WO2015041700A1

WO2015041700A1 - Method of extending a bore using a laser drill head

Info

Publication number: WO2015041700A1
Application number: PCT/US2013/061227
Authority: WO
Inventors: Tamas BOZSO; Robert BOZSO; Gabor Molnar
Original assignee: SLD Enhanced Recovery Inc
Current assignee: SLD Enhanced Recovery Inc
Priority date: 2013-09-23
Filing date: 2013-09-23
Publication date: 2015-03-26
Anticipated expiration: 2016-03-23

Abstract

A method to extend an earthen bore (90) using a laser drill head (50A) to remove formation material (19) using a plurality of laser light-emitting elements (66 and 45) that together emit a plurality of laser light beams (64a and 64b) to impinge on a portion of the wall (94) of the bore (90) to be extended. Embodiments of the method enable an oblique extension (80 and 81) of the bore (90) by providing a plurality of central laser light-emitting elements (66) and a plurality of peripheral laser light-emitting elements (45), together forming a cluster, activating the central laser light-emitting elements (66) while activating a first peripheral sub-group (71) of laser light-emitting elements (45) at a first power level and one of deactivating and activating at a second power level, less than the first power level a second peripheral sub-group (72) of laser light-emitting elements (45) to modify an aggregate laser light beam (59A) emitted from the laser drill head (50A) to impinge to a greater extent on a side of the bore distal to the second peripheral sub-group

Description

METHOD OF EXTENDING A BORE

USING A LASER DRILL HEAD

BACKGROUND

Field of the Invention

[0001] The present invention relates to drilling earthen bores for the recovery of minerals in the earth's crust More specifically, the present invention relates to a method of extending an earthen bore using a laser dri ll head.

Background of the Related Art

[0002] The invention relates to a procedure for extending an earthen bore using a laser drill head. The laser drill head emits laser light of sufficient power to melt and/or to thermally degrade formation rock at a portion of a wall of an earthen bore to be extended. As a result of the impingement of the laser light onto a wall of the bore at the portion of the bore to be extended, formation rock is changed to molten rock dross and/or to thermally degraded material and is removed from the extended portion of the bore.

[0003] Using conventional laser drill heads, the physical structure and configuration of the portion of the bore adjacent to the portion to be extended, i.e., the structure and configuration of the portion of the bore that contains the laser drill head, is a critical and detenninative factor that influences the direction in which the bore is extended. For example, if the portion of the bore adjacent to the portion to be extended is generally straight and contains the elongate laser drill head, the extended portion of the bore is highly likely, using conventional laser drilling methods, to be aligned with the portion of the bore that contains the laser drill head. "Straight-line" boring with a conventional laser drill head occurs because laser light is emitted from & leading end of as elongate laser drill head and travels in a straight line to impinge upon a portion of the bore wall. If the elongate laser drill head is positioned in a generally straight portion of an earthen bore and then activated to extend the bore by melting and/or thermally degrading formation rock at a portion of the wall of the bore that is aligned with a leading end of the laser drill head, then the bore is extended in a direction generally aligned with the laser drill head, or straight forward.

[0004] Depending on die dip angle, stratification or other physical characteristic of geologic features penetrated by the earthen bore, it may be desirable to deviate from the conventional "straight-ahead" extension mode of conventional laser drilling devices. A conventional method of deviating the path of an earthen bore as it is being extended is to deploy a laser drill head having a biasing structure that displaces at least a portion of the laser drill head to cock or tilt the laser drill head within the earthen bore in which it resides. The cocked or tilted laser drill head causes the laser light emitted from the leading end of die laser drill head to change in angle and to impinge on a portion of the wall of the bore that is aligned with the laser drill head in its cocked or tilted configuration. It will be understood that this method will result in the extension of the earthen bore at an angle to the existing portion of the bore in which the laser drill head is disposed.

[0005] A disadvantage of this method is that it requires an activatable or deployable structure on the laser drill head that biases the laser drill head upon activation or deployment Some manner of actuating the biasing structure on the laser drill head will be needed, and this requirement adds complexity and expense to the compact laser drill head. Another disadvantage of mis method is mat biasing of the laser drill head within the bore may create unwanted excessively sharp bends or turns immediately ahead of the laser drill head, and sharp bends or turns may impair the ability of the laser drill head to be advanced into, or to be pulled back from, the extended portion of the bore for further operations.

[0006] Another method of redirecting an earthen bore as it is extended is to deflect the laser light beam or beams using optical means. This is difficult to do in a downhole environment and, again, a mechanically complex actuator is required in order to position an optical element to redirect the laser light beams.

[0007] U.S. Patent 6,895,678 discloses a bore navigation system that includes a mechanical component comprising multiple journal crosses, a gyroscope, as well as evaluation and control electronics. The system determines its position in the bore, and influences the behavior of the drilling head. Mechanical and electro-mechanical units are used to determine and/or modify the position of the laser drill head, and these units must be located inside the laser drill head or connected to it. These sensitive instruments must be tolerant of the hostile environmental conditions which affect the laser drill head and operate reliably in such conditions. This requires the supply of additional energy and control to an extremely complex and expensive laser drill head.

[0008] EP 2065552 discloses a system and a procedure to create lateral direction bores. This system is almost exclusively suited to creating lateral bores that are perpendicular to the main bore.

[0009] U.S. Patent 4,594,790 discloses a bore monitoring system which uses a ring laser gyroscope to accurately determine the position of the laser drill head in a bore and to keep the laser drill head in a desired position. Ring laser gyroscopes are provided for positioning and the position of the laser drill head is continuously measured inside the bore. However, the gyroscopes cannot be used for modifying the relative position of the laser drill head in relation to the bore.

[0010] What is needed is a method to enable the path of a bore extended using a laser drill head to be modified at will, within a short amount of time and without significant expenditure or added mechanical complexity in the laser drill head. What is needed is a method to extend the path of a bore as it is extended using a laser drill head and that requires no highly specialized equipment or special modes of control and utilization, and a method that can be used in a fast and cost-efficient manner.

