Cleaning boreholes formed by millimeter wave drilling

Abstract

A bottomhole assembly includes a body that defines a passage therethrough defining a waveguide for an electromagnetic wave. The body includes an uphole end and a downhole end. The uphole end is configured to be coupled to a workstring and further defines the passage extending uphole to a topside facility. The downhole end includes an outlet of the passage. The downhole end includes an emitter configured to emit the electromagnetic wave. A reamer extends from the body. The reamer is configured to scrape slag, produced by electromagnetic wave drilling, from a wall of a wellbore.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit, under 35 U.S.C. § 119(e), of U.S. Provisional Application No. 63 / 762,857, filed on Feb. 25, 2025, entitled “Cleaning Boreholes Formed By Millimeter Wave Drilling,” the entirety of which is incorporated by reference herein.TECHNICAL FIELD

[0002] The subject matter described herein relates to cleaning boreholes and wellbores.BACKGROUND

[0003] A waveguide is a structure that guides waves, such as electromagnetic waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Waveguides can be used in non-conventional drilling techniques, such as thermal drilling and / or millimeter wave drilling, to form a borehole of a well. Waveguides can be used to transmit electromagnetic waves into the borehole to enable drilling at deeper subsurface depths than conventional, rotary drilling.SUMMARY OF THE INVENTION

[0004] The disclosure relates to a millimeter wave drill pipe system.

[0005] An example implementation of the subject matter described within this disclosure is a bottomhole assembly with the following features. A body defines a passage therethrough defining a waveguide for an electromagnetic wave. The body includes an uphole end and a downhole end. The uphole end is configured to be coupled to a workstring and further defines the passage extending uphole to a topside facility. The downhole end includes an outlet of the passage. The downhole end includes an emitter configured to emit the electromagnetic wave. A reamer extends from the body. The reamer is configured to scrape slag, produced by electromagnetic wave drilling, from a wall of a wellbore.

[0006] Aspects of the example bottomhole assembly, which can be combined with the example bottomhole assembly alone or in combination with other aspects, include the following. The reamer is a static reamer.

[0007] Aspects of the example bottomhole assembly, which can be combined with the example bottomhole assembly alone or in combination with other aspects, include the following. The reamer is actuable between a first position and a second position.

[0008] Aspects of the example bottomhole assembly, which can be combined with the example bottomhole assembly alone or in combination with other aspects, include the following. The reamer is actuable in a longitudinal direction.

[0009] Aspects of the example bottomhole assembly, which can be combined with the example bottomhole assembly alone or in combination with other aspects, include the following. The reamer has sufficient hardness to scrape slag off a wall of the wellbore but low enough hardness to not cause dimensional changes to the wall of the wellbore.

[0010] Aspects of the example bottomhole assembly, which can be combined with the example bottomhole assembly alone or in combination with other aspects, include the following. The reamer is configured to be rotated by the body by rotation of the workstring.

[0011] An example implementation of the subject matter described within this disclosure is a method that includes the following features. A wellbore is formed by an electromagnetic wave directed by an electromagnetic waveguide. Slag, produced by forming the wellbore by the electromagnetic wave, is scraped from a wall of the wellbore by a reamer.

[0012] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. Forming the wellbore includes the following features. The electromagnetic wave is directed, from an electromagnetic wave generator, in a downhole direction by a workstring and the electromagnetic waveguide therethrough. A geologic formation, in which the wellbore is formed, is melted or sublimated at a downhole end of the wellbore to form slag. Slag is removed from a bottomhole end of the wellbore by purge gas flowing from the electromagnetic waveguide and up through an annulus defined by an outer surface of the electromagnetic waveguide and an inner surface of the wellbore.

[0013] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. The slag is deposited along an inner surface of the wellbore. Scraping includes the following features. The reamer is rotated by the electromagnetic waveguide. The electromagnetic waveguide is lowered towards a downhole end of the wellbore while rotating the reamer. The electromagnetic waveguide is raised to a set stand-off height. The wellbore continues to be formed with the electromagnetic wave.

[0014] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. The scraped slag is removed from the wellbore by purge gas.

[0015] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. The reamer is extended from a body of the waveguide prior to or during scraping.

[0016] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. The reamer is retracted towards the waveguide body during or after scraping.

[0017] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. Extending and retracting are in a longitudinal direction.

