Apparatus and method for providing a separable electrical connection

Abstract

Device and method for producing a separable electrical connection in a borehole at least partially filled with a liquid. The device comprises a first connecting element with a first contact element; a second connecting element with a second contact element; wherein the first connecting element is provided for being fixed in a liquid-filled section of the borehole; wherein the second connecting element is provided for being inserted into the liquid-filled section of the borehole to connect with the first connecting element; and wherein the first contact element and / or the second contact element are exposed without protection.

Description

Field of invention

[0001] The disclosure relates to a device for producing a separable electrical connection in a borehole at least partially filled with liquid and a method for producing a separable electrical connection in a borehole at least partially filled with liquid. State of the art

[0002] Electrical connections for boreholes are known from the prior art. DE 10 2017 006 286 B3 describes, as an example, connectors with a multi-layer insulating gel sealing arrangement.

[0003] However, the prior art has disadvantages regarding the complexity of the connection setup. In the prior art, the contact elements must be protected from exposure to any fluid present in the borehole before the electrical connection is established. Typically, a protective device is moved during the connection process, allowing the actual connection setup to take place in a dry environment. Disclosure of the invention

[0004] The object of the invention is to provide a device for producing a separable electrical connection in a borehole at least partially filled with a liquid, which is an improvement over the prior art. In particular, a device is to be provided in which at least one contact element of the electrical connection is exposed without protection.

[0005] The problem is solved by a device for producing a separable electrical connection in a borehole at least partially filled with a liquid according to claim 1 and a method for producing a separable electrical connection according to the dependent claim.

[0006] One aspect concerns a device for creating a separable electrical connection in a borehole at least partially filled with liquid. The device comprises a first connecting element with a first contact element; a second connecting element with a second contact element; wherein the first connecting element is designed to be fixed in a liquid-filled section of the borehole; wherein the second connecting element is designed to be inserted into the liquid-filled section of the borehole to connect with the first connecting element; and wherein the first contact element and / or the second contact element are exposed without protection.

[0007] Another aspect concerns a method for producing a separable electrical connection between a first connecting element, comprising a first contact element, and a second connecting element, comprising a second contact element, in a borehole at least partially filled with a liquid. The method comprises inserting the first connecting element into the borehole; securing the first connecting element in the borehole; inserting the second connecting element into a liquid-filled section of the borehole, wherein the first contact element and / or the second contact element are exposed to the liquid, at least temporarily, during the insertion of the second connecting element; and bringing the first contact element into contact with the second contact element in the liquid-filled section of the borehole.

[0008] Where the following list contains "or", it means "and / or" unless otherwise stated.

[0009] In typical embodiments, the separable electrical connection comprises a first connecting element and a second connecting element. The separable electrical connection is typically established between the first connecting element and the second connecting element.

[0010] Typically, the first connecting element is designed to be fixed in a fluid-filled section of a borehole. The borehole is typically at least partially filled with a fluid, particularly water or oils. The fluid is typically electrically conductive, with a particular electrical conductivity of at least 100 µS / cm, at least 500 µS / cm, at least 1 mS / cm, or at least 5 mS / cm. The borehole may be at least 20 m, 50 m, 100 m, 250 m, 500 m, 1 km, 2 km, or at least 5 km long. In typical embodiments, the borehole is a vertical bore into the subsurface. In other embodiments, at least part of the borehole may be a horizontal borehole.

[0011] The first connecting element can be fixed in the borehole as part of a drill string or pipe installed there. In typical embodiments, the drill string or pipe installed in the borehole extends to the surface. In typical embodiments, the first connecting element is not anchored to the surface in the fluid-filled section of the borehole.

[0012] Typically, the first fastener is mechanically or chemically bonded to the borehole wall. A mechanical bond might include, for example, a swage packer or a bridge plug. The mechanical bond can be introduced into the borehole using a clamping device. In particular, the clamping device is tensioned in a desired installation position of the first fastener. Typically, the mechanical bond might involve mechanical deformation of the first fastener. A chemical bond might, in particular, involve bonding with a cement, adhesive, or resin. Typically, the first fastener is open along a longitudinal axis.