BRIEF SUMMARY OF THE PRESENT INVENTION

[0011] An embodiment of the method of extending an earthen bore of the present invention comprises the steps of providing a laser drill head having a leading end, a receiving end opposite the leading end, and a plurality of laser light-emitting elements directed to emit laser light from the leading end, the plurality of laser light-emitting elements arranged in a configuration including a central group, having one or more central laser light-emitting elements, generally surrounded by a plurality of peripheral laser light-emitting elements, the peripheral laser light-emitting elements including a first peripheral sub-group of laser light-emitting elements, having a contiguous plurality of the peripheral laser light-emitting elements, and a second peripheral sub-group of laser light- emitting elements having a contiguous plurality of the peripheral laser light-emitting elements that are not within the first peripheral sub-group, providing an umbilical having a surface end, a connected end, and a plurality of laser light-transmitting optical fibers, connecting the connected end of the umbilical and the receiving end of the laser drill head, coupling a connected end of each of the plurality of laser light-transmitting fibers of the umbilical to at least one of the plurality of laser light-emitting elements in the laser drill head, introducing the laser drill head into a portion of the earthen bore to be extended, transmitting laser light through one of the plurality of laser light-transmitting optical fibers connected to the central group of laser light-emitting elements while transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the first peripheral sub-group of laser light-emitting elements, at least one of transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements, at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements, and transmitting no laser light through the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group, and at least one of melting and thermally degrading formation material proximal to the portion of the earthen bore using laser light emitted from the leading end of the laser drill head to extend the earthen bore in a direction that is oblique to a straight-forward direction relative to the portion of the bore in which the laser drill bead is introduced, wherein the oblique direction is proximal to the first peripheral sub-group of laser light-emitting elements and distal to the second peripheral sub-group of laser light emitting elements. An embodiment of the method adapted for maximizing the obliqueness of the direction of the extended bore relative to the straightforward direction comprises these steps wherein the step of at least one of transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements, at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements, and transmitting no laser light through the plurality of laser light-transmitting optical fibers connected to the second peripheral subgroup comprises the step of transmitting laser light through the plurality of laser light- transmitting optical fibers connected to the second peripheral sub-group of laser light- emitting elements at a power level that is substantially lower than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements to maximize the obliqueness of the direction of the extended portion of the earthen bore relative to the straight-forward direction. Another embodiment of the method adapted to minimize the obliqueness of the direction of the extended bore relative to the straightforward direction comprises these steps wherein the step of at least one of transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements, at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements, and transmitting no laser light through the plurality of laser light-transmitting optical fibers connected to the second peripheral subgroup comprises the step of transmitting laser light through the plurality of laser light- transmitting optical fibers connected to the second peripheral sub-group of laser light- emitting elements at a power level that is only slightly lower than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements to minimize the obliqueness of the direction of the extended portion of the earthen bore relative to the straight-forward direction.

[0012] An embodiment of the method of the present invention may further comprise the steps of providing a central group laser fight source connected to an input end of the laser light-transmitting optical fibers having a connected end that is connected to the central group of laser light-emitting elements, providing a first peripheral subgroup laser light source connected to an input end of the laser light transmitting optical fibers having a connected end that is connected to the first peripheral sub-group of laser light-emitting elements, and providing a second peripheral sub-group laser light source connected to an input end of the laser light transmitting optical fibers having a connected end connected to tire second peripheral sub-group of laser light-emitting elements. An embodiment of this method, wherein at least one of transmirtinti laser liaht through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light- emitting elements and transmitting no iaser light to the second peripheral sub-group of laser light emitting elements, may comprise at least one of reducing an electrical current to the second peripheral sub-group Iaser light source to a level that is less than the level of electrical current provided to the first peripheral sub-group laser light source to transmit Iaser light at a power level that is less than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements, and disconnecting the second peripheral sub-group Iaser light source from an electrical current supply to transmit no laser light to the second peripheral sub-group of light- emitting elements.

[0013] Another embodiment of the method of extending an earthen bore comprises the steps of providing an elongate laser drill head having a leading end, a connected end opposite the leading end, and a plurality of laser light-emitting elements directed to emit laser light from the leading end, at least some of the plurality of laser light-emitting elements being selectively controllable to emi laser light, introducing the laser drill head into the earthen bore, transmitting to a first group of the plurality of Iaser light-emitting elements laser light at a first power level while transmitting to a second group of the plurality of laser light-emitting elements laser light at a second power level that is less than the first power level, at least one of melting and thermally degrading an amount of a formation material making up the earth's crust and proximal to the earthen bore to be extended using the laser drill head, and removing the at least one of melted and thermally degraded formation material from the earthen bore to extend the bore, wherein the second group of laser light-emitting elements are disposed proximal to a periphery of the plurality of Iaser light-emitting elements, and wherein the first group and the second group of Iaser light-emitting elements are generally clustered together to dispose each laser light-emitting element proximal to the other laser light-emitting elements of the plurality. An embodiment of the method may further comprise the steps of connecting, to each of the laser light-emitting elements of the laser drill head a laser-fight transmitting optical filler having an input end and a connected end, receiving, into the connected end of the laser drill head, the connected end of the Iaser light-transmitting optical fibers, and coupling a connected end of at least one laser light-transmitting optical fiber to at least one laser-light emitting element in the laser drill head. An embodiment of the method may include providing an elongate laser drill head having a plurality of laser light- emitting elements directed from a leading end of the laser drill head and connected at a connected end to a plurality of laser light-transmitting optical fibers, each of which transmits laser light from at least one laser light source to at least one of the plurality of laser light-emitting elements, and selecting the second group of laser light-emitting elements from among a plurality of laser light-emitting elements disposed proximal to the peripheiy of the laser light-emitting elements and proximal to a side of the bore thai is distal to the direction in which an extension of the bore is to be directed.

[0014] Another embodiment of the method of extending an earthen bore of the present invention comprises the steps of providing an elongate laser drill head having a leading end, a connected end opposite the leading end, and a plurality of laser light- emitting elements directed to emit laser light from the leading end, at least some of the plurality of laser light-emitting elements being controllably deactivatable, introducing the laser drill head into the earthen bore, transmitting to a first group of the plurality of laser light-emitting elements laser light at a first power level while a second group of the plurality of laser light-emitting elements are selectively deactivated, at least one of melting and thermally degrading an amount of a formation material making up the earth's crust and proximal to the earthen bore to be extended using the laser drill head, and removing the at least one of melted and thermally degraded formation material from the earthen bore to extend the bore, wherein the second group of laser light -emitting elements are disposed proximal to a periphery of the plurality of laser light-emitting elements, and wherein the first group and the second group of laser light-emitting elements are generally clustered together to dispose each laser light-emitting element proximal to the other laser light-emitting elements. Another embodiment of this method includes the step of substantially deactivating the second group of laser light-emitting elements by isolating an input end of a laser light-transmitting optical fiber capable of transmitting laser light to each of the laser light-emitting elements of the second group by deactivating the laser light-source that feeds laser light into that optical fiber. For example, one or more laser light-emitting elements may be deactivated bv switching off the electrical power supply to a laser light source at the surface that feeds laser light into an input end of the laser light-transmitting optical fiber or fiber bundle that transmits laser light to the laser light-emitting elements chosen for deactivation. Another embodiment of the method further comprises the steps of providing an elongate laser drill head having a plurality of laser light-emitting elements directed from a leading end of the laser drill head and connected at a connected end to a plurality of laser light-transmitting optical fibers, each of which transmits laser light from at least one laser light source to at least one of the plurality of laser light-emitting elements, activating a first group of the laser light-emitting elements to emit laser light at a first power level while isolating a second group of the laser light-emitting elements from the laser light source, and selecting the second group of laser light-emitting elements from among a plurality of laser light- emitting elements disposed proximal to a periphery of the laser light-emitting elements and proximal to a side of the bore that is distal to the direction in which an extension of the bore is to be directed.

