CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. Provisional Patent Application No. 63/399,416 filed on August 19, 2022, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present invention relates to a reamer particularly suited for use with a horizontal directional drilling rig.

BACKGROUND

[0003] Horizontal drilling rigs are used to cut holes along paths extending from an entrance point to an exit point. The paths pass below ground and beneath obstacles. During use of conventional horizontal drilling rigs, pilot holes of a relatively small size are cut with pilot bits coupled to a drill string that is powered by the drilling rig. Once the pilot hole is cut, the pilot bit is retracted from the hole, and a reamer is subsequently attached to the drill string, and the reamer makes a reaming cut to enlarge the hole to a desired size. In some instances, separate drilling rigs are positioned on opposite sides of the obstacle. In some instances, at least one of the entrance point and exit point may be underwater. This conventional process is associated with high time and cost requirements to create the reamed hole.

SUMMARY

[0004] The present disclosure provides a method for forming an underground bore from a first location to a second location. The method comprises drilling a pilot hole from the first location toward the second location using a pilot drill string and advancing a reamer over and along the pilot drill string from the first location toward the second location while the pilot drill string is at least partially positioned in the pilot hole. In one embodiment, the drilling step comprises completely drilling the pilot hole from the first location to the second location before starting the advancing step. Alternatively, the advancing step can start before the drilling step is completed all the way to the second location. In addition, at least a portion of the drilling step can be performed while at least a portion of the advancing step is being performed. Preferably, the reamer includes a hollow reamer drill string sized to receive the pilot drill string, and the advancing step includes positioning the reamer drill string circumferentially around the pilot drill string and moving the reamer string axially or longitudinally relative to the pilot drill. In this regard, the method can further include supplying fluid to an annular space between the pilot drill string and the reamer drill string.

[0005] After the advancing step, the method can further include pulling a swab through the bore from the second location to the first location. For example, pulling a swab can include coupling the swab to the reamer drill string and pulling the reamer drill string out of the bore at the first location. In addition, after the advancing step (and after the optional step of pulling a swab), the method can further include coupling a pipe to the pilot drill string and pulling the pilot drill string out of the bore at the first location.

[0006] The above-described method can be performed using a drilling system including a pilot drill including the pilot drill string and a reamer adapted to form a reamed hole larger than the pilot hole. The reamer is adapted to slide over a portion of the pilot drill string such that, after the pilot drill forms a pilot hole, the reamer can be advance along the portion of the pilot drill string to form the reamed hole. In one embodiment, the drilling system further comprises a seal positioned between the pilot drill and the reamer to inhibit the passage of fluid past the seal. For example, the reamer can include a hollow portion dimensioned to receive the pilot drill string, and the seal is positioned in the hollow portion of the reamer (e g., the seal can be secured to the reamer and dimensioned to slidably engage the pilot drill string).

[0007] Preferably, the pilot drill further includes a pilot bit attached to the pilot drill string and having a pilot bit diameter larger than a diameter of the pilot drill string. Similarly, the reamer can include a reamer head attached to a reamer drill string and having a reamer head diameter larger than the diameter of the pilot bit.

[0008] The portion of the pilot drill string along which the reamer is designed to be advanced includes a largest outer diameter, and the reamer includes a smallest inner diameter that is preferably 1.1 to 1.8 (more preferably 1.2 to 1.5) times the largest outer diameter of the portion of the pilot drill string. The reamer further includes a largest inner diameter that is preferably 1.2 to 2.0 (preferably 1.4 to 1.8) times the largest outer diameter of the portion of the pilot drill string.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a schematic view of a drilling site in accordance with the prior art.

[0010] FIG. 2 is a schematic view of a drilling site.

[0011] FIG. 3 is a perspective view of a hammer pilot bit.

[0012] FIG. 4 is a perspective view of another pilot bit including polycrystalline diamond carbon cutters.

[0013] FIG. 5 is a perspective view of a reamer.

[0014] FIG. 6 is an end view of the reamer of FIG. 5.

[0015] FIG. 7 is a cross-sectional view of the reamer of FIG. 5 taken along section line 7 — 7 in FIG. 6.

[0016] FIG. 8 is a section view of the reamer of FIG. 5 taken along section 8 — 8 in FIG. 7.

[0017] FIG. 9 is a cross-sectional view of the reamer of FIG. 7 with a pilot drill string extending through an opening of the reamer.

[0018] FIG. 10 is a flow chart illustrating a method for pipe laying.

