WO2018189273A1

WO2018189273A1 - Boring tool and method for producing a borehole in the ground

Info

Publication number: WO2018189273A1
Application number: PCT/EP2018/059343
Authority: WO
Inventors: Steffen Praetorius
Original assignee: Herrenknecht Ag
Priority date: 2017-04-12
Filing date: 2018-04-11
Publication date: 2018-10-18
Also published as: EP3388620A1; EP3388620B1

Abstract

The invention relates to a boring device for producing a borehole (100) in the ground from a starting point (120) to a target point, along a boring line, comprising at least one first ground loosening means (11) arranged on the front end of the boring device (10), for loosening the ground from a heading face of the borehole in the heading direction during the heading process, a first receiving element (13) for the loosened ground (subsequent borings), and at least one conveyor means (15) for transporting the borings out of the first receiving element (13) out of the borehole, characterised in that the boring device is provided with at least one second ground loosening means (16) arranged on the rear end (14) of the boring device (10), for loosening ground from the wall (101) of the already created borehole in the return direction during the return out of the borehole, at least one second receiving element (17) for receiving borings during the return of the boring device, and at least one transport means (26) for transporting the borings out of the at least one second receiving element (17) to the conveyor means (15) or out of the borehole.

Description

description

Drilling device and method for creating a hole in the ground

The invention relates to a drilling device for creating a hole, in particular a blind hole, in the ground starting from a starting point to a target point along a drilling line with at least one first arranged on the front of the drilling device Bodenlösemittel for releasing the soil from a working face of the bore in the forward drive direction with at least one first receiving means for the dissolved soil (hereinafter cuttings), with at least one conveying means for removing the cuttings from the first receptacle out of the borehole. Also relevant to the invention is a propelling member for advancing and retracting a drilling apparatus, and a method for creating a bore, in particular a blind hole, in the ground from a starting point to a target point along a drilling line, where the ground is released along the drilling line by means of a boring device with the drilling apparatus being moved via propulsion elements, with a feed device at the starting point, in particular a press frame, along the drilling line to the destination point, and a drilling system for creating a hole, in particular a blind hole, in the ground starting from a starting point to a destination point along a drilling line ,

When drilling boreholes from a start point to a destination point along a given drilling line, various types of tunnel boring machines are used as drilling devices depending on the soil or rock to be used. Such drills are used when the drilling machine is advanced in advance without pilot drilling or the like along the drilling line. The movement can take place, inter alia, by advancing or pushing the pipe segments themselves outside the created tunnel. Such a feed then takes place via a feed device, for example a so-called pipe thruster or a Press frame when individual pipe segments are pressed into the ground. The release of the soil takes place with a drilling tool, such as a cutting wheel. The loosened cuttings are brought by the drilling tool into an area behind the cutting wheel and carried away from there (for example, DE3514563A). The choice of the type of drill is made depending on the geology.

If, for example, geologies occur in which boreholes are subject to strong convergence and / or brittle rock conditions, this has an effect on the drilling method to be chosen. These conditions usually occur in hard rock with moderate compressive strengths and greater depths. Experience has shown that the borehole is traced parallel to the drilling progress. Time-dependent convergence can occur during the entire drilling period. This can lead to a jamming of the drilling process by convergence and / or Nachbruch.

Furthermore, the drilling process is affected by the presence of geologies that tend to swell or even dissolve when using water or the like, as is the case with clay, mudstone, salt or shale, for example. Here usually only dry boring methods are used. Wet drilling methods like HDD are ruled out here. In dry drilling methods, for example, no bentonite suspension can be used to reduce skin friction during the advance of drill pipes as a well construction, for example in microtunneling. This significantly reduces the potential drill length and increases the risk of drilling down the wellbore due to trailing or convergence.

Under certain circumstances, it is necessary to drill holes that are not continuous. Such wells also called blind holes are used in particular in repositories to create from a distance below ground holes in which then hazardous materials such as radioactive materials may be stored in protective containers. Here, the hole is created and then the drilling device must be removed from the hole again.

When creating holes that are not continuous and possibly not accessible because of the diameter, it is problematic, the drilling device off again to remove the borehole. It is known to create such holes in which the drill is advanced by means of drill pipes analogous to the microtunnelling method of a route by means of press frame. The drilling device has a cutting wheel with overcut. Furthermore, the cutting wheel is divided into two parts. The drilling device optionally has an additional outer shell as a lost coat. When the target point is reached, the outer part is released from the cutting wheel and can remain in the ground. The machine itself is separated from the outer shell and is pulled out of the borehole together with the inner cutter wheel through the drill pipes acting as a lost extension. This is complicated, expensive and associated with high costs. Convergences and debris can cause sticking during drilling.

