Flexible hose with thrusters for horizontal well drilling

Abstract

A flexible hose assembly for horizontal well drilling is provided. The flexible hose assembly has a number of spaced thruster couplings along its length to impart drilling force to a nozzle blaster at an end of the flexible hose. The thruster couplings have rearwardly oriented thruster ports which impart a forward drilling force upon exit of high pressure water through the thruster ports. At least one of the thruster ports is an adjustable thruster port having variable opening area, variable discharge angle or both. The opening area and discharge angle can be adjusted or controlled to regulate the amount of thrust imparted to the flexible hose and the nozzle blaster, as well as to clear the bore of debris and prevent its accumulation behind the nozzle blaster. A method of horizontal well drilling using the above-described flexible hose is also provided. The method is particularly useful at shallow depths, such as 50-2000 feet.

Description

[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09/825,329 filed Apr. 3, 2001, which claims the benefit of U.S. Provisional Patent Application Serial No. 60/195,076 filed Apr. 6, 2000.

FIELD OF THE INVENTION

[0002] The invention relates to horizontal well drilling and more particularly to a flexible hose assembly for horizontal well drilling.

BACKGROUND OF THE INVENTION

[0003] In the process of drilling for hydrocarbons such as oil and natural gas, vertical or substantially vertical wells have been used most often in the past. Those wells will produce for a given amount of time, then begin to dry up. At that point, it is advantageous to drill out horizontally or laterally at an angle from the vertical well in order to try and increase production of, for example, crude oil.

[0004] There have been several attempts to find an economically viable and reliable system for drilling into the untapped pay zones adjacent an existing vertical well. Horizontal drilling has been proposed as an alternative and has been described in U.S. Pat. Nos. 5,853,056, 5,413,184, 5,934,390, 5,553,680, 5,165,491, 5,458,209, 5,210,533, 5,194,859, 5,439,066, 5,148,877, 5,987,385, 5,899,958, 5,892,460, 5,528,566, 4,947,944, 4,646,831, 4,786,874, 5,410,303, 5,318,121, 4,007,797, 5,687,806, 4,640,362, 5,394,951, 1,904,819, 2,521,976 and Re. 35,386, the contents of all of which are incorporated herein by reference.

[0005] U.S. Pat. No. 5,413,184 describes a method of horizontal drilling that utilizes a flexible hose and a high pressure nozzle blaster to bore into the earth's strata at significant depths, such as 4000 feet. The nozzle blaster uses high pressure water to clear a path through the strata. The nozzle blaster is advanced through the strata by applying weight to the hose, i.e., slacking off the tension in the vertical portion of the hose. Essentially, the weight of the 4000 feet of hose above the nozzle blaster is used to apply drilling force to the nozzle blaster, thus forcing it along the horizontal path. While this method is effective at significant depths due to the large amount of weight available, it is less effective at shallower depths. At shallow depths, there simply is not enough weight available to supply sufficient force to advance the nozzle blaster through the strata.

[0006] In addition, drilling substantial lateral or horizontal distances from the vertical well can be very difficult or time consuming or otherwise inhibited due to the accumulation of the loose cuttings from drilling in the lateral bore hole.

[0007] Thus, there is a need for an apparatus that will effectively advance a drilling tool such as a nozzle blaster horizontally or laterally at an angle relative to an existing vertical or substantially vertical well, through the earth's strata for horizontal or lateral drilling at shallow depths. Preferably, such an improved apparatus will also effectively reduce or prevent the accumulation of cuttings within a lateral bore.

SUMMARY OF THE INVENTION

[0008] A flexible hose assembly for horizontal well drilling is provided. The assembly includes a flexible hose. The flexible hose assembly has a proximal end and a distal end, wherein the proximal end is located rearward of the distal end. The flexible hose has a plurality of thruster ports disposed therein with at least one of the thruster ports being disposed rearward of the distal end of the flexible hose assembly. Each of the thruster ports is adapted to direct a jet of pressurized fluid in a direction such that a centerline drawn through the jet forms an acute discharge angle with the longitudinal axis of the flexible hose rearward from the location of the thruster port. At least one of the thruster ports is an adjustable thruster port.