[0013] Typically, the first connecting element is linked to a functional element connected to the borehole. The functional element may include a sensor, in particular for acquiring hydrogeological data or borehole parameters such as temperature, pressure, the acidity or alkalinity of the borehole fluid (pH value), or the redox potential (EH value); a data storage device, in particular for storing sensor data; an energy storage device, in particular for storing electrical energy; or an actuator, in particular for manipulating a valve, gate, or mechanical connection, a motor, or a pump. The functional element typically includes a microprocessor, in particular for processing data or controlling the functional element.In typical embodiments, the functional element is inserted into the borehole together with the first connecting element or is formed as a single unit with the first connecting element. The functional element can also be referred to as a landing pod.

[0014] Typically, the second connecting element is designed to be inserted into the fluid-filled section of the borehole for connection with the first connecting element. In particular, once inserted into the fluid-filled section, the second connecting element may be completely surrounded by the fluid.

[0015] In typical embodiments, the device includes a cable connecting the second connecting element to an evaluation unit located outside the borehole. The evaluation unit typically includes a communication device with the first connecting element. In particular, the evaluation unit can read sensors or data storage devices of a functional element connected to the first connecting element. In typical embodiments, the evaluation unit can control the functional element. In particular, the evaluation unit can transmit operating instructions to the functional element; for example, the evaluation unit can program the microprocessor of the functional element or store operating instructions in the data storage device. The second connecting element can typically establish unidirectional or bidirectional data transmission between the evaluation unit and the functional element.In some embodiments, the evaluation unit can supply energy to the energy storage device, in particular by charging electrical energy into the energy storage device. In other embodiments, the evaluation unit can control the actuator of the functional element.

[0016] Typically, the length of the cable connecting the second connecting element to an evaluation unit is at least equal to the distance of the first connecting element from the surface or from the evaluation unit. In typical embodiments, the cable length is at least 50 m, 100 m, 250 m, 500 m, 1 km, 2 km, or at least 5 km. In some embodiments, the cable comprises a plurality of individual cables connected to form the cable. In other embodiments, the cable comprises a steel cable. Typically, the cable comprises one or more conductors.

[0017] Typically, the cable is electrically insulated from the second connecting element. In particular, the second connecting element has a feedthrough for the cable into its interior. This feedthrough is typically sealed against the fluid in the borehole, and in particular, watertight. It is also typically pressure-tight, especially against the pressure of the fluid column above the second connecting element.

[0018] Typically, the second connecting element has a fastening device for attaching it to a rod, a piston that can be pumped into the borehole, a winch, or a borehole tractor. In particular, the fastening device can enable the positioning of the second connecting element within the borehole.

[0019] The first connecting element has a first contact element, and the second connecting element has a second contact element. Typically, the first contact element is in contact with the second contact element when the first and second connecting elements are connected.

[0020] Typically, the first contact element is electrically connected to the functional element. Typically, the second contact element is electrically connected to the cable, and in particular to the evaluation unit.

[0021] In typical embodiments, the first connecting element and the second connecting element each have a plurality of contact elements. In particular, the first connecting element has 2, 3, 4, 5, 8, 10 or more contact elements. In particular, the second connecting element has 2, 3, 4, 5, 8, 10 or more contact elements. Typically, the first connecting element and the second connecting element have the same number of contact elements. In typical embodiments, the arrangement of the contact elements of the first connecting element and the contact elements of the second connecting element is the same, so that, in particular, when the first connecting element is connected to the second connecting element, all contact elements of the first connecting element are in contact with contact elements of the second connecting element.

[0022] In typical embodiments, the plurality of contact elements of the first connecting element or the plurality of contact elements of the second connecting element is arranged along a longitudinal axis of the borehole. In particular, the plurality of contact elements of the first connecting element or the plurality of contact elements of the second connecting element do not overlap along the longitudinal axis of the borehole.

[0023] Typically, at least one of the contact elements, in particular the first or second contact element, is exposed in a disconnected state, especially to the fluid in the borehole. The disconnected state includes, in particular, a state in which the first and second contact elements are not in physical contact with each other.

[0024] Typically, at least one of the contact elements has a self-passivating surface. This self-passivating surface forms a non-conductive surface layer, particularly upon contact with the liquid, for example, water, which electrically insulates the contact element from the liquid.

