CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional application Serial No. 61/784,199, filed March 14, 2013, and entitled "Drilling Rig for Drilling from Underground Tunnels," which is hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

BACKGROUND

[0003] Embodiments described herein relate generally to systems and methods for accessing and producing subsurface hydrocarbons. More particularly, Embodiments described herein relate to automated drilling rigs for accessing and producing subsurface hydrocarbons from an underground tunnel.

[0004] In drilling a borehole into an earthen formation, such as for the recovery of hydrocarbons or minerals from a subsurface reservoir, it is conventional to erect a large drilling oil rig at the surface, connect a drill bit onto the lower end of a "drill string," and then rotate the drill bit with weight-on-bit (WOB) applied to drill the borehole along a predetermined path toward the subsurface reservoir. In general, the bit may be rotated by means of either a "rotary table" or a "top drive" associated with a drilling rig and/or a downhole motor incorporated into the drillstring adjacent to the bit. During the drilling process, a drilling fluid, also referred to as "drilling mud" or simply "mud," is pumped under pressure from the surface down the drill string, out the face of the drill bit into the borehole bottom, and then back up to the surface through the annular space ("wellbore annulus") between the drill string and the borehole sidewall. The drilling fluid performs several functions such as carrying formation cuttings to the surface, cooling the drill bit, and forming a protective cake on the borehole wall (to stabilize and seal the borehole wall). The drilling fluid returned to the surface is conditioned by removing the formation cuttings and entrained gases, and then re-circulated down the drill string. [0005] Heavy oil deposits in remote locations provide relatively new and untapped sources of hydrocarbons. However, the harsh conditions as well as the environmental sensitivity of many such locations present challenges to conventional surface drilling and production operations. For example, extreme temperatures over extended periods of time can be hard on surface equipment and personnel. In addition, because the relatively large surface footprint of conventional drilling rigs and associated equipment, as well as noise generated by such rigs and equipment, may have negative impacts on sensitive environments, obtaining governmental approval and drilling permits in many locations can be difficult. Such governmental approval and permitting issues are further exasperated by the fact that the recovery of heavy oil deposits typically requires a relatively high well density, and many state laws require removal of an existing drilling pad before a new drilling pad may be put in place. A potential solution to these challenges is to place a drilling rig below ground. However, conventional drilling rigs are simply too large to be placed within an underground or subterranean tunnel while maintaining realistic costs.

BRIEF SUMMARY OF THE DISCLOSURE

[0006] These and other needs in the art are addressed in one embodiment by a rig for drilling a borehole from an underground tunnel. In an embodiment, the rig comprises a base assembly. In addition, the rig comprises a drilling assembly mounted to the base assembly. Further, the rig comprises an upper frame assembly mounted to the drilling assembly above the base assembly. Still further, the rig comprises a support hood coupled to the drilling assembly and positioned above the upper frame assembly. The support hood is configured to bear against a ceiling of the tunnel during drilling operations.

[0007] These and other needs in the art are addressed in another embodiment by a rig for drilling a borehole from an underground tunnel. In an embodiment, the rig comprises a base assembly. In addition, the rig comprises a drilling assembly mounted to the base assembly. Further, the rig comprises an upper frame assembly. Still further, the rig comprises a pipe handling assembly mounted to the drilling assembly and a track assembly positioned above the pipe handling assembly. The track assembly is configured to deliver pipe joints to the pipe handling assembly during drilling operations.

[0008] These and other needs in the art are addressed in still another embodiment by a method of drilling a borehole from an underground tunnel. In an embodiment, the method comprises supplying a plurality of pipe joints to a drilling rig. In addition, the method comprises gripping a first pipe joint with a pipe handling assembly, and coupling the first pipe joint to a drill string with the pipe handling assembly. Further, the method comprises applying a vertical load to the drill string. Still further, the method comprises bearing against a ceiling of the tunnel while applying the vertical load to the drill string.