[0019] FIGS. 11 A-l 1H are schematic views of various components at a drilling site as the method for pipe laying of FIG. 10 is carried out.

[0020] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. DETAILED DESCRIPTION

[0021] FIG. 1 illustrates an exemplary prior art drilling site 100 which spans an obstacle 104 beneath a surface 108. The drilling site 100 has an entrance point 112 and an exit point 116 on opposite sides of the obstacle 104. A drilling rig 120 is positioned adjacent the entrance point 112. In conventional drilling sites 100, a pilot drill including a pilot bit 124 coupled to a pilot drill string 128 is driven by the drilling rig 120 from the entrance point 112 to the exit point 116 to cut a hole H along a desired path P below the obstacle 104. The drilling rig 120 is powered by a power unit 132. The drilling site 100 further includes a mud rig 136 which may be self- powered separately from the power unit 132. The power unit 132 powers a control trailer 140. An operator in the control trailer 140 controls the movement and relative position of the pilot bit 124 to follow the desired path P, as is generally known in the art. During drilling, cuttings from within the hole created by the pilot bit 124 are pumped to the mud rig 136 for removal from the hole. Once an amount of the pilot drill string 128 is received under the surface 108, an excavator 144 may lift an additional segment or segments of the pilot drill string 128 from a storage vehicle 148 to be connected to the pilot drill string 128 having the pilot bit 124 attached thereto. In some occasions, a crane (not shown) may replace or be used in conjunction with the excavator 144 to lift segments of the pilot drill string 128. The additional segment or segments of the pilot drill string 128 are passed through the entrance point 112 until the pilot bit 124 emerges from the exit point 116. In some instances, the exit point 116 may be underwater. Once the pilot bit 124 cuts a pilot hole along the path P, the pilot drill string 128 is fully retracted from the entrance point 112. While retracting the pilot bit 124, segments of the pilot drill string 128 may be temporarily stored on the storage vehicle 148. The pilot bit 124 can be removed from the pilot drill string 128, and a hole opener 152 may be secured to the pilot drill string 128 in place of the pilot bit 124. The drilling rig 120 can then drive the hole opener 152 to open (i.e., make larger in diameter) the hole cut by the pilot bit 124 along the path P. Once the hole is opened by the hole opener 152, a product pipe (e.g., an oil or communications pipeline) may be positioned within the hole H and extending along the path P.

[0022] FIG. 2 illustrates an exemplary drilling site 200 employing a reamer (e.g.„ a casing reamer) having a reamer 204. As will be described in detail below with regard to FIGS. 11 A- 11H, the reamer 204 allows for more efficient use of the drilling rig 120, more consolidated positioning of components of the drilling site 200 (e.g., adjacent the entrance point 112), and faster and easier location of a product pipe in a desired hole. As schematically illustrated in FIG. 2 and further illustrated in FIGS. 11 A-l 1H, the reamer 204 is configured to be coupled to a reamer drill string 208 (e.g., a plurality of segments of a reamer drill string) while the pilot drill string 128 is below the surface 108 between the entrance point 112 and the exit point 116. The illustrated reamer drill string 208 is larger than the pilot drill string 128 to allow the reamer drill string 208 to surround and slide over the pilot drill string 128. The reamer 204 can thus be positioned below the surface 108 at the same time (e.g., simultaneously) as the pilot bit 124. In some cases, the pilot bit 124 and the reamer 204 may operate (e.g., be advanced and drill, ream) at substantially the same time (e.g., simultaneously).

[0023] FIGS. 3 and 4 illustrate exemplary pilot bits 124. FIG. 3 illustrates a tri-cone bit 400 including three rotating cones 404 each having cutters 408 mounted thereon. The cutters 408 are configured to break working material as the tri-cone bit 400 is forced into working material. The tri-cone bit 400 includes jet nozzles 412 configured to eject cutting fluid towards the cones 404 and the cutters 408. FIG. 4 illustrates another pilot bit 500 including poly crystalline diamond cutters 504. Various types of pilot bits 124 may be used with the reamer 204. The type, materials, geometries, mechanical properties etc. of the pilot bit 124 may be selected based on known or suspected geology and/or conditions (e.g., moisture, density, etc.) beneath the surface.

