WO2017105883A1

WO2017105883A1 - Wear-resistant electrode for a movable electrical connection

Info

Publication number: WO2017105883A1
Application number: PCT/US2016/064877
Authority: WO
Inventors: Daniel HENDRICKS; Neil Cannon; Jacques Orban; Scott Richard WOOLSTON
Original assignee: Schlumberger Technology Corporation; Schlumberger Canada Limited; Services Petroliers Schlumberger; Schlumberger Technology B.V.
Priority date: 2015-12-18
Filing date: 2016-12-04
Publication date: 2017-06-22

Abstract

Devices and methods to exchange electrical signals between objects presenting relative motion employing polycrystalline diamond electrodes are provided. The electrical connections may be formed between objects in rotational or translational relative motion.

Description

WEAR-RESISTANT ELECTRODE FOR A MOVABLE ELECTRICAL

CONNECTION

CROSS-REFERENCE

The present document is claims the benefit of and priority to U.S. Provisional

Application Serial No.: 62/269,245, filed December 18, 2015, which is incorporated herein by reference in its entirety.

BACKGROUND

This disclosure relates to wear-resistant polycrystalline diamond (PCD) electrodes to establish electrical connections between objects with relative movement.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as an admission of any kind.

While drilling through geological formations or prospecting boreholes, various sensors and tools may be placed in the wellbore to improve the operations. Often, these downhole devices communicate with surface-located control equipment through electrical signals. The signals may be transmitted through a drill string or a wireline, which employs electrical connections between components that move relative to each other. The high pressure, large forces and high temperatures in the wellbore environment makes engineering of these electrical connections particularly challenging. One technique to implement electrical connections between two moving parts is to use a spring loaded first electrode in the surface of one part electrode pressed against a second electrode in the surface of the second part. This design, which subjects the electrodes to some wear, may be implemented with graphite or metal brushes. The materials employed are very susceptible to wear damage, which limits their use in the hostile environment of wellbore applications. SUMMARY

A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

Embodiments of the disclosure relate to the use of polycrystalline diamond electrodes to produce wear-resistant electrical connections. The polycrystalline diamond (PCD) may be treated to obtain resistive or capacitive electrical connections. The electrical connection may be formed by using a polycrystalline electrode in contact with a non-polycrystalline electrode. The contact surface between of the electrodes may be of distinct shapes. In some examples, multiple electrode contact surfaces insulated from each other with PCD insulators or other wear-resistant insulators are employed to provide a multipole electrical connection.

In another example, the disclosure provides a drilling system containing PCD electrodes to provide electrical communication between a devices disposed in the surface and devices disposed in the wellbore. The electrical communication may be used for exchange of data or power between the devices disposed in the surface and the devices disposed in the wellbore. The electrical communication is provided through contact surfaces between electrodes attached to objects that rotate relative to each other. Furthermore, this disclosure discusses methods to transmit electrical signals between moving objects through contact surfaces using wear-resistant PCD electrodes. In some applications, the signals may be signals for control, sensing, imaging, or telemetry. In other applications, the signals may be provided for power. The transmission of signal may be of resistive or of capacitive nature. In further examples, multiple electrical signals may be exchange through different contact surfaces to obtain multipole transmission.

Various refinements of the features noted above may be undertaken in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:

FIG. 1 is a schematic diagram of a drilling system that includes a drill string carrying electrical signals through rotary connections, in accordance with an embodiment;

FIG. 2 is a flowchart of a method for manufacturing PCD with conductive electrical properties, in accordance with an embodiment;

FIG. 3 is a flowchart of a method for manufacturing PCD electrodes, in accordance with an embodiment;

FIG. 4 is a flowchart of a method to exchange electric signals between moving parts employing at least one PCD electrode, in accordance with an embodiment; FIG. 5 is a schematic diagram of an electrical connection through a contact surface established between moving parts, in accordance with an embodiment;