[0009] Embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical advantages of the invention in order that the detailed description of the invention that follows may be better understood. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:

[0011] Figure 1 is a schematic side view of an embodiment of a subterranean drilling system including an automated modular underground drilling rig disposed in a subterranean tunnel in accordance with the principles disclosed herein;

[0012] Figure 2 is an enlarged front view of the underground drilling rig of Figure 1 disposed within the subterranean tunnel;

[0013] Figure 3 is a perspective view of the underground drilling rig of Figure 1;

[0014] Figure 4 is a side view of the underground drilling rig of Figure 1;

[0015] Figure 5 is a perspective view of the base assembly of Figure 1;

[0016] Figure 6 is a schematic top view of the clamping assembly mounted to the base assembly of Figure 5;

[0017] Figure 7 is a side view of the base assembly and the drilling assembly of Figure 1; [0018] Figure 8 is a perspective view of the base assembly and the drilling assembly of Figure 7;

[0019] Figure 9 is an enlarged partial front perspective view of the base assembly and the drilling assembly of Figure 7;

[0020] Figure 10 is a perspective view of the upper frame assembly of Figure 1;

[0021] Figure 11 is a cross-sectional view along section 11-11 of Figure 4;

[0022] Figure 12 is a perspective view of an embodiment of a pipe carriage in accordance with the principles disclosed herein for delivering drilling pipe joints to the underground drilling rig of

Figure 1;

[0023] Figure 13 is a perspective view of the pipe handling assembly of Figure 1;

[0024] Figures 14-18 are sequential schematic top views of the pipe carriage of Figure 12 moving along the track assembly of the underground drilling rig of Figure 1 to deliver drilling pipe joints to the pipe handling assembly of Figure 13; and

[0025] Figures 19-21 are sequential schematic side views illustrating an embodiment of a method in accordance with the principles disclosed herein for delivering and installing the underground drilling rig of Figure 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0027] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0028] In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to . . . ." Also, the term "couple" or "couples" is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms "axial" and "axially" generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms "radial" and "radially" generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. Any reference to up or down in the description and the claims will be made for purposes of clarity, with "up," "upper," "upwardly," or "upstream" meaning toward the surface of the borehole and with "down," "lower," "downwardly," or "downstream" meaning toward the terminal end of the borehole, regardless of the borehole orientation.

[0029] Referring now to Figure 1, a subterranean or underground drilling system 10 is shown. In this embodiment, system 10 includes a first or upper operating tunnel 12 and a second or lower operating tunnel 14. Each tunnel 12, 14 has a roof or ceiling 12a, 14a, respectively, and a floor 12b, 14b, respectively. A plurality of laterally spaced, parallel bores or conduits 60 extend vertically between tunnels 12, 14. Each conduit 60 has a central or longitudinal axis 65, a first or upper end 60a at floor 12b of upper tunnel 12, and a second or lower end 60b at ceiling 14a of lower tunnel 14. Upper ends 60a of each conduit 60 that is not being used for drilling operations is preferably closed off or plugged (e.g., with a steel cap) to reduce the risk of equipment or personnel falling therein. Axes 65, and hence conduits 60, are vertically oriented and spaced apart a horizontal distance D ₆ o preferably between 40.0 and 50.0 ft. In addition, each conduit 60 is insulated and has a diameter preferably between 20.0 and 24.0 in.

[0030] An automated modular underground drilling rig 100 is disposed in upper tunnel 12 over one conduit 60. A blowout preventer 40 ("BOP 40") is disposed in lower tunnel 14 below rig 100 and the associated conduit 60. A drill string 32 formed from a plurality of drill pipe sections or joints connected together end-to-end extends from rig 100, through conduit 60 and BOP 40, and into the earthen formation 8 below lower operating tunnel 14. A drill bit is connected to the lower end of drill string 32. Rig 100 applies WOB and rotates the drill bit via drill string 32 to drill a borehole 30 into formation 8 along a predetermined trajectory. Rig 100 can also be employed to trip drill string 32 out of borehole 30 following drilling operations. [0031] A rail system 20 including a track 21 and one or more cars 22 is provided in each tunnel 12, 14. Each track 21 is disposed on the floor 12b, 14b of the corresponding tunnel 12, 14, and extends the entire length of the corresponding tunnel 12, 14. Cars 22 are moveably disposed on tracks 21 such that they can roll along the length of tracks 21. Because rail systems 20 are generally disposed along the floor 12b, 14b of tunnels 12, 14, systems 20 may also be referred to as a "lower" or "floor" rail systems 20. In addition, a rail system 80 including a pair of laterally- spaced tracks 81 (note: only one track 81 is visible in Figure 1) is provided in upper operating tunnel 12. Tracks 81 are disposed proximate ceiling 12a and extend along the length of tunnel 12. Because rail system 80 is generally disposed along ceiling 12a, system 80 may also be referred to as an "upper" or "ceiling" rail system 80. As will be described in more detail below, ceiling rail system 80 supports a plurality of pipe carriages 180 that move along tracks 81 to deliver drill pipe joints to rig 100 during drilling operations and take drill pipe joints from rig 100 during tripping operations. In this embodiment, rail systems 20, 80 are automated to minimize human intervention in drilling and tripping operations. For example, rail systems 20, 80 can be electrically powered, and monitored and controlled in tunnels 12, 14 from a remote location.

