foreign water through the insufficiently sealed annular space between the outer standpipe and the adjacent rock when the pump is operated. Characterized in that in the invention a seal between the outer standpipe and the mountains are restored, the original state of the mountains is restored. The water-bearing layer from which the water is obtained is sealed off from other horizons in the area of the ingraum. A lowering funnel extending into other layers around the well, as is customary in the prior art, is avoided in the invention. The fresh water obtained retains its original quality.

In addition, the present invention can be used not only for the extraction of groundwater from a water horizon, but also in several water horizons. In this case, the outer standpipe or the standpipe string is divided and releases the respective water-bearing layers. Filter tube areas are provided in the water-bearing layers, through which groundwater is obtained. Otherwise, the outer standpipe string is sealed in the manner described above.

In connection with the present invention, it is particularly favorable if the binder has a highly and permanently plastic behavior in the set state, that is to say is extremely viscous. This ensures that there is no destruction of the well or of the binder layer, particularly in areas where earth movements occur, which in turn can lead to an inflow of contaminated foreign water.

A water / solid mixture based on marl has proven to be the most sealing binder, which also shows a highly and permanently plastic behavior. The flowability in the not yet set state, but also the plastic behavior in the set state, is improved above all by adding a proportion of up to 30%, preferably around 20%, bentonite to the marl. It goes without saying that each individual value is possible in the specified interval from 0% to 30%.

Exemplary embodiments of the invention are described below with reference to the drawing. It shows

1 is a schematic cross-sectional view of a fountain according to the invention, Fig. 2 is an enlarged view of the lower well area and

3 shows a view corresponding to FIG. 1 of a further embodiment, in which groundwater is obtained from two water horizons.

In the individual figures, a well 1 is shown, which in the present case is used for the extraction of groundwater. Basically, wells of the type shown can also be used for observing or lowering groundwater. In the embodiment shown in FIG. 1, the fountain 1 has a standpipe 2, which is referred to below as the inner standpipe. A filter tube area 3 connects to the inner standpipe 2 and is used to extract the groundwater. The filter tube area 3 has perforations, the opening width of which is smaller than the filter gravel of the filter gravel jacket 5, which is arranged around the filter tube area 3. Inside the inner standpipe 2 there is a pump 6, the pump line 7 of which leads to a well head 8.

The inner standpipe 2 in the present case is a pipe string made up of a plurality of individual pipe pieces which are attached to one another. The FilteπOhrbereich 3 is a separate piece of pipe that is connected to the pipe string. It goes without saying that it is also possible in the case of short standpipes that the pipe string consists of only one piece, and the filter pipe area 3 can also be formed in one piece with the standpipe. In the following, only the term "standpipe" is used, regardless of whether this standpipe has one or more pipe sections.

In the illustrated embodiments, it is now the case that a spraying device 9 is assigned to the filter tube area 3, via which the filter tube area 3 and / or the filter gravel jacket 5 can be sprayed in order to regenerate this area. The spray device 9 is connected to a pressure line 10 for supplying the spray device 9 with a medium to be sprayed. As can be seen in particular from FIG. 2, the spraying device 9 in the embodiment shown has an annular channel 11 fastened to the filter tube area 3 and having a plurality of nozzles 12. In the case of filter tube regions 3 which have a greater length than shown in FIG. 1, can also be provided a plurality of ring channels which are connected to the pressure line 10. In the exemplary embodiment shown, the nozzles 11 are aligned parallel to the tube axis adjacent to the wall of the filter tube region 3. The nozzle jet emerging from the nozzle 12, which widens towards the outside, thus acts on the wall of the filter tube region 3 and also loosens the filter gravel of the filter gravel jacket 5, which leads to regeneration. In the present case, the nozzles 12 each have a spring-loaded check valve 13, which is only indicated schematically. This prevents filter gravel or other particles from penetrating and clogging of the nozzle 11.

If only one ring channel 11 is used, the spraying device has a base plate 13 which is placed on the end of the filter tube region 3. The spraying device 9 thus forms the lower end of the inner standpipe strand. When using several ring channels, it is understood that the lower base plate 13 is omitted. The spraying device 9 itself, like the pressure line 10, is made of stainless steel in order to ensure permanent operation. The pressure line 10 is attached to the outside of the inner standpipe 2, which is not shown in detail.

1 and 3 that the pump line 7 of the pump 6 communicates with an outlet 14 on the well head 8. The outlet 14 is a discharge line through which the groundwater can be discharged. If there is no drainage of the groundwater via the outlet, which is the rule, the groundwater is fed via the groundwater line 15 to its further use. In the exemplary embodiment shown, the pump line 7, the outlet 14 and the groundwater line 15 are connected to one another via a three-way valve 16. Via the three-way valve 16, the groundwater obtained can be drained off before, during or after a spraying operation, without having to dismantle the well head 8, expand the pump 6 or interrupt the groundwater line 15.

