Abrasive suspension eroding system

Abstract

An abrasive suspension eroding system has an eroding unit (11), which can be lowered into an existing drilled hole (1), in order to generate a high-pressure erosion jet for the abrasive suspension eroding of material (6, 20) in an existing drilled hole (1). The eroding unit (11) can be connected to a drilling fluid line (9) and is configured to generate a high-pressure erosion jet from a drilling fluid abrasive suspension device.

Claims

1. An abrasive suspension eroding system comprising an eroding unit which can be let down into an existing borehole for producing a high-pressure erosion jet for the abrasive suspension eroding of material in the existing borehole, wherein the eroding unit is connectable to a drilling fluid conduit and is configured to produce a high-pressure erosion jet from a drilling fluid-abrasive agent suspension, the eroding unit comprising a distal nozzle head section and a proximal anchoring section, wherein the nozzle head section is distally movable relative to the anchoring section, the nozzle head section comprising a distal nozzle head and a proximal nozzle head base, wherein the nozzle head is rotatable relative to the nozzle head base about a rotation axis, the eroding unit comprising at least one first nozzle and at least one second nozzle, wherein the at least one first nozzle is aligned for producing an obliquely radially outwardly directed erosion jet and the at least one second nozzle for producing an obliquely radially inwardly directed erosion jet, wherein the at least one second nozzle has a distance to the rotation axis of the nozzle head.

2. An abrasive suspension eroding system according to claim 1, further comprising: a drilling fluid high-pressure pump; and an abrasive agent supply unit which is fluid-connectable to the eroding unit via the drilling fluid conduit and which is fluidically connectable to the drilling fluid conduit upstream of the drilling fluid high-pressure pump.

3. An abrasive suspension eroding system according to claim 1, wherein the anchoring section comprises lateral anchoring elements and can be anchored in the existing borehole in rock and/or in a pipe element by way of the lateral anchoring elements.

4. An abrasive suspension eroding system according to claim 3, further comprising a control unit signal-connected to the eroding unit and by way of which an anchoring of the anchoring section and/or a distal moving of the nozzle head section relative to the anchoring section is controllable.

5. An abrasive suspension eroding system according to claim 3, wherein the nozzle head section can be anchored in the existing borehole in the rock and/or in the pipe element in a distally extended position relative to the anchoring section by additional lateral anchoring elements.

6. An abrasive suspension eroding system according to claim 1, wherein the nozzle head is eccentrically rotatable.

7. An abrasive suspension eroding system according to claim 1, wherein the eroding unit further comprises at least another first nozzle to provide at least two first nozzles which are aligned at a different angle with respect to the rotation axis, and/or wherein the eroding unit further comprises at least another second nozzle to provide at least two second nozzles, of which at least one is aligned such that the erosion jet intersects the rotation axis and/or at least one is aligned such that the erosion jet runs skewly to the rotation axis.

8. An abrasive suspension eroding system according to claim 1, further comprising: a drilling fluid high-pressure pump; and an abrasive agent supply unit configured to deliver an abrasive agent to a drilling fluid to form the drilling fluid-abrasive agent suspension at a location outside of the eroding unit, wherein the drilling fluid-abrasive agent suspension is delivered to the drilling fluid conduit via at least the drilling fluid high-pressure pump.

9. An abrasive suspension eroding system according to claim 8, wherein the abrasive agent is delivered to the drilling fluid at a position upstream of the drilling fluid high-pressure pump with respect to a flow of the drilling fluid to form the drilling fluid-abrasive agent suspension.

10. An abrasive suspension eroding system according to claim 8, further comprising: a drilling fluid supply pump configured to supply the drilling fluid to the abrasive agent supply unit, the abrasive agent supply unit being located between the drilling fluid high-pressure pump and the drilling fluid supply pump.

