Auto-extending/retracting electrically isolated conductors in a segmented drill string Number:7,150,329 from the United States Patent and Trademark Office (PTO) owispatent

Title: Auto-extending/retracting electrically isolated conductors in a segmented drill string

Abstract: A system includes a drill string made up of a plurality of connectable pipe sections. An assembly is provided for use with each pipe section including contact arrangement for forming an isolated electrical connection between attached pipe sections at each end of each pipe section. An electrically conductive arrangement is located in the innermost passage of each pipe section and is in electrical communication with the contact arrangement to extend therebetween in a way which provides an electrically conductive path that is arranged against the inner wall of the innermost passage of each pipe section in cooperation with the contact arrangement to form an overall electrically isolated conductive path through the drill string. The electrically conductive arrangement resiliently biases the electrically conductive path against the inner wall, which path may take the form of a helix.

Patent Number: 7,150,329 Issued on 12/19/2006 to Chau

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Inventors:	Chau; Albert W. (Woodinville, WA)
Assignee:	Merlin Technology, Inc (Renton, WA)
Appl. No.:	11/348,684
Filed:	February 7, 2006

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Related U.S. Patent Documents

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	Application Number	Filing Date	Patent Number	Issue Date
	11014430	Dec., 2004	7028779
	10313303	Jan., 2005	6845822
	09954573	Dec., 2003	6655464
	09793056	Sep., 2002	6446728
	09317308	May., 2001	6223826

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Current U.S. Class:	166/380 ; 166/65.1; 175/320; 439/578
Current International Class:	E21B 19/16 (20060101)
Field of Search:	166/380,65.1 175/320 439/557,578

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References Cited [Referenced By]

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U.S. Patent Documents

	4690212		September 1987		Termohlen
	4902246		February 1990		Samchisen
	5002503		March 1991		Cambell et al.
	5131464		July 1992		Lenhart et al.
	5141051		August 1992		Lenhart
	5155442		October 1992		Mercer
	5337002		August 1994		Mercer
	5366018		November 1994		Van Steenwyk et al.
	5444382		August 1995		Mercer
	5633589		May 1997		Mercer
	5667009		September 1997		Moore
	5993253		November 1999		Sai
	6050353		April 2000		Logan et al.
	6223826		May 2001		Chau et al.
	6257332		July 2001		Vidrine et al.
	6402524		June 2002		Wurm et al.
	6446728		September 2002		Chau et al.
	6655464		December 2003		Chau et al.
	6845822		January 2005		Chau et al.
	7028779		April 2006		Chau

Primary Examiner: Neuder; William
Attorney, Agent or Firm: Pritzkau Patent Group, LLC

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Parent Case Text

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RELATED APPLICATIONS

The present application is a Continuation of U.S. application Ser. No. 11/014,430 filed Dec. 16, 2004 now U.S. Pat. No. 7,028,779; which is a Continuation of U.S. application Ser. No. 10/313,303 filed Dec. 6, 2002 and issued as U.S. Pat. No. 6,845,822 on Jan. 25, 2005; which is a Continuation-In-Part of U.S. application Ser. No. 09/954,573 filed Sep. 10, 2001 and issued as U.S. Pat. No. 6,655,464 on Dec. 2, 2003; which is a Continuation-In-Part of U.S. application Ser. No. 09/793,056 filed Feb. 26, 2001 and issued as U.S. Pat. No. 6,446,728 on Sep. 10, 2002; which is a Continuation of U.S. application Ser. No. 09/317,308 filed May 24, 1999 and issued as U.S. Pat. No. 6,223,826 on May 1, 2001; all of which are incorporated herein by reference.