[0009] A method of horizontal well drilling is also provided which includes the following steps: a) providing a flexible hose assembly including a flexible hose that has a proximal end and a distal end, wherein the proximal end is located rearward of the distal end, the flexible hose having a plurality of thruster ports disposed therein with at least one of the thruster ports being disposed rearward of the distal end of the flexible hose, each of the thruster ports being adapted to direct a jet of pressurized fluid in a direction such that a centerline drawn through the jet forms an acute discharge angle with the longitudinal axis of the flexible hose rearward from the location of the thruster port, at least one of the thruster ports being an adjustable thruster port; b) lowering the flexible hose assembly to a desired depth in a vertical well, and redirecting the flexible hose assembly along a direction at an angle to the longitudinal axis of the vertical well; c) forcing at least 2,000 psi fluid through the flexible hose and the thruster ports in the flexible hose; and d) drilling a horizontal bore into the earth's strata adjacent the vertical well.

[0010] A flexible hose assembly for horizontal well drilling is also provided. The assembly includes a flexible hose. The flexible hose assembly has a proximal end and a distal end, wherein the proximal end is located rearward of the distal end. The flexible hose has a plurality of thruster ports disposed therein with at least one of the thruster ports being disposed rearward of the distal end of the flexible hose assembly. Each of the thruster ports is adapted to direct a jet of pressurized fluid in a direction such that a centerline drawn through the jet forms an acute discharge angle with the longitudinal axis of the flexible hose rearward from the location of the thruster port. Each of the thruster ports has an opening with a cross-sectional area selected from the group consisting of closed polygons, closed curvilinear shapes, and shapes having at least one linear edge.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a side view of a thruster coupling according to a first preferred embodiment of the invention.

[0012] FIG. 2 is a cross-sectional view of the thruster coupling taken along line 2-2 in FIG. 1.

[0013] FIG. 3 is a longitudinal cross-sectional view of the thruster coupling taken along line 3-3 in FIG. 2.

[0014] FIG. 4 is a perspective view of a flexible hose having thruster couplings according to the present invention.

[0015] FIG. 5A is a perspective view of a nozzle blaster for use with the present invention.

[0016] FIG. 5B is an alternate perspective view of a nozzle blaster for use with the present invention.

[0017] FIG. 6 is a perspective view of a flexible hose having thruster ports provided directly in the sidewall according to an embodiment of the invention.

[0018] FIG. 7 is a side view of a thruster coupling having adjustable thruster ports according to a second preferred embodiment of the invention.

[0019] FIG. 8 is a cross-sectional view of the thruster coupling taken along line 8-8 in FIG. 7.

[0020] FIG. 9 is a close-up view of an adjustable thruster port indicated at broken circle 9 in FIG. 7.

[0021] FIG. 10 is an alternative preferred embodiment of a thruster coupling having adjustable thruster ports.

[0022] FIG. 11 is a further alternative preferred embodiment of a thruster coupling having adjustable thruster ports.

[0023] FIG. 12 is a perspective view of a flexible hose having thruster couplings according to the embodiment illustrated in FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0024] In the description that follows, when a preferred range such as 5 to 25 (or 5-25) is given, this means preferably at least 5, and separately and independently, preferably not more than 25. As used herein, the following terms having the following meanings: “gal/min” means gallons per minute and “psi” means pounds per square inch.

[0025] As used herein, the term vertical well refers to a well bore in the earth having an opening at the earth's surface. A vertical well can be substantially vertical relative to the earth's surface, or it can be drilled at an angle, e.g. an acute angle, relative to the earth's surface instead of straight down. Also as used herein, when a horizontal well bore or a horizontal well or direction is mentioned, the word “horizontal” indicates a well bore or direction that is at an angle relative to the vertical well from which the horizontal bore is drilled or depends. For example, as used herein when a horizontal bore is drilled from a vertical well bore, it is not necessary or required that either the vertical well bore be truly vertical, or that the horizontal bore drilled therefrom be truly horizontal. All that is required is that the vertical well bore have an opening at the earth's surface and that the horizontal bore be drilled out from the vertical well at an angle relative to the vertical well. Commonly, the vertical well is truly or substantially vertical, and the horizontal bore drilled therefrom is truly or substantially horizontal; however this is not required or necessary in the present invention.

[0026] The invention can be used with respect to oil wells, natural gas wells, water wells, solution mining wells, and other wells. The invention includes a flexible hose assembly comprising a flexible hose with thrusters and a nozzle blaster for horizontal well drilling. The hose assembly is fed down into the bore of an existing vertical well to a specified depth, at which point it is redirected along a horizontal direction that can be substantially perpendicular to the vertical well. Preferably, the hose assembly is fed into the well by a coil tubing injector as known in the art. Redirection of the hose assembly is preferably accomplished via an elbow or shoe in upset tubing as is known in the art, less preferably via some other known means.