Especially with disposal bores, it may be necessary to bring special expansion in the hole. This may not be applicable as a drill pipe. It must then be created an undeveloped hole. For this, if necessary, the HDD method would own, but which is not applicable in the aforementioned geologies. That's why microtunneling is used. But pulling the drill backwards becomes a risk. Furthermore, due to the convergences and the possible Nachfall the problem is to provide a hole with straight straight diameter undeveloped, then then bring the final expansion in the hole. Even if the machine has been successfully withdrawn, the hole may not be usable for the final removal or storage of the containers due to the demolition and the convergences.

The object of the invention is to overcome the aforementioned difficulties.

The object is achieved by a drilling apparatus having at least one second soil dissolving means disposed at the rear of the drilling apparatus for releasing soil from the wall of the already established borehole in the retreating direction upon withdrawal from the borehole, with at least one second receptacle for receiving cuttings during the retreat of the boring cuttings Drilling device, and with at least one transport means for removing the cuttings from the at least one second receptacle to the conveyor or from the borehole out. By re-cutting the necessary hole diameter for the successful withdrawal of the drilling device is ensured. On the other hand, the broadening and the same diameter completion of the hole / blind hole is achieved by clearing of Nachbruch in the tunnel sole and the cutting of converged rock parts in the planned cavity. Thus, the final expansion can be safely introduced, even under the above-described mountain conditions / geologies.

The second soil release agent may be a passive cutting edge or an active cutting ring.

A further teaching of the invention provides that the soil release agent in the advancing direction is a separating wheel in full section or partial section with a drive. For the drill head, funding and rear transport each advantageously has its own drive. The separation of drill head drive and conveyor drive is important in order to ensure the necessary torque at the drill head over long distances without the losses on the conveyor. It is also advantageous if the drilling head and means of transport can be operated independently of the conveying means by e.g. to loosen jammed boulders or break.

A further teaching of the invention provides that the conveying means are a screw conveyor, a liquid circuit with a pump, for example a centrifugal or jet pump, or a belt conveyor and / or that the transport means are a screw conveyor, a liquid circuit with a pump, a circulating conveying medium, in which the cuttings are conveyed by means of circulating vessels or paddles, or is a belt conveyor.

A further teaching of the invention provides that the drilling device is made up of several sections, that the soil release agent is arranged at the front section and that at least one control means, preferably in the form of at least one hydraulic cylinder, is provided between the front section and at least one further section of the drilling device ,

Another teaching of the invention provides that the drilling device is made up of several sections, that at one section the second soil solvent is arranged, and that at least one control means, preferably in the form of at least one hydraulic cylinder is provided between this and at least one further portion of the drilling device, which is arranged from the first soil release means behind the second soil release agent. This makes it possible to keep the drilling device or the rear-facing cutting device controlled on the desired axis.

A further teaching of the invention provides that a measuring device is provided at least at this further section for determining bottom projections of the borehole wall into the borehole or from loosened soil on the bottom of the borehole. By using such measuring technique it becomes possible to record the contour of the borehole. Furthermore, it is advantageous if the position of the machine can be determined by the measuring device to the desired axis of the borehole. Furthermore, monitoring of the nominal diameter in comparison to the actual diameter of the borehole is advantageous. That measurement can be done for example by laser measurement or acoustically.

Furthermore, the object is achieved by a method for creating a hole, in particular a blind hole, in the ground starting from a starting point to a target point along a drilling line, in which the soil along the drilling line by means of a drilling device, in particular a drilling device as described above, is achieved wherein the drilling device is moved via at least one propulsion element, in particular a propulsion element as described above, with a feed device at the starting point, in particular a press frame, along the drilling line to the target point, and in reaching the target point, the drilling device along the drilling line by removing the propulsion elements is retracted by means of the feed device, wherein upon retraction into the borehole protruding bottom projections of the borehole wall are released from a arranged at the back of the drilling device second soil solvent and thereby dissolved soil and more r dissolved soil located on the bottom of the borehole is taken up by the drilling device and transported away from the borehole.

