SE545263C2 - Method for rehabilitating a drilled well - Google Patents

Abstract

The invention relates to a method for rehabilitating a drilled well. In the method, the pumping means (17) are removed from the drilled well (10). In addition, an inner pipe (21), which extends to the bedrock (13), is installed in the drilled well (10). The inner pipe (21) is sealed to the drilled well (10) by filling the space (23) between the drilled well and the inner pipe (21) with a sealing agent (24) and expanding part of the inner pipe's (21) end portion (25) onto the drilled well (10). In addition, in the method the expansion is performed before or after the filling.

Description

METHOD FOR REHABILITATING A DRILLED WELL The drilled invention relates to a method for rehabilitating a well, in which method the pumping means in the drilled. well are removed. and. an inner' pipe, which. extends down to the bedrock, is installed in the drilled well. A drilled well includes a drill hole, which extends through The hole is drilled In Finland, the surface soil layers to the bedrock. until ground water is reached. there is generally a few metres to a few tens of metres of surface soil. In the bedrock, the hole is generally a few tens of metres, even two hundred metres deep. In the portion of the surface-soil lay- er, a casing pipe is installed, which extends for some dis- tance into the bedrock. The casing pipe is sought to be set tightly into the bedrock, to avoid loose soil and surface wa- ter from flowing into the drilled well.

An iron pipe, traditionally used in drilling, forms the cas- into the bedrock flow the ing pipe, which extends for some distance too. Nonetheless, surface water can into drilled well. dirty as the water surface varies and which In addition, time progresses, iron oxides, can cloud the water and cause taste changes, can detach from the iron pipe. There such a drilled well. äIG two known methods for rehabilitating One way to repair a well is to replace the rusty old iron pipe with a stainless steel pipe. In other words, the iron pipe must first be removed, which is time-consuming. In addition, the tightness of the steel pipe to the bedrock is equally un- certain as that of the original iron pipe. Another way is to install a plastic pipe, which is sealed to the iron pipe, as an inner pipe inside the iron pipe. In practice, it is impos- sible to make a durable seal, because the expanding sealing agent used in sealing shrinks as it dries. The seal can then even separate and drop deeper into the drilled well, so that lthere will be no seal at all between the iron pipe and the inner pipe. Rusty water can then continue to be a problem. A plastic pipe can also be too tight for the existing submersi- ble pump, which then must be replaced during rehabilitation. FIlO6057B describes a næthod and arrangement for installing and sealing a pipe in a drilled well.

The invention is intended to create a new type of method for rehabilitating a drilled well, which is simpler than previ- ously, but using which rehabilitation is simpler than before, the end result being permanent. The characteristic features of the method according to the present invention are stated in the accompanying Claims. The problems of the prior art are resolved by means of the method according to the invention. First of all, the rustiness of the water is eliminated. At the same time, loose soil and. surface water* are prevented from entering the drilled well. In addition, the end result remains despite changes in the water level, and the actual rehabilitation is rapid. In the following, the invention is described in detail with reference to the accompanying drawing showing one embodiment of the invention, in which Figure l shows a schematic diagram of a known drilled well, Figure 2a shows the initial stage of the næthod according to the invention, Figure 2b shows the middle stage of the method according to the invention, Figure 3 shows the final stage of the method according to the invention, Figure 4a shows the equipment used in the method according to the invention, Figure 4b shows the inner pipe used in the method according to the invention, Figure 5a shows an alternative initial stage of the method according to the invention, Figure 5b shows an alternative middle stage of the næthod according to the invention. Figure 1 shows a known, previously drilled drilled wellwhich can be rehabilitated using the method The drilled wellpresently in use, according to the invention. includes a drilled drill hole 11, layer 12 to the bedrock which extends through the surface-soil The drill hole 11 is drilled un- til the groundwater is reached. A casing pipe 22, which also extends some way into the bedrock 13, is generally installed on the surface-soil portion. It is sought to set the casing pipe tightly into the bedrock, to avoid loose soil and sur- face water entering the drilled well.