[0024] FIGS. 5-8 illustrate the reamer 204 in detail. As illustrated in FIG. 5, the illustrated reamer 204 includes a body 212 extending along a longitudinal axis LA. In the illustrated embodiment, the body 212 is annularly shaped and includes an opening 214 extending along the longitudinal axis LA. The body 212 has a first longitudinal end 216 and an opposite second longitudinal end 220. In the illustrated embodiment, the longitudinal axis LA passes centrally through the first longitudinal end 216 and the second longitudinal end 220. The opening 214 is a through opening spanning the first longitudinal end 216 and the second longitudinal end 220. In the illustrated embodiment, the opening 214 has a first side 214a adjacent the first longitudinal end 216 and an opposite second side 214b adjacent the second longitudinal end 220. The first longitudinal end 216 is configured to be coupled to a reamer head 224. The second longitudinal end 220 is configured to be coupled to the reamer drill string 208 and thus the drilling rig 120. Accordingly, the body 212 is configured to be moved (e.g., advanced and/or retreated) by the drilling rig 120 along the longitudinal axis LA and thus the path P. The body 212 is at least one of translatable along and rotatable about the longitudinal axis LA. In the illustrated embodiment, the body 212 is both rotated about and translated along the longitudinal axis LA.

[0025] With reference to FIG. 7, the body 212 has an inner surface 228 and an opposite outer surface 232. In the illustrated embodiment, both the inner surface 228 and the outer surface 232 are generally annularly shaped. Other cross-sectional shapes of the inner surface 228 and the outer surface 232 are possible. The body 212 further includes a cutter mount 236 extending radially outwardly from the outer surface 232 of the body 212. The cutter mount 236 is coupled to the body 212 for movement (e.g., translation along the longitudinal axis LA, rotation about the longitudinal axis LA) therewith. At least one cutter 240 is coupled to the cutter mount 236 and extends away from the body 212 and away from the longitudinal axis LA. In other words, the cutter 240 is coupled to the body 212 for movement with the body 212. The cutter 240 is positioned further from the longitudinal axis LA than the pilot bit 124 and the reamer head 224 such that the cutter 240 is configured to open (i.e., enlarge) the hole created by the pilot bit 124. The cutters 240 may be removable and replaceable relative to the cutter mounts 236.

[0026] FIGS. 6 and 8 illustrate the reamer head 224 in more detail. The reamer head 224 is positioned adjacent the first longitudinal end 216 of the body 212 such that the reamer head 224 can contact a pilot hole drilled by the pilot bit 124 prior to the cutters 240. The illustrated reamer head 224 is annularly shaped. The reamer head 224 includes an inner surface 228, an outer surface 248, and an axial end surface 252. The reamer head 224 also includes a head cutter 256 positioned on at least one of the axial end surface 252 and the outer surface 248. As illustrated in FIGS. 6 and 8, the illustrated reamer head 224 includes a plurality of head cutters 256 positioned on both the axial end surface 252 and the outer surface 248.

[0027] The reamer head 224 may be selectively coupled to the reamer 204 by threads. Accordingly, the reamer head 224 may be replaceable relative to the reamer 204 when the head cutters 256 become damaged or worn. The reamer head 224 has an outer surface 248 which includes a head thread 256, and the inner surface 228 of the body 212 includes a body thread 260 positioned adjacent the first longitudinal end 216 thereof. The head thread 256 and the body thread 260 are configured to engage one another to secure the reamer head 224 to the body 212. [0028] With continued reference to FIG. 8, a seal 264 is positioned at least partially within the opening 214 of the body 212. More specifically, the seal 264 is positioned on the inner surface 228 of the body 212. In the illustrated embodiment, a spacer 268 is positioned between the seal 264 and another seal 272. In the illustrated embodiment, the seals 264, 272 are each shaped as an annulus having rectangular cross-sections. However, in other embodiments, more, fewer (e.g., one), and/or differently shaped seals 268 and/or spacers 272 can be provided. As illustrated by the interference in FIG. 9 between the seal 268 and the pilot drill string 128, the seal 268 is configured to press against the pilot drill string 128 when the reamer 204 is moved (i.e., advanced or retreated) relative to the pilot drill string 128.