As can also be seen from FIGS. 1 and 3, the pressure line 10 is provided with a supply device 17 arranged above ground for supplying the medium to the spraying device 9. Gases or liquids, which can also contain solids, can be supplied as the medium. Depending on the application, ozone can be used to kill microorganisms or others Water treatment agents for influencing the water quality are supplied via the feed device 17. The spraying device 9 can thus perform a double function, namely on the one hand to clean or regenerate the filter tube area 3 and the filter gravel jacket 5 and on the other hand to influence the drinking water quality.

The feed device 17 itself can be designed to feed the medium under constant pressure. It is also possible to generate pressure surges via the feed device 17 at regular or irregular intervals. For this purpose, the feed device 17 has a corresponding pump 18. Furthermore, a pressure limiter 19 is provided in order to avoid unintended overpressures. Furthermore, the feed device 17 has a timer 20 in order to carry out the spraying and thus the regeneration only over a predetermined period, which enables automatic operation. In this connection, it is also provided that both the feed device 17 and the outlet 14 or the three-way valve 16 are coupled to a controller 21, so that, depending on the spraying, groundwater is automatically discharged from the outlet 14 for a predetermined time interval results.

In connection with the automatic operation, the valve 16 in the present case has a motor drive (not shown). This makes it possible to open the valve 16 for a predetermined time interval for the discharge of extracted groundwater via the outlet 14, specifically at the start of the spraying or at a predetermined time after the spraying has started. The duration of the time interval for draining the water through the outlet 14 depends on empirical values. Alternatively, it can be provided that the controller 21 is assigned a corresponding monitoring sensor, via which the water quality is monitored. As soon as the water quality is sufficient, the valve 16 switches over again and the water is returned to its further use via the groundwater line 15.

Otherwise, it goes without saying that the valve 16 can be a manually operated valve. In this case, the controller 21 is then not required. In the illustrated embodiments, it is otherwise the case that the inner standpipe 2 is arranged in an outer standpipe 22. The outer standpipe

22 can be designed in the same way as that described above with regard to the inner standpipe 2. However, no filter tube area 3 is provided there. The outer standpipe 22 is with the surrounding bracket

23 firmly connected. Otherwise, the inner standpipe 2 can be pulled out of the outer standpipe 22. For this it is only necessary to disassemble the well head 2 and pull the pump 6. The inner standpipe 2, which otherwise has no fixed connection with the outer standpipe 22, can then be pulled. The outer standpipe 22 ensures that the borehole is kept open. 1 and 3, the filter tube area 3 projects beyond the lower end of the outer standpipe 22, so that the extraction of the groundwater via the filter tube area of the inner standpipe 2 can take place unaffected by the outer standpipe 22.

To position the inner standpipe 2, spacers (not shown) are provided on the outside thereof, which ensure that the inner standpipe 2 is arranged essentially centrally in the outer standpipe 22, although this is not clearly shown in the figures. The radial extension of the spacers is larger than the outside diameter of the pressure line 10, so that an additional protective effect for the pressure line 10 results from the spacers.

Furthermore, it is the case with the illustrated embodiments that the outer standpipe 22 is sealed with the surrounding mountains 23 via a hydraulic mineral binding agent 24 in such a way that groundwater only consists of the water-bearing layers (in FIG. 1) or A and B (in FIG 3) in which the filter tube area 3 is located, while a water inflow of extraneous water from other layers is avoided. In the present case, the binder 24 is one that exhibits a highly and permanently plastic behavior after setting. In the present case, a water-solid mixture on a natural basis with a predominant proportion of fine-grained marl with a small proportion of approximately 20% fine-grained bentonite serves as the hydraulic binder. The embodiment shown in FIG. 3 differs from that shown in FIG. 1 in that the inner pipe string 3 has two filter pipe regions 3 in different horizons. Here, groundwater is extracted from water-bearing layers A, B. It goes without saying that a plurality of filter tube areas is also possible.

The regeneration of the well 1 shown in FIGS. 1 and 3 takes place in such a way that a regeneration medium, for example water, is first supplied under pressure via the feed device 17. Pressure surges are generated which act on the filter gravel casing 5 on the one hand and on the outside of the filter pipe area 3 on the other hand, so that blockages in the pores and capillaries of the filter gravel casing 5 and on the perforations 4 of the filter pipe area 3 are released. At the same time, the pump 6 remains in pump mode, so that the dissolved particles are removed. Immediately after the start of the spraying, the valve 16 is set via the control 21 in such a way that the ground water contaminated due to the regeneration of the lower well area is discharged via the outlet 14. After the end of the spraying and a subsequent predetermined time interval, the valve 16 is moved into its basic position, the outlet 14 being closed and the access to the groundwater line 15 being opened again.

1, groundwater is obtained only from horizon A, but not from other horizons.