[0032] Referring now to Figures 2-4, automated modular underground drilling rig 100 is shown. Rig 100 has a central axis 105 substantially aligned with axis 65 during drilling and tripping operations, and includes a base assembly 120, a drilling assembly 140 mounted to base assembly 120, an upper frame assembly 160 positioned atop drilling assembly 140, a bearing or support hood 220 supported by upper frame assembly 160, and a pipe handling assembly 190 positioned adjacent the drilling assembly 140. As will be described in more detail below, bearing hood 220 is braced against ceiling 12a of tunnel 12 during drilling operations. Base assembly 120, drilling assembly 140, frame assembly 160, hood 220, and pipe handling assembly 190 will each be described in turn.

[0033] Referring now to Figure 5, base assembly 120 is shown. Base assembly 120 generally supports rig 100 along floor 12b. In this embodiment, base assembly 120 includes a base or trolley 126, a rig floor 124 pivotally coupled to trolley 126, a plurality of positioning assemblies 130 positioned about the perimeter of trolley 126, and a clamping system 114 mounted to rig floor 124. Trolley 126 is generally rectangular in shape and has a first or front end 126a, a second or rear end 126b, and lateral sides 126c, 126d extending between ends 126a, 126b. A vertical central axis 125 is oriented perpendicular to trolley 126 and extends through the center of trolley 126. Each end 126a, 126b of trolley 126 is provided with a pair of wheels or rollers 122 and a coupling 133 to facilitate the movement of rig 100 through tunnel 12 along rail system 20. In particular, rollers 122 are positioned to roll along track 21 of upper tunnel 12 and couplings 133 provide robust connection points at which base assembly 120 can be pushed or pulled along track 21.

[0034] Rig floor 124 is pivotally coupled to trolley 126 with a pair of hinges 137 extending therebetween proximal rear end 126b. Thus, floor 124 can rotate relative to trolley 126 about a horizontal axis extending between hinges 137. As will be described in more detail below, rotation of floor 124 allows rig 100 to traverse through portions of tunnel 12 having a vertical height less than the overall height of rig 100 when fully assembled and erected as shown in Figure 3. Rig floor 124 includes a cover plate 127 having a central drilling hole 129 and a plurality of mounting apertures 123 disposed about central aperture 129. As will be described in more detail below, drilling hole 129 provides a path for pipe joints and drill string 32 to be run into and out of conduit 60 and borehole 30 during drilling and tripping operations, and drilling assembly 140 is mounted to base assembly 120 via mounting holes 123.

[0035] A positioning assembly 130 is disposed at each corner of rectangular trolley 126 and function to secure and maintain the position of base assembly 120 and drilling rig 100 within tunnel 12 during drilling and tripping operations. In this embodiment, each positioning assembly 130 includes an actuator 132, a housing 134 rigidly mounted to trolley 126, a screw jack 138 extending downward from housing 134, and a foot 136 mounted to the lower end of screw jack 138. Actuator 132 extends from housing 134 and is coupled to screw jack 138. In particular, actuator 132 rotates screw jack 138 to vertically raise and lower foot 136 relative to housing 134, trolley 126 and tunnel floor 12b. To secure trolley 126 and rig 100 in position during drilling and tripping operations, screw jacks 138 are extended downward until feet 136 engage tunnel floor 12b and lift rollers 122 from track 21. To enable movement of trolley 126 and rig 100 along track 21, screw jacks 138 are lifted upward until rollers 122 engage track 21 and feet 136 disengage floor 12b.