[0027] The hose assembly includes a flexible hose having a proximal end and a distal end, such that proximal end is located rearward of the distal end. Preferably, the flexible hose is supplied with a plurality of thruster couplings disposed along the length of the hose. Each coupling contains one or more thrusters or thruster ports, each thruster port comprising a hole or opening through the coupling wall to allow the passage of water or other pressurized fluid or liquid therethrough. In one preferred embodiment, the thruster ports are oriented in a substantially rearward direction about the circumference of the thruster coupling such that high pressure water or other fluid exits the holes at a substantially rearward angle and enters the horizontal bore in a direction effective to impinge upon the walls of the bore, thus thrusting the hose (and thereby the nozzle blaster) forward through the bore.

[0028] In a further preferred embodiment, the thruster ports are adjustable, meaning that they have variable opening area or diameter, variable discharge angle or both. In this embodiment, the opening diameter or the angle of discharge of the adjustable thrusters can be varied to deliver a variable degree of thrust to the hose assembly (and nozzle blaster) depending on how much force is required or desired to effectively drill through the strata ahead of the nozzle blaster (e.g. sandstone requires comparatively less thrust or drilling force relative to granite or igneous rock). In addition, varying the angle of discharge can aid in steering the flexible hose assembly as it drills a horizontal bore, and in clearing the horizontal bore of drill cuttings and other debris.

[0029] With reference to FIG. 4, there is shown generally a flexible hose assembly 10 according to the invention, which preferably comprises a nozzle blaster 24 and a flexible hose 11. Flexible hose 11 has and comprises a plurality of flexible hose sections 22, a pair of pressure fittings 23 attached to the ends of each hose section 22, and a plurality of thruster couplings 12, each of which joins a pair of adjacent pressure fittings 23. Hose assembly 10 comprises a nozzle blaster 24 at its distal end and is connected to a source (not shown) of high pressure fluid, preferably an aqueous liquid, preferably water, less preferably some other liquid, at its proximal end. Couplings 12 are spaced at least, or not more than, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 feet apart from each other in hose 11. The total hose length is preferably at least or not more than 100 or 200 or 400 or 600 or 700 or 800 or 900 or 1000 or 1200 or 1400 or 1600 or 1800 or 2000 feet. Hose sections 22 are preferably flexible hydraulic hose known in the art, comprising a steel braided rubber-Teflon (polytetrafluoroethylene) mesh, preferably rated to withstand at least 5,000, preferably at least 10,000, preferably at least 15,000, psi water pressure. High pressure water is preferably supplied at at least 2,000, 5,000, 10,000, 15,000, or 18,000 psi, or at 5,000 to 10,000 to 15,000 psi. When used to drill horizontally from a vertical well, the hose extends about or at least or not more than 7, 10, 50, 100, 200, 250, 300, 350, 400, 500, 1000, or 2000 feet horizontally from the original vertical well. In one embodiment the hose extends about 440 feet horizontally from the original vertical well.