[0015] The object of the invention was accomplished by providing a procedure for modifying the path of a bore created with laser drilling, during which formation rock defining the wall of the bore is irradiated with laser light, at least one of melted or thermally degraded by heat from the laser light beam being directed at the wall of the bore to be extended, and by removing the molten rock dross or thermally degraded material from the bore to extend the bore. By selecting from the plurality of laser light- emitting elements a first group of laser light-emitting elements to be operated at a first, higher power level and a second group of laser light-emitting elements to be operated at one of a second, lower power level or without power, the bore is extended in a direction that deviates from a path that is aligned with the laser drill head.

[0016] The laser drill head used in the method of the present invention emits a aggregate laser light beam assembled from a plurality of individual laser light beams. One or more individual light beams are deactivated, and the remaining, modified aggregate laser light beam will lack the symmetry of the original aggregate laser light beam. More specifically, where the one or more deactivated individual laser light beams are strategically selected based on a position proximal to a periphery of a cluster of the plurality of laser light-emitting elements, the remaining, modified aggregate laser light beam will be asymmetric in a manner that skews the remaining, modified aggregate laser light beam and causes the removal of formation material more on the side of the bore that is distal to the position within the cluster from the strategically selected, deactivated laser light elements. This method uses the asymmetry to produce an extended bore having an oblique path that turns or bends from a straightforward path generally obtained using a symmetric aggregate laser fight beam.

[0017] The use of the method of the present invention requires an operator of the method to select a planned oblique path that differs from the straightforward path of the earthen bore to be extended. The use of the method of the present invention further requires the orientation of the laser drill head to be determined so that the direction of deviation of the extended bore can be planned and the setting of the laser drill head to achieve that deviation can be implemented.

[0018] The method of the present invention enables the path of the extended bore to be modified without complex mechanical components that generally require actuation and multiple additional components to actuate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] F!G. 1 is a schematic illustrating a system that can be used to implement an embodiment of a method of the present invention.

[0020] FIG. 2 is perspective view of an alternative spool that can be used to store an umbilical of a system of FIG. 1.

[0021] FIG. 3 is a top view of a second alternative spool that can be used to store an umbilical of a system of FIG. 1.

[0022] FIG. 4 is a perspective view of a portion of a laser drill head connected to an umbilical which can be used to implement an embodiment of the method of the present invention.

[0023] FIG. 5 is a side elevation view of an earthen bore being extended in a conventional manner using a laser drill head emitting a generally symmetrical laser light beam; [0024] FIGs. 6 is one possible configuration of an aggregated laser light beam generated by a laser drill head operated in a conventional manner to extend the bore of FIG. 5.

[0025] FIG. 7 is another possible configuration of an aggregated laser light beam generated by a laser drill head operated in a conventional manner to extend the bore of FIG. 5.

[0026] FIG. 8 is another possible configuration of an aggregated laser light beam generated by a laser drill head operated in a conventional manner to extend the bore of FIG. 5.

j0027j FIG. 9 illustrates one possible configuration of a modified, aggregated laser light beam generated by a laser drill head operated in accordance with the method of the present invention to produce an oblique extension of the bore.

[0028] FIG. 10 illustrates the initial stage of an oblique extension of the bore of FIG. 5 generated using a laser drill head operated in accordance with the method of the present invention to produce the modified, aggregated laser light beam of FIG. 7.

[0029] FIG. 11 illustrates an oblique extension of the bore of FIG. 9 using an embodiment of the method of the present invention.

[0030] FIG. 12 illustrates a further oblique extension of the bore of FIG. 11 using an embodiment of the method of the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE METHOD

[003] j FIG. 1 is a schematic illustrating a system 10 that can be used to implement an embodiment of a method of the present invention. A borehole 90 is drilled into the earth's crust 11 so that a portion 17 of the borehole 90 penetrates a geologic formation material 19 bearing a fluid medium such as, for example, hydrocarbons. The system 10 of FIG. 1 comprises a first coiled tubing unit 130 at the surface 15 having a source of fluid 112 such as, for example, water or pressurized gas, that is fluidically coupled through a fluid leader 113 to a fluid conduit (not shown) within a first umbilical 134. The system 10 further comprises a second coiled tubing unit 30 at the surface 15 having a source of fluid 12 such as, for example, water or pressurized gas, that is fluidically coupled through a fluid leader 13 to a fluid conduit (not shown) within a second umbilical 34. The system 10 further comprises a portable electric generator 14 electrically coupled through a power supply leader 18 to power a laser light generator 16 that is, in turn, optically coupled through a laser leader 26 to a plurality of optical laser light-transmitting fibers 47 (not shown in FIG. 1 see FIG. 4) within the second umbilical 34. It will be understood that the system 10 may comprise multiple portable electric generators 14 that are electrically coupled through multiple power supply leaders 18 to power multiple laser light generators 16 that are optically coupled through multiple laser leaders 26 to one or more of the plurality of optical laser light-transmitting fibers 47 (not shown in FIG. 1 - see FIG. 4), and these components may be individually activated and/or deactivated to implement embodiments of the method of the present invention.

[0032] The system 10 of FIG. 1 may further comprise a wellhead 25 sealing the surface end 91 of the bore 90 through which the first umbilical 134 and the second umbilical 34 are received into the bore 90, a working fluid tank 20 coupled through a working fluid leader 22 to the wellhead 25 to enable the introduction and removal of working fluid 21 into and from an annulus 24 between the first umbilical 134 and the second umbilical 34, on the one hand, and the wall 94 of the bore 90, on the other hand. The system 10 of FIG. 1 may further comprise a first spool 130 on which an extended length of the first umbilical 134 may be stored, a second spool 30 on which an extended length of the second umbilical 34 may be stored, and a coiled tubing unit guide support 27 to support an umbilical guide 38 having a plurality of rolling elements 37 therein to reduce friction of movement of the first umbilical 134 and the second umbilical 34 into and from the wellhead 25 and the bore 90.