[0025] Typically, the self-passivating surface comprises a transition metal, especially niobium (Nb) or tantalum (Tb).

[0026] Typically, the self-passivating surface can be advantageously worn away mechanically, for example by friction against another surface, so that, in particular, an electrically conductive connection can be established. If the self-passivating surface is located in the liquid during a wear process, an electrical connection can advantageously be established between two surfaces, in particular between the surface of the first contact element and the surface of the second contact element, whereby sections of the surface that are not in direct physical contact are insulated by the self-passivation.

[0027] In typical embodiments, all contact elements, in particular the first contact element and the second contact element, have a self-passivating surface.

[0028] Typically, one of the contact elements comprises a U-shaped contact surface, particularly along the longitudinal axis of the borehole. In particular, the U-shaped contact surface is resiliently designed. This can advantageously ensure a stable yet separable contact between the contact elements. Typically, the U-shaped contact surface is designed such that a desired position of the contact element is centered in the longitudinal direction. In other words, the contact of the U-shaped contact element is preferably established substantially centered in the longitudinal direction. In embodiments, at least one of the contact surfaces, and in particular a plurality or all of the contact surfaces, is designed as a linear contact surface.

[0029] In embodiments, one of the contact elements comprises a plurality of U-shaped contact surfaces. In particular, one of the contact elements comprises 2, 3, 4, 5, 6, 8, 10, or 12 U-shaped contact surfaces, arranged, for example, radially or rotationally symmetrically about a longitudinal axis of the connecting element or about the longitudinal axis of the borehole. In typical embodiments, the plurality of U-shaped contact surfaces are substantially symmetrical with respect to a plane perpendicular to the longitudinal axis of the connecting element. In embodiments, one of the contact elements comprises a contact housing or a holder with a plurality of openings for the passage of U-shaped contact surfaces. Typically, the contact housing or the holder comprises an insulating plastic or a ceramic. The contact housing or the holder may, in particular, comprise polyetherketones (PEK), especially polyetheretherketone (PEEK), polyvinylidene fluoride (PVDF), or polyetherimides (PEI).

[0030] Typically, another contact element comprises a cylindrical, hollow cylindrical, or annular contact surface. In typical embodiments, the axis of rotation of the cylindrical or hollow cylindrical base of the contact surface is aligned along the longitudinal axis of the borehole. In typical embodiments, the contact surface extends continuously around the cylinder. In other embodiments, the contact surface is structured around the cylindrical shape, in particular, the contact surface includes recesses. In other embodiments, the contact element comprises a recess, in particular to define a preferred position for the U-shaped contact surface. In other embodiments, the cylindrical, hollow cylindrical, or annular contact surface is embedded in a support structure. In particular, the support structure can isolate contact surfaces and advantageously reduce the material requirement for the self-passivating materials.The support structure can comprise polyetheretherketone (PEEK) or polyetherimide (PEI).

[0031] Typically, the length of the U-shaped contact surface is equal to or greater than the length of the cylindrical, hollow cylindrical, or annular contact surface. In particular, the length of the U-shaped contact surface is at least 105%, 125%, 150%, or 200% of the length of the cylindrical, hollow cylindrical, or annular contact surface. In typical embodiments, the length of the U-shaped contact surface is at least 10 mm, at least 25 mm, or at most 35 mm or at most 50 mm; in particular, the length of the U-shaped contact surface is at least 10 mm and at most 50 mm; preferably, the length of the U-shaped contact surface is 30 mm. A longer U-shaped contact surface advantageously increases the insertion positions of the second connecting element at which contact can be established between the first and second contact elements.In contrast, a shorter, U-shaped contact surface can advantageously enable more compact designs and can reduce the material requirement, especially for a material that forms a self-passivating surface.

[0032] Typically, the U-shaped contact surfaces protrude from a base body, in particular a cylindrical base body, of the connecting element. Specifically, the maximum distance of the U-shaped contact surface to the longitudinal axis of the connecting element is at least 3%, at least 5%, or at least 7.5%, or at most 10%, at most 15%, or at most 25% greater than the circumradius of the base surface of the base body.