[0030] As illustrated in FIG. 1, in a first preferred embodiment thruster coupling 12 comprises a coupling or fitting, preferably made from metal, preferably steel, most preferably stainless steel, less preferably aluminum. Less preferably, coupling 12 is a fitting made from plastic, thermoset, or polymeric material, able to withstand 5,000 to 10,000 to 15,000 psi of water pressure. Still less preferably, coupling 12 is a fitting made from ceramic material. It is important to note that when a drilling fluid other than water is used, the material of construction of the couplings 12 must be selected for compatibility with the drilling fluid and yet still withstand the desired fluid pressure. Coupling 12 has two threaded end sections 16 and a middle section 14. Preferably, end sections 16 and middle section 14 are formed integrally as a single solid part or fitting. Threaded sections 16 are female-threaded to receive male-threaded pressure fittings 23 which are attached to, preferably crimped within the ends of, hose sections 22 (FIG. 4). Alternatively, the fittings 23 can be attached to the ends of the hose sections 22 via any conventional or suitable means capable of withstanding the fluid pressure. In the illustrated embodiment, each fitting 23 has a threaded portion and a crimping portion which can be a unitary or integral piece, or a plurality of pieces joined together as known in the art. Alternatively, the threaded connections may be reversed; i.e. with male-threaded end sections 16 adapted to mate with female-threaded pressure fittings attached to hose sections 22. Less preferably, end sections 16 are adapted to mate with pressure fittings attached to the end of hose sections 22 by any known connecting means capable of providing a substantially water-tight connection at high pressure, e.g. 5,000-15,000 psi. Middle section 14 contains a plurality of holes or thruster ports 18 which pass through the thickness of wall 15 of coupling 12 to permit water to jet out. Though the thruster ports 18 are shown having an opening with a circular cross-section, the thruster port openings can be provided having any desired cross section; e.g. polygonal, curvilinear or any other shape having at least one linear edge, such as a semi-circle. Coupling 12 preferably is short enough to allow hose 11 to traverse any bends or elbows in the upset tubing and any shoes or adapters used therewith. Therefore, coupling 12 is formed as short as possible, preferably having a length of less than about 3, 2, or 1.5 inches, more preferably about 1 inch or less than 1 inch. Hose 11 (and therefore couplings 12 and hose sections 22) preferably has an outer diameter of about 0.25 to about 1.25 inches, more preferably about 0.375 to about 0.5 inches, and an inner diameter preferably of about 0.125 inches. Couplings 12 have a wall thickness of preferably about 0.025-0.25, more preferably about 0.04-0.1, inches.

[0031] Optionally, hose 11 is provided with couplings 12 formed integrally therewith, or with thruster ports 18 disposed directly in the sidewall of a contiguous, unitary, non-sectioned hose at spaced intervals along its length (see FIG. 6). A hose so comprised obviates the need of threaded connections or other connecting means as described above.

[0032] In the embodiments shown in FIGS. 1 and 7, thruster ports 18 have hole axes 20 which form a discharge angle &bgr; with the longitudinal axis of the coupling 12. The discharge angle &bgr; is preferably 5° to 95°, more preferably 10° to 90°, more preferably 10° to 80°, more preferably 15° to 70°, more preferably 20° to 60°, more preferably 25° to 55°, more preferably 30° to 50°, more preferably 40° to 50°, more preferably 40° to 45°, more preferably about 45°. The thruster ports 18 are also oriented such that a water jet passing through them exits the coupling 12 in a substantially rearward direction; i.e. in a direction such that a centerline drawn through the exiting water jet forms an acute angle (discharge angle &bgr;) with the longitudinal axis of the flexible hose rearward from the location of the thruster port, toward the proximal end of the hose assembly. In this manner, high-pressure water jets 30 emerging from thruster ports 18 impart drilling force or thrust to the nozzle blaster, thus forcing the nozzle blaster forward into the earth strata (see FIG. 4). As illustrated in FIG. 2, a plurality of thruster ports 18 are disposed in wall 15 around the circumference of coupling 12. There are 2 to 6 or 8 ports, more preferably 3 to 5 ports, more preferably 3 to 4 ports. Thruster ports 18 are spaced uniformly about the circumference of coupling 12, thus forming an angle &agr; between them. Angle &agr; will depend on the number of thruster ports 18, and thus preferably will be from 45° or 60° to 180°, more preferably 72° to 120°, more preferably 90° to 120°. Thruster ports 18 are preferably about 0.010 to 0.017 inches, more preferably 0.012 to 0.016 inches, more preferably 0.014 to 0.015 inches in diameter.

[0033] As best seen in FIGS. 1 and 2, thruster ports 18 are formed in the wall 15 of coupling 12, extending in a substantially rearward direction toward the proximal end of the hose assembly 10, connecting inner opening 17 at the inner surface of wall 15 with outer opening 19 at the outer surface of wall 15. The number of couplings 12, as well as the number and size of thruster ports 18 depends on the desired water pressure and water flow rate. If a water source of only moderate delivery pressure is available, e.g. 5,000-7,000 psi, then relatively fewer couplings 12 and thruster ports 18, as well as possibly smaller diameter thruster ports 18 should be used. However, if higher pressure water is supplied, e.g. 10,000-15,000 psi, then more couplings 12 and thruster ports 18 can be utilized. The number of couplings 12 and thruster ports 18, the diameter of thruster ports 18, and the initial water pressure and flow rate are all adjusted to achieve water flow rates through nozzle blaster 24 of 1-10, more preferably 1.5-8, more preferably 2-6, more preferably 2.2-3.5, more preferably 2.5-3, gal/min.