[0033] The first coiled tubing unit 130 and the second coiled tubing unit 30 of the system 10 may each comprise rotatable axles 132 and 32, respectively, enabling the spooling out and the spooling in of the first umbilical 134 and the second umbilical 34, respectively, using motors (not shown) and related gears (not shown). In FIG. 1, the first coiled tubing unit 130 and the second umbilical 34 have together been reeled out to introduce a sufficient length of the first umbilical 134 and the second umbilical 34 through the wellhead 25 to position the laser drill head 50 connected to a connected and leading end 36 of the first umbilical 134 and the second umbilical 34 adjacent to a desired oblique borehole redirection location (not shown in FIG. 1 - see FIGs. 11 and 12), and an optional deployable seal 54 has been deployed to engage the wall 94 of the bore 90 adjacent thereto. Once the laser drill head 50 is in the desired position, it can be activated to emit a laser light beam 59 onto a portion of the bore to be extended 60. j0034| FIG. 2 is a perspective view of a second umbilical ,storage spool 32A that can be used to store the second umbilical 34 of a system of the present invention by coiling the second umbilical 34 against the interior wall 33 of the spool 32 A. After a portion of the interior wall 33 is covered with outer coils 42 of the second umbilical 34, additional, smaller coils can be disposed within the initial, outer coils 42 for additional storage capacity. FIG. 3 is a top view of a another alternative umbilical storage spool 32B that can be used to store the second umbilical 34 of a system of the present invention by wrapping coils 44 around an exterior wall 41 of a center post 38 of the spool 34B. After a portion of the exterior wall 41 is covered with coils 44 of the umbilical 34, additional, larger coils can be disposed about the initial, inner coil 40 for additional storage capacity. It will be understood that these storage spools can also be used in conjunction with the fi rst umbi lical 134 of the system 10, and that the selection of the second umbilical 34 for use in the illustrations of FIGs. 2 and 3 is not exclusive.

[0035] FIG. 4 is a perspective view of a laser drill head 50 that can be connected to a leading end 36 of the second umbilical 34 and used to implement an embodiment of the method of the present invention. The laser drill head 50 comprises a clustered plurality of optical laser light-emitting elements 66 and 45 optically coupled to a plurality of elongate optical laser light-transmitting fibers or fiber bundles 47 that transmit laser light (not shown) provided from one or more laser light sources 16 (only one shown on FIG. 1 ) through the laser leader 26 (only one shown on FIG. 1) to a surface end (not shown - see FIG. 1) of the optical fibers 47. Returning to FIG. 4, the optical elements 66 and 45 in the laser drill head 50 of FIG. 4 are disposed in a generally clustered pattern within a leading end 56 of the laser drill head 50. The optical laser light-emitting elements 66 and 45 may be disposed in a number of various patterns or positions w ithin the laser drill head 50, as will be discussed in more detail in connection with FIGs. 6-8 and 10.

[0036] Optionally, the laser drill head 50 of FIG. 4 further comprises at least one fluid injection port 46 disposed within the leading end 56 of the laser drill head 50 and positioned to inject a laser-compatible fluid such as, for example, aw inert gas, provided to the laser drill head 50 through a fluid conduit 49 of the second umbilical 34. The laser-compatible fluid, such as nitrogen, displaces laser-incompatible materials, such as oil or drilling mud, from the section of the bore to be extended 60 (see FIG. 1). The laser-compatible fluid is released into a section of a bore 90 (not shown in FIG. 4 see FIG. 1) adjacent a bore wall 94 (not shown) to be extended 60 using laser light (not shown) emitted from the optical laser light-emitting elements 66 and 45 of the laser drill head 50.

[0037] In the laser drill head 50 of FIG. 4, the optional fluid injection port 46 is illustrated as being disposed generally interior to the clustered pattern of laser light- emitting elements 66 and 45. The laser light-emitting elements 66 and 45 illustrated in FIG. 4 are of two groups: a central group 66 and a peripheral group 45. The central group 66 of laser light-emitting elements are centrally located within the leading end 56 of the laser drill head 50 and the peripheral group 45 of laser light-emitting elements are peripherally and contiguously surrounding the centrally group 66 of laser light-emitting elements. It will be understood that the spacing of the central group 66 and the peripheral group 45 of laser light-emitting elements, respectively, is an arrangement and a configuration that may be used in implementing embodiments of the method of the present invention. j0038j In FIG. 4, the fluid injection port 46 or, in other embodiments of the laser drill head 50, a plurality of fluid injection ports 46, may be strategically disposed in a variety of positions within the laser drill head 50 to direct a stream of injected laser-compatible fluid into the bore portion to be extended 60 (see FIG. 1) at angle that is oblique relative to an axis 62 of the laser drill head 50 shown in FIG. 4. It will be understood that, in FIG. 4, an interval of the exterior portion 67 is illustrated as being removed from the second umbilical 34 to reveal the plurality of laser light- transmitting optical fibers or fiber bundles 47 and a fluid conduit 49 supplying laser-compatible fluid to the fluid injection port(s) 46 in the laser dr ill head 50. It will be understood that the optical fibers or optical fiber bundles 47 and the fluid conduit 49 are encased within the exterior portion 67 of the second umbilical 34 for protection against damage and wear. [0039] FIG. 5 is a sectional elevation view of an alternative laser drill head 50A positioned within an earthen bore 90. The laser drill head 50A receives the connected end of the plurality of optical fibers or optical fiber bundles 47 within the receiving end 53 of the laser drill head 50A. It will be noted that the protective exterior portion 67 of the second umbilical 34 is omitted from FIG. 5 to reveal the plurality of optical fibers or optical fiber bundles 47 that are connected to the laser light-emitting elements 66 and 45. The individual laser light-emitting elements 66 and 45, and the fluid injection port(s) 46 are omitted from FIG. 5 for simplicity. It should be noted that the design, structure and shape of the laser drill head 50A may vary. One or more radial seals 54 may be provided on the laser drill head 50A to provide stand-off between the laser drill head 50A and the wall 94 of the bore 90 and to seal between the laser drill head 50A and the wall 94 of the bore 90 to promote removal of debris resulting from the boring process through one or more debris removal conduits 93 in the laser drill head 50A. It will be understood that the rapid heating of the laser-compatible fluid introduced into the portion of the bore to be extended will cause the fluid to expand and to sweep debris (not shown) resulting from the laser drilling process through the debris removal conduits 93 as the bore 90 is extended in the general direction of arrow 77. Upon activation, an aggregate laser light beam 59 is emitted from the laser light-emitting elements 66 and 45 (not shown in FIG. 5 see FIG. 4) together clustered at the leading end 56 of the laser drill head 50A. The aggregate laser light beam 59 impinges on a portion of the bore to be extended 60 which comprises formation material 19, as also shown in FIG. 1, to remove formation material 19 to extend the bore 90.