11. An abrasive suspension eroding system according to claim 1, further comprising: a drilling fluid high-pressure pump; and an abrasive agent supply unit configured to deliver an abrasive agent to a drilling fluid at a position downstream of the drilling fluid high-pressure pump with respect to a flow of the drilling fluid to form the drilling fluid-abrasive agent suspension.

12. An abrasive suspension eroding system according to claim 11, further comprising: a drilling fluid supply pump configured to supply the drilling fluid to the drilling fluid high-pressure pump, the abrasive agent supply unit being downstream of the drilling fluid high-pressure pump, wherein the drilling fluid high-pressure pump is located between the abrasive agent supply unit and the drilling fluid supply pump.

13. A borehole facility comprising: a drilling fluid conduit; and an abrasive suspension eroding system comprising an eroding unit which can be let down into an existing borehole for producing a high-pressure erosion jet for an abrasive suspension eroding of material in the existing borehole, wherein the eroding unit is connectable to the drilling fluid conduit and is configured to produce a high-pressure erosion jet from a drilling fluid-abrasive agent suspension, wherein the eroding unit is fluid-connected to the drilling fluid conduit, the eroding unit comprising a distal nozzle head section and a proximal anchoring section, wherein the nozzle head section is distally movable relative to the anchoring section, the nozzle head section comprising a distal nozzle head and a proximal nozzle head base, wherein the nozzle head is rotatable relative to the nozzle head base about a rotation axis, the eroding unit comprising at least one first nozzle and at least one second nozzle, wherein the at least one first nozzle is aligned for producing an obliquely radially outwardly directed erosion jet and the at least one second nozzle for producing an obliquely radially inwardly directed erosion jet, wherein the at least one second nozzle has a distance to the rotation axis of the nozzle head.

14. A borehole facility according to claim 13, wherein the abrasive suspension eroding system further comprises a drilling fluid high-pressure pump and an abrasive agent supply unit which is fluid-connected to the eroding unit via the drilling fluid conduit and which is fluid-connected to the drilling fluid conduit upstream of the drilling fluid high-pressure pump.

15. A method for an abrasive-suspension eroding of material within an existing borehole, the method comprising the steps of: letting down an eroding unit into the existing borehole, wherein the eroding unit is fluid-connected to an abrasive agent supply unit via a drilling fluid conduit, feeding abrasive agent into the drilling fluid conduit by way of the abrasive agent supply unit, pumping a drilling fluid-abrasive agent suspension through the drilling fluid conduit to the eroding unit by way of a drilling fluid high-pressure pump, producing a high-pressure erosion jet of the drilling fluid-abrasive agent suspension by way of the eroding unit, and eroding material in the existing borehole by way of the high-pressure erosion jet of the drilling fluid-abrasive agent suspension, wherein a distal nozzle head section of the eroding unit is distally moved relative to a proximal anchoring section of the eroding unit and a distal nozzle head of the nozzle head section is rotated relative to a proximal nozzle head base of the nozzle head section about a rotation axis, wherein an obliquely radially outwardly directed erosion jet is produced by at least one first nozzle of the nozzle head and an obliquely radially inwardly directed erosion jet is produced by at least one second nozzle of the nozzle head, wherein the at least one second nozzle has a distance to the rotation axis of the nozzle head.

16. A method according to claim 15, further comprising an anchoring of the proximal anchoring section by way of lateral anchoring elements.

17. A method according to claim 16, further comprising an anchoring of the distal nozzle head section in a position which is extended distally relative to the anchoring section, by way of additional lateral anchoring elements.

18. A method according to claim 15, further comprising a controlling of anchoring of the eroding unit and/or of the distal moving by way of a control unit which is signal-connected to the eroding unit.

19. A method according to claim 15, further comprising a rotating of the distal nozzle head of the nozzle head section relative to the proximal nozzle head base of the nozzle head section about a rotation axis which runs eccentrically to a longitudinal axis of the nozzle head.