[0018] Aspects of the example method, which can be combined with the example method alone or in combination with other aspects, include the following. A stand-off distance between a downhole end of the waveguide and a bottomhole end of the wellbore is maintained during reaming operations.

[0019] An example implementation of the subject matter described within this disclosure is a system with the following features. An electromagnetic wave emitter is configured to emit an electromagnetic wave. The electromagnetic wave emitter is located at a topside facility. A surface waveguide system is configured to direct the electromagnetic wave into a workstring. The workstring extends from the topside facility and into a borehole. A bottomhole assembly us at a downhole end of the workstring. The bottomhole assembly includes the following features. A body defines a passage therethrough defining a waveguide for an electromagnetic wave. The body includes an uphole end and a downhole end. The uphole end is configured to be coupled to a workstring and further defines the passage extending uphole to a topside facility. A downhole end defines an outlet of the passage and includes an emitter configured to emit the electromagnetic wave. A reamer extends from the body. The reamer is configured to scrape slag, produced by electromagnetic wave drilling, from a wall of a wellbore.

[0020] Aspects of the example system, which can be combines with the example system alone or in combination with other aspects, include the following. The reamer is a static reamer.

[0021] Aspects of the example system, which can be combines with the example system alone or in combination with other aspects, include the following. The reamer has sufficient hardness to scrape slag off of the wellbore but low enough hardness to not cause dimensional changes to a wall of the wellbore.

[0022] Aspects of the example system, which can be combines with the example system alone or in combination with other aspects, include the following. The reamer is configured to be rotated by the body by rotation of the workstring.

[0023] Aspects of the example system, which can be combines with the example system alone or in combination with other aspects, include the following. The reamer is actuable between a first position and a second position.

[0024] Aspects of the example system, which can be combines with the example system alone or in combination with other aspects, include the following. The reamer is actuable in a longitudinal direction.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other features will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0026] FIG. 1 is a diagram illustrating an exemplary embodiment of a millimeter wave drilling system including a multi-piece corrugated waveguide as described herein;

[0027] FIG. 2 is a diagram illustrating a cross sectional view of a borehole including a waveguide for low loss transmission of millimeter wave radiation as described herein;

[0028] FIGS. 3A-3D illustrate a cross sectional view of a wellbore in various stages of drilling and cleaning operations;

[0029] FIGS. 4A-4C illustrate a cross sectional view of a wellbore in various stages of drilling and cleaning operations;

[0030] FIG. 5 is a flowchart of an example method that can be used with aspects of this disclosure.DETAILED DESCRIPTION

[0031] A waveguide is a structure that guides waves, such as electromagnetic (EM) waves or sound, with minimal loss of energy by restricting the transmission of energy to one direction. Waveguides can be employed, for example, in millimeter wave drilling (MMWD) operations, to efficiently convey EM waves to depths necessary to form a well. The design and materials used to form the waveguide can affect the transmission efficiency of the EM waves transmitted in a particular transmission mode. For example, EM waves can be transmitted over long distances using a waveguide including a series of corrugated features. The corrugated features can include a pattern of repeating ridges or grooves that can extend within a length of a tube. The pattern of corrugated features (e.g., ridges, grooves, or the like) can be shaped to aid the propagation of the EM wave and can be dimensioned according to the properties (e.g., frequency) of the wave that the waveguide is designed to efficiently propagate. Corrugated waveguides can often include a dielectric or conductive coating that can improve the transmission efficiency of the waveguide.

[0032] Drilling operations, whether they include MMWD or conventional drilling, involve accommodating various geologic properties and contaminants. For example, porosity, liquid content, and hardness are factors that can determine types of drill bits and / or an intensity of EM energy used for drilling. Similarly, while drilling, unexpected “kicks” of high pressure gas or liquid can occur. Protection and monitoring systems to accommodate such situations have been developed; however, many such components for protection, monitoring, and dealing with variable drilling operations are discrete, individual components that can take-up a large footprint at a drill site and can require separate and costly maintenance.

[0033] The various implementations described herein can be employed in a variety of industries and applications wherein EM waves are transmitted, such as oil and gas production, nuclear energy, fusion reactors, drilling and mining operations, and sound or audio applications. The design and manufacturing approach of downhole waveguides can provide a less expensive alternative for any industry or application compared to purchasing multiple EM generator for multiple locations, or modifying existing structures to incorporate dedicated static waveguide systems. For operations within hazardous environments, some downhole and / or topside waveguides described herein can also provide an option to keep an EM source in a safe environment and direct EM radiation to where it is needed within the hazardous environment instead of moving the EM source within the hazardous environment, reducing the probability of a spark or arc occurring.