[0040] The composition of the aggregate laser light beam 59 can be varied and generally depends on the number, configuration and orientation of the laser light-emitting elements 66 and 45 (not shown in FIG. 5 - see FIG. 4) of the laser drill head 50A. For example, but not by way of limitation, FIG. 6 is an example of a sectional view of an aggregate laser light beam 59 comprising a plurality of clustered individual laser light beams 64 that can be made to project from the leading end 56 of the laser drill head 50A to impinge onto a portion of the bore to be extended 60 that is generally linearly aligned with (he leading end 56 of the laser drill head 50A. The sectional view of an aggregate laser light beam 59 illustrated in FIG. 6 is comprised of a central group 64a of laser light beams 64a surrounded by a peripheral group 64b of laser light beams that includes a plurality of contiguous and peripheral laser light beams that generally surround the central group 64a.

[0041 ] FIG. 7 is another example of an aggregate laser light beam 59 comprising a central group 64a that is a single, large central laser light beam surrounded by a peripheral group 64b that includes a plurality of contiguous peripheral laser light beams. Together, the central group 64a and the peripheral group 64b form the aggregate laser light beam 59.

[0042] FIG. 8 is yet another example of an aggregate laser light beam 59 comprising a central group 64a that includes a plurality of centrally located, overlapping laser light beams surrounded by a peripheral group 64b that includes a plurality of contiguous peripheral laser light beams. Together, the central group 64a and the peripheral group 64b form form the aggregate laser light beam 59. It should be noted that the peripheral group 64b of laser light beams of the aggregate laser light beam 59 of FIG. 8 partially overlap at least the outer edge of the central group 64a.

[0043] Particularly with the example of the aggregate laser light beam 59 of FIG. 8 , it can be seen that a central group 64a and a peripheral group 64b of laser light beams may be spaced to together make up an aggregate laser light beam 59 with no gaps or spaces. It will be understood from FIGs. 6-8 that the number, size and configuration of the laser light-emitting elements 66 and 45 can be varied in spacing, number and degree of o verlap to obta in an aggregate laser l ight beams 59.

[0044] Embodiments of the method of the present invention involve the strategic deactivation of one or more of the laser light-emitting elements 45 (not shown in FIGs. 6- 8 - see FIG. 4) that produce the laser light beams 64 that make up the peripheral group 64b to modify the aggregate laser light beam 59 and to thereby extend the bore 90 in an oblique direction relative to the straight-forward direction ahead of and aligned with the laser drill head 50A. The implementation of the method of the present invention is provided by a modification of the aggregate laser light beam 59 implemented by- operating the laser light-emitting elements 66 and 45 in a manner that causes an imbalance in the amount of laser light power delivered to a first side of an imaginary midline of the aggregate laser light beam 59 as compared to the amount of laser light delivered to a second, opposite side of the midline. For example, in one embodiment of the method of the present invention, selected laser light-emitting elements 45 (see FIG. 4) that contribute the peripheral group 64b of the laser light beams 64 (see FIGs. 6-8) may be deactivated by controlling one or more of the independently controllable laser light sources (see component number 16 on FIG. 1 ) to create an asymmetrical impingement of the aggregate laser light beam 59 on the portion of the bore to be extended 60.

[0045] FIGs. 9 and 10 are illustrative of an embodiment of the method. FIG. 9 illustrates the method being implemented using the alternative laser drill head 50A of FIG. 5. In FIG. 9, the modified aggregate laser light beam 59A emitted from the leading end 56 of the laser drill head 50A is skewed or imbalanced relative to the laser drill head 50A and relative to the imaginary midline 9 illustrated in FIG. 9 to extend the bore 90 in a direction that is generally indicated by the arrow 77 but skewed to the left to be oblique to the midline 9 of the laser drill head 50A. It will be understood that the modified aggregate laser light beam 59A of FIG. 9 impinges upon and heats a portion 65 of the formation material 19 that is generally not aligned with the laser drill head 50A and. at the same time, does not impinge upon, or impinges less upon, a portion 69 of formation material 19 that is more aligned with the laser drill head 50A than the portion 65. This modified aggregate laser light beam 59A is imbalanced in the amount of laser light power impinged on the sides of the midline 9. and can be generated by strategically selecting one or more individual laser light-emitting elements 45 (see FIG. 4) that contribute to the peripheral group 64b of laser light beams for deactivation, for reduced power and/or for intermittent activation.

[0046] The modified aggregate laser light beam 59A of FIG. 9 may be achieved using an embodiment of the method of the present invention illustrated by FIG. 10. FIG. 10 is a sectional view of the modified aggregate laser light beam 59A of FIG. 9 revealing a cluster of laser light beams comprised of: a central group 70 of a plurality of laser light beams 64a emitted from one or more central laser light-emitting elements 66 (not shown in FIG. 10 see FIG. 4); and a first peripheral sub-group 71 of a plurality of peripheral laser light beams 64b (the power level indicated by the cross-hatching) emitted from a plurality of peripheral laser light-emitting elements 45. FIG. 10 also reveals a phantom location of a second peripheral sub-group 72 of a plurality of peripheral laser light beams 64c that have been deactivated to create an imbalance about an imaginary midline 9 to provide a greater amount of laser light power on a first (left) side of a midline 9 (projected downwardly from FIG. 9) as compared to the second (right) side of the midline 9 of the laser dri!l head 50A. The pattern of laser light beams 64a making up the centra) group 70 and laser light beams 64b the first peripheral sub-group 71 ate vertically aligned with the main portion of the modified aggregate laser light beam 59A of FIG. 9 to illustrate the modifying effect of the deactivated second peripheral sub-group 72 of laser light emitting elements 45 (not shown on FIG. 10 see FIG. 4) on the modified aggregate laser light beam 59A and its impingement pattern on the portion of the bore to be extended 60.