FIG. 6 is a schematic diagram of an electrical connection employing two unleached PCD electrodes, in accordance with an embodiment;

FIG. 7 is a schematic diagram of an electrical connection employing two leached PCD electrodes, in accordance with an embodiment;

FIG. 8 is a schematic diagram of an electrical connection employing one unleached PCD electrode and one leached PCD electrode, in accordance with an embodiment;

FIG. 9 is a schematic diagram of an electrical connection employing one leached PCD electrode and one metallic conductor, in accordance with an embodiment; FIG. 10 is a schematic diagram of an electrical connection employing one unleached

PCD electrode and one metallic conductor, in accordance with an embodiment;

FIG. 11 is a pair of graphs contrasting the difference between a capacitive and a resistive connection employing static PCD electrodes, in accordance with an embodiment; FIG. 12 is a graph illustrating the transmission of electric signals through a rotating journal bearing connection employing leached PCD electrodes, in accordance with an

embodiment;

FIG. 13 is a graph illustrating the transmission of electric signals through a rotating shear cutter connection employing an unleached PCD electrode and a conductor electrode, in accordance with an embodiment;

FIG. 14 is a frequency response graph illustrating the effect of oil and oil-based mud in an electrical connection between two PCD electrodes, in accordance with an embodiment;

FIG. 15 is a frequency response graph illustrating the effect of brine in an electrical connection between two PCD electrodes, in accordance with an embodiment;

FIG. 16 is a schematic diagram of a journal bearing connection employing two PCD electrodes, in accordance with an embodiment;

FIG. 17 is a schematic diagram illustrating eccentricity perturbations to a journal bearing connection, in accordance with an embodiment; FIG. 18 presents graphs illustrating the effect of eccentricity perturbations to electrical properties of the journal bearing connection, in accordance with an embodiment;

FIG. 19 presents a schematic diagram illustrating a journal bearing design employing an outer split ring, in accordance with an embodiment;

FIG. 20 is a frequency response graph comparing the performance of a solid journal bearing, as described in FIG. 16, with a split journal bearing, as described in FIG. 19.

FIG. 21 is a schematic diagram of a conical electrical connection employing two PCD electrodes, in accordance with an embodiment;

FIG. 22 is a flowchart of a method for manufacturing PCD with insulating electrical properties, in accordance with an embodiment; FIG. 23 is a schematic diagram of a dipole electrical connection through the contact surface established between moving parts, in accordance with an embodiment;

FIG. 24 is a schematic diagram of a dipole rotary electrical connection employing journal bearings within a wellbore application, in accordance with an embodiment;

FIG. 25 is a schematic diagram of a dipole rotary electrical connection employing conical electrodes within a wellbore application, in accordance with an embodiment; and

FIG. 26 is a schematic diagram of a multi-pole electrical connection employing counter- rotating surfaces within a wellbore application, in accordance with an embodiment.

DETAILED DESCRIPTION One or more specific embodiments of the present disclosure will be described below.

These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a

development effort might be complex and time consuming, but would be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

Drilling applications often use a drill bit attached to the bottom-hole assembly at the end of a drill string. Drilling occurs when a rig induces a rotation in the drill bit through the drill string. An inner spindle rotates relative to an outer shaft and pushes the drill bit against the geological formation. In order to improve drilling performance, several devices such as downhole tools and sensors can be attached to the bottom-hole assembly. These downhole devices may use an electrical connection with control equipment located in the surface. This connection is often implemented through conductors within the drill string. However, the relative rotation between the spindle and the stationary outer shaft in the drill string may require engineering of an electrical connection between moving parts. Friction from the relative motion between the electrodes establishing this electrical connection, along with the hostile wellbore environment, generates conditions for wear of the electrodes.

Poly-crystalline diamond (PCD) is a material manufactured through sintering of diamond grit. Additives, such as cobalt, act as catalyst to the sintering process and remain present in the structure. While the diamond itself is an electrical insulator, the residual cobalt may be electrically conductive. The resulting product, a hard material with potential to transmit electricity, can be used to manufacture polycrystalline diamond electrodes that are resistant to wear.