If sufficient regeneration of the lower well area can no longer be achieved via the spraying described above, the inner standpipe 2 is pulled together with the filter tube area 3, the spraying device 9 and the pressure line 10. For this purpose, the well head 8 is first removed and the pump 6 is pulled. After pulling the inner standpipe 2, the filter gravel casing 5 collapses and can be rinsed out. After cleaning the filter tube area 3, the inner standpipe can again be introduced into the outer standpipe 22 together with the pressure line 10 of the spraying device 9. The required amount of filter gravel is then introduced through the annular space provided between the inner and the outer standpipe, which is kept open by the spacers. After insertion the pump and completion of the well by placing the well head, the well 1 can continue to be operated.

Claims

claims:

1. Well (1) for the extraction, observation and / or lowering of groundwater, with a standpipe (2) having at least one filter pipe region (3), and with at least one pump (6) arranged in the standpipe (3), characterized in that the filter tube area (3) is assigned a spray device (9) for spraying the filter tube area (3) and / or the well area adjacent to the filter tube area (3) and that the spray device (9) is provided with at least one pressure line (10) for supplying the spray device (10) is connected to a medium to be atomized.

2. Fountain according spoke 1, characterized in that the spraying device (9) has at least one on the filter tube area (3) attached annular channel (11) with a plurality of nozzles (12).

3. Well according spoke 1 or 2, characterized in that at least some of the nozzles (12) are aligned parallel to the tube axis adjacent to the wall of the filter tube area (3) or at an acute angle to the tube axis.

4. Fountain according to one of the preceding claims, characterized in that the nozzles (12) are adjustable.

5. Well according to one of the preceding claims, characterized in that at least one nozzle (12) has a valve, preferably a spring-loaded

Check valve has.

6. Fountain according to one of the preceding claims, characterized in that the spraying device (9) has a bottom plate (13) connected to the annular channel (11), which is placed on the end of the filter tube region (3) and that, preferably, the nozzles (12) of the ring channel (11) connected to the base plate (13) are not directed downwards.

7. Fountain according to one of the preceding claims, characterized in that the pressure line (10), in particular made of plastic or stainless steel, is attached to the outside of the standpipe (2).

8. Well according to one of the preceding claims, characterized in that the pump line (7) of the pump (6) communicates with an outlet on the well head (8), via which the pumped water can be discharged before, during or after a spraying, without removing the well head (8) or removing the pump (6).

9. Fountain according to one of the preceding claims, characterized in that the pressure line (10) is connected to a supply device arranged above ground (17) for supplying a liquid and / or a gaseous medium to the spraying device (9).

10. Fountain according to one of the preceding claims, characterized in that the feed device (17) is designed to feed the medium under constant pressure and / or under pressure surges.

11. Fountain according to one of the preceding claims, characterized in that the feed device (17) has a pressure limiter (19) and / or a timer (20).

12. Fountain according to one of the preceding claims, characterized in that the feed device (17) is coupled to the outlet (14) in such a way that, depending on the spraying, water is automatically discharged from the outlet for a predetermined time interval.

13. A method for the regeneration of a well (1) provided for the extraction, observation and / or lowering of groundwater, according to one of the preceding claims, characterized in that for the regeneration of the filter tube region (3) a medium via a pressure line (10) in the area of the filter tube area (3) arranged spraying device (9), which injects the medium into the frying area adjacent to the filter tube area (3) or jets it onto the filter tube area (3).

14. The method according to claim 13, characterized in that drain bursts are generated during the injection.

15. The method according spoke 13 or 14, characterized in that the medium comprises water and / or water treatment agent, in particular hydrogen oxide and / or charcoal dust.

16. Well (1) for the extraction, observation and / or lowering of groundwater, with a standpipe (2) having at least one filter pipe region (3), and with at least one pump (6) arranged in the standpipe (2), in particular according to one of the preceding claims, characterized in that the standpipe (2) is arranged as an inner standpipe in an outer standpipe (22), that the outer standpipe (22) is firmly connected to the surrounding brackets (23) and that the inner standpipe ( 2) is designed to be pullable from the outer standpipe (22).

17. Fountain according to one of the preceding claims, characterized in that the filter tube area (3) over the lower end of the outer standpipe

(22) survives.

18. Fountain according to one of the preceding claims, characterized in that spacers for positioning the inner standpipe (2) are provided.

19. Well according to one of the preceding claims, characterized in that the radial extent of a spacer is greater than the outer diameter of the pressure line (10).

20. Well (1) for the extraction of groundwater, with an outer standpipe (22) firmly connected to the rock (23), and at least one filter pipe area (3) arranged in a water-bearing layer (A, B), in particular according to one of the preceding claims, characterized in that the outer standpipe (22) is sealed via a hydraulic mineral binder (24) with respect to the surrounding structures (23) in such a way that water only comes from the water-bearing layer (A, B) in which the filter tube area is located (3) is located, is recovered, and a water inflow of foreign water from other layers is avoided.

21. Fountain according to one of the preceding claims, characterized in that the binder (24) has a highly and permanently plastic behavior after setting.

22. Fountain according to one of the preceding claims, characterized in that the binder (24) is used as a water / solid mixture with a predominant proportion of fine-grained marl, preferably with a proportion of up to 30% bentonite.