[0029] With continued reference to FIG. 9, the inner surface 228 of the body 212 is configured to receive the pilot drill string 128 through the opening 214 of the body 212. More specifically, the pilot drill string 128 extends through both the first side 214a and the second side 214b of the opening 214. Accordingly, the drilling rig 120 can advance the reamer 204 along the pilot drill string 128 to follow the path P. The pilot bit 124 and pilot drill string 128 are drawn in dashed lines in FIG. 9 for clarity. The pilot bit 124 has an outer diameter DI which is slightly larger than an outer diameter D2 of the pilot drill string 128. In the illustrated embodiment, the outer diameter DI of the pilot bit 124 is about 12-3/4” and the largest outer diameter D2 of the portion of the pilot drill string designed to fit inside the reamer is 7-5/8” for the pipe and 8-3/4” for the tool joints.

[0030] Adjacent the axial end surface 252, the inner surface 244 of the reamer head 224 has a smallest inner diameter D3 that is slightly larger than the largest outer diameter D2 of the pilot drill string 128. In the illustrated embodiment, the inner diameter D3 of the reamer head 224 is about 10-5/8”, which is about 1.2 to 1.4 times the outer diameter D2 of the pilot drill string 128. Accordingly, the pilot drill string 128 is movable rotationally and axially relative to the reamer head 224. The outer surface 248 of the reamer head 224 defines an outer diameter D4 of the reamer head 224 that is larger than the outer diameter DI of the pilot bit 124. In the illustrated embodiment, the outer diameter D4 of the reamer head 224 is about 1.5 times the outer diameter DI of the pilot bit 124. Accordingly, the reamer head 224 can approximately align and center the longitudinal axis LA of the reamer 204 with the path P as the reamer 204 moves along the pilot drill string 128. The seal 264 has an inner diameter D5 that is smaller than the outer diameter D2 of the pilot drill string 128 such that the seal 264 presses against and substantially seals the pilot drill string 128. In the illustrated embodiment, the inner diameter D5 of the seal 264 is about 6-3/8” . The inner surface 228 of the body 212 has a largest inner diameter D6 that is greater than the outer diameter D2 of the pilot drill string 128. In the illustrated embodiment, the inner diameter D6 of the body 212 is about 12-4/5”. Accordingly, in the illustrated embodiment, the inner diameter D6 is about 1.4 to 1.7 times larger than the largest outer diameter D2 and an annular space 280 of about 1.5” to 3.0” (and preferably about 2.0” to 2.6”) is defined between the pilot drill string 128 and inner surface 228 of the body 212.

[0031] The cutter mount 236 is positioned between the first longitudinal end 216 and the second longitudinal end 220 of the body 212. The cutters 240 on the cutter mount 236 are configured to cut a reaming diameter D7 (FIG. 9) corresponding to the size of a reamed hole. The reaming diameter D7 in the illustrated embodiment is 36-1/4” but can vary depending on the needs of the particular project (e.g., from 18” to 72”). The cutters 240 in the illustrated embodiment are mounted to the cutter mount 236 and thus the body 212 in a staggered relationship relative to the longitudinal LA such that the cutters 240, as the reamer 204 is advanced, can open a previously drilled pilot hole PH. In the illustrated embodiment (FIGS. 6 and 7), the cutters 240 are mounted circumferentially about the longitudinal axis LA with increasing distances from the longitudinal axis LA for each successive cutter 240. In the illustrated embodiment, the cutters 240 are mounted to the cutter mounts 236 in rows that are spaced from other cutter mounts 236 and rows to locate the cutters 240 spaced furthest from the longitudinal axis LA to correspond to the reaming diameter D7. The reaming diameter D7 effectively relates to the desired size of the reamed hole RH. The reaming diameter D7 is greater than the outer diameter DI of the pilot bit 124. In the illustrated embodiment, the reaming diameter D7 is approximately 3..0 times larger than the outer diameter DI of the pilot bit 124. In other embodiments, the reaming diameter D7 may be, for example, between 1.5 times and 6.0 times larger than the outer diameter DI of the pilot bit 124.

[0032] One exemplary reamer drill string 208 is illustrated schematically in FIG. 9. Other connections between the reamer drill string 208 and the reamer 204 are possible. The illustrated reamer drill string 208 is connected to the outer surface 232 of the body 212. A connection pin 288 or other securing mechanism may couple the drill string 208 to the reamer 204. A cutting fluid inlet 284 to the reamer 204 is positioned adjacent the second end 220 thereof. The reamer 204 may receive cutting fluid (e.g., a bentonite mixture) from the drilling rig 120. The body 212 further includes a nozzle 292 (further illustrated in FIGS. 5-7) in fluid communication with the annular space 280. In the illustrated embodiment, the body 212 includes a plurality of nozzles 292. The nozzles 292 are configured to eject fluid from the annular space 280. The drilling rig 120 is configured to pump cutting fluid between the reamer drill string 208 and the pilot drill string 128 and out the nozzles 292 to allow provide sufficient lubrication to the cutters 240 during reaming.