[0047] It will be understood that, as an alternative to deactivation of the second peripheral sub-group 72 of laser light-emitting elements to modify the aggregate laser light beam 59A, the second peripheral sub-group 72 of laser light beams 64c may be produced by laser light-emitting elements 45 operated at a power level that is lower than the power level at which the laser light-emitting elements 45 operate to produce the first peripheral sub-group 71 of laser light beams 64b. it should be understood that, in FIG. 10, the lack of cross-hatching in the second peripheral sub-group 72 of laser light beams 64c may indicate either a deactivated laser light-emitting element 45 (see FIG. 4) or a laser light-emitting element 45 operating at a reduced power level that is less than the power level at which the laser light-emitting elements 45 operate to produce the first peripheral sub-group 71 of laser light beams 64b.

[0048] FIG. 10 can be used to illustrate another distinct mode of operation of the laser drill head 50A. in the alternate mode, the central group 70 of laser light beams 64a, emitted by a corresponding plurality of central light-emitting elements 66, are used for straight-line boring. A first peripheral sub-group 71 of peripheral laser light beams 64b, emitted by a corresponding plurality of peripheral light-emitting elements 45, and a second peripheral sub-group 72 of peripheral light-emitting beams 64e, emitted by a corresponding plurality of peripheral light-emitting elements 45, together remain one of deactivated and activated to operate at the same power level during straight-line boring. It will be understood that this mode of operation will produce an aggregate laser light beam 59 that has no imbalance of power level across an imaginary midline 9. An extension 80 of the bore 90 having a direction that is oblique to the straight-fine path or midline 9 can be bored by maintaining the power level of the first peripheral sub-group 71 of laser fight-emitting elements 45 (see FIG. 4) at a power level that may be less than, equal to or more than the power level of the active central group 70 (see FIG. 4) of laser light-emitting elements 66, while the second peripheral sub-group 72 of peripheral laser light-emitting elements 45 remain one of deactivated or operated at a reduced power levef, relative to the power level at which the first peripheral sub-group 71 of peripheral laser light-emitting elements 45 is operated. ^'This condition is illustrated by the absence of cross-hatching in the phantom positions of the second peripheral sub-group 72 of laser light beams 64c.

[0049] It will be understood that the above-described modes of operation enable the laser drill head 50A to emit a modified aggregate laser light beam 59A that provides more laser light power on a side of the midline 9 of the aggregate laser f ight beam 59 A that is proximal to the direction of the desired oblique extension 80 (see FIG. 1 1 ) and less laser light power on an opposite side of the aggregate laser light beam 59A and the midline 9 that is distal to the direction of the desired oblique extension 80.

[0050] FIG. 11 illustrates an oblique extension 80 of the bore 90 of FIG. 9 using the method of the present invention and using a modified aggregate laser light beam 59A illustrated in FIG. 10. The oblique extension 80 of the bore 90 extended using the laser drill head 50.A enables the bore 90 to be directed generally in the direction of the arrow 77 but also towards, for example, a productive portion of a geologic formation (not shown) to the left of the midline 9 such as, for example, a portion of the formation distal to and above a water / oil interface, a portion of the formation proximal to a fault, a portion of the formation with more favorable porosity or permeability, or to a portion of the formation distal to and below a gas / oil interface, ft will be noted that the modified aggregate laser light beam 59A emitted from the leading end 56 of tire laser drill head 50A remains in the bore 90 deviation mode in FIG. 11 to provide continued bending or turning of the oblique extension 80 of the bore 90 to the left of the midline 9. it will be noted that the obliqueness of the oblique extension 80 of the bore 90 is more noticeable when viewed relative to a midline 9 of the laser dr ill head 50A which is generally aligned with the portion of the bore 90 that existed prior to the use of aw embodiment of the method of the present invention (see, for example, FIG. 4).

[0051 ] FIG. 12 illustrates a further oblique extension 81 of the bore of FIG. 1 1 using an embodiment of the method of the present invention that is more pronounced and further deviated from midline 9 than the oblique extension 80 illustrated in FIG. 11. It will be understood that the radius of bending or turning provided by the use of the embodiment of the method illustrated in FIGs. 9-12 can vary according to the imbalance of the power of the laser light beam 59A generated by the laser dn!l head 50A operated in accordance with the method of the present invention. For example, a large imbalance may be obtained by operating the first peripheral sub-group 71 of laser light-emitting elements 45 to produce peripheral laser light beams 64b at a very high power level while deactivating the second peripheral sub-group 72 of laser light emitting elements 45 to produce an absence of laser light beams 64c. and the large imbalance will miminize the oblique extension radius of bending or turning, as indicated in FIG. 12 in the shift of the angle of the bore 90 from a midline 9 to a new midline 9A. As a further example, a very small imbalance may be obtained by operating the first peripheral sub-group 71 of laser light-emitting elements 45 to produce peripheral laser light beams 64b at a given power level while operating the second peripheral sub-group 72 of laser light emitting elements 45 at a power level that is only slightly less than the power level of the first peripheral sub-group 71 to produce a small imbalance that will maximize the oblique extension radius of bending or turning (not illustrated, but less of a shift than indicated by midline 9A).

[0052] It will be understood that among the factors that affect the radius of bending or turning of the bore 90, i.e. the path of the bore 90 as it deviates from a straightforward portion, as illustrated in FIG. 9, to an oblique portion 80 and 81 , as illustrated in the lower portions of FIGs. I I and 12, respectively, and resulting from the use of an embodiment of the method of the present invention include the size of the bore 90, the size of the laser drill head 50A, the size, configuration, composition and power level of the laser light beams 64a, 64b and 64c that make up and contribute to the modified aggregate laser light beam 59 A. It will be understood that the composition of the formation material 19 being removed using heat generated by the impingement of laser light and the laser-compatibility of fluids in the bore 90 and intermediate the laser light- emitting elements 66 and 45 at the leading end 56 of the laser drill head 50A and the portion of the bore to be extended 60.