[0036] Referring now to Figures 5 and 6, clamping system 114 is attached to drilling rig floor 124 below plate 127 and is generally disposed about drilling hole 129. In this embodiment, clamping system 114 has a vertical central axis 115 coaxially aligned with axis 125 of trolley 126, an upper clamp assembly 116 and a lower clamp assembly 118 positioned immediately below upper clamp assembly 116. Upper clamp assembly 116 includes a pair of radially opposed clamping members 116a, 116b configured to be moved radially inward and outward relative to axis 115, and lower clamp assembly 118 includes a pair of radially opposed clamping members 118a, 118b configured to be moved radially inward and outward relative to axis 115. In addition, upper clamp assembly 116 can pivot or rotate about axis 115 relative to lower clamp assembly 118. In general, during threaded joint makeup operations (i.e., during drilling operations), lower clamp assembly 118 grips the uphole end of drillstring 32 while a new pipe joint is threaded into the uphole end to increase the length of drillstring 32. To sufficiently tighten and pre-load the threaded connection between the drillstring 32 and the new pipe joint, lower clamp assembly 118 continues to grip the uphole end and prevent its rotation while upper clamp assembly 116 moves into engagement with lower end of the new pipe joint, grips, and applies rotational torque to the new pipe joint. Conversely, during threaded joint breaking operations (during tripping operations), lower clamp assembly 118 grips drillstring 32 immediately below the threaded connection between two pipe joints in drill string 32 to be broken and prevents rotation of drill string 32 below that connection while upper clamp assembly 116 moves into engagement with drill string 32 immediately above the connection, grips and applies rotational torque to break the connection between assemblies 116, 118. Examples of clamp assemblies that can be used for clamp assembly 114 are disclosed in U.S. patent application Serial No. 61/783,859, which is hereby incorporated herein by reference in its entirety.

[0037] Referring now to Figures 7-9, drilling assembly 140 is shown mounted to base assembly 120. Drilling assembly 140 provides rotational torque to drill string 32 and WOB during drilling operations to drill borehole 30. In this embodiment, drilling assembly 140 includes a first pair of vertical support posts 142, a second pair of vertical support posts 148, a plurality of diagonal support members 144, a pair of linear actuators 146, and a drilling carriage 150. Each post 142 is oriented parallel to axis 105, and has a first or upper end 142a secured to upper frame assembly 160, and a second or lower end 142b secured within one hole 123 in drilling floor 124 (see also Figure 5). Similarly, each post 148 is oriented parallel to axis 105, and has a first or upper end 148a secured to upper frame assembly 160 and a second or lower end 148b secured to drilling floor 124. Each support member 144 has a first or upper end 144a pinned to upper frame assembly 160 with a connection pin 149a and a second or lower end 144b pinned to trolley 126 with a connection pin 143. In this embodiment, two support members 144 extend upward from lateral side 126c of trolley 126 (see also Figure 5) and taper towards each other to form a truss support, while the other two members 144 extend upward from lateral side 126d of trolley 126 and taper towards each other to form a truss support.

[0038] Referring still to Figures 7-9, each linear actuator 146 is oriented parallel to axis 105 and has a first or upper end 146a, a second or lower end 146b, a post section 146c extending axially from the upper end 146a, and a sleeve section 146d disposed about the post section 146c. Sleeve section 146d extends axially up and down relative to the corresponding post section 146d. Upper ends 146a are secured to upper frame assembly 160 and lower ends 146b are secured within holes 123 in drilling floor 124 (see also Figure 5).

[0039] Drilling carriage 150 includes a body 152 and a top drive 154 mounted to body 152. Body 152 is provided with a first pair of through bores 158 extending axially therethrough and a second pair of through bores 156 extending axially therethrough. Support posts 142 are slidingly received within the first pair of bores 158, and sleeve sections 146d are secured within the second pair of bores 156. Thus, as actuators 146 move sleeve sections 146d axially up and down, body 152 is translated axially up and down and is guided by posts 142. Top drive 154 is configured to receive an upper end of a drill pipe joint (a single joint or joint disposed at the upper end of drill string 32) and rotate the drill pipe joint about axis 105, thereby facilitating the makeup or breakup of threaded joints or rotating the drill bit at the lower end of string 32.

[0040] Referring now to Figures 10 and 11, upper frame assembly 160 is shown. Upper frame assembly 160 functions as an upper support and bracing structure for the modular underground drilling rig 100 and serves to interconnect tracks 81 with rig 100. In this embodiment, upper frame assembly 160 has a central axis 165 and includes a frame member or plate 162 and a pipe carriage track assembly 170 coupled to the plate 162. Frame assembly 160 is symmetric about axis 165, which is oriented perpendicular to and intersects axis 105. Plate 162 has a first or front end 162a, a second or rear end 162b, and lateral sides 162c, 162d disposed on opposite sides of axis 165. In addition, plate 162 includes a front section 167 extending from end 162a and a rear section 163 extending from section 167 to rear end 162b. Front section 167 includes a first pair of vertical through bores 164 and a second pair of vertical through bores 166. Upper ends 142a of posts 142 are secured within bores 164 and upper ends 146a of actuators 146 are secured within bores 166 (see also Figure 8). In particular, upper end 146a of each linear actuator 146 extends through one hole 166 and is secured therein with a tie head 147 that extends axially upward from front section 167.