A further teaching of the invention provides that with a measuring device bottom projections of the borehole wall, which project into the borehole, or dissolved soil on the bottom of the borehole is determined, and / or that the position of the arranged at the back of the boring device second soil release means in relation on the Drilling and / or the optimal position of the borehole wall in the ground is controlled, wherein preferably the control takes place in dependence on the measurement result of the measuring device. By using such measuring technique it becomes possible to record the contour of the borehole. Furthermore, it is advantageous if the position of the machine can be determined by the measuring device to the desired axis of the borehole. Furthermore, monitoring of the nominal diameter in comparison to the actual diameter of the borehole is advantageous. This makes it possible to control the drilling device during retraction and so to keep the backward cutting device controlled on the desired axis.

Furthermore, the object is achieved by a drilling system for creating a bore, in particular a blind hole, in the ground, starting from a starting point to a target point along a drilling line, in particular according to a previously described method, with a previously described drilling device and at least one propulsion element described below.

The propelling member is a propelling member for advancing and retracting a drilling apparatus having a force transmitting member extending in the boring direction and having at its end portions a connecting member for releasably connecting with the drilling apparatus or other propelling elements, comprising at least one conveying element disposed in or is provided on the power transmission element, with at least one receptacle of supply lines, which is provided in or on the force transmission element, and with at least one moving element, via which the propulsion element is movable relative to the borehole wall in contact therewith, wherein the moving element via a spacer element on the Power transmission element is arranged.

The propulsion elements are designed such that they transmit the forces for propulsion and retreat, record the funding and the necessary lines for the operation of the drilling device. At the same time, the shape of the propulsion elements is designed so that the propulsion and retraction are also possible at Nachbruch and convergences in a certain extent. This is achieved in that the propulsion elements are not tubular and thus have no narrow annular gap to the mountains, but provide enough space to accommodate Nachbruch / pass or allow convergences. The reduced contact area by the movement elements, for example In the form of sliding elements such as skids or tubes in the lower area ensures a well calculable low skin friction between propulsion element and mountains.

Another teaching of the invention provides, with regard to the drilling system and the propulsion element, that the conveying element is a screw conveyor or a pipeline.

A further teaching of the invention provides, with regard to the drilling system and the drive element, that at least three spacer elements are radially arranged radially on the force transmission element.

A further teaching of the invention provides, with regard to the drilling system and the propulsion element, that at least one spacing element is designed to be adjustable in length during use in the borehole, in particular via a hydraulic cylinder. This makes it possible to control the drilling device or the rearward cutting device and to keep controlled on the target axis.

A further teaching of the invention provides, with regard to the drilling system and the propulsion element, that the propulsion element has at least one measuring device for determining soil projections of the borehole wall into the borehole or of dissolved soil on the bottom of the borehole. By using such measuring technique it becomes possible to record the contour of the borehole. Furthermore, it is advantageous if the position of the machine can be determined by the measuring device to the desired axis of the borehole. Furthermore, monitoring of the nominal diameter in comparison to the actual diameter of the borehole is advantageous.

A further teaching of the invention provides, with regard to the drilling system and the propulsion element, that the propulsion element is designed such that the movement elements only selectively support the borehole wall in relation to the propulsion element.

The invention will be explained in more detail with reference to an embodiment in conjunction with a drawing. Showing:

1 is a schematic sectional view of a drilling device according to the invention, 2 is a schematic sectional view of a driving element according to the invention,

3 is a front view of FIG. 2,

4 is a schematic sectional view of a drilling device according to the invention and a propulsion element according to the invention with control and measuring device according to the invention,

5 is a front view of FIG. 2 with measuring device,

6 to 10 and 13 a schematic representation of the steps of the method according to the invention,

Fig. 1 1 is a schematic representation of a well with Nachfall and convergence, and

Fig. 12 is a schematic representation of a borehole after performing the method according to the invention.

Fig. 1 shows a schematic sectional side view of a drilling device according to the invention 10. This has a first soil release agent 1 1 in the form of a front cutting wheel. The cutting wheel 1 1 is driven by a drive 12. Behind the cutting wheel 1 1, a first receptacle 13 is provided for receiving the detached from the cutting wheel 1 1 soil, which is described below as cuttings. Into the receptacle 13 protrudes the conveyor 15 for the removal of the cuttings from the first receptacle 13 from the borehole 100 out. Arranged on the rear side 14 of the drilling apparatus 10 is a second soil dissolving means 16 for releasing soil from the wall 101 of the already created borehole 100 in the withdrawal direction during the withdrawal from the borehole 100. The second soil release agent 16 is designed here as a circumferential annular cutting edge which is arranged diagonally. The second soil release agent / the annular cutting edge 16 can also serve to receive replacements 103 or cuttings located on the sole 102. This passes into a second receptacle 17. In this engages a possibly separate powered transport 26 here in Form of circulating paddle to receive and request the cuttings placed there, preferably in the conveyor 15 through the opening 18.