With this in mind, FIG. 1 illustrates a drilling system 10 that includes a logging tool employing a rotary electrical connection. The drilling system 10 may be used to drill a well into a geological formation 12 and employ downhole tools to identify characteristics of the geological formation 12 or to monitor the conditions of other tools in the bottom-hole assembly 34. In the drilling system 10, a drilling rig 14 at the surface 16 may rotate a drill string 18 having a drill bit 20 at its lower end. As the drill bit 20 is rotated, a drilling fluid pump 22 is used to pump drilling fluid 23, which may be referred to as "mud" or "drilling mud," downward through the center of the drill string 18 in the direction of the arrow to the drill bit 20. The drilling fluid 23, which is used to cool and lubricate the drill bit 20, exits the drill string 18 through the drill bit 20. The drilling fluid 23 then carries drill cuttings away from the bottom of a wellbore 26 as it flows back to the surface 16, as shown by the return drilling fluid 24 represented by arrows through an annulus 30 between the drill string 18 and the geological formation 12.

As illustrated in FIG. 1, the lower end of the drill string 18 includes a bottom-hole assembly 34 that may include the drill bit 20 along with various downhole tools. The downhole tools may collect a variety of information relating to the geological formation 12 and/or the state of drilling of the well. For instance, a measurement-while-drilling (MWD) tool 36 may measure certain drilling parameters, such as the temperature, pressure, orientation of the drilling tool, and so forth. Likewise, a logging- while-drilling (LWD) tool 38 may measure the physical properties of the geological formation 12, such as density, porosity, resistivity, lithology, and so forth. In certain embodiments, the tools may be located on a stabilizer blade of the bottom-hole assembly 34 or even the drill bit 20. The MWD tool 36 and/or the LWD tool 38 may collect a variety of data 40 that may be sent to the surface for processing. The data 40 that is collected may include electrical current levels that return to the electrical resistivity tool that may contain information relating to characteristics of the geological formation 12. The data 40 may also be encoded telemetry signals for monitoring and/or controlling downhole tools placed in the bottom-hole assembly 34. The data 40 may be sent via a control and data acquisition system 42 to a data processing system 44. The control and data acquisition system 42 may receive the data 40 in any suitable way. In a wired drill string, the data is transmitted through an electrical connection running through the drill string 18. Due to the relative rotation between the wired drill string 18 and the drilling rig 14, the electrodes establishing the electrical connection at the rotating contact surface are subject to friction from the relative motion. In several embodiments, PCD electrodes are used to provide a wear-resistant rotary electrical connection.

The flowchart in FIG. 2 describes a method to manufacture a conductive PCD 58. A mixture of diamond grains along with a conductive catalyst (grit) is placed against a base material 60. Cobalt may be used as a catalyst in the manufacture of conductive PCD. It is expected that PCD with similar electrical properties can be obtained by employing other metal catalysts such as nickel-chromium, manganese, iron, nickel, ruthenium, rhodium, palladium and platinum in the sintering process. Application of pressure 62 and heat 64 leads to sintering of the PCD. At the end of the process, pressure and heat can be removed 66 resulting in a wear- resistant PCD conductor.

In several applications, a PCD electrode with specific geometries are employed. The flowchart in FIG. 3 describes a method to obtain a shaped PCD electrode 68. The grit materials along with the desired catalyst are mixed 70 and placed in the regions of an object where the electrical connection is desired. In some embodiments, the region will have a metallic contact to facilitate the electrical connection with a wire. Sintering is performed 74 and the material can be machined into the desired shape 76. The electrode surface may be leached as an optional process. The leaching changes the electrical properties of the electrode, as described below.