[0034] In the first preferred embodiment illustrated in FIG. 1, the thruster ports 18 are provided as unobstructed openings or holes through the side wall of the thruster coupling 12. The ports 18 are provided or drilled at an angle so that the exiting pressurized fluid jets in a rearward direction as explained above.

[0035] In the second preferred embodiment illustrated in FIG. 7, the thruster couplings 12 and thruster ports 18 are similarly provided as described above shown in FIG. 1, except that the thruster port or ports 18 include a shutter 31. The shutter 31 is preferably an iris as shown in FIG. 7, and shown close-up in FIG. 9. The shutter 31 is actuated by a servo controller 32 (pictured schematically in the figures) which is controlled by an operator at the surface via wireline, radio signal or any other suitable or conventional means. The servo controller 32 is preferably provided in the sidewall of the coupling 12 as shown in FIG. 8, or is mounted on the inner wall surface of the coupling 12. The servo controller 32 has a small motor to control or actuate the shutter 31 to thereby regulate the diameter or area of the opening 34 for the thruster port 18. A fully open shutter 31 results in the maximum possible thrust from the associated thruster port 18 because the maximum area is available for the expulsion of high pressure fluid. An operator can narrow the opening 34 by closing the shutter 31 to regulate the amount of thrust imparted to the hose assembly by the associated thruster port 18. The smaller diameter the opening 34, the less thrust provided by the thruster port 18. Although an iris is shown, it will be understood that other mechanisms can be provided for the shutter 31 which are conventional or which would be recognized by a person of ordinary skill in the art; e.g. sliding shutter, flap, etc. The servo controller 32 is preferably a conventional servo controller having a servo motor that is controlled in a conventional manner. Servo controllers are generally known or conventional in the art.

[0036] In addition to providing thrust to the hose (and nozzle blaster 24), thruster ports 18 equipped with shutters 31 can be used to guide or steer the hose assembly 10 as it drills a horizontal bore. It will be understood by a person of ordinary skill in the art that during use, the hose assembly 10 is very rigid, i.e. it is biased in a straight or linear configuration due to the internal fluid pressure (e.g. 5,000 or 10,000 or 15,000 psi). This is because the internal fluid pressure seeks to expand the hose assembly 10 from within, thereby forcing the assembly to remain stiff and straight without bending. By regulating the relative thrust provided by different thruster ports 18 at spaced circumferential locations about the hose assembly at a particular axial position along its length, the assembly 10 can be steered at that axial location.

[0037] For example, referring to FIG. 8, if thruster port 18a provides greater thrust than either of ports 18b or 18c, then the hose assembly 10 will be driven in a lateral direction (relative to the hose's longitudinal axis) substantially opposite the position of the thruster port 18a as a result of the excess thrust (i.e. direction indicated by arrow B in FIG. 8). The lateral thrust is countered by and must be balanced against the assembly's 10 straight and rigid bias (described above) to provide the desired lateral positioning or steering effect. The assembly's straight and rigid bias makes control of the assembly 10 via the thrusters easier to achieve because the assembly is constantly trying to right or straighten itself. Therefore, the thrusters' port openings 34 can be finely regulated to control the amount of thrust acting against the straightening bias to provide very precise lateral positioning and steering capability for the hose assembly 10.

[0038] Likewise, a corresponding lateral thrust can be imparted by either of thruster ports 18b and/or 18c in the appropriate direction. It will be understood that the relative thrust of all the thrusters located at the same axial position along the length of the hose assembly 10 (i.e. all the thrusters in a single thruster coupling 12) can be simultaneously regulated in concert to guide the lateral position of the hose assembly 10 at that location. By similarly coordinating the relative thrust of all the groups of thruster ports 18 disposed at discrete axial positions along the length of the hose assembly 10, an operator can guide or steer the assembly 10 as it drills horizontally from the vertical well to thereby provide a specific desired configuration for the hose assembly 10 along its entire length as it drills. This way, a horizontal bore having a desired nonlinear shape or overall configuration can be drilled; the horizontal bore need not be straight. Alternatively, if a straight or linear horizontal bore is desired, the hose assembly 10 (particularly at or near its distal end where the nozzle blaster 24 is located) can be steered to ensure a straight path despite the presence of obstructions or other forces that could divert the blaster's 24 path.