[0033] In typical embodiments, the U-shaped contact surface or the cylindrical, hollow cylindrical, or annular contact surface includes chamfers or radii, particularly to facilitate the insertion of the second connecting element into the first connecting element. Typically, the chamfers or radii are oriented along the longitudinal axis of the connecting element.

[0034] In typical embodiments, the first contact element comprises a U-shaped contact surface. Typically, the second contact element comprises a cylindrical contact surface.

[0035] In typical embodiments, the first contact element comprises a hollow cylindrical contact surface. Typically, the second contact element comprises a U-shaped contact surface. Typically, the inner diameter of the hollow cylindrical contact surface is less than or equal to the inner diameter of a tubing of the borehole.

[0036] Typically, the first connecting element comprises a first, in particular mechanical, positioning element, and the second connecting element comprises a second, in particular mechanical, positioning element. The first and second positioning elements are configured such that a preferred position of the second connecting element relative to the first connecting element can be set. In particular, one of the connecting elements may have a recess and another of the connecting elements may have a protrusion, wherein, in particular, the shape of the protrusion substantially mirrors the shape of the recess.

[0037] In typical embodiments, the connecting elements each comprise a plurality of contact elements. Typically, each contact element has a fixed function assigned to it. Examples include contact elements for supplying power to an energy storage device, contact elements for reading or programming sensors or data storage devices, or contact elements for controlling an actuator.

[0038] In some embodiments, the first connecting element and the second connecting element comprise a different number of contact elements. In particular, the first connecting element comprises fewer contact elements than the second connecting element. For example, the first connecting element may lack a contact element for controlling an actuator if no actuator is connected to the first connecting element.

[0039] In typical embodiments, a plurality of first connecting elements are fixed in the borehole. This can advantageously allow for a plurality of functional elements at different positions, particularly at different depths of the borehole. For example, borehole parameters can be measured at different positions, or actuators can be provided at different positions within the borehole. In these embodiments, the plurality of first connecting elements are of the same design and, in particular, comprise the same number of contact elements.

[0040] Typically, the second connecting element can pass through at least some of the plurality of first connecting elements. In embodiments, the second connecting element can pass through all of the first connecting elements. This can, in particular, allow access to first connecting elements fixed deeper in the borehole. Typically, inserting the second connecting element into the fluid-filled section of the borehole can involve movement from the borehole opening deeper into the borehole or movement toward the borehole opening. Typically, the first connecting element comprises an opening at both axial ends, in particular for inserting the second connecting element.

[0041] Typically, a separable electrical connection allows the fluid in the borehole to flow through. Specifically, a fluid can flow through the separable electrical connection, for example, essentially along the borehole axis. In other words, the separable electrical connection is open. The separable electrical connection is typically sealless, meaning it lacks a separate seal around the electrical contact area.

[0042] Typically, the second connecting element comprises a central connecting element that joins the second contact element, the cable, and the fastening device. The central connecting element is typically made of steel, stainless steel, aluminum, or titanium. The second connecting element also typically has an end element connected to the central connecting element, which in particular has an interface, for example a thread, for connecting further elements, for example a centering device.

[0043] In typical embodiments, to create a separable electrical connection between a first connecting element, comprising a first contact element, and a second connecting element, comprising a second contact element, in a borehole at least partially filled with a liquid, the first connecting element is inserted into the borehole. Typically, the first connecting element is permanently inserted into the borehole. The first connecting element can be inserted as part of a borehole extension or as a single, fixed component.

[0044] Typically, the first connecting element is attached at a point of use within the borehole. Specifically, the first connecting element is attached at a predefined location, for example, at a predefined depth within the borehole.

[0045] Typically, the second connecting element is inserted into the fluid-filled section of the borehole. This second connecting element can be inserted into the borehole by gravity, particularly attached to the cable, a drill string, a continuous tube (coil tubing), by pumping, or using a borehole tractor.

[0046] Typically, the first contact element or the second contact element is exposed to the fluid in the borehole, at least temporarily, during the insertion of the second connecting element. In particular, the fluid is in physical contact with the first contact element or the second contact element, at least temporarily. Typically, neither the first connecting element nor the second connecting element has a protective device to prevent exposure to the fluid.