[0033] FIG. 10 is a flow chart illustrating a method for pipe laying 600 from the entrance point 112 to the exit point 116. The flow chart is a general representation of operation of the drilling rig 120, pilot bit 124, and reamer 204 in creating a hole H spanning the entrance point 112 and the exit point 116. Once the hole H is created, product pipe (e.g., pipe, cable, tubing, etc.) is located in the hole H, and is utilized in a desired manner. The method for pipe laying 600 illustrated in FIG. 10 and described below may be carried out in the order illustrated in FIG. 10. Alternatively, steps 604-628 of the method for pipe laying 600 may be carried out in differing orders and/or simultaneously with one another at any given time. FIGS. 11 A-l 1H illustrate the position of the components at the drilling site 200 as the method for pipe laying 600 is carried out.

[0034] At step 604 (FIG. 10), the pilot bit 124 and thus the pilot drill string 128 are advanced with the drilling rig 120 to drill at least a portion of a pilot hole. The pilot hole has a diameter (e.g., DI, a first diameter) corresponding to the outer diameter DI of the pilot bit 124. In other embodiments, the pilot bit may be non-circularly shaped, but have an effective size (e.g., a first size). FIG. 11A illustrates the pilot bit 124 retracted from the entrance point 112 prior to drilling a portion of a pilot hole PH (FIG. 1 IB) along the path P. Where the pilot bit 124 is non-circular, the pilot bit 124 may cut a pilot hole PH corresponding to the effective size of the pilot bit 124. FIG. 1 IB illustrates the pilot bit 124 driven by the drilling rig 120 a portion of the path P between the entrance point 112 and the exit point 116.

[0035] At step 608 (FIG. 10), the reamer 204 is coupled to the drilling rig 120 via the reamer drill string 208. The reamer drill string 208 is positioned radially surrounding the pilot drill string 128. At step 612, the reamer 204 is advanced by the drilling rig 120 along the pilot drill string 128 and the pilot hole PH to ream the pilot hole PH to a reamed hole RH which has a diameter (e.g., D7, second diameter) corresponding to the positioning of the cutter 240. The diameter D7 of the reamed hole RH is greater than the diameter DI of the pilot hole PH. FIG. 11C illustrates the reamer 204 advanced to a position adjacent the position of the pilot bit 124 as shown in FIG. 1 IB. In other embodiments, the pilot bit 124 may be driven by one drilling rig 120 (e.g., via the pilot drill string 128), and the reamer 204 may be driven by another independently operating drill rig 120 (e g., via the reamer drill string 208). In other embodiments, such as the embodiment illustrated in FIG. 1 ID, a single drill rig 120 may include a first drilling mechanism 120a coupled to the pilot bit 124 via the pilot drill string 128 a second drilling mechanism 120b coupled to the reamer 204 via the reamer drill string 208. In such embodiments, the first and second drilling mechanisms 120a, 120b may be operable independently of one another to independently drive the pilot bit 124 and the reamer 204, respectively. In further embodiments, the same drilling rig 120 may selectively drive either the pilot bit 124, the reamer 204, or both the pilot bit 124 and the reamer 204. In such embodiments, it is possible to independently advance the pilot bit 124 and the reamer 204 along the path P from the entrance point 112 towards the exit point 116. In most instances, in sequential order, the pilot hole PH is drilled by the pilot bit 124, and then the reamed hole RH is reamed by the reamer 204 to take advantage of the centering effect of the reamer 204 and the reamer drill string 208 surrounding the pilot drill string 128. However, in other embodiments where the pilot bit 124 has an outer diameter DI smaller than the inner diameter D3 of the reamer head 224, it is envisioned that in some instances (e.g., breaking up large or dense rocks), the reamer 204 may advance at least partially beyond (e.g., forwards relative to) the pilot bit 124. In such instances, to ensure alignment of the pilot bit 124 and reamer 204 on the path P, axial advancement of the reamer 204 along the path P may be limited because the reamer 204 is not actively steered. In other instances, the pilot bit 124 and the reamer 204 may be simultaneously advanced from the entrance point 112 towards the exit point 116 with the pilot bit 124 leading the way and steering along the desired path P.