The cutting wheel 1 1 is arranged on a first portion 19. This is movably provided with respect to the second section 20 via control cylinders 21. The conveyor 15 is driven by a drive 22. The transport means 26 has its own drive 24.

The conveying means 15 has on the rear side 14 a connection 23 in the form of a flange for a driving element 30 according to the invention. In the area of the annular cutting edge 16, a laser target 25 for direction monitoring of the pipe jacking is arranged.

FIG. 2 shows a propulsion element 30 according to the invention. This has a central force transmission element 31 extending in the excavation device. In this, a section of the conveyor 15, here a screw conveyor, provided. At its outer ends, the power transmission element 31 in each case has a connection 32 in the form of a flange. Via screw connections, the propulsion element 30 can be connected with its connections 32 to the drilling device 10 according to the invention or to other propulsion elements 30. This provides a connection with which both tensile and compressive forces can be transmitted. On the power transmission element 31, a receptacle 33 is provided, in which, for example, supply lines 34 (see Figure 3) are arranged. The receptacle 33 is preferably designed so that the supply lines 34 can be inserted into the receptacle 33. For the Aufnahme33 is executed u-shaped and can be closed with a lid 35. At the force transmission element 31 here preferably star-shaped spacer elements 36 are arranged, at the end of which movement elements 37 are preferably designed here as a tube. The movement elements 37 are here sliding elements over which the drive element 30 along the borehole 100 can be moved. Holes are provided in the connection 32, into which bolts 38 for producing the connection of the individual connection elements 32 with one another can be introduced.

FIG. 4 shows a drilling device 10 according to the invention with connecting elements 30 arranged thereon and behind. The drilling device 10 and the Connecting elements 30 are arranged in the borehole 100. The first propulsion element 30 thereby represents a control and measuring element. The spacer elements 36 are provided with hydraulic cylinders 39, so that they can be changed in their length in the direction of arrow A. The first propulsion element 30 acts as a kind of third section 27 of the drilling device 10th If the boring device 10 is retracted in the direction of the arrow B via the driving elements 30, the cuttings 103 located on the sole 102 can be conveyed into the second receptacle 17 in the direction of the arrow via the annular cutting edge 16.

About the change in length of the spacers 36 by extending and retracting the hydraulic cylinder 39, the moving elements 37 are moved in the direction of arrow A. As a result, the moving elements 37 are either moved away from the conversion 101 of the borehole or pressed into this. As a result, the position of the force transmission element 31 changes, whereby the position of the annular cutting edge 16 with respect to the wall 101 is also moved directly in the direction of the arrow A.

Furthermore, FIGS. 4 and 5 show a measuring device 40, which is arranged circumferentially on the force transmission element 31. With the measuring device 40, the contour of the borehole 100 can be measured. It can thus breakouts 104 and, for example, caused by convergence projections 105 are detected. Based on the measurement data of the measuring device 40 can then be controlled via the hydraulic cylinder, the position of the annular cutting edge 16 so that when retracting an optimal borehole shape with respect to the intended hole line can be created.

The difference between a borehole contour and methods according to the invention is shown in FIGS. 11 and 12. FIG. 11 shows a borehole 100 with outbreaks 104 and protrusions 105 with respect to the borehole conversion 101. In the area of the outbreaks 104, cuttings 103 are located on the bottom 102 of the borehole 100. In FIG. 12, the borehole 100 is cleared of cuttings 103 102. Furthermore, the projections 105, which were caused by convergence or sources, peeled off by the annular cutting edge 16 on the drilling apparatus 10 and the cuttings 103 incurred thereby also carried away.

In such an adjusted hole 100 then required for example for the final disposal expansion elements 1 10 in the borehole 100 by means of a press frame 50th be introduced as feed and retraction element, as shown in Figure 13. The press frame 50 is arranged in an underground section 120 of a repository mine from which the bore 100 is generated. The arrangement of the press frame 50 in the path 120 is also shown in FIG. The press frame 50 is aligned in the direction of a Bohrlochansatzpunktes 106.