20. A method according to claim 15, wherein the feeding of the abrasive agent into the drilling fluid conduit by way of the abrasive agent supply unit takes place upstream of the drilling fluid high-pressure pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a schematic view of a first schematic application example of the abrasive suspension eroding system which is disclosed herein, for eroding a narrowing in a deep-sea bore;

(3) FIG. 2 is a schematic view of a second schematic application example of the abrasive suspension eroding system which is disclosed herein, for radially cutting open a well of a deep-sea bore;

(4) FIG. 3 is a schematic view of a third schematic application example of the abrasive suspension eroding system which is disclosed herein, for fishing in a deep-sea bore;

(5) FIG. 4 is a schematic view of a fourth schematic application example of the abrasive suspension eroding system which is disclosed herein, for the lateral feed advance into a branching of a deep-sea bore;

(6) FIG. 5 is a schematic view of a first exemplary embodiment of a borehole facility with the abrasive suspension eroding system which is disclosed herein;

(7) FIG. 6 is a schematic view of a second exemplary embodiment of a borehole facility with the abrasive suspension eroding system which is disclosed herein;

(8) FIG. 7 is six momentary views a)-f) of an eroding unit of an exemplary embodiment of the abrasive suspension eroding system which is disclosed herein, in each case in different stages of the advance;

(9) FIG. 8 is a perspective view of a nozzle head of an exemplary embodiment of the abrasive suspension eroding system which is disclosed herein;

(10) FIG. 9 is a lateral view of a nozzle head of an exemplary embodiment of the abrasive suspension eroding system which is disclosed herein;

(11) FIG. 10 is a view of the face side of a nozzle head of an exemplary embodiment of the abrasive suspension eroding system which is disclosed herein; and

(12) FIG. 11 is a procedural diagram of an exemplary embodiment of the method which is disclosed herein, for the abrasive suspension eroding of material within an existing borehole.

DESCRIPTION OF PREFERRED EMBODIMENTS

(13) Referring to the drawings, a deep-sea bore 1 in the sea bed 3 is shown in FIG. 1. The deep-sea bore 1 serves for drilling oil or natural gas and comprises wells 5 which are set on one another into a well, through which the oil or natural gas was brought to the surface. If the deep-sea bore 1 is no longer to be used for drilling for oil or natural gas, then it must be closed for the protection of the environment, so that oil or natural gas cannot flow through the deep-sea bore 1 into the sea. If however, as is shown here, at well 5 has become damaged or has been pressed in for example due to tectonic shifts or a lowering of the seabed inherent of the drilling for oil, then a plug must be placed below or distally of such a damage, in order to ensure that no oil or natural gas escapes due to the damage. The damage here is shown in the form of a narrowing 6. Here, it is to be noted that with regard to the deep-sea bore 1, it does not need necessarily need to be the case of a vertical bore, but the deep-sea bore 1 can also be slanted, horizontal and/or branched.

(14) In order to now be able to place a plug below or distally of the narrowing 6, the cross section at the narrowing 6 must be opened to such an extent that a suitable tool for placing a plug passes through it. Conventional solutions with a drill cutting head however are often deflected laterally at such a narrowing 6 and bind. For this reason, here an abrasive suspension eroding system is used in combination with a drilling fluid conduit 9 of a borehole facility 10, wherein the drilling fluid conduit 9 is normally envisaged for efficiently conveying drilled rock to the surface on drilling with a drilling cutting head. The drilling fluid conduit 9 is brought into the deep-sea bore 1 via a platform 7 of the borehole facility 10, here in the form of a ship. An eroding unit 11 is fluid-connected to the drilling fluid conduit 9 at the distal end of the drilling fluid conduit 9. The eroding unit 11 is positioned in the deep-sea bore 1 within the well 5 directly above the narrowing 6. The eroding unit 11 is mechanically coupled to the drilling fluid conduit 9 in a manner such that the eroding unit 11 is positionable from the platform 7 by way of rolling in and rolling out the drilling fluid conduit 9. Herein, the intrinsic weight of the drilling fluid conduit 9 and of the eroding unit 11 can be used in the distal direction or an advance device can be provided, in particular for the advance given horizontal or relatively non-steep sections of the stretch.