[0034] In some implementations, a downhole waveguide can be configured for use in MMWD during formation of a borehole. The transmission efficiency of some implementations of the dynamic waveguides described herein can also be improved by dimensioning features of internal geometry in regard to a particular transmission mode, for example, transverse electric (TE), transverse magnetic (TM), transverse electromagnetic (TEM), hybrid electric (HE), hybrid magnetic (HM), and / or hybrid electromagnetic (HEM) modes. Some implementations of the dynamic waveguides described herein can provide efficient transmission of EM waves in a variety of transmission modes.

[0035] Some implementations of the systems described herein can be formed by assembling multiple sections of a workstring that define a waveguide. Such a workstring is able to form and advance through a borehole. The workstring includes different sections with differing temperature tolerances, with sections nearer a downhole end of the workstring having a greater temperature tolerance than sections farther away from the downhole end of the workstring. The sections of the workstring can be coupled together at a topside facility, with new portions added as the workstring progresses through the borehole.

[0036] FIG. 1 is a diagram illustrating an exemplary implementation of a MMWD system 100 including an example multi-piece waveguide 108. The MMWD system 100 shown in FIG. 1 includes a gyrotron 102 connected via power cable 104 to a power supply 106 supplying power to the gyrotron 102. While primarily described as using a gyrotron, other EM sources, such as a maser or other millimeter (mm) wave emitter can be used without departing from this disclosure. The high power millimeter wave beam output by the gyrotron 102 is guided by a waveguide 108. While primarily described throughout this disclosure as pertaining to millimeter wavelength energies, the subject matter described herein can be applied to other wavelengths without departing from this disclosure. The waveguide 108 can include a waveguide bend 118, a window 120, a waveguide section 126 with opening 128 for off gas emission and pressure control. A section of the waveguide is below ground 130 to help seal the borehole 148. This section can include a wellhead, blow out preventer, lubricator, or any other components commonly used in the creation of wellbores and boreholes.

[0037] As part of the waveguide 108 transmission line, there is an isolator 110 to prevent reflected power from returning to the gyrotron 102 and an interface for diagnostic access 112. The diagnostic access is connected to diagnostics electronics and data acquisition 116 by low power waveguide 114. In some implementations, at the window 120, there is a pressurized gas supply unit 122 connected by plumbing 124 to the window to inject a clean gas flow across a surface of the window to help reduce prevent window deposits, such as dust or other particulates. A second pressurization unit 136 is connected by plumbing 132 to the waveguide opening 128 to help control the pressure in the borehole 148 and to introduce and remove borehole gases as needed. The window gas injection unit 122 can be operated at slightly higher pressure relative to the borehole pressure unit 136 to maintain a gas flow across the window surface. A branch line 134 in the borehole pressurization plumbing 132 can be connected to a pressure relief valve 138 to allow exhaust of volatized borehole material and window gas through a gas analysis monitoring unit 140 followed by a gas filter 142 and exhaust duct 144 into the atmosphere 146. In some implementations, the exhaust duct 144 can return the gas to the pressurization unit 136 for reuse.

[0038] Pressure in the borehole 148 can be increased in part or in whole by the partial volatilization of the subsurface material being melted. A thermal melt front 152 at a downhole end of the borehole 148 can be propagated into the subsurface strata under the combined action of the millimeter wave power and gas pressure leaving behind a slag deposit, resulting in, for example, a ceramic or glass coated borehole wall 150. The borehole wall 150 can act as a dielectric waveguide to transmit the millimeter wave beam to the thermal front 152. Alternatively or in addition, pressure can be controlled at an uphole end of the borehole 148 to increase or reduce the velocity of the purge gas flow to maintain effective particle transport from the hole propagation region to the surface.