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Claims

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What is claimed is:

1. A drill string, comprising: a plurality of pipe sections each of which includes a section length defining an innermost passage between opposing first and second ends of each pipe section that are removably connectable with other ones of the pipe sections to form a length of the drill string; an electrical contacting arrangement for forming an isolated electrical connection between attached ones of the pipe sections and installed in the innermost passage at each opposing end of each pipe section; and an electrically conductive arrangement located in the innermost passage of each pipe section and in electrical communication with said electrical contacting arrangement at each opposing end of each pipe section to extend therebetween in a way which provides an electrically conductive path that is arranged against the inner wall of the innermost passage of each pipe section to form an electrically isolated conductive path through each pipe section, such that attached ones of the pipe sections form an overall electrically isolated path as part of said drill string.

2. The drill string of claim 1 wherein said electrical contacting arrangement includes a pair of adapters for installation of a first one of the adapters in a first end of the innermost passage of each pipe section and installation of a second one of the adapters in a second end of the innermost passage of each pipe section, said first and second adapters being configured for establishing said isolated electrical connection between attached ones of the pipe sections.

3. The drill string of claim 1 wherein the electrically conductive arrangement resiliently biases the electrically conductive path against the inner wall.

4. The drill string of claim 3 wherein said electrically conductive path at least generally forms a helix that is biased against the inner wall and said helix having opposing helix ends that are electrically attached to the electrical contacting arrangement at the opposing ends of the pipe section.

5. The drill string of claim 1 wherein said electrically conductive path includes a coil spring having a coil length that is extended along the innermost passage of the pipe section and having opposing spring ends that are electrically attached to the electrical contacting arrangement at opposing ends of the pipe section and said coil length is configured to resiliently bias against the inner wall of the innermost passage.

6. The drill string of claim 5 wherein said coil spring is a helical coil spring.

7. The drill string of claim 6 wherein said innermost passage includes a passage diameter and wherein said coil length, prior to insertion into the innermost passage, includes an outer diameter that is greater than the passage diameter of the innermost passage.

8. The drill string of claim 7 wherein said coil length includes a cylindrical outline defining said outer diameter.

9. The drill string of claim 5 wherein said coil spring includes an outermost electrical insulating layer.

10. The drill string of claim 5 wherein said coil spring includes a base wire, having an electrical resistance, coated with a lower resistance layer.

11. The drill string of claim 10 wherein said lower resistance layer is a copper cladding.

12. The drill string of claim 11 including an electrically insulating jacket covering said copper cladding.

13. The drill string of claim 5 wherein said coil spring includes a base wire that is generally circular in cross-section.

14. The drill string of claim 5 wherein said coil spring includes a base wire that is generally rectangular in cross-section.

15. The drill string of claim 5 wherein said coil spring includes a base wire having a pair of opposing major surfaces.

16. The drill string of claim 1 wherein the electrically conductive arrangement includes an insulated electrical conductor in the innermost passage, extending between the electrical contacting arrangement at opposing ends of the pipe section and a support arrangement which supports the insulated electrical conductor proximate to the inner wall.

17. The drill string of claim 16 wherein the support arrangement is configured for resiliently supporting the insulated electrical conductor proximate to the inner wall.

18. The drill string of claim 17 wherein the support arrangement includes a helical coil spring for supporting the electrical conductor along a helical path proximate to the inner wall.

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Description

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BACKGROUND OF THE INVENTION

The present invention relates generally to underground directional boring, underground resource extraction and more particularly, to automatically extending and retracting electrically isolated conductors provided in a segmented drill string. An associated method is also disclosed.

Guided horizontal directional drilling techniques are employed for a number of purposes including, for example, the trenchless installation of underground utilities such as electric and telephone cables and water and gas lines. As a further enhancement, state of the art directional drilling systems include configurations which permit location and tracking of an underground boring tool during a directional drilling operation. As will be seen, the effectiveness of such configurations can be improved by providing an electrical pathway between a drill rig which operates the boring tool and the boring tool itself.

Turning to FIG. 1, a horizontal boring operation is illustrated being performed using a boring/drilling system generally indicated by the reference numeral 10. The drilling operation is performed in a region of ground 12 including an existing underground utility 14. The surface of the ground is indicated by reference number 16.