(15) The eroding unit 11 comprises a distal nozzle head section 13 and a proximal anchoring section 15. The anchoring section 15 can be anchored by way of lateral anchoring elements 16, here in the form of toggle levers. The nozzle head section 13 is extendable in the distal direction relative to the anchoring section 15. A nozzle head 17 which is rotatable relative to a nozzle head base 19 of the nozzle head section 17 is located at the distal end of the nozzle head section 13. Several outlet nozzles are arranged at a face side of the nozzle head 17. The outlet nozzles are arranged such that exiting erosion jets form a jet fan. On rotation of the nozzle head 17, each erosion jet which encloses an angle with the rotation axis R sweeps a cone-surface-shaped eroding surface. Concerning erosion jets which have a radially inwardly directed component and which intersect the rotation axis R or run skew to this, an eroding surface in the form of an outer surface of a rotation body of two cones or truncated cones which lie on one another with their tips results.

(16) The borehole facility 10 further comprises a drilling fluid return 14, through which the drilling fluid together with the eroded material and the abrasive agent is flushed to the surface to the platform 7. The drilling fluid thus runs through a circuit, wherein the drilling fluid which is delivered to the surface is separated from the eroded material and abrasive agent on the platform 7 and is processed for reuse.

(17) In FIG. 2, another embodiment of a nozzle head 17 is used, in order to laterally erode open a well 5, in order to ensure that a concrete plug which is to be poured in at a later stage is anchored radially in the rock and that the well cannot be pressed upwards. One or more exit nozzles are directed radially outwards for the lateral eroding-open, so that a disc-like eroding surface which severs the well 5 at the peripheral side forms on rotation of the nozzle head 17.

(18) In FIG. 3, a fish 20 in the form of a packer is located in the well 5 and blocks this. Instead of applying a conventional method for fishing, the fish can be advancingly eroded by the eroding unit 11. The erosion jets, to which abrasive agent is added, given exist pressures of 500 or 700 bar can also erode very hard tool materials. Here, a derrick or a drilling rig is shown as a platform 7, in contrast to FIGS. 1 and 2.

(19) With the embodiment in FIG. 4, a so-called side tracking is operated with the eroding unit 11. Herein, the eroding unit can be steered into a lateral branching and can be used there for eroding blockages or narrowings. The deflecting of the eroding unit 11 into the branching can hereby take place via a side-tracing guide 21. It is to be understood that the deflection takes place given switched-off eroding jets, so that the side tracking guide 21 is not advancingly eroded.

(20) In FIG. 5, the circuit of the borehole facility 10 is shown schematically in more detail. The components which are located on the platform 7 are represented in dashed boxes. The eroding unit 11 which received into the existing borehole facility 1 is connected to the platform 7 via a drilling fluid conduit 9 and a signal lead 23. A drilling fluid high-pressure pump 25 which is arranged on the platform 7 pumps drilling fluid at a high pressure through the drilling fluid conduit 9 to the eroding unit 11. A control unit 27 is signal-connected to the eroding unit 11 via the signal lead 23 in order to switch, control, regulate, anchor and/or advance this. Herein, the signal lead 23 can be bidirectional, so that not only can the eroding unit 11 receive control commands but can also send signals of sensors, operating state variables, error notices, camera pictures or the like, to the control unit 27. For example, position or speed meters can measure the position of actuators for the anchoring elements 16, 53, the speed of the nozzle head 17 or the feed speed, temperature sensors control the temperature, acceleration sensors measure the spatial orientation, structure-borne sound or infrared sensors scan the environment or depth and inclination meters assist in the position evaluation. The obtained information can be displayed to the user by way of the control unit 27 or be used directly for the regulation and control of the operation of the eroding unit 11.