[0039] It will be understood that when complex shape or drilling pathway configurations are desired, it would be very difficult for a human operator to properly control and regulate the relative thrust for all of the thruster ports 18 along the hose assembly's length. Therefore, it is desirable and preferred to have the adjustable thruster ports 18 controlled by a computer 40 that has been programmed with the desired drilling configuration. Means and methods for programming a computer to control a plurality of servo controllers (for regulating shutters 31) are conventional, and are well understood by persons of ordinary skill in the art.

[0040] Preferably, the flexible hose 11 is provided with a plurality of position indicating sensors 35 along its length. Position indicating sensors 35 are shown schematically in FIG. 4 attached to the thruster couplings 12 and nozzle blaster 24. Alternatively, the position indicating sensors 35 can be provided in the coupling walls, or in the hose wall along its length. The position indicating sensors 35 can emit a radio signal or can be monitored by wireline from the surface to determine the location and configuration of the flexible hose. The adjustable thruster ports 18 can be controlled as described above based on position and configuration information received from these position indicating sensors 35. Preferably, the computer receives information from the position indicating sensors 35 and regulates the adjustable thrusters based on that information to achieve the desired steering and position control of the hose assembly 10 as it drills a horizontal bore.

[0041] FIG. 10 shows an alternative preferred embodiment of the adjustable thruster ports 18. In this embodiment, the adjustable thruster ports 18 comprise flap shutters 31a adjacent to, and adapted to seal off, the outer openings 19 of the ports 18. In this embodiment, the flap shutters 31a are servo controlled similarly as described above, and can be opened or closed to variable degrees as desired to provide a desired amount of thrust. One advantage of this embodiment is that in addition to regulating the flowrate of the jets 30, the flap shutters 31a also can be used to regulate the discharge angle &bgr;. This embodiment is less preferred because the flap shutters 31a are liable to catch on the horizontal bore wall or on some obstruction therein. Further, the flap shutters can inhibit the passage of rearwardly traveling cuttings to exit the horizontal bore as described below.

[0042] FIG. 11 shows yet another alternative preferred embodiment of the invention, where the thruster ports 18 are provided in servo-controlled pivot arms 38. In this embodiment, the discharge angle &bgr; between the centerline drawn through the exiting water jet 30 and the longitudinal axis of the flexible hose can be regulated. The smaller angle &bgr;, the larger axial thrust force vector for a given fluid pressure and discharge rate; conversely, the larger angle &bgr;, the smaller axial thrust force vector for the same fluid pressure and discharge rate. Thus, the degree of forward thrust for the hose assembly 10 can be controlled for a given fluid pressure and discharge rate by regulating the discharge angle of the water jets 30. This is achieved by controlling the pivot arms 38 to provide the desired discharge angle &bgr;. Preferably, the pivot arms 38 are adjustable to provide a discharge angle in the range of 10° to 90°, 10° to 80°, 15° to 70°, 20° to 60°, 25° to 50°, 30° to 50°, or 40° to 50° in a rearward direction toward the proximal end of the hose assembly 10.

[0043] In addition to providing thrust, the thruster ports 18 also provide another important function. Thruster ports 18 keep the bore clear behind nozzle blaster 24 as the rearwardly jetting high pressure fluid (water) washes the drill cuttings out of the horizontal bore so that the cuttings do not accumulate in the horizontal bore. The high pressure water or aqueous liquid forced through the thruster ports 18 also cleans and reams the bore by clearing away any sand and dirt that has gathered behind the advancing nozzle blaster 24, as well as smoothing the wall of the freshly drilled bore.

[0044] This is an important feature because, left to accumulate, the cuttings and other debris can present a significant obstacle to horizontal drilling, effectively sealing of already-drilled portions of the horizontal bore around the advancing hose assembly 10. This can make removal of the hose assembly 10 difficult once drilling is completed. In a worst case, the remaining debris can cause the horizontal bore to reseal once the hose assembly 10 has been withdrawn. By forcing these cuttings rearward to exit the lateral bore, the rearwardly directed water jets 30 ensure the horizontal bore remains substantially open and clear after drilling is completed and the hose assembly 10 is removed. By providing the thruster ports 18 along substantially the entire length of the hose assembly 10, drill cuttings can be driven out of the horizontal bore from great distances into the horizontal bore, preferably at least 50, 100, 200, 250, 300, 350, 400, 500, 1000, or more, feet.