System 10 includes a drill rig 18 having a carriage 20 received for movement along the length of an opposing pair of rails 22 which are, in turn, mounted on a frame 24. A conventional arrangement (not shown) is provided for moving carriage 20 along rails 22. During drilling, carriage 20 pushes a drill string 26 into the ground and, further, is configured for rotating the drill string while pushing. The drill string is made up of a series of individual drill string or pipe sections 28, each of which includes any suitable length such as, for example, ten feet. Therefore, during drilling, pipe sections must be added to the drill string as it is extended or removed from the drill string as it is retracted. In this regard, drill rig 18 may be configured for automatically or semi-automatically adding or removing the drill string sections as needed during the drilling operation. Underground bending of the drill string enables steering, but has been exaggerated for illustrative purposes.

Still referring to FIG. 1, a boring tool 30 includes an asymmetric face 32 and is attached to the end of drill string 36. Steering of the boring tool is accomplished by orienting face 32 of the boring tool (using the drill string) such that the boring tool is deflected in the desired direction. Boring tool 30 includes a mono-axial antenna such as a dipole antenna 44 which is driven by a transmitter 46 so that a magnetic locating signal 48 is emanated from antenna 44. In on embodiment, power may be supplied to transmitter 46 from a set of batteries 50 via a power supply 52. In another embodiment (not shown), to be described in further detail below, an insulated electrical conductor is installed within the drill string between the drill rig and the boring tool in order to carry power to transmitter 46. A control console 54 is provided at the drill rig for use in controlling and/or monitoring the drilling operation. The control console includes a display screen 56, an input device such as a keyboard 58 and a plurality of control levers 60 which, for example, hydraulically control movement of carriage 20 along with other relevant functions of drill rig operation.

Drill pipe 28 defines a through passage (not shown) for a number of reasons, including considerations of design, manufacturing methods, strength, and weight, but also because typical horizontal directional drilling also requires the use of some type of drilling fluid (not shown), most commonly a suspension of the mineral bentonite in water (commonly referred to as "drilling mud"). Drilling mud, which is generally alkaline, is emitted under pressure through orifices (not shown) in boring tool 30 after being pumped through the innermost passage of drill pipes 28 which make up drill string 26. Drilling mud is typically pumped using a mud pump and associated equipment (none of which are shown) that is located on or near drill rig 18. The pressures at which the drilling mud is pumped can vary widely, with a commonly encountered range of operation being 100 PSI to 4,000 PSI, depending on the design and size of the particular drill rig. For proper operation, pipe connections between drill pipe sections 28 must not only be sufficiently strong to join the sections against various thrust, pull and torque forces to which the drill string is subjected, but they must also form a seal so as to not allow the escape of drilling mud from these connections which could result in an unacceptable drop in drilling mud pressure at the orifices of the boring tool.

Continuing to refer to FIG. 1, drilling system 10 may include a portable locator/controller 70 held by an operator 72 for sensing locating signal 48 in a way which allows the underground position of boring tool 30 to be identified. Such portable detectors are described, for example, in U.S. Pat. Nos. 5,155,442, 5,337,002, 5,444,382 and 5,633,589 as issued to Mercer et al, all of which are incorporated herein by reference. Alternatively, one or more detectors (not shown) designed for positioning at fixed, above ground locations may be used, as described in U.S. patent application Ser. No. 08/835,834, filing date Apr. 16, 1997, which is commonly assigned with the present application and is incorporated herein by reference.

Guided horizontal directional drilling equipment is typically employed in circumstances where the inaccuracies and lack of steering capability of non-guided drilling equipment would be problematic. A typical example is the situation illustrated in FIG. 1 in which the intended drill path requires steering the boring tool around, in this instance beneath, obstacles such as utility 14. Guided drilling is also important where the intended path is curved (not shown) or the target destination is more than a short distance (typically over 50 feet) from the starting point. In the latter situation, simply aiming a non-guided boring tool at the target destination from