(21) Abrasive agent is added to the drilling fluid, so as to be able to use the drilling fluid which is available to the eroding unit 11 at a high pressure of 500-700 bar via the drilling fluid conduit 9 for abrasive eroding. In the embodiment which is shown in FIG. 5, this takes place upstream which is to say at the suction side of the drilling fluid high-pressure pump 25. For this an abrasive agent supply unit 29 is arranged upstream of the drilling fluid high-pressure pump 25 between a supply pump 31 and a booster pump 33. The abrasive agent supply unit 29 comprises a mixing chamber 35 and a refilling funnel 37, wherein abrasive agent can be filled into the refilling funnel 37 in a manual or automatic manner and can run into the mixing chamber 35 which is arranged therebelow. This can take its course in a manner exclusively on account of gravity or only assisted by gravity. Alternatively or additionally, a conveying screw or the like can be used for leading abrasive agent in a defined abrasive agent flow into the mixing chamber 35 in a controlled manner. Alternatively or additionally, the drilling fluid flow which is produced by the supply pump 31 and the booster pump 33 can also be used for sucking the abrasive agent by way of the Venturi effect in the context of a mixing chamber 35 which functions as a jet pump. The abrasive agent is mixed with the drilling fluid within the mixing chamber 35 and downstream of the mixing chamber 35 forms a drilling fluid-abrasive agent suspension which is suitable for abrasive eroding. Here for example granite sand is a possible abrasive agent. The mixing ratio between the abrasive agent and the drilling fluid in the drilling fluid-abrasive agent suspension which is suitable for abrasive eroding can lie at about 1:9 and can be adjustable depending on the cutting performance requirements or can be set for a certain application purpose. At the suction side, the supply pump 31 is connected to a drilling fluid tank 39, from which the supply pump 31 obtains the drilling fluid. The drilling fluid tank 39 in turn is filled by way of already used and recovered drilling fluid.

(22) For this, the drilling fluid-abrasive agent suspension together with eroded material such as eroded rock or the material of a fish or of a well wall can brought to the surface by way of a suction pump 41 via the drilling fluid return 14 which is received in the borehole 1. The suction pump 41 can possibly also only assist an already existing pressure difference and/or one which is produced by the drilling fluid high-pressure pump 25, said pressure difference pressing the drilling sludge upwards. The drilling fluid which is brought to the surface is led into a processing module 43. The processing module 43 comprises a shaker or shale shaker which separates the drilling fluid from rock, so that the drilling fluid can be recycled and can be led from the processing module 43 into the drilling fluid tank 39. Here, the processing module 43 also comprises an abrasive agent separator 44, so that the abrasive agent can also be reused and possibly in a direct manner can be fed again in wet or moist form or after a drying, to the circuit via the refilling funnel 37. Additionally to the abrasive agent, an additive such as long-chained polymers can also be admixed via the mixing chamber. Such long-chained polymers can be water-soluble and can serve for improving the focusing of the erosion jets or of the abrasive agent which is contained therein, for increasing the exit speed and for reducing the wearing in high-pressure components.

(23) In the embodiment according to FIG. 6, the mixing chamber 35 of the abrasive agent supply unit 29 is arranged in the circuit downstream of the drilling fluid high-pressure pump 25. The abrasive agent supply unit 29 hereby comprises a pressure tank 45 and a high-pressure pump 47. The pressure tank 45 comprises an abrasive agent-water suspension or drilling fluid-abrasive agent suspension which by way of the high-pressure pump 25 is put under a pressure which is similar to that produced by the drilling fluid high-pressure pump 25. The abrasive agent as described beforehand is led and/or delivered into the mixing chamber 35, but now under high pressure. The pressure tank 45 can be configured such that a loading for the eroding is sufficient, so that the pressure tank 45 must firstly be relieved of pressure for a further eroding step, in order to fill it again for a new eroding step. Alternatively or additionally, the pressure tank 45 can also be filled cyclically and in an automatic manner via a lock system, so that a continuous operation without pressure relief is possible. Even if this embodiment is more complex than that which is shown in FIG. 5, here it is advantageous that the drilling fluid high-pressure pump 25 is not subjected to an increased wearing due to abrasive agent.