[0039] FIG. 2 is a diagram illustrating a cross sectional view of an example borehole including a multi-piece corrugated waveguide, which can be configured for low loss transmission of millimeter wave radiation. FIG. 2 provides a more detailed view of MMWD and corresponds to the MMWD system described in U.S. Pat. No. 8,393,410 to Woskov et. al, entitled “Millimeter-wave Drilling System”, the entirety of which is hereby incorporated by reference. The borehole 200 with annulus 205, glassy / ceramic wall 210 and permeated glass 215 has a waveguide assembly 220 inserted to improve the efficiency of millimeter wave beam propagation. In some implementations, the waveguide assembly can include a multi-piece corrugated waveguide that can be assembled sequentially in sections as the borehole 148 is formed. In some implementations, multiple waveguide assemblies can be inserted into the borehole. For example, multiple waveguide assemblies can be stacked upon one another to a distance of 1 km, 5 km, 10 km or more below a surface of a well.

[0040] As shown in FIG. 2, the diameter of the waveguide assembly 220 can be smaller than the borehole diameter to create an annular gap 225 for exhaust and particle extraction. The standoff distance 230 of the leading edge of the multi-piece corrugated waveguide 220 from the thermal melt front 235 of the borehole is far enough to allow the launched millimeter wave beam divergence 240 to fill the dielectric borehole 200 with the guided millimeter-wave beam 245. The standoff distance 230 is also far enough to keep the temperature at the waveguide assembly 220 low enough for survivability. The inserted waveguide assembly 220 also acts as a conduit for a pressurized gas flow 250 from the surface. This gas flow keeps the waveguide assembly 220 clean and contributes to the extraction and displacement of the rock material from the bore hole. The gas flow 250 from the surface mixes 255 with the volatilized out gassing of the rock material 260 to carry the condensing rock vapor to the surface through annular space 225. in some instances, the exhaust gas flow 265 is sufficiently large to limit the size of the volatilized rock fine particulates and to carry them all the way to the surface. While the borehole 200 is illustrated as a vertical borehole for ease of illustration, the subject matter described herein is applicable to horizontal or deviated boreholes as well.

[0041] FIGS. 3A-3D illustrate a cross sectional view of an example wellbore or borehole 300 in various stages of drilling and cleaning operations. The wellbore or borehole 300 is substantially similar to borehole 200 and borehole 148 previously described. The systems and components of FIGS. 1-2 can be incorporated and / or integrated with the implementations described in FIGS. 3A-3D and FIGS. 4A-4C without departing from this disclosure. A bottomhole assembly 302 is located at a downhole end of the waveguide assembly 220 (FIG. 2) and is connected to the waveguide assembly 220 by an uphole end of the bottomhole assembly 302. The bottomhole assembly 302 includes a body 304 defining a central passage 306. The passage 306 further defines the central waveguide continuing from the waveguide assembly 220. A downhole end of the bottomhole assembly 302 defines an opening of the central passage and an emitter configured to emit the electromagnetic wave 308 from the bottomhole assembly 302.

[0042] Extending radially from the body 304 of the bottomhole assembly 302 is a reamer 310. The reamer 310 include blades or other cutting / scraping components extending towards a wall of the wellbore 300 when the bottomhole assembly 302 is located within the wellbore 300. The reamer is arranged and configured to scrape the slag 312 (e.g., the ceramic or glass coating previously described) from the wall of the wellbore 300. In the illustrated implementation, the reamer 310 is a static reamer. That is, the static reamer 310 includes no actuable components and, in some implementations, rotates in unison with the body 304 of the bottomhole assembly 302, for example, when the workstring (e.g., waveguide assembly 220) is rotated by a rotary table or top drive. While primarily described as rotating in unison with the body 304, separate downhole motors, such as electric or pneumatic motors, can be used to rotate the reamer 310 separately from the body 304 without departing from this disclosure.

[0043] The static reamer 310 is sized such that an outer, circumferential edge of the reamer 310 extends a sufficient distance from the body 304 to scrape the slag 312 from a wall of the wellbore 300 without cutting, scraping, or otherwise removing rock from the wall of the wellbore 300. Alternatively or in addition, the scraping / cutting surfaces of the reamer 310 can be made of a material of sufficient hardness to remove the slag 312, but a hardness less than that of the rock making up the wall of the wellbore 300. Such a hardness reduces the likelihood or fully prevents the reamer from dimensionally changing the wall of the wellbore 300. While not illustrated, additional components, such as centralizers, can be included along the workstring to improve operations.