[0053] It will be understood that, while FIG. 1 illustrates only a single laser light source 16 at the earth's surface and coupled to feed laser light into a surface end of second umbilical 34 to transmit laser light through laser light-transmitting optical fibers or fiber bundles 47 of ihe second umbilical 34 to the laser drill head 50A. a plurality of laser light sources 16 can be used to separately and independent feed laser light of varying power levels into a plurality of laser light-transmitting optical fibers or fiber bundles 47 of the second umbilical 34. Alternately, a plurality of laser light sources 16 can be used to separately and independent feed laser light into a plurality of laser light- transmitting optical fibers or fiber bundles 47 of the second umbilical 34, and one or more laser light sources 16 can be deactivated by, for example, disconnecting the one or more laser light sources 16 from one or more portable electric generators 14 thai provide electrical power to the one or more laser light sources 16 to be disconnected. In this way, the modified aggregate laser light beam 59A can be emitted from the laser light-emitting elements 66 and 45 at the leading end 56 of the laser drill head 50A to extend the bore 90 in an oblique direction.

[0054] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the phrase "aggregated laser light beam" means a concentrated collection of individual laser light beams that together impinge upon and impart thermal heating to formation rock aligned with the collection of laser light beams, It will be understood that each individual laser light beam may partially overlap with one or more adjacent laser light beams at the point of impingement and at the periphery of the adjacent individual light beams. Aggregate laser light beams also include a collection of clustered individual light beams that together impinge on targeted formation rock although they may each be separated one from the others by small gaps at the point of impingement. It will be understood that the small gaps in the latter example would not prevent the rapid generation of thermal heat within the small gaps due to heat transfer from the adjacent impingement of laser light beams. [0055] As used herein, the word "group," as it pertains to laser light-emitting elements, may include a single laser light-emitting elements or a plurality of laser light- emitting elements, unless specifically stated as a plurality. For example, the central group of laser light-emitting elements may comprise a single laser light-emitting element, unless otherwise stated to be a plurality of elements. Similarly, a second peripheral subgroup of peripheral laser light-emitting elements may comprise a single peripheral laser light-emitting element, unless otherwise stated to be a plurality of elements.

[0056] As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms "^"preferably," "preferred," "prefer," "optionally," "may," and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[0057] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The systems and apparatuses illustrated in the drawings were chosen and described in order to best explain the principles of the method of the present invention and to illustrate practical applications in order to better enable those of ordinary skill in the art to understand the method of the present invention for various embodiments with various modifications as are suited to the particular" use contemplated,

[0058] It will be understood that the appended drawings are but illustrations involving systems and apparatuses that can be used to implement an embodiment of the method of the present invention, and that the scope of the invention is not limited by the systems and apparatuses in the drawings.

[0059] The scope of the invention is limited only by the claims that follow.

Claims

We claim:

1. A method of extending an earthen bore, comprising:

providing a laser drill head having a leading end, a receiving end opposite the leading end, and a plurality of laser light-emitting elements directed to emit laser light from the leading end. the plurality of laser light-emitting elements arranged in a configuration including a central group, having one or more central laser light-emitting elements, generally surrounded by a plurality of peripheral laser light-emitting elements, the peripheral laser light-emitting elements including a first peripheral sub-group of laser light-emitting elements, including a contiguous plurality of the peripheral laser light- emitting elements, and a second peripheral sub-group of laser light-emitting elements including a contiguous plurality of the peripheral laser light-emitting elements that are not within the first peripheral sub-group;

providing an umbilical having a surface end, a connected end, and a plurality of laser light-transmitting optical fibers;

connecting the connected end of the umbilical and the recei ving end of the laser drill head;

coupling a connected end of each of the plurality of laser light-transmitting fibers of the umbilical to at least one of the plurality of laser light-emitting elements in the laser drill head:

introducing the laser drill head into a portion of the earthen bore to be extended; transmitting laser light through at least one of the plurality of laser light- transmitting optical fibers connected to the central group of laser light-emitting elements while transmitting laser light through some of the plurality of laser light-transmitting optica! fibers connected to the first peripheral sub-group of laser light-emitting elements: at least one of transmitting laser light through some of the plurality of laser light- transmitting optical fibers connected to the second peripheral sub-group of laser light- emitting elements, at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements, and transmitting no laser light through the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group; and

at feast one of melting and thermally degrading formation material proximal to the portion of the earthen bore using laser light emitted from the leading end of the laser drill head to extend the earthen bore in a direction that is oblique to a straight-forward direction relative to the portion of the bore in which the laser drill head is introduced; wherein the oblique direction is proximal to the first peripheral sub-group of laser light-emitting elements and distal to the second peripheral sub-group of laser light emitting elements.

2. The method of claim L wherein at least one of transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements, at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light- emitting elements, and transmitting no laser light through the plurality of laser light- transmitting optical fibers connected to the second peripheral sub-group comprises: transmitting laser light through the plurality of laser light-transmitting optical fibers connected to the second peripheral sub- group of laser light-emitting elements at a power level that is substantially lower than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements to maximize the obliqueness of the direction of the extended portion of the earthen bore relative to the straight-forward direction.

3. The method of claim 1 , wherein at least one of transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements, at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light- emitting elements, and transmitting no laser light through the plurality of laser light- transmitting optical fibers connected to the second peripheral sub-group comprises: transmitting laser light through the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements at a power level that is only slightly lower than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements to minimize the obliqueness of the direction of the extended portion of the earthen bore relative to the straight-forward direction.

4. The method of claim 1 , further comprising: providing a central group laser light source connected to an input end of the laser light-transmitting optical fibers having a connected end that is connected to the central group of laser light-emitting elements;

providing a first peripheral sub-group laser light source connected to an input end of the laser light transmitting optical fibers having a connected end that is connected to the first peripheral sub-group of laser light-emitting elements; and

providing a second peripheral sub-group laser light source connected to an input end of the laser light transmitting optical libers having a connected end connected to the second peripheral sub-group of laser light-emitting elements.

5. The method of claim 4, wherein at least one of transmitting laser light through some of the plurality of laser light-transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements at a power level that is lower than a power level of the laser light transmitted to the first peripheral sub-group of laser light- emitting elements and transmitting no laser light to the second peripheral sub-group of laser light emitting elements comprises:

at least one of reducing an electrical current to the second peripheral sub-group laser light source to a level that is less than the level of electrical current provided to the first peripheral sub-group laser light source to transmit laser light at a power level that is less than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements, and disconnecting the second peripheral sub-group laser light source from an electrical current supply to transmit no laser light to the second peripheral sub-group of light-emitting elements.