[0041] Upper frame assembly 160 further includes a plurality of screw jacks 169. In this embodiment, a total of three screw jacks are included - two screw jacks 169 disposed on the front section 167 on opposing sides of the axis 165 and one screw jack 169 disposed on the rear section 163 substantially along the axis 165. Each of the screw jacks 169 are coupled to a motor 169a, which is configured to force each screw jack 169 to rotate, thereby either extending or retracting each screw jack 169 axially with respect to the axis 105. As is best shown in Figure 2, screw jacks 169 are coupled to the hood 220, which is braced against the ceiling 12a of a tunnel 12. As will be described in more detail below, screw jacks 169 allow for enhanced adjustability of the height of hood 220 within a subterranean tunnel (e.g., tunnel 12) in addition to the screw jacks 138 disposed on trolley 126 of base assembly 120, previously described. Further, as will also be described in more detail below, screw jacks 169 transfer reactive forces from the drill bit, through drill string 32 and rig 100 to ceiling 12a of tunnel 12 via hood 220 to rigidly brace rig 100 during drilling operations.

[0042] Referring again to Figures 10 and 11, a central through bore 168 extends axially through section 167 of plate 162 and is coaxially aligned with the axis 105. Bore 168 is sized and positioned to receive top drive 154 when carriage 150 is disposed in its uppermost position (see also Figure 9). Rear section 163 includes a pair of apertures or holes 161. Upper ends 148a of support posts 148 are secured within holes 161 (see also Figure 8).

[0043] A pipe carriage positioning mechanism 177 is mounted to rear section 163 and includes a gear or toothed sprocket 179 positioned on the underside of plate 162 and a motor (not shown) to rotate sprocket 179 about a vertical axis 177a. As will be described in more detail below, sprocket 179 engages mating teeth 183 provided on an upper frame member 184 of a pipe carriage 180 to: (a) position the carriage 180 such that a pipe joint 34 carried by carriage 180 can be supplied to pipe handling assembly 190 during drilling operations, and (b) position the carriage 180 such that a pipe joint 34 removed from drill string 32 can be placed on carriage 180 with pipe handling assembly 190 during tripping operations.

[0044] Referring still to Figures 10 and 11, track assembly 170 facilitates the movement of carriages 180 to and from rig 100. In this embodiment, track assembly 170 includes an arcuate rail or track 172 and a pair of switches 174 coupled to track 172. Track 172 has a generally semi-circular section 171 with ends 171a, 171b, and a pair of S-shaped transition sections 173; one transitions section 173 extends from each end 171a, 171b. Section 171 is centered on axis 165 in bottom view (Figure 11) and extends around positioning mechanism 177. Each transition section 173 has a first end 173a coupled to one switch 174 and a second end 173b contiguous with a corresponding end 171a, 171b of section 171.

[0045] As best shown in Figure 10, each switch 174 includes a rectangular housing 175 and a track selector sled 176 moveably disposed within housing 175. Housing 175 has a first or laterally outer end 175a, a second or laterally inner end 175b, and two support members 175c extending between the ends 175a, b. Ends 175a, 175b are referred to herein as an "outer" and "inner" because they are arranged distal and proximal axis 165, respectively. Sled 176 supports a straight track section 176a and an arcuate track section 176b. Sled 176 is moved laterally inward and outward between ends 175 a, 175b to position either track section 176a or track section 176b into alignment with a corresponding track 81 of ceiling track system 80 (see also Figure 1). As will be described in more detail below, when track section 176a is aligned with a corresponding track 81, carriages 180 cannot be transferred between tracks 81, 172; however, when track section 176b is aligned with a corresponding track 81, carriages 180 can be transferred between tracks 81, 172. In general, any suitable mechanism known in the art can be used to move sled 176 relative to housing 175 including, without limitation, a hydraulic actuator, an electric motor, etc. The movement of sled 176 to selectively align track sections 176a, 176b with track 81 is preferably automated to minimize human intervention.