[0045] Nozzle blaster 24 is of any type known in the art, for example, the type shown in FIGS. 5A-5B. Nozzle blaster 24 comprises a plurality of holes 50 disposed about a front portion 46a which preferably has a substantially domed shape. Holes 50 are positioned to form angle &thgr; with the longitudinal axis of nozzle blaster 24. Angle &thgr; is 10°-30°, more preferably 15°-25°, more preferably about 20°. Nozzle blaster 24 also comprises a plurality of holes 46b, which are oriented in a reverse or rearward direction on a rear portion 60 of nozzle blaster 24, the direction and diameter of holes 46b being similar to that of thruster ports 18 disposed around couplings 12. Holes 46b serve a similar function as thruster ports 18 to impart forward drilling force to nozzle blaster 24 and to wash drill cuttings rearward to exit the horizontal bore. Optionally, front portion 46a is rotatably coupled to rear portion 60, with holes 50 oriented at an angle such that exiting high-pressure water imparts rotational momentum to front portion 46a, thus causing front portion 46a to rotate while drilling. Rear portion 60 is either fixed with respect to hose 11 unable to rotate, or is rotatably coupled to hose 11 thus allowing rear portion 60 to rotate independently of hose 11 and front portion 46a. In this embodiment, holes 46b are oriented at an angle effective to impart rotational momentum to rear portion 60 upon exit of high-pressure water, thus causing rear portion 60 to rotate while drilling. Holes 50 and 46b can be oriented such that front and rear portions (46a and 60 respectively) rotate in the same or opposite directions during drilling.

[0046] Thruster ports 18 and 46b are oriented in a reverse or rearward direction, relative to forward direction A (FIGS. 1 and 4), toward the proximal end of the hose assembly to thrust the nozzle blaster forward to drill the bore. High pressure water is propelled through thruster ports 18 forming high pressure water jets 30 which impinge on the walls of the bore at such an angle as to impart drilling force to the nozzle blaster 24. Thus, the present invention has great utility at shallow depths where the length (and thereby the weight) of flexible hose in the vertical well is generally insufficient to supply adequate drilling force to the nozzle blaster 24 to propel it forward while drilling. As such, the present invention is effectively used to drill horizontal bores at depths of at least, or not more than, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or 2000 feet. However, the invented hose assembly can also be advantageously used to drill horizontal bores at greater depths, e.g. 5,000, 8,000, 10,000, or 15,000 feet or greater.

[0047] Although the hereinabove described embodiments of the invention constitute the preferred embodiments, it should be understood that modifications can be made thereto without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A flexible hose assembly for horizontal well drilling comprising a flexible hose, said flexible hose assembly having a proximal end and a distal end, said proximal end being located rearward of said distal end, said flexible hose having a plurality of thruster ports disposed therein with at least one of said thruster ports being disposed rearward of said distal end of said flexible hose assembly, at least one of said thruster ports being adapted to direct a jet of pressurized fluid in a direction such that a centerline drawn through said jet forms an acute discharge angle with the longitudinal axis of said flexible hose rearward from the location of said thruster port, at least one of said thruster ports being an adjustable thruster port.

2. A flexible hose assembly according to claim 1, said flexible hose further comprising a plurality of flexible hose sections and at least one thruster coupling, said thruster coupling being joined to adjacent flexible hose sections, said adjustable thruster port being disposed in said thruster coupling.

3. A flexible hose assembly according to claim 2, further comprising a plurality of said thruster couplings, each thruster coupling having at least one adjustable thruster port.

4. A flexible hose assembly according to claim 1, said hose comprising flexible hydraulic hose rated to withstand at least 5,000 psi.

5. A flexible hose assembly according to claim 3, said thruster couplings being spaced at least 10 feet apart from each other in said hose.

6. A flexible hose assembly according to claim 3, each of said thruster couplings comprising two threaded end sections and a middle section, each of said end sections adapted to mate with a pressure fitting attached to a section of said flexible hose.

7. A flexible hose assembly according to claim 1, said adjustable thruster port having a variable opening area, said jet being discharged from said thruster port through said opening.

8. A flexible hose assembly according to claim 1, said adjustable thruster port having a variable discharge angle.

9. A flexible hose assembly according to claim 7, said adjustable thruster port comprising a shutter for regulating the area of said opening of said thruster port.

10. A flexible hose assembly according to claim 9, said shutter being an iris.

11. A flexible hose assembly according to claim 9, further comprising a servo controller for actuating said shutter to thereby regulate said opening area of said adjustable thruster port.