[0036] As illustrated in FIG. 1 ID, the pilot bit 124 can be further advanced until it protrudes from the exit point 116. In some instances, after the pilot bit 124 drills to (e.g., protrudes from) the exit point 116, the operator in the control trailer 140 may be prompted to verify that the exit point 116 is correct. Once the pilot bit 124 protrudes from the exit point 116, the reamer 204 can also be further advanced along the pilot drill string 128 to protrude from the exit point 116 (FIG.

1 IE). In some cases, the reamer 204 may be advanced from either the entrance point 112 or an intermediate point between the entrance point 112 and the exit point 116 after the operator verifies that the exit point 116 is correct. In some cases, as the reamer 204 continues cutting the reamed hole RH, cuttings and residual cutting fluid C are retained in the reamed hole RH.

[0037] In some instances, it may be advantageous, cost effective, and/or required to remove the cuttings and residual cutting fluid C from the reamed hole RH. In step 616 (FIG. 10), a swab tool 296 is coupled to either the pilot drill string 128 or the reamer drill string 208. In typical operation, the swab tool 296 is coupled to the drilling rig 120 via the pilot drill string 128 (or the reamer drill string 208) after reaming the reamed hole RH. However, the swab tool 296 may be coupled to the drilling rig 120 via the pilot drill string 128 (or the reamer drill string 208) at any time before, simultaneously, or after reaming of the pilot hole PH to the reamed hole RH. For example, if a reamed hole RH becomes filled with cuttings, residual cutting fluid C, or other debris, the swab tool 296 may clean the reamed hole RH before a product pipe PP is inserted into the reamed hole RH. FIG. 1 IF illustrates the swab tool 296 adjacent the exit point 116. The swab tool 296 is retreated from adjacent the exit point 116 to adjacent the entrance point 112. During swabbing, the swab tool 296 gathers cuttings, residual cutting fluid C, or other debris, and passes them to the mud rig 136 for further processing and/or off-boarding therefrom, and potentially into a reservoir R. In instances where the swab tool 296 is coupled to the reamer drill string 208, the swab tool 296 may gather cuttings, residual cutting fluid C, or other debris with the pilot drill string 128 in its original place (e.g., adjacent the exit point 116) until the reamed hole RH has been conditioned and is ready for installation of the product pipe PP.

[0038] After swabbing, the product pipe PP is secured, directly or indirectly via the pilot drill string 128, to the drilling rig 120. In the illustrated embodiment of FIG. 11G, the pilot drill string 128 is connected to the product pipe PP adjacent the exit point 116. The product pipe PP can then be pulled, by the pilot drill string 128 and the drilling rig 120 into the reamed hole RH. In other embodiments, the drilling rig 120 may push the product pipe PP from the entrance point 112 to the exit point 116. Either way, the product pipe is positioned in the reamed hole RH by driving action of the drilling rig 120. [0039] Various sequences of drilling and reaming are possible. For example, as illustrated and described above with regard to FIGS. 11 A-l 1C, the pilot bit 124 may stop at an intermediate point between the entrance point 112 and the exit point 116, and the reamer 204 can then be driven by the drilling rig 120 to catch up to the pilot bit 124. This process may be carried out multiple times before the pilot bit 124 drills and the reamer 204 reams along the entirety of the path P.

[0040] During reaming of the pilot hole PH to the reamed hole RH, a few different operations occur. As discussed above, while reaming, cleaned cutting fluid may be supplied from the mud rig 136 via the annular space 280 between the pilot drill string 128 and the reamer drill string 208 as well as the nozzle(s) 292. Also during reaming of the pilot hole PH to the reamed hole RH, the reamer head 224 and the pilot drill string 128 itself may center the longitudinal axis LA of the reamer 204 on the path P. The seal 268 may continuously wipe the pilot drill string 128. The seal 268 may also redirect fluid within the annular space 280 towards the nozzle(s) 292.

[0041] As illustrated in FIGS. 11 A-l 1H, the drilling rig 120 may utilize the reamer 204 to remain positioned adjacent the entrance point 112 during both drilling and reaming.

Accordingly, excess costly and time inefficient movement of the drilling rig 120 between the entrance point 112 and the exit point 116 may be avoided. Additionally, this may allow for less equipment to be positioned adjacent the exit point 116. In instances where the exit point 116 is underwater, this may be a highly time and cost-effective capability for improved operation at the drilling site 200.

[0042] Various features of the invention are set forth in the following claims.