(24) FIGS. 7a)-f) show an eroding unit 11 in a more detailed manner in different stages on eroding a fish 20. Firstly, in a), the eroding unit 11 is positioned in front of the fish 20, so that the erosion jets can advancingly erode the fish. 20. For this, the anchoring section 15, given a suitable axial position, is anchored laterally with first anchoring elements 16 in the form of toggle levers. The nozzle head 17 is rotated and the erosion jets of drilling fluid-abrasive agent suspension which exit out of the exit nozzles form cone-surface-shaped eroding surfaces which advancingly erode the material of the fish 20. For this, the nozzle head 17 at its distal face side comprises at least two nozzles with different alignments. A first nozzle 49 is herein aligned such that an erosion jet which is directly obliquely radially outwards is produced, and a second nozzle 51 is herein aligned such that an obliquely radially inwardly directed erosion jet is produced. The first nozzle 49 as well as the second nozzle 51 has a distance to the rotation axis R of the nozzle head 17. The cone-surface-shaped eroding surface which is produced by the first nozzle 49 has a proximal-side cone tip, whereas the cone-surface-shaped eroding surface which is produced by the second nozzle 51 has a distal-side cone tip. By way of this, given a distal advance of the first nozzle 49 and of the second nozzle 51, the erosion jets can erode once radially from the inside to the outside and once radially from the outside to the inside in a complementary manner and thus efficiently advancingly erode a volume.

(25) On eroding, the nozzle head section 13 is extended distally relative to the anchored anchoring section 15 so that the cone-surface-shaped eroding surfaces sweep a volume of the fish 20, in order to hence advancingly erode this. In b), a maximal distal position of the nozzle head section 13 relative to the anchoring section 15 is reached, so that the rest of the fish 20 cannot be advancingly eroded if the eroding unit 11 is not advancingly driven. This can be effected via an advance device or, as is shown in c) and d), via second anchoring elements 53 which in the form of toggle levers are extended laterally out of the nozzle head section 13 and anchor the nozzle head section 13 in the well 5. The first anchoring elements 16 of the anchoring section 15 are retracted again. From c) to d), by way of retracting the anchored nozzle head section 13 into the anchoring section 15, one succeeds in the no longer anchored anchoring section 15 not pulling distally to the nozzle head section 13. The control unit 27 which controls all of this ensures a corresponding necessary feed of the drilling fluid conduit 9 and of the signal lead 23. In d), the nozzle head section 13 is then maximally retracted into the anchoring section 15, so that the second anchoring elements 53 can be retracted whist the first anchoring elements 16 can be extended again (see e)). In e), a further eroding step begins as in a) now for the remainder of the fish 20 at a deeper or more distal position. In f), the fish 20 has been completely advancingly eroded and the well section can be reached for placing the plug which lies below the (no longer existing) fish 20.