The drilling device 10 according to the invention is arranged in the press frame 50 in the direction of the Bohrlochchansatzpunktes 106 (see Figure 7). When the cutting wheel 1 1 of the boring device 10 is put into operation, the press frame 50 pushes the boring device 10 in the direction of the drilling line D (see FIG. 8) until there is sufficient space in the area of the press frame 50 to arrange the first driving element 30 (see FIG. 9). The first drive element 30 is then pushed by the press frame 50 with its front terminal 32 against the terminal 23 and the two elements are connected with bolts 38. At the same time the supply lines 34 are inserted into the receptacle 33. The receptacle 33 is then closed with the lid 35.

Subsequently, the feed element 30 and the drilling device 10 is advanced through the press frame in the drilling direction D for creating the borehole 100, until again sufficient space for another driving element 30 in the region of the press frame 50 is. This is repeated until the borehole 100 has arrived at the destination point. Subsequently, the driving elements 30 and the drilling device 10 are withdrawn via the press frame 50 in the direction of arrow B, as shown in FIG. 4, the borehole 100 being straightened by means of the annular cutting edge 16 with respect to the nominal line. Furthermore, the cuttings 103 located on the sole 102 are received by the drilling device 10. The feed elements 30 are successively removed and further retracted from the press frame in the direction of arrow B in the route 120 inside.

After removal of the drilling device 10 can then as shown in Figure 13, the final expansion 1 10 are introduced. Rapid disassembly, which then cleans up the wellbore 100 as described, allows the final disassembly 10 to be inserted into the wellbore 100 without further delays, thus minimizing further convergence or resulting protrusions 105 and outbreaks 104, respectively can. By the method described above and the illustrated system consisting of drilling device 10 and before operating elements 30, it is possible to drill boreholes or blind bores also in geology efficient, which require a dry work. Furthermore, it is possible to achieve larger jacking lengths, since the friction of the drill string is minimized compared to the use of solid tubes. Furthermore, the risk of sticking during the drilling progress is minimized because the mountains are given room for convergence and at the same time no jamming of the jacking pipes can be made against the borehole. Furthermore, it is not necessary to use lost expansion. It is also possible to create and re-drill holes between two achievable points in the previously described manner or using the method according to the invention, the drilling system according to the invention and its components according to the invention. It is also possible to drive on multiple holes in order to recut.

The invention can be used in particular in non-accessible diameter ranges up to diameters, from which, for example, segment lining can be used. However, this is not restrictive. As an alternative to a route underground, the invention can also be applied from a launch pit or the like above ground.

LIST OF REFERENCE NUMBERS

Drilling device 50 press frame first soil solvent / front 100 wellbore

Cutting wheel 101 wall

Drive 102 sole

first picture 103 Nachbruch / Bohrklein Back 104 Outbreak

Conveyor 105 Projection of second soil release agent / 106 Borehole set point Cutting ring 1 10 Expansion element Second receptacle 120 Distance

opening

first section A arrow direction second section B arrow direction

Control cylinder C Arrow direction

Drive D Drilling direction connection / flange

drive

laser target

Mode of Transport

third section

propulsion element

Power transmission element

connection

admission

supply line

cover

spacer

mover

bolt

hydraulic cylinders

measuring device

*****

Claims

claims

A drilling apparatus for creating a well (100) in the ground from a starting point (120) to a target point along a drilling line

with at least one first soil dissolving means (1 1) arranged at the front side of the boring device (10) for releasing the soil from a working face of the boring in the advancing direction during excavation,

with at least one first receptacle (13) for the dissolved soil (hereinafter cuttings),

with at least one conveying means (15) for removing the cuttings from the first

Pickup (13) out of the hole,

characterized in that the drilling device is provided:

with at least one second soil dissolving means (16) disposed on the back side (14) of the drilling apparatus (10) for releasing soil from the wall (101) of the already created wellbore in the withdrawal direction upon withdrawal from the wellbore, with at least one second receptacle (17 ) for picking up cuttings on retraction of the drilling apparatus, and

with at least one transport means (26) for removing the cuttings from the at least one second receptacle (17) to the conveying means (15) or out of the borehole.