[0046] Referring now to Figures 11 and 12, pipe carriage 180 is shown. As previously described, pipe carriages 180 move along tracks 81 to deliver drill pipe joints 34 to rig 100 during drilling operations and take drill pipe joints from rig 100 during tripping operations (see also Figure 1). Each carriage 180 supports a plurality of elongate cylindrical pipe joints 34 in vertical orientations. Pipe joints 34 are added to drill string 32 to lengthen drill string 32 during drilling operations, and removed from drill string 32 to shorten drill string 32 during tripping operations. Each pipe joint 34 has a first or upper end 34a comprising an internally threaded box end, a second or lower end 34b comprising an externally threaded pin end, a cylindrical outer surface 34c extending between ends 34a, 34b, and a throughbore 34d extending between the ends 34a, 34b. [0047] Each pipe carriage 180 includes a frame 182 and a pair of supports 187 extending upward from frame 182. Frame 182 has a vertical central axis 185, a first or upper end 182a, and a second or lower end 182b. An arc-shaped horizontal frame member 184 is disposed at upper end 182a, an arc-shaped horizontal frame member 186 disposed at lower end 182b, and a pair of elongate supports 188 extending vertically between members 184, 186.

[0048] Upper frame member 184 has a uniform radius of curvature equal to the radius of curvature of semi-circular section 171 and includes a plurality of circumferentially-spaced teeth 183 along its radially inner concave side and a plurality of circumferentially-spaced receptacles 189 along its radially outer convex side. Each receptacle 189 is sized and shaped to mate and engage one pipe joint 34 proximal its upper end 34a. As is best shown in Figure 11, teeth 183 are sized to mate and engage with sprocket 179. Members 187 extend axially upward from upper frame member 184. The upper end of each member 187 is coupled to track 81, 172 by a roller or other means that allows carriage 180 to be controllably moved thereon.

[0049] Referring still to Figures 11 and 12, lower frame member 186 is oriented parallel to upper frame member 184 and also has a uniform radius of curvature equal to the radius of curvature of semi-circular section 171. In addition, lower frame member 186 includes a plurality of circumferentially-spaced cylindrical recesses 181 extending axially from the top surface of frame member 186. Each recess 181 in lower frame member 186 is substantially coaxially aligned with one receptacle 189 of upper frame member 184. As is best shown in Figure 12, each recess 181 is sized and shaped to receive lower end 34b of one pipe joint 34 seated in a corresponding receptacle 189.

[0050] Referring now to Figures 4 and 13, pipe handling assembly 190 is shown. Pipe handling assembly 190 transfers pipe joints 34 between carriage 180 and rig 100, as well as initiates the threading/unthreading of pipe joints 34 to the upper end of drill string 32 during drilling/tripping operations, respectively. In this embodiment, pipe handling assembly 190 includes a pipe manipulator 192 and a mounting assembly 200 coupling manipulator 192 to posts 148. Manipulator 192 includes a body or housing 194 and a pipe handling arm 196 extending from housing 194. Arm 196 is extended and retracted from housing 194 with an actuator 198 mounted to housing 194. In general, actuator 198 can be any suitable device for extending and retracting arm 196 including, without limitation, an electric motor, a hydraulic motor, or the like. [0051] Housing 194 has a horizontal central axis 195, a first end 194a, a second end 194b, and a receptacle 194c extending axially from end 194b. First end 194a is positioned proximal central axis 105 of rig 100 and second end 194b is positioned distal axis 105, and thus, ends 194a, 194b may be referred to herein as "inner" and "outer", respectively, relative to axis 105.

[0052] Arm 196 includes an elongate body 199 extending from housing 194 and a curved claw or finger 191 moveably coupled to end 199a of body 199 distal housing 194. In particular, curved finger 191 has a first end 191a pivotally coupled to end 199a and a second end 191b opposite end 191a. Finger 191 generally extends across end 199a of body 199, thereby defining a bay or receptacle 193 therebetween. As will be described in more detail below, finger 191 is configured to pivot about end 191a to grasp and release drill pipe joints 34, as well as accommodate drill pipe joints 34 having different outer diameters. As best shown in Figure 13, a vertical roller 197a is rotatably mounted to end 191b of finger 191 and another vertical roller 197b is rotatably mounted to end 199a of body 199 generally opposite roller 197a. Further, in this embodiment, a third roller 197c is rotatably mounted to finger 191, between the ends 191a, b and adjacent the roller 197a (note: the roller 197c is shown in Figure 13 with hidden lines). In this embodiment, rotation of roller 197b is powered with an actuator 201 mounted to body 199, however, rollers 197a, 197c are not driven and are free to rotate in either direction. As will be described in more detail below, a pipe joint 34 is received within receptacle 193 and engaged by rollers 197a, 197b, 197c. Roller 197b is then rotated with actuator 201 to rotate pipe joint 34 disposed between rollers 197a, 197b, 197c to thread/unthread a threaded connection between the pipe joint 34 and the drillstring 32. In general, actuator 201 can be any suitable device for rotating roller 197b including, without limitation, an electric motor, a hydraulic motor, or the like.