At the upper end of the drilled well 10 an installation well 15 extending below the frost limit 14 is formed, which is in- sulated to prevent the drilled well 10 and the water pipe 16 from freezing. As pumping equipment 17, a submersible pump 18 with a hose 19 and cable are lowered into the drilled well 10. In the installation well 15 are the necessary connectors, usually an elbow fitting 20 for the hose 19. During use, cur- rent is fed by the cable to the submersible pump, from which water rises through the hose 19 to the installation well 15 the and from there to the point of use. After installation, end of the casing pipe 22 is plugged and the installation well 15 is insulated and closed to prevent freezing. method for The relates to a drilled well. invention rehabilitating a In the method, the pumping means 17 are first removed from the drilled well 10. Usually, a hose and cable are connected to the submersible pump. In the rehabilitation, an inner pipe 21, which extends to the bedrock 13, is in- stalled in the drilled well 10. Figures 2a - 3 also show a casing pipe 22 previously installed in the drilled well 10 and the inner pipe 21 according to the invention. Both pipes extend to the bedrock 13. According to the invention, the in- ner pipe 21 is sealed to the drilled well 10 by filling the space 23 between the drilled well 10 and the inner pipe 21 with a sealing agent 24. In addition, part of the end portion 25 of the inner pipe 21 is expanded onto the drilled well 10. The sealing is then certain and permanent. In Figures 5a and 5b the drilled well is without a casing pipe. The casing pipe being previously used has then been removed in the rehabili- tation and the drilled well implemented using only the inner Alternatively, the question is of a new drilled well, pipe. in which only an inner pipe has been installed. In the method according to the invention, expansion is per- formed before or after filling. 2a - 3, In the embodiment of Figures filling takes place first, after which the pipe is expanded. The pipe of Figures 5a and 5b is first expanded, after which the gap is filled.

A steel pipe, which is stainless or acid-resistant, is in- stalled as the inner pipe 21. This avoids rusty water, be- cause nothing' dissolves fronl the steel pipe, nor does the steel pipe corrode. The steel pipe can also be formed from pipe parts 26, in which there are sleeves to make connections (Figure 4b). Alternatively, straight pipe parts are used, which are joined together by separate muffs 27. In both cases the pipe parts and miffs are riveted together. Sealing agent finally seals even the smallest gaps.

The properties of the inner pipe's 21 end portion 25 prefera- bly differ from those of the rest of it. For example, the end portion's wall thickness is less than elsewhere in the inner pipe. On the other hand, the end portion can be of some other material than steel. The forming of the end portion is then facilitated, and the end portion conforms to the surface shapes of the drilled well's wall. Expansion increases the structure's tightness and stops the sealing agent running. Relative to the depth of the drilled well, expanding the in- ner pipe over a short length is sufficient to implement the In the the invention. invention, which is 50 - inner pipe500 mm, is expanded over a distance L, preferably 100 -mm. The distance to be shaped is then short, but sufficient.

The expansion is preferably carried out in a single stage.

In the embodiment according to Figures 2a - 3, the inner pipe 21 is installed inside the iron pipe that is the casing pipe 22 in the drilled well 10, when the space 23 between the in- ner pipe 21 and the iron pipe is filled with a sealing agent 24. Thus, it is unnecessary to remove the iron pipe previous- ly installed as a casing pipe, which accelerates rehabilita- tion. At the same time, however, the iron pipe is isolated from water, so that rust cannot enter the water. The sealing agent can also travel into the space between the casing pipe 22 and the drill hole 11, which only increases the tightness. Of course, the casing pipe can be removed before installation of the inner pipe. Correspondingly, the inner pipe can be in- stalled and sealed in a new drilled well too, so that the flow of surface water into the drilled well can be completely prevented. Surprisingly, the sealing agent 24 is fed from below upwards. The sealing' agent is then certain to travel to the point where sealing is needed. Preferably feeding is continued un- til the sealing agent discharges from the upper end of the inner pipe. The inner pipe is then sealed over its entire length.

In the invention, the sealing agent 24 used is pumped con- crete. Concrete is easy to handle and in practice non-toxic.

In addition, at a suitable composition and with an additive treatment concrete is easy to pump and hardens rapidly. For example, the concrete's hardening can be accelerated using a suitable accelerant.

In the invention, a tool 28, which in Figure 4a is lowered into the drilled well 10, is used for sealing. More general- ly, the inner pipe 21 is expanded using a tool 28, which is lowered. from. above inside the inner* pipe 21 in the inner pipe's 21 end portion 25. The actual pipes are not shown in Figure 4a.

In Figure 2a, the inner pipe 21 is slightly lower than the casing pipe 22 at a suitable point. In addition, the toolhas already been lowered to a suitable depth. The tool can be installed in the drilled well together with the inner pipe.