[0047] Typically, the first contact element is brought into contact with the second contact element. In particular, the second contact element is mechanically moved towards the first contact element. In typical embodiments, bringing them into contact involves material removal from a surface, especially a contact surface, of at least one of the contact elements. Typically, bringing them into contact involves material removal from a surface of the first contact element and material removal from a surface of the second contact element.

[0048] In typical embodiments, a force is exerted, particularly by the U-shaped contact element, on a contact surface between the first and second contact elements. Typically, this force acts essentially perpendicular to the contact surface and can lead to material removal from the self-passivating surface. In other words, material is removed from the self-passivating surface of at least one of the contact elements by means of scratching.

[0049] Typically, the first and second contact elements remain in physical, and especially electrically conductive, contact after material removal. Immediate contact after material removal advantageously prevents the re-formation of a self-passivating surface in the immediate contact area. In areas of the contact element surface from which material has been removed, but where there is no immediate contact between the first and second contact elements, a self-passivating surface advantageously re-forms, particularly due to the presence of liquid.

[0050] This advantageously allows for reliable isolation of the connecting elements outside the desired connection.

[0051] After the separable electrical connection is broken, the first and second contact elements are typically exposed to the liquid again without protection. This advantageously leads to the formation of a new self-passivating surface, and the first or second contact element is once again insulated.

[0052] In typical embodiments, inserting the second connecting element into the fluid-filled section of the borehole involves moving the second connecting element towards the borehole opening. Typically, a plurality of first connecting elements are fixed in the borehole, particularly in different sections of the borehole. The second connecting element can typically be inserted into the first connecting element by moving either towards or away from the borehole opening. In other words, the second connecting element can be inserted into the first connecting element from both sides, specifically from above as well as from below.

[0053] In typical embodiments, the first or second contact element is not de-energized when the connection is brought into contact or after it is broken. This can advantageously allow immediate use of the separable electrical connection after the physical and electrical contact has been established.

[0054] The invention enables a simplified, wet-pluggable, separable electrical connection. In particular, the connection can be achieved without separate sealing of the contact elements. The invention achieves insulation of the contact elements, especially through a self-passivating surface. At points where the contact elements are exposed to the fluid in the borehole, an insulating surface layer forms due to the advantageous properties of the contact elements. When the contact elements are in contact with each other, an electrical connection is advantageously ensured.

[0055] The invention reduces the complexity of the electrical connection, particularly during operation. This reduces maintenance requirements and simplifies connection establishment. The invention allows for connection elements without devices to protect the contact elements from exposure to the fluid in the borehole and reduces the required installation space for the contact elements. Brief description of the drawing

[0056] The invention is explained in more detail below with reference to the accompanying drawings, the figures of which show schematic representations: Fig. 1 shows an embodiment of the invention in a longitudinal section. Fig. 2a shows a connecting element according to the invention in a longitudinal section; Fig. 2 shows another connecting element according to the invention in a front view; Fig. 3 shows a method according to the invention. Description of embodiments

[0057] Typical embodiments are described below with reference to the figures, although the invention is not limited to these embodiments. Rather, the scope of the invention is defined by the claims. In describing the embodiments, the same reference numerals may be used in different figures and for different embodiments to make the description clearer. However, this does not mean that corresponding parts of the invention are limited to the variants shown in the embodiments. For the sake of clarity, some features that have already been described in connection with other figures are not described again. In some cases, features that are shown multiple times in a figure are only identified by reference numerals once.

[0058] The Figure 1Figure 100 shows a device for producing a separable electrical connection in a borehole 200 that is at least partially filled with a liquid. In the Fig. 1 Only a section of borehole 200 is shown. Borehole 200 extends across the area described in the Fig. 1 beyond the section shown. The device comprises a first connecting element 10 with first contact elements 11, 12, 13 and a second connecting element 20 with second contact elements 21, 22, 23. In the Figure 1 The first connecting element 10 comprises three first contact elements 11, 12, 13 and the second connecting element 20 comprises three second contact elements 21, 22, 23.