[0053] Referring still to Figure 13, mounting assembly 200 moveably couples pipe manipulator 192 to posts 148. Mounting assembly 200 includes a pair of guide collars 202 mounted to housing 194 and disposed about posts 148. Collars 202 slidingly engage posts 148 as mounting assembly 200, and hence pipe manipulator 192 moves vertically up and down along posts 148. Such vertical movement of pipe manipulator 192 is controlled by an actuator 212 coupled to housing 194. In particular, actuator 212 rotates an externally threaded vertical shaft 208 coupled to rig floor 124 with a support post 210. Shaft 208 threadably engages a ball nut 214 disposed on post 210, and thus, as shaft 208 is rotated in one direction, mounting assembly 200 and pipe manipulator 194 move upward along posts 148, and as shaft 208 is rotated in the opposite direction, mounting assembly mounting assembly 200 and pipe manipulator 194 move downward along posts 148. In general, actuator 212 can comprise any suitable device for rotating shaft 208 including, without limitation, a hydraulic actuator, an electric motor, etc.

[0054] Referring now to Figures 1, 8, and 13, during drilling operations, carriages 180 deliver pipe joints 34 to rig 100 (see also Figure 1); pipe handling assembly 190 removes a joint 34 from carriage 180, positions the joint 34 in line with the upper end of drill string 32, and threads the lower end of the pipe joint 34 into drill string 32. Clamping system 114 then completes the makeup and preloading of the threaded connections between pipe joint 34 and drill string 32 as previously described. In this embodiment, top drive 154 engages the upper end of lengthened drill string (i.e., the upper end of pipe joint 34 added to the drill string 32) either before or after actuation of clamping system 114. Once clamping system 114 has been released from pipe joint 34, top drive 154 rotates drill string 32 while applying WOB to advance the drill bit at the lower end of drill string 32 along a predetermined trajectory. This process is repeated with additional pipe joints 34 to drill borehole 30. It should be appreciated that this process is performed in reverse to trip drill string 32 out of borehole 30.

[0055] Pipe joints 34 are delivered to rig 100 using carriages 180, tracks 81, and track assembly 170. In Figures 14 and 15, carriage 180 is shown bypassing rig 100; in Figures 16 and 17, carriage 180 is shown delivering pipe joints 34 to drilling rig 100; and in Figure 18, carriage 180 is shown being positioned along track assembly 170 with sprocket 179 to align one pipe joint 34 with pipe handling assembly 190. In general, pipe joints 34 are loaded on carriage 180, and carriage 180 moves along track 81 in tunnel 12 toward rig 100. At rig 100, the position of switch 174 determines whether carriage 180 is directed to rig 100 or bypasses rig 100. As shown in Figures 14 and 15, with switch 174 positioned to align the straight track sections 176a with tracks 81, carriage 180 continues along track 81 and passes track assembly 170, thereby bypassing rig 100. However, as shown in Figures 16 and 17, with switch 174 positioned to align curved track section 176b with track 81, carriage 180 is directed onto track assembly 170. As shown in Figure 18, carriage 180 continues along track assembly 170 until sprocket 179 of rig 100 engages teeth 183 of carriage 180, thereby allowing sprocket 179 to fine tune the position of carriage 180 to align pipe joints 34 (one at a time) with pipe handling assembly 190. [0056] Referring now to Figures 1, 4, 5, 8, 11, 12, and 13, sprocket 179 aligns one pipe joint 34 with pipe handling assembly 190. Next, actuator 198 actuates to extend arm 199 and finger 191 is actuated to open receptacle 193 to receive the aligned pipe joint 34 therein. With pipe joint 34 sufficiently disposed in receptacle 193, finger 191 is actuated to grasp the pipe joint 34 with rollers 197a, 197c. Actuator 198 then continues to extend arm 199 to align the pipe joint 34 with drilling hole 129 in rig floor 124. Next, roller 197b is rotated to drive the rotation of the drill pipe joint 34 about axis 105 and pipe handling assembly 190 is lowered with actuator 212 to initiate the threading of the lower end 34b of the pipe joint 34 into the upper end of drill string 32. Clamping assembly 114 completes the makeup, thereby incorporating pipe joint 34 into drill string 32. Drilling carriage 150 is then lowered until top drive 154 engages upper end 34a of the pipe joint 34. Next, top drive 154 drives the rotation of pipe joint 34 as actuators 146 urge carriage 150 downward, thereby applying WOB and rotating the drill bit with drill string 32 to lengthen borehole 30. As linear actuators 146 urge carriage 150, drill string 32, and the drill bit downward, upward reactive forces are transferred to the surrounding formation by engagement of hood 220 and ceiling 12a of tunnel 12 to effectively braces rig 100 within tunnel 12.