[0044] In operation, As shown in FIG. 3A, the bottomhole assembly 302 emits EM waves to melt and / or vaporize the geologic formation 314 at the downhole end of the wellbore 300. As shown in FIG. 3B, the bottomhole assembly 302 emits the EM waves until the wellbore 302 has been extended a set distance (ΔH). During these operations purge gas 316 flows through the passage 306 and up an annulus defined by an outer surface of the work string and an inner surface of the wellbore 300. The purge gas 316 flow shapes the melt front up the sides of the wellbore 300 as shown in FIG. 3C. Once the set distance (ΔH) is reached, in some instances, the EM wave is shut off, and the workstring is rotated. Such rotation rotates the bottomhole assembly 302 and the reamer 310. During rotation, purge gas 316 still flows and the bottomhole assembly 302 is lowered towards a bottomhole end of the wellbore 300. This action removes the slag 312 from the wall of the wellbore 300 to form slag particles 318 of sizes and weights sufficiently small to be carried through the annulus uphole to the topside facility. In some instances, the workstring is rotated while the EM wave is being emitted.

[0045] FIGS. 4A-4C illustrate a cross sectional view of a wellbore in various stages of drilling and cleaning operations using a reamer 410. The reamer 410 is substantially similar to the reamer 310 previously described with the exception of any differences described herein. The reamer 410 is a dynamic reamer. That is, the reamer 410 is actuable between a first, retracted position (FIG. 4A) and a second, extended position (FIGS. 4B-4C). In some implementations, the dynamic reamer 410 is actuable in a longitudinal direction substantially parallel with the workstring and the wellbore 300. The longitudinal actuation allows the standoff distance (ΔS) to remain substantially constant while reaming and forming the wellbore 300. That is, the dynamic reamer 410 can extend a fixed standoff distance that allows the EM wave to continue forming the wellbore 300 during reaming operations. Alternatively or in addition, the EM wave is emitted for a period of time, and then the dynamic reamer 410 is actuated to perform reaming operations. After reaming operations are complete, the dynamic reamer 410 retracts and emitting the EM wave begins again. Alternatively or in addition, the dynamic reamer 410 can conduct reaming operations with the dynamic reamer 410 in the extended position, the retracted position, or during a transitional state.

[0046] In some implementations, the actuation between the retracted position and the extended position can be rapid, acting as a hammer in a downward direction. Such “hammer” action can, in some implementations, be used to remove slag 312 that has bonded with the wall of the wellbore that may otherwise be difficult to remove, for example, with the static reamer 310 previously described. Actuation of the dynamic reamer 410 can be performed mechanically, electrically, electromagnetically, pneumatically, hydraulically, or with any combination.

[0047] FIG. 5 is a flowchart of an example method 500 that can be used with aspects of this disclosure. At 502, a wellbore is formed by an electromagnetic wave directed by an electromagnetic waveguide. In some implementations, such operations include directing the electromagnetic wave from an electromagnetic wave generator in a downhole direction by a workstring defining the electromagnetic waveguide therethrough. A geologic formation is melted or sublimated to form a wellbore. At a downhole end of the wellbore, this process can produce slag that coats an interior surface of the wellbore.

[0048] At 504, slag, produced by forming the wellbore by the electromagnetic waveguide, is scraped from a wall of the wellbore by a reamer. In some implementations, scraping includes rotating the reamer, for example, by the electromagnetic waveguide. In some instances, the electromagnetic waveguide is lowered towards a downhole end of the wellbore while the reamer is rotated. Once the slag is knocked from the wall of the wellbore, the slag from a bottomhole end of the wellbore by purge gas flowing from the electromagnetic waveguide and up through an annulus. The annulus is defined by an outer surface of the electromagnetic waveguide and an inner surface of the wellbore. After the slag is scraped or otherwise knocked away from the wall of the wellbore and removed from the wellbore, the electromagnetic waveguide is raised, lowered, or otherwise adjusted to a set stand-off height, and the electromagnetic wave continues to form the wellbore.

[0049] In implementations using the dynamic reamer, the reamer is extended from the body of the waveguide during or prior to scraping. The reamer is retracted towards the waveguide body after scraping. In implementations using the dynamic reamer, the stand-off distance between a downhole end of the waveguide and a bottomhole end of the wellbore is maintained during reaming operations. In some implementations, the electromagnetic waveguide is raised, lowered, or otherwise adjusted to a set stand-off height, and the electromagnetic wave continues to form the wellbore.