The flowchart in FIG. 4 illustrates a method to establish an electrical connection between objects with relative movement between them 88, such as in a wired drill string. Electrodes are manufactured attached to the objects that will be in contact 90. Once the objects are assembled, a contact surface is formed between the two electrodes 92. As long as the electrode surfaces remain in contact, an electrical signal injected in a first electrode 94 can be collected in the second electrode 96, regardless of relative motion. The diagram in FIG. 5 illustrates an example of a connection between two electrodes as described above. The two objects 100 and 102 are configured to move relative to each other with relative motion 104. An electrical connection between the two objects is desired to close an electrical circuit 106 with some electrical device 112. Electrode 108A is manufactured attached to object 100 whereas electrode 108B is manufactured attached to object 102. When the two electrodes 108A and 108B are placed against each other, the electric circuit is closed through the contact surface 110. The hardness of the PCD electrodes 108 allow wear-resistant connection through the contact surface 110 between objects 100 and 102 in the absence of lubricants, and under pressure or vibrations. In some applications, the relative motion 104 between the objects 100 and 102 can be parallel to the contact surface 110. In other applications, the relative motion between the electrodes will be a rotary one, as described below. The objects may also present a circular motion. The connection may be effective regardless of the type of motion, as long as the contact surface 110 between the two electrodes is preserved to an extent that electrical signals can be transmitted between the two electrodes.

Changes in the PCD electrode surface can produce different types of connections. The standard manufacture of a PCD electrode sintered with cobalt will produced exposed cobalt layers in the surface. The diagram in FIG. 6 illustrate a connection of two PCD electrodes 108A and 108B. The exposed cobalt layers in the surface of the electrodes will come into contact and may establish a resistive electrical connection. In contrast, a capacitive electrical connection may be obtained through leaching of PCD electrodes, as illustrated in FIG. 7. Through the optional leaching process 78 of FIG. 3, residual cobalt 114 is removed from the contact surface region 116 of the PCD electrode 112A, leaving the PCD structure unharmed. The PCD electrode 112B is similarly treated, with the contact surface region 116 leached. The leached contact surface regions 116 establishes a diamond dielectric between the residual cobalt 114 within the PCD electrodes 112A and 112B. This configuration provides a capacitive connection in the contact surface 110. This connection is functional in dry conditions as well as when immersed in oil-based mud or water based mud, as is common in wellbore applications. A similar capacitive connection, illustrated in FIG. 8, can be obtained when a leached PCD electrode 112A is placed in contact with an unleached PCD electrode 108B.

The diagram in FIG. 9 illustrates the use of a leached PCD electrode 112A forming a capacitive connection with a wear-resistant metallic electrode 118 in a manner similar to the one described above, as is appropriate in some applications. The diagram in FIG. 10 illustrates the application of a resistive connection between an unleached PCD electrode 108 A and a wear- resistant metallic electrode 118. This electrode 118 can be made from wear-resistant metallic conductors such as Stellite or tungsten carbide. Other softer metals, such as copper, can be used to assemble the metallic electrode 118 as well. The use of a metallic electrode can make the connection less resistant to wear damage, but in some applications their use may be more appropriate.

With the foregoing in mind, FIG. 11 provides an illustration of the distinction between a capacitive and a resistive connection. In a capacitive connection an output electric signal will be proportional to variations in the input electric signal, i.e. the derivative of the input signal. By contrast, in a resistive connection, an output electric signal will be directly proportional to the electric input signal. In fact, plot 128 shows the effect of a capacitive connection established by static PCD electrodes. Signals are represented by the voltage 132 as a function of time 134. When a step input voltage 137 is applied to the connection, a pulse 138 in the output signal 136 appears at the instant the input voltage changes. In the other times, the output signal 136 vanishes as result of the constant input voltage 137. Furthermore, plot 130 shows the effect of a resistive connection established by static PCD electrodes. The output signal 140 is directly proportional to the input signal 139 during the entire time.