[0057] In general, the time and associated cost for forming underground tunnels is directly related to the size of the tunnels (e.g., diameter, height and width, etc.). Accordingly, in some cases it may be desirable to transport rig 100 to the drilling location in a tunnel having a height less than the fully assembled rig 100. For example, Figures 19-21 illustrate the transport of rig 100 to a drilling site through a portion of tunnel 12 having a height less than the assembled height of rig 100, and the subsequent installation rig 100 at the drilling site. Referring first to Figure 19, rig floor 124 is pivoted via hinges 137 away from trolley 126, thereby rotating upper frame assembly 160 towards the floor 12b and decreasing the overall height of rig 100. This enables rig 100 to pass through sections of tunnel 12 having a height less than the height of the fully deployed rig 100. During transport through tunnel 12, feet 136 are raised from floor 12b and wheels 122 roll along tracks 21.

[0058] Referring now to Figures 20 and 21, at the drilling location along tunnel 12, drill rig floor 124 is rotated about the hinges 137 onto trolley 126 resulting in upper frame assembly 160 being rotated to a vertical, deployed position. It should be appreciated that a cut out or recess 13 is provided along ceiling 12a at the drill site to provide sufficient space for upper frame assembly 160 to be rotated to a vertical position. In addition, feet 136 are lowered into engagement with floor 12b and base assembly 120 is lifted upward to disengage wheels 122 from tracks 21. Next, drilling assembly 140, support hood 220, and track assembly 170 are coupled to upper frame assembly 160 and the pipe handling assembly 190 is coupled to posts 148. The vertical spacing between hood 220 and ceiling 12a may then be adjusted until hood 220 contacts and engages ceiling 12a, thereby effectively bracing rig 100 within tunnel 12.

[0059] In the manner described, embodiments of modular drilling rig 100 can be used to drill a borehole from a subterranean tunnel. By drilling from a tunnel (e.g., tunnel 12) as opposed to above-ground, personnel and equipment are protected from harsh weather conditions at the surface, and the footprint of drilling operations at the surface is significantly decreased. In addition, rig 100 is preferably fully automated to minimize human intervention and associated risk in underground operations. For example, actions such as the delivery of pipe joints 34, the makeup and/or break up of connections between pipe joints 34 and drill string 32, the application of WOB by carriage 150, and application of rotational torque by top drive 154 are all preferably automated processes that are monitored and controlled by a remote control system.

[0060] Although embodiments described and disclosed herein have included a pair of linear actuators 146 within drilling assembly 140, it should be appreciated that more or less than two linear actuators 146 may be used while still complying with the principles disclosed herein. Additionally, while embodiments described and disclosed have included a total of four positioning assemblies 130 mounted to trolley 126, it should be appreciated that in other embodiments, more or less than four positioning assemblies may be included while still complying with the principles disclosed herein. Further, it should be appreciated that in other embodiments, either the roller 197a, and/or the roller 197b on manipulator 192 may be driven to the rotate in order to also rotate a pipe joint 34 disposed within the receptacle 193 while still complying with the principles disclosed herein. Still further, while embodiments described and disclosed herein have included a total of three upper screw jacks 169, in other embodiments, the number and arrangement of screw jacks 169 may be varied while still complying with the principles disclosed herein. Also, in other embodiment, no screw jacks 169 may be included and the tie heads 147 may directly couple to the hood 220, in order to brace rig 100 against the ceiling 12a of tunnel 12 during drilling operations.

[0061] While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the invention. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.