(26) FIGS. 8, 9 and 10 show the nozzle head 17 in more detail. At the proximal side, the nozzle head 17 is connectable to the nozzle head base 19 via a pipe connection 55. The pipe connection 55 is arranged concentrically to the rotation axis R and forms the feed of drilling fluid-abrasive agent suspension out of the drilling fluid conduit 9 into the nozzle head 17. The nozzle head 17 is itself rotatable with respect to the pipe connection 55, wherein the longitudinal axis L of the nozzle head 17 is eccentrically offset with respect to the rotation axis R. The cylinder-shaped envelope which with respect to the radius of the nozzle head 17 is radially enlarged by this offset and which is swept by the nozzle head 17 on rotation about the rotation axis R is represented in a dashed manner. The nozzle head 17 comprises three sections. A proximal entry section 57, a distal head section 59 and a middle section 61 which connects the entry section 57 to the head section 59. The pipe connection 55 leads into a proximal face side of the entry section 57. A flow guidance element with a spiral-shaped flow channel which brings the drilling fluid-abrasive agent suspension into rotation is seated within the middle section 61. The nozzles 49, 51 are arranged at a distal, face side of the head section 59 which here is preferably provided with at least one concave deepening 63. In this embodiment, there are two inner (first) nozzles 49a, 49b which are aligned inwards, wherein the erosion jet from an inner nozzle 49b intersects the rotation axis and the erosion jet from the other inner nozzle 49a runs skew to the rotation axis R. Optionally or additionally, the erosion jets here run at a different angle with respect to the rotation axis R. Optionally or additionally, there are two outer (second) nozzles 51a, 51b which are aligned outwards and whose erosion jets likewise run at a different angle with respect to the rotation axis R. Optionally or additionally, a virtual connection line between the first inner nozzles 49a, 49b here does not run perpendicularly to a virtual connection line between the second outer nozzles 5a, 51b (see FIG. 10). Optionally or additionally, the virtual connection line between the first inner nozzles 49a, 49b here does not run through the longitudinal axis L of the nozzle head 17 and/or not through the rotation axis R. Optionally or additionally, the distances of the first inner nozzles 49a, 49b to the longitudinal axis L and/or to the rotation axis R are different in each case. In FIG. 10, it is illustrated by way of the dashed cycles with a different radius that different cone-surface-shaped eroding surfaces are swept by the respective erosions jets due to the specific alignment of the second outer nozzles 51a, 51b. In each case the erosion jets of the first two inner nozzles 51a, 51b sweep different cone-surface-shaped eroding surfaces.

(27) FIG. 11 schematically shows method steps as a flow diagram. Before, after or during a letting-down 1101 of an eroding unit into the existing borehole, abrasive agent is fed 1103 into the drilling fluid conduit by way of the abrasive agent supply unit, preferably upstream of the drilling fluid high-pressure pump 25. The drilling fluid-abrasive agent suspension which hence arises is pumped 1105 through the drilling fluid conduit to the eroding unit and a high-pressure erosion jet of the drilling fluid-abrasive agent suspension is produced 1107. Material in the existing borehole is then eroded 1109 by the thus produced high-pressure erosion jet. All method steps are preferably carried out in parallel. A distal moving 1111 of the nozzle head section 13 relative to the anchoring section 15, an anchoring 1113 of the anchoring section 15 and/or of the nozzle head section 13 and an eccentric rotating 1115 of the nozzle head 17 is preferably carried out parallel to the other method steps.

(28) The numbered indications of the components or movement directions as “first”, “second”, “third” etc. have herein been selected purely randomly so as to differentiate the components or the movement directions amongst one another, and can also be selected in an arbitrarily different manner. Hence these entail no hierarchy of significance.

(29) Equivalent embodiments of the parameters, components or functions which are described herein and which appear to be evident to a person skilled in the art in light of this description are encompassed herein as if they were explicitly described. Accordingly, the scope of the protection of the claims is also to include equivalent embodiments. Features which are indicated as optional, advantageous, preferred, desired or similarly denoted “can”-features are to be understood as optional and as not limiting the protective scope.

(30) The described embodiments are to be understood as illustrative examples and no not represent an exhaustive list of possible alternatives. Every feature which has been disclosed within the framework of an embodiment can be used alone or in combination with one or more other features independently of the embodiment, in which the features have been described. Whilst at least one embodiment is described and shown herein, modifications and alternative embodiments which appear to be evident to a person skilled in the art in the light of this description are included by the protective scope of this disclosure. Furthermore the term “comprise” herein is neither to exclude additional further features or method steps, nor does “one” exclude a plurality.

(31) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.