[0059] The first connecting element 10 is fixed in the borehole 200. In particular, the first connecting element 10 is connected to a functional element 31. The first connecting element 10 is embedded in the functional element 31 and is fixed in the borehole 200 by the functional element 31. The first contact elements 11, 12, 13 of the first connecting element 10 are connected to the functional element 31 via electrical conductors 32. Each of the first contact elements 11, 12, 13 is assigned a separate electrical conductor 32. The first contact elements 11, 12, 13 essentially have a flat contact surface 16. Typically, the contact surface 16 has a self-passivating surface.

[0060] The first connecting element 10 has an opening at each end along a longitudinal axis of the borehole 200. The opening is designed such that the second connecting element 20 can be inserted through both ends of the first connecting element 10. The second connecting element 20 can be passed through the first connecting element 10, in particular along the longitudinal axis of the first connecting element 10.

[0061] The second connecting element 20 has a cable head 35 for receiving a cable 33. The cable head 35 connects the interior of the second connecting element 20 to the cable 33. The cable head 35 is typically designed with a seal. The cable 33 connects the second connecting element 20 to an evaluation device outside the borehole 200. The cable 33 can be used to position the second connecting element 20 in the borehole 200, in particular for positioning it along a longitudinal axis of the borehole 200. The second connecting element 20 has a termination element 37. The termination element 37 and the cable head 35 are arranged at opposite ends of the second connecting element 20.In particular, the cable head 35 is arranged at one end of the second connecting element 20 facing the mouth of the borehole 200 and the end element 37 is arranged at one end of the second connecting element 20 facing away from the mouth of the borehole 200.

[0062] The second contact elements 21, 22, 23 have a U-shaped contact surface. The U-shaped contact surface essentially follows a circular arc. Each of the second contact elements 21, 22, 23 is connected to the cable 33 via connecting leads 41, 42, 43. The connecting leads 41, 42, 43 are connected from the cable head 35 to the second contact elements 21, 22, 23 through a hollow interior of the second connecting element 20. The second contact elements 21, 22, 23 are inserted into an electrically insulating holder 25. Typically, the second contact elements 21, 22, 23 are spring-loaded or spring-loaded within the holder 25.

[0063] In the Fig. 1The first connecting element 10 and the second connecting element 20 are in contact with each other. Specifically, the first contact elements 11, 12, 13 are in contact with the second contact elements 21, 22, 23. The second contact elements 21, 22, 23 exert a force on the surface of the first contact elements 11, 12, 13. When the second connecting element 20 is inserted into the first connecting element 10, the force exerted by the second contact elements 21, 22, 23 on the first contact elements 11, 12, 13 removes material from the surface of the first contact elements 11, 12, 13 and the second contact elements 21, 22, 23.

[0064] The Figure 2a Figure 1 shows a second connecting element 20 according to the invention in a longitudinal section. The second connecting element of the Fig. 2aThe device has two secondary contact elements 21, 22. These secondary contact elements 21, 22 are ring-shaped, i.e., hollow cylindrical. They are mounted in an electrically insulating holder 25 and are insulated from each other by the holder 25. Each secondary contact element 21, 22 is connected to a connecting lead 41, 42. The end element 37 has a thread for receiving additional elements or attachments. Typically, the end element 37 is screwed onto the secondary connecting element 20 and can therefore be easily adjusted or replaced.

[0065] The Figure 2b Figure 1 shows a second connecting element 20 according to the invention in a front view. The second connecting element of the Fig. 2bThe second connecting element 20 has two second contact elements 21, 22. The second contact elements 21, 22 are U-shaped. The contact surfaces of the second contact elements 21, 22 project radially beyond a substantially cylindrical base of the second connecting element. The second connecting element 20 has an electrically insulating holder 25, which substantially follows the outer contour of the second connecting element 20. The holder 25 has a plurality of slit-shaped openings 28; in Fig. 4, two slit-shaped openings 28 are shown, and four further slit-shaped openings are not visible due to the perspective of the illustration. In total, the holder has six slit-shaped openings 28. The second contact elements 21, 22 are received in the slit-shaped openings 28 and project radially beyond them. Each of the second contact elements 21, 22 comprises six U-shaped contact surfaces.