[0050] Certain exemplary embodiments have been described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the systems, devices, and methods disclosed herein. One or more examples of these embodiments have been illustrated in the accompanying drawings. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. Further, in the present disclosure, like-named components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-named component is not necessarily fully elaborated upon.

[0051] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,”“approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

[0052] One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the present application is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated by reference in their entirety.

Claims

1. A bottomhole assembly comprising:a body defining a passage therethrough defining a waveguide for an electromagnetic wave, the body comprising:a uphole end configured to be coupled to a workstring further defining the passage extending uphole to a topside facility; anda downhole end comprising an outlet of the passage, the downhole end comprising an emitter configured to emit the electromagnetic wave; anda reamer extending from the body, the reamer configured to scrape slag, produced by electromagnetic wave drilling, from a wall of a wellbore.

2. The bottomhole assembly of claim 1, wherein the reamer is a static reamer.

3. The bottomhole assembly of claim 1, wherein the reamer is actuable between a first position and a second position.

4. The bottomhole assembly of claim 3, wherein the reamer is actuable in a longitudinal direction.

5. The bottomhole assembly of claim 1, wherein the reamer has sufficient hardness to scrape slag off a wall of the wellbore, but low enough hardness to not cause dimensional changes to the wall of the wellbore.

6. The bottomhole assembly of claim 1, wherein the reamer is configured to be rotated by the body by rotation of the workstring.

7. A method comprising:forming a wellbore by an electromagnetic wave directed by an electromagnetic waveguide; andscraping slag, produced by forming the wellbore by the electromagnetic wave, from a wall of the wellbore by a reamer.

8. The method of claim 7, wherein forming the wellbore comprises:directing the electromagnetic wave from an electromagnetic wave generator in a downhole direction by a workstring and the electromagnetic waveguide therethrough;melting or sublimating a geologic formation, in which the wellbore is formed, at a downhole end of the wellbore to form slag; andremoving slag from a bottomhole end of the wellbore by purge gas flowing from the electromagnetic waveguide and up through an annulus defined by an outer surface of the electromagnetic waveguide and an inner surface of the wellbore.

9. The method of claim 7, further comprising depositing the slag along an inner surface of the wellbore, wherein scraping comprises:rotating the reamer by the electromagnetic waveguide;lowering the electromagnetic waveguide towards a downhole end of the wellbore while rotating the reamer;raising the electromagnetic waveguide to a set stand-off height; andcontinuing forming the wellbore with the electromagnetic wave.

10. The method of claim 7, further comprising removing the scraped slag from the wellbore by purge gas.

11. The method of claim 7, further comprising extending the reamer from a body of the waveguide prior to or during scraping.

12. The method of claim 11, further comprising retracting the reamer towards the waveguide body during or after scraping.

13. The method of claim 11, wherein extending and retracting are in a longitudinal direction.

14. The method of claim 11, wherein a stand-off distance between a downhole end of the waveguide and a bottomhole end of the wellbore is maintained during reaming operations.

15. A system comprising:an electromagnetic wave emitter configured to emit an electromagnetic wave, the electromagnetic wave emitter located at a topside facility;a surface waveguide system configured to direct the electromagnetic wave into a workstring;the workstring extending from the topside facility and into a borehole; anda bottomhole assembly at a downhole end of the workstring, the bottomhole assembly comprising:a body defining a passage therethrough defining a waveguide for an electromagnetic wave, the body comprising:a uphole end configured to be coupled to a workstring further defining the passage extending uphole to a topside facility; anda downhole end comprising an outlet of the passage, the downhole end comprising an emitter configured to emit the electromagnetic wave; anda reamer extending from the body, the reamer configured to scrape slag, produced by electromagnetic wave drilling, from a wall of a wellbore.

16. The system of claim 15, wherein the reamer is a static reamer.

17. The system of claim 15, wherein the reamer has sufficient hardness to scrape slag off of the wellbore, but low enough hardness to not cause dimensional changes to a wall of the wellbore.

18. The system of claim 15, wherein the reamer is configured to be rotated by the body by rotation of the workstring.

19. The system of claim 15, wherein the reamer is actuable between a first position and a second position.

20. The system of claim 19, wherein the reamer is actuable in a longitudinal direction.

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