2. Drilling device according to claim 1, characterized in that it is at the bore (100) is a blind hole, and / or that it is at the bottom solvent (1 1) in the advancing direction to a Scheiderad in full or partial section with a drive ,

3. Drilling device according to claim 1 or 2, characterized in that it is the conveyor (15) is a screw conveyor, a liquid circuit with pump or a belt conveyor, and / or that it is the transport means (26) to a screw conveyor, a fluid circuit with pump, a circulating fluid or a belt conveyor is.

4. Drilling device according to one of claims 1 to 3, characterized in that the drilling device of several sections (19, 20) is constructed such that at the front portion (19) the first soil release agent (1 1) is arranged, and that between front section (19) and at least one further portion (20) of the drilling device at least one control means (21), preferably in the form of at least one hydraulic cylinder, is provided.

5. Drilling device according to one of claims 1 to 4, characterized in that the drilling device (10) of a plurality of sections (19, 20) is constructed such that at a portion (20) the second soil solvent (16) is arranged, and that between at least one control means, preferably in the form of at least one hydraulic cylinder, is provided in this and at least one further section of the drilling apparatus (10) arranged behind the second soil dissolving means, as seen from the first soil dissolving means.

6. Drilling device according to one of claims 1 to 5, characterized in that at least at this further portion, a measuring device (40) for detecting soil projections (105) of the borehole wall into the borehole (100) or from dissolved soil (103) on the Sole (102) of the borehole (100) is provided.

A method of creating a well (100) in the ground from a starting point (120) to a target point along a drilling line, wherein the soil is released along the drilling line by means of a drilling apparatus (10) according to any one of claims 1 to 6; wherein the drilling device (10) is moved via at least one driving element (30) with a feed device (50) at the starting point (120) along the drilling line to the destination point, characterized in that after reaching the target point the drilling device (10) along the drilling line by removal the propulsion elements (30) are moved back by means of the advancing device (50), whereby bottom projections (105) of the borehole wall (101) projecting into the borehole (100) from a second soil dissolving medium (10) arranged on the rear side (14) of the boring device (10) 16), and the soil (103) and further soil (103) located on the bottom of the well are detached from the drilling apparatus ung (10) recorded and removed from the borehole.

8. The method according to claim 7, characterized in that with a measuring device (40) bottom projections (105) of the borehole wall (101) which project into the borehole (100) or dissolved soil (103) on the bottom (102) of the borehole (100) and / or that the position of the second soil release means (16) disposed on the backside (14) of the drilling apparatus (10) is controlled with respect to the drilling line and / or the optimal location of the wellbore wall (101) in the ground; and / or in that a press frame is used as feed device (50), and / or that the bore (100) is a blind hole.

9. The method according to claim 8, characterized in that the control takes place as a function of the measurement result of the measuring device (40).

A drilling system for creating a well (100) in the ground from a starting point (120) to a target point along a drilling line with a drilling apparatus (10) according to any one of claims 1 to 6 and at least one propulsion member (30) for advancing and retracting Drilling device (10) having a force-transmitting element (31) extending in the drilling direction, having at its end portions a connecting element (32) for releasable connection with the drilling device (10) or further driving elements (30), with at least one conveying element (15 ) provided in or on the power transmission member (31) and at least one receptacle (33) of supply conduits (34) for the drilling apparatus (10) provided in or on the power transmission member (31) and at least one Movement element (37), via which the drive element (30) is movable relative to the borehole wall (101) in contact therewith, wherein the B Ewegungselement (37) via a spacer element (36) on the force transmission element (31) is arranged.

1 1. A drilling system according to claim 10, characterized in that it is the bore (100) is a blind hole, and / or that it is in the conveying element (15) of the driving element (30) is a screw conveyor or a pipeline.

12. A drilling system according to claim 10 or 1 1, characterized in that at least three spacer elements (36) are radially arranged radially on the force transmission element (31) of the driving element (30).

13. Drilling system according to one of claims 10 to 12, characterized in that at least one spacer element (36) of the driving element (30) adjustable in length during use in the borehole (100), in particular via a hydraulic cylinder (39).

14. A drilling system according to any one of claims 10 to 13, characterized in that the propulsion element (30) at least one measuring device (40) for detecting soil projections (105) of the borehole wall into the wellbore (100) or from dissolved soil (103) on the Sole (102) of the borehole (100).

15. Drilling system according to one of claims 10 to 14, characterized in that the propulsion element (30) is designed so that the moving elements (37) only selectively the borehole wall (101) against the propulsion element (30) are supported, and / or that the drilling system for carrying out a method according to any one of claims 7 to 9 is usable.

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