The graph in FIG. 12 shows a plot of voltage 132 as function of time 134, demonstrating a successful rotary connection established between leached PCD electrodes in the manner of FIG. 7. A 100Hz square wave 144 is transmitted through two leached PCD electrodes in a journal bearing geometry rotating at 100 RPM. Due to the capacitive connection, the output signal is a 100Hz train of pulses 145. The graph in FIG. 13 shows a voltage 132 as function of time 134, demonstrating a successful rotary connection established between a PCD electrode and a copper electrode in the manner of FIG. 10. In the graph of FIG. 13, a 20Hz square wave 147 is transmitted from a PCD electrode to a copper electrode in a shear cutter geometry with a relative rotation of 80 RPM. The PCD electrode successfully transmits the signal, as shown by an output signal 148. The output signal 148 is also a 20Hz square wave proportional to the input.

The fluid surrounding the electrodes may also change characteristics of the electrical connection. The graph 150 in FIG. 14 shows the frequency response of the impedance in a connection between PCD electrodes in dry conditions 158, compared to immersion in oil 159 and in oil-based mud 160. The graph 162 in FIG. 15 shows the frequency response of the impedance in a connection between PCD electrodes in brine solutions with different resistivities, as shown in curves 164-168. The application of PCD electrodes for rotary connections in drilling applications may take these effects into consideration during the design of the apparatus.

As detailed above, some embodiments allow a resistive connection whereas other allow a capacitive connection between the moving electrodes to establish electrical communication between electrical devices. In some applications, such as the transmission of electric power downhole, or data using DC or low frequency signals, a resistive connection may be more appropriate. In other applications, such as control, sensing, imaging, or telemetry employing high frequency signals (>1 kHz), a capacitive connection is more appropriate. This connection is compatible with common modulation protocols employing high frequency carriers such as frequency modulation, phase-shift keying, and other well-known methods.

As described above, the PCD electrodes can establish connection between two flat surfaces, such as in a shear cutter geometry. Furthermore, a journal bearing conductor can be made using PCD electrodes, as illustrated in FIG. 16. Two obtain this arrangement, two PCD electrodes are sintered in the shape of a ring or a cylinder. The inner electrode 172 is

dimensioned such that it can freely rotate inside the outer electrode 170 and that a cylindrical contact surface 174 is constantly preserved between the electrodes. The inner electrode can be attached to an object, such as an inner spindle, that is rotating relative to an object connected to the outer electrode such as a housing.

Due to vibrations or other conditions, the alignment between the two electrodes in a journal bearing configuration may change. As seen in FIG. 17, the distance between the outer electrode axis 184 and the inner electrode axis 186, known as eccentricity, may change due to mechanical loads, leading to a potentially unstable electrical connection. In particular, the graph 190 in FIG. 18 shows that capacitance 192 as function of eccentricity 194 increases in a PCD journal bearing connection 196. The diagram in FIG. 19 illustrates a geometry leading to a more stable connection employing journal bearings electrodes. The outer electrode 202 is split in three parts and pressed against the inner electrode 200 with a garter spring 204 to form the cylindrical contact surface 206. This mitigates eccentric movement and minimizes changes in capacitance, as seen in the frequency response graph 210 in FIG. 20. The split journal bearing connection 214 has more robust impedance than the solid journal bearing connection 212, particularly at low frequencies. Furthermore, the spring loaded split bearing design reduces the impedance in the connection, a characteristic that may be beneficial in applications employing a resistive connection. Designs with two, four or more splits in the outer electrode may also be used to obtain similar results.

A further geometry used to implement a rotary connection is through the use of cone- shaped PCD electrodes. An example, as illustrated in FIG. 21, shows an inner cone 220 connected to an outer cone 222. The two contacting cones can freely rotate in relation to each other around the axis 224. A slanted contact surface 226 is established. Modifications such as removal of the edge of the inner cone or spring loading of the cones against each other may be employed to improve the connection.