[0066] The Figure 3Figure 300 shows a method 300 according to the invention. The method 300 comprises inserting the first connecting element with a first contact element into the borehole. The inserted first connecting element is secured in the borehole 320. The second connecting element with a second contact element is inserted into the borehole 330, wherein the first contact element or the second contact element is exposed to the fluid in the borehole, at least temporarily, during the insertion 330 of the second connecting element. The method 300 further comprises bringing the first contact element into contact with the second contact element in a fluid-filled section of the borehole 340.

Claims

1. Device (100) for producing a separable electrical connection in a borehole (200) at least partially filled with a liquid, comprising: a first connecting element (10) with a first contact element (11, 12, 13); a second connecting element (20) with a second contact element (21, 22, 23); wherein the first connecting element (10) is provided to be fixed in a liquid-filled section of the borehole (200); wherein the second connecting element (20) is provided to be inserted into the liquid-filled section of the borehole (200) for connection with the first connecting element (10); and wherein the first contact element (11, 12, 13) and / or the second contact element (21, 22, 23) are exposed without protection.

2. Device according to claim 1, wherein at least one of the contact elements (11, 12, 13, 21, 22, 23) has a self-passivating surface.

3. Device according to one of the preceding claims, wherein one of the contact elements (11, 12, 13, 21, 22, 23) comprises a stirrup-shaped contact surface, in particular wherein a further contact element (11, 12, 13, 21, 22, 23) comprises a cylindrical or a hollow cylindrical contact surface.

4. Device according to one of the preceding claims, wherein the second connecting element (20) can be inserted into the first connecting element (10) from both sides.

5. Device according to one of the preceding claims, wherein the first connecting element (10) is connected to a functional element (31) connected to the borehole, which comprises a sensor, a data storage device, an energy storage device and / or an actuator.

6. Device according to one of the preceding claims, further comprising a cable (33) for connecting the second connecting element (20) to an evaluation device outside the borehole (200).

7. Device according to one of the preceding claims, wherein the first connecting element (10) and the second connecting element (20) each have a plurality of contact elements (11, 12, 13, 21, 22, 23) and the plurality of contact elements (11, 12, 13, 21, 22, 23) are arranged along a longitudinal axis of the borehole (200).

8. Device according to one of the preceding claims, wherein the first connecting element (10) and the second connecting element (20) have the same number of contact elements (11, 12, 13, 21, 22, 23).

9. Device according to one of the preceding claims, wherein the first connecting element (10) is essentially hollow cylindrical.

10. Device according to one of the preceding claims, wherein the second connecting element (20) has a fastening device for attachment to a rod, a piston, a winch and / or a borehole tractor.

11. Method (300) for producing a separable electrical connection between a first connecting element (10), comprising a first contact element (11, 12, 13), and a second connecting element (20), comprising a second contact element (21, 22, 23), in a borehole (200) at least partially filled with a liquid, the method comprising: inserting (310) the first connecting element (10) into the borehole (200); securing (320) the first connecting element (10) in the borehole (200); inserting (330) the second connecting element (20) into a liquid-filled section of the borehole (200), wherein the first contact element (11, 12, 13) and / or the second contact element (21, 22, 23) are exposed to the liquid at least temporarily during the insertion of the second connecting element (20);and bringing into contact (340) the first contact element (11, 12, 13) with the second contact element (21, 22, 23) in the liquid-filled section of the borehole (200).; 12. Method according to claim 11, wherein the first contact element (11, 12, 13) is exposed to the liquid unprotected after the first connecting element (10) has been fastened (310) in the borehole (200).

13. Method according to one of claims 11 or 12, wherein bringing into contact (340) the first connecting element (10) and the second connecting element (20) comprises material removal from a surface of at least one of the contact elements (11, 12, 13, 21, 22, 23).

14. Method according to one of claims 11 - 13, wherein the insertion (330) of the second connecting element (20) into the liquid-filled section of the borehole (200) comprises a movement of the second connecting element (20) towards an opening of the borehole (200).

15. Method according to one of claims 11 - 14, wherein the second connecting element (20) is inserted (330) by means of a rod, a pump, a winch and / or a borehole tractor.

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