6. A method of extending an earthen bore, comprising:

providing a laser drill head having a leading end, a receiving end opposite the leading end, and a plurality of laser light-en titling elements directed to emit laser light from the leading end and including a central group of laser light-emitting elements, a first peripheral sub-group having a plurality of laser light-emitting elements and a second peripheral sub-group having a plurality of laser light emitting elements, at least some of the first and second peripheral sub-groups of laser light-emitting elements being control !ably selectively variable in the power level provided thereto, and the first peripheral sub-group and the second peripheral sub-group together generally surrounding the central group;

intr oducing the laser drill head into the earthen bore;

transmitting laser light to the central group of laser light-emitting elements through a plurality of laser light-transmitting optical fibers connected to the central group of laser light-emitting elements;

transmitting laser light to the first peripheral sub-group of laser light-emitting elements through a plurality of laser light-transmitting optical fibers connected to the first peripheral sub-group of laser light-emitting elements;

at least one of deactivating the second peripheral sub-group of laser-light emitting elements and transmitting laser light to the second peripheral sub-group of laser light- emitting elements through a plurality' of laser light transmitting optical fibers connected to the second peripheral sub-group of laser light-emitting elements at a power level that is lower than the power level of the laser light transmitted to the first peripheral sub-group of laser light-emitting elements:

at least one of melting and thermally degrading an amount of a formation material making up the earth's crust and proximal to the earthen bore to be extended using the laser drill head;

removing the at least one of melted and thermally degraded formation material from the earthen bore to extend the bore; and

extending ihe earthen bore in a direction that is oblique to a straight- forward direction aligned with the laser drill head;

wherein the extended portion of the earthen bore is proximal to the first peripheral sub-group; and

wherein the extended portion is distal to the second peripheral sub-group.

7. The method of claim 6, wherein the second peripheral sub-group of laser light- emitting elements are deactivated by terminating an electrical current supply to at least one laser light source that feeds laser light into an input end of the plurality of laser light- transmitting optical fibers that transmits laser light to the laser light-emitting elements of the second peripheral sub-group.

8. The method of claim 6, wherein the second peripheral sub-group of laser light- emitting elements are operated at a power level that is lower than the power level at which the laser light-emitting elements of the first peripheral sub-group are operated by decreasing the electrical current supply to at least one laser light source that feeds laser light into an input end of the plurality of laser light-transmitting optical fibers that transmits laser light to the laser light-emitting elements of the second peripheral subgroup.

9. The method of claim 6, further comprising:

supplying a laser-compatible fluid through a fluid conduit to the laser drill head; connecting a fluid port in the laser drill head to the fluid conduit;

introducing a laser-compatible fluid into the portion of the bot e to be extended to displace laser-incompatible fluids; and

using the laser-compatible fluid to sweep one of melted formation materials and thermally degraded formation materials from the portion of the bore to be extended.

10. The method of claim 9, further comprising;

providing a protective outer portion around the plurality of laser-light transmitting optical fibers and the fluid conduit to protect against wear and damage.

1 1. The method of claim 10, wherein the laser drill head further comprises:

a deployable seal disposed cireiimferentially about the laser drill head to engage and seal with the wall of the bore to be extended: and

one or more debris removal conduits within the laser drill head for the removal of one of molten formation material and thermally degraded formation material from the portion of the bore to be extended.

12. A method of extending an earthen bore, comprising:

providing an umbilical having a surface end, a connected end, a plurality of laser light-transmitting optical fibers and a fluid conduit surrounded by a protective outer cover;

providing a laser drill head having a leading end, a receiving end, a fluid port, at least one central laser light-emitting element near the center of the leading end, and a plurality of peripheral laser light-emitting elements surrounding the at least one central laser light-emitting elements within the leading end of the laser drill head, the central and peripheral laser light-emitting elements disposed to emit laser light directed outwardly away from the leading end of the laser drill head;

connecting the central laser light-emitting element to at least one laser light- transmitting optical fiber of the umbilical:

connecting a first contiguous peripheral sub-group of the peripheral laser light- emitting elements to a plurality of laser light- transmitting optical fibers of the umbilical; connecting a second contiguous peripheral sub-group of the peripheral laser light- emitting elements to a plurality of laser light-transmitting optical fibers of the umbilical; connecting the fluid port to the fluid conduit of the umbilical;

introducing the laser drill head into a portion of a bore to be extended;

connecting the central laser light-emitting element to a central laser light source through the at least one laser light-transmitting optical fiber of the umbilical connected to the central laser light-emitting element;

connecting the first contiguous peripheral sub-group of the peripheral laser light- emitting elements to a first contiguous peripheral laser light source through the plurality of laser light-transmitting optica! fibers of the umbilical connected to the first contiguous sub-group of laser light-emitting elements;

connecting a second contiguous peripheral sub-group of the peripheral laser light- emitting elements to a second contiguous peripheral laser light source through the plurality of laser light-transmitting optica! fibers of the umbilical connected to the second contiguous sub-group of iaser light-emitting e!ements;

connecting the fluid port to a source of laser-compatible fluid through the fluid conduit of the umbilical connected to the fluid port;

providing electrical current to the Iaser light source connected to the at least one centra! laser-light emitting element to emit laser light therefrom;

providing electrical current to the laser light source connected to one of the first contiguous peripheral sub-group of the peripheral laser light-emitting elements and the second contiguous peripheral sub-group of the peripheral Iaser light-emitting elements to supplement the laser light emitted from the central laser light-emitting element of the Iaser drill head;

impinging the laser light emitted from the laser drill head on a portion of a wall of the bore to be extended;

at least one of melting and thermally degrading an amount of formation material in the wall; and

removing the at least one of melted and thermally degraded formation material from the portion of the bore to be extended to extend the bore;

wherein the bore is extended in a direction that is oblique relative to a straightforward direction that is aligned with the leading end of the laser drill head; wherein the extended portion of the bore is proximal to the one of the first contiguous peripheral sub-group of the peripheral laser light-emitting elements and the second contiguous peripheral sub-group of the peripheral laser light-emitting elements that is connected to the laser light source lo which electrical current is provided; and wherein the extended portion of the bore is distal to the one of the first contiguous peripheral sub-group of tire peripheral laser light-emitting elements and the second contiguous peripheral sub-group of the peripheral laser light-emitting elements that is not connected to the laser light source to which the electrical current is provided.

13. The method of claim 12, further comprising:

providing electrical current to the laser light source connected to the other of the first contiguous peripheral sub-group of the peripheral laser light-emitting elements and the second contiguous peripheral sub-group of the peripheral laser light-emitting elements at a power level that is less titan the power level at which the one of the first contiguous peripheral sub-group of the peripheral laser light-emitting elements and the second contiguous peripheral sub-group of the peripheral laser light-emitting elements is connected to supplement the laser light emitted from the central laser light-emitting element of the laser drill head and to decrease a rate of change of the oblique direction.