As discussed above, the sintering of PCD using a conductive catalyst, as described above, generates a PCD electrode. The flow chart in FIG. 22 illustrates a method to obtain a

poly crystalline diamond insulator 228. The addition of catalysts such as magnesium carbonate, other carbonates or ceramics to the grit mixture 230 followed by sintering using pressure 232 and heat 234 generates an electrical insulating PCD after removal of heat and pressure 236. The PCD insulator may also be manufactured by a thorough leaching of a conductive PCD produced in the manner of FIG. 2. Regardless of the process, the resulting insulator PCD has hardness similar to that of the electrode PCD. In some applications, adequate arrangement of conductive PCD electrodes and insulating PCD layers, in the manner of FIG. 4, can be used to obtain wear- resistant multi-pole connections, as detailed below.

The diagram in FIG. 23 illustrates an embodiment of a dipole electrical connection between moving parts employing mixed layers of PCD electrodes and insulators. Objects 240A and 240B vibrate in relationship to each other in some direction 242. A dipole connection from the two conductive channels 254 embedded in object 240A to the sensor 252 embedded in object 240B is desired. By the method of FIG. 4, two PCD elements 244A and 244B are manufactured with a PCD insulator 248 placed between two conductive PCD electrodes 246. The PCD insulator 248 prevents electrical signals in electrode 246A from into leaking to electrode 246B. Provided the range of vibration motion is limited and the contact surfaces 256A and 256B are preserved, a robust dipole connection is established between the regardless of the movement between objects 240A and 240B. Note that this type of multi-pole connection can also be obtained by using other wear-resistant insulators disposed between PCD electrodes. Insulators can be made with ceramics or other known materials. With the foregoing in mind, FIG. 24 illustrates an application of dipole rotary electrical connection in a wellbore application. An outer shaft 270 houses a spindle 272 that may rotate relative to the outer shaft. For this application, an electrical connection between a wire 274A, attached to the outer shaft, and a wire 274B, attached to the spindle, is desired. To implement this rotary connection, PCD electrodes in a split-ring journal bearing configuration is employed. The outer PCD electrode 260B is pressed against the inner PCD electrode 262B by the garter spring 266B, establishing the contact surface 276B. The connection between the outer journal bearing PCD electrode 260B and wire 274A is established through a fused outer copper ring 268A. Similarly, the connection between the inner journal bearing PCD electrode 262B and wire 274B is established through a fused inner copper ring 268B. Note that there is no electrical connection between outer copper ring 268A and inner copper ring 268B to avoid wear during rotation of the spindle 272. To obtain a dipole connection, a second contact surface 276A is established between journal bearing PCD electrodes 260A and 262A with a garter spring 266A, as described above. In order to prevent leakage current between the two conductive contact surfaces 276A and 276B, an insulating PCD journal bearing 264 is placed between the electrodes.

The diagram in FIG. 25 illustrates another embodiment of a dipole rotary electrical connection for a wellbore application. An outer shaft 292 houses a spindle 290 that provides rotation movement downhole. Inner PCD electrodes 296A and 296B are in contact with outer PCD electrodes 294A and 294B. Insulating PCD journal bearings 300 are provided to prevent leakage between the slanted contact surfaces 298 A and 298B. The two insulated contact surfaces 298A and 298B generates a dipole electrical connection.

The diagram in FIG. 26 illustrates an embodiment of a multipole rotating electrical connection for a drilling apparatus in shear cutter geometry. An outer shaft 312 houses a rotating spindle 310. Outer PCD electrodes 314A are attached to the outer shaft 312 whereas inner PCD electrodes are attached to the spindle 310, establishing the contact surfaces 318. Outer PCD insulators 315A and inner PCD insulators 315B can be added to the system. Intercalation of PCD insulators and PCD electrodes arranged in a counter-rotating geometry allow for multiple independent electrical signals to be transmitted through the several contact surfaces, resulting in a multipole rotary electrical connection. In this counter-rotating geometry, rotation of the inner spindle 310 will cause a relative counter-rotation between inner electrodes 314B and outer electrodes 314A while preserving the contact surfaces 318. Similar relative counter-rotation will be observed between outer insulators 315A and outer electrodes 315B. The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Claims