Thus, both the inner pipe and the tool can be installed in a single work stage. At the same time, it is easy to align the tool with the correct point in the inner pipe's end portion.

Alternatively, the inner pipe is installed first, after which the tool is lowered in the inner pipe. In the invention, two sleeves 29 and 30, which are arranged at a distance from each other, are fitted to the tool 28. Each sleeve has its own task and sealing can be performed simply and rapidly by the joint operation of the sleeves.

According to Figure 2a, the upper sleeve 29 is located at the inner pipe's 21 end portion 25 and the lower sleeve 30 below the end portion 25. In addition, the inner pipe 21 extends lower than the casing pipe The sleeves can be operated independently of each other. In other words, the sleeves' properties can be controlled inde- pendently. Figure 2a shows two connections 31 and 32, to which medium hoses (not shown) are connected. Compressed air, for example, is used as the medium. The left-hand connection 31 extends to the upper sleeve 29 and the right-hand connec- tion 32 extends to the lower sleeve 30. In Figures 2a and 2b the upper sleeve 29 is sealed to the inner pipe 21 and the lower sleeve 30 is sealed to the bedrock 13. After this, the sealing agent 24 is fed into the space between the sleevesand 30 through a third connection 33 (Figure 2b). The third connection 33 extends through the upper sleeve 29 and opens into the space between the sleeves 29 and 30. The sleeves prevent the sealing agent from flowing down into the drilled well and, on the other hand, from entering the inner pipe Thus, when pumping is continued the sealing agent rises be- tween. the casing' pipe 22 and. the inner* pipe 21. A. little sealing agent can also go between the casing pipe 22 and the drill hole 11. Pumping is continued until the sealing agent discharges into the area of the casing pipe's upper end.

Figure 3 shows a partial magnification of the sealing point in the method's final stage. After the feeding of the sealing agent 24, the upper sleeve 29 is used to expand the inner pipe's 21 end portion 25 onto the bedrock 13, after which the tool 28 is removed from the drilled well. Here only the upper sleeve 29, by which the inner pipe 21 is expanded onto the drill hole 11, is shown. The expansion prevents the sealing agent from flowing. The pressurization of the sleeve can then lbe rapidly removed, and the tool can be lifted out of the drilled well, which shortens the time taken for the rehabili- tation. If necessary, the sleeve can be left in place until the concrete has hardened.

In the invention a sealing agent is used and finally the in- ner pipe is expanded onto the bedrock. The sealing is then guaranteed to hold. At the same time this avoids removing the casing pipe, which accelerates the drilled well's rehabilita- tion.

The sleeve is a cylinder about 500-mm long, around which is strong rubber. When pressurized, the cylinder shortens, com- pressing the rubber longitudinally, so that the rubber ex- pands, sealing to the wall of the pipe or drilled well and preventing the sealing agent from escaping. In the invention, the pressure is maintained for even further. In the initial stage both sleeves are pressurized, when the upper sleeve seals to the inner pipe and the lower sleeve to the bedrock, i.e., to the drill hole. Finally, the pressure in the upper sleeve is raised further, when the end of the inner pipe's end. portion expands, sealing' to the bedrock. At the same time, the flow of sealing agent to the drilled well is pre- vented. After expansion, the double sleeve is removed from the drilled well and the submersible pump is reinstalled.

Concrete, which can be pumped but which hardens rapidly, is preferably used as the sealing agent. The seal then remains even if conditions change. As an auxiliary device, a motor- ized base machine 34 can be used, which includes means 35 for creating compressed air and devices 36 for mixing and pumping concrete. The base machine 34 preferably has a crawler chas- sis, so that the drilled well can be reached without breaking the surface soil. The amount of concrete used depends on the inner pipe's diameter and length. However, the volume to be sealed is generally tens of litres, so that nmterial costs are small. In addition, pumped concrete enters even small gaps, sealing effectively.

The tool described can also be used for high-pressure jetting a drilled well. Using the two sleeves, water is fed at high pressure into a restricted space in the drilled well. The wa- ter veins are then opened and thus water production is im- proved. The tool is cleaned between the feeding of the seal- ing agent and the high-pressure jetting, which, however, must be done in any event after rehabilitation.