12. A flexible hose assembly according to claim 11, said servo controller being controlled via wireline or radio signal.

13. A flexible hose assembly according to claim 2, said thruster coupling comprising 2-8 thruster ports evenly spaced around the circumference of said thruster coupling.

14. A flexible hose assembly according to claim 8, said adjustable thruster port comprising a servo-controlled pivot arm, said pivot arm being adjustable to regulate said discharge angle.

15. A flexible hose assembly according to claim 14, said pivot arm being adjustable to provide said discharge angle in the range of 10° to 90° in a rearward direction toward said proximal end of said hose assembly.

16. A flexible hose assembly according to claim 1, said flexible hose being 400-2000 feet in length.

17. A flexible hose assembly according to claim 1, further comprising a nozzle blaster joined to said flexible hose at said distal end of said hose assembly, at least one of said thruster ports being disposed in said flexible hose rearward of the point where said flexible hose joins said nozzle blaster.

18. A method of horizontal well drilling comprising the following steps:

a) providing a flexible hose assembly comprising a flexible hose having a proximal end and a distal end, said proximal end being located rearward of said distal end, said flexible hose having a plurality of thruster ports disposed therein with at least one of said thruster ports being disposed rearward of said distal end of said flexible hose, at least one of said thruster ports adapted to direct a jet of pressurized fluid in a direction such that a centerline drawn through said jet forms an acute discharge angle with the longitudinal axis of said flexible hose rearward from the location of said thruster port, at least one of said thruster ports being an adjustable thruster port;

b) lowering said flexible hose assembly to a desired depth in a vertical well, and redirecting said flexible hose assembly along a direction at an angle to the longitudinal axis of said vertical well;

c) forcing at least 2,000 psi fluid through said flexible hose and said thruster ports in said flexible hose; and

d) drilling a horizontal bore into the earth's strata adjacent said vertical well.

19. A method according to claim 18, said adjustable thruster port having a variable opening area, said jet being discharged from said thruster port through said opening.

20. A method according to claim 18, said adjustable thruster port having a variable discharge angle.

21. A method according to claim 19, said adjustable thruster port comprising a shutter for regulating the area of said opening of said thruster port.

22. A method according to claim 21, said shutter being an iris.

23. A method according to claim 21, further comprising a servo controller for actuating said shutter to thereby regulate said opening area of said adjustable thruster port.

24. A method according to claim 23, said servo controller being controlled via wireline or radio signal.

25. A method according to claim 20, said adjustable thruster port comprising a servo-controlled pivot arm, said pivot arm being adjustable to regulate said discharge angle.

26. A method according to claim 25, said pivot arm being adjustable to provide said discharge angle in the range of 10° to 90° in a rearward direction toward said proximal end of said hose assembly.

27. A method according to claim 18, further comprising the step of drilling a horizontal bore from a vertical well at a depth of 50-2000 feet.

28. A method according to claim 18, further comprising the step of withdrawing said hose assembly from said horizontal bore, and during said withdrawing step forcing fluid through said thruster ports to clean and ream said horizontal bore.

29. A method according to claim 18, said flexible hose assembly further comprising a nozzle blaster attached to said flexible hose at said distal end thereof, at least one of said thruster ports being disposed in said flexible hose rearward of the point where said flexible hose joins said nozzle blaster.

30. A flexible hose assembly according to claim 1, said fluid being aqueous liquid.

31. A method according to claim 18, said fluid being aqueous liquid.

32. A flexible hose assembly according to claim 1, further comprising at least one position indicating sensor.

33. A flexible hose assembly according to claim 32, comprising a plurality of said position indicating sensors provided along the length of said flexible hose assembly.

34. A flexible hose assembly for horizontal well drilling comprising a flexible hose, said flexible hose assembly having a proximal end and a distal end, said proximal end being located rearward of said distal end, said flexible hose having a plurality of thruster ports disposed therein with at least one of said thruster ports being disposed rearward of said distal end of said flexible hose assembly, at least one of said thruster ports being adapted to direct a jet of pressurized fluid in a direction such that a centerline drawn through said jet forms an acute discharge angle with the longitudinal axis of said flexible hose rearward from the location of said thruster port, each of said thruster ports having an opening with a cross-sectional area selected from the group consisting of closed polygons, closed curvilinear shapes, and shapes having at least one linear edge.