CLAIMS CLAIMS:

1. A drilling system comprising:

a drill string configured to be disposed in a wellbore through a geological formation, the drill string configured to rotate in relation to a rig disposed at a surface of the geological formation; a downhole tool attached to the drill string;

an electrical device disposed at the surface and in electrical communication with the downhole tool; and

a wear-resistant rotary electrical connection comprising:

a first polycrystalline diamond electrode; and

a second electrode configured to establish a first contact surface with the first

polycrystalline diamond electrode,

wherein the wear-resistant rotary electrical connection is configured to establish the electrical communication between the electrical device and the downhole tool.

2. The drilling system of claim 1, wherein the second electrode is a leached or an unleached polycrystalline diamond electrode.

3. The drilling system of claim 1, wherein the second electrode is a wear-resistant metallic electrode.

4. The drilling system of claim 1, wherein the wear-resistant rotary electrical connection

comprises:

a third electrode;

a fourth electrode configured to establish a second contact surface with the third electrode; and

at least one polycrystalline diamond insulator configured to separate the first contact surface from the second contact surface.

5. The drilling system of claim 4, wherein the first and the second contact surfaces are

intercalated with the polycrystalline diamond insulators and disposed in counter-rotating geometry.

6. The drilling system of claim 1, wherein the first polycrystalline diamond electrode and the second electrode are arranged in a journal bearing geometry.

7. The drilling system of claim 1, wherein the first contact surface is flat.

8. The drilling system of claim 1, wherein the wear-resistant rotary electrical connection

comprises a drilling fluid surrounding the first polycrystalline diamond electrode and the second electrode.

9. A system comprising a wear-resistant electrical connection, the system comprising:

a first object in a first housing;

a second object in the first housing, wherein the second object is mechanically coupled to the first object and configured to move in relation to the first object;

a first polycrystalline diamond electrode attached to the first object; and

a second electrode attached to the second object,

wherein the first and the second objects are configured to cause a first contact surface between the first polycrystalline diamond electrode and the second electrode while the second object moves in relation to the first object.

10. The system of claim 9, wherein the second object is configured to move in relation to the first object in a circular motion.

11. The system of claim 9, wherein the second object is configured to move in relation to the first object in a direction parallel to the first contact surface.

12. The system of claim 9, comprising:

a third electrode;

at least one wear-resistant insulator configured to separate the first contact surface from the second contact surface.

13. The system of claim 9, wherein the wear-resistant insulator is a polycrystalline diamond insulator.

14. The system of claim 9, wherein the second electrode is a polycrystalline diamond electrode.

15. The system of claim 9, wherein the second electrode is a wear-resistant metallic electrode.

16. The system of claim 9, comprising a metallic conductor fused to the first polycrystalline diamond electrode wherein the metallic conductor is metallic conductor is configured to inject an electrical signal into the first polycrystalline diamond electrode or collect an electrical signal from the first polycrystalline diamond electrode, or a combination thereof.

17. A method for transmitting electrical signals through a wear-resistant electrical connection comprising:

establishing a first contact surface between a first electrode attached to a first object and a second electrode attached to a second object, wherein the first electrode comprises

polycrystalline diamond, and wherein the first object is configured to move in relation to the second object;

injecting an input electric signal into the first electrode; and

collecting an output electric signal from the second electrode.

18. The method of claim 17, wherein the input electric signal comprises a control, sensing, imaging, or telemetry signal or any combination thereof.

19. The method of claim 17, wherein the input electric signal is configured to provide power to a downhole tool attached to the second object.

20. The method of claim 17, comprising:

establishing a second contact surface between a third electrode attached to the first object and a fourth electrode attached to the second object, wherein the first contact surface and the second contact surface are electrically insulated from one another;

injecting a second input electric signal into the third electrode; and

collecting a second output electrical signal from the fourth electrode.