Figures 5a and 5b show a second embodiment of the method ac- cording to the invention. Here the upper sleeve 29 is sealed against the inner pipe 21 and the lower sleeve 30 is located at the inner pipe's 21 end portion 25. Then the lower sleeve is used to expand the inner pipe's 21 end portion 25 bed- rock 13, after which sealing agent 24 is fed into the space between the sleeves 29 and 30. In other words, enlargement is performed. before filling. Sealing' agent 24 discharges from between the sleeves, through one or more openings 37 formed in the inner pipe 21, into the space 23, thus sealing the in- ner pipe 21 to the drilled well 10. Finally, the tool 28 is removed from the drilled well 10. The same reference numbers are used for functionally similar components.

In the inner pipe's 21 end portion 25 there are one or more openings 37, which are covered by a structure permitting an outflow. At its simplest, the structure comprises a rubber sleeve 38, in which there is a flap 39 at each opening. Here the flap 39 is formed by a V-shaped cut made in the sleeve. Concrete can then be fed from inside the inner pipe, between the inner pipe and the bedrock, through the openings. At the llend of the pumping the flap presses against the inner pipe, closing the opening. This prevents the concrete from flowing back into the pipe.

The end result is similar in both methods but using the sec- ond embodiment the inner pipe can be expanded to the clean rock wall. In addition, the expansion of the inner pipe and its sealing for concreting are one and the same work stage, which accelerates sealing.

The method according to the invention can be adapted to be used to create a new drilled well too. A steel pipe is then installed as the casing pipe, which is concrete to the drill hole. Finally, the end of the steel pipe is expanded onto the bedrock, which prevents the concrete from flowing. After the concrete has hardened the steel pipe remains tightly in place.

Claims (8)

1.Claims 1. Method for rehabilitating a drilled well, in which method a pumping means (17) in the drilled well (10) are re- moved and an inner pipe (21), which extends down to a bedrock (13), is installed in the drilled well (10), and the inner pipe (21) is sealed to the drilled well (10) by filling the space (23) between the drilled well (10) and the inner pipe (21) with a sealing agent (24) and expanding part of an end portion (25) of the inner pipe (21) onto the drilled well (10), and that in the method the expansion is performed be- fore or after the filling and the inner pipe (21) is expanded using a tool (28), which is lowered from above to the inner pipe's (21) end. portion (25), inside the inner pipe (21) characterized in that: two sleeves (29, 30), which are arranged at a distance from each other, are fitted to the tool (28) and, i) the upper sleeve (29) is sealed to the inner pipe (21) and the lower sleeve (30) is placed at the inner pipe's (21) end (30) to the bedrock and the lower sleeve (21) (25) portion (25), is used to expand the inner pipe's end portion (13), after which the sealing agent (24) (29, 30), is fed into the space between the sleeves from where the sealing agent (24) dis- charges through one or more openings (37) formed in the inner pipe (21) into the space (23), and finally the tool (28) is removed from the drilled well (10), or, ii) the upper sleeve (29) is located at the inner pipe's (21) end portion (25) and the lower sleeve (30) below the end por- tion (25), the upper sleeve (29) is sealed to the inner pipe (21) and the lower sleeve (30) is sealed to the bedrock (13), after which the sealing agent (24) is fed into the space between the sleeves (29, 30), and, lO ized in that the inner pipe after feeding the sealing agent (24), (21) (25) the inner pipe's end portion is expanded to the bedrock (13) by the upper sleeve (29), after which the tool (28) is removed from the drilled well (10).

2. Method according to Claim 1, characterized in that a steel pipe, which is stainless or acid-resistant, is in- stalled as the inner pipe (21). Method according to any of Claims 1 - 52, character- ized in that the inner pipe (21) is installed in the drilled well (10) inside an iron pipe that is as a casing pipe (22), and the space (23) between the inner pipe (21) and the casing pipe (22) is filled with a sealing agent (24). 4

3. Method according to any of Claims 1 - äß, character- ized in that the sealing agent (24) is fed downwards from above. Äš. Method according to Claim ëí, characterized in that pumped concrete is used as the sealing agent (24). Éä. Method according to any of Claims 1 - êi, character- (21) preferably 100 - 300 mm. is expanded over a distance (L) that is 50 - 500 mm, _ï§. Method according to any of the previous claims, characterized in that the tool (28) is lowered into the drilled well (10) along with the inner pipe (21). Që. Method according to any of Claims l - ëf, character- ized in that the inner pipe (21) is formed from pipe parts (26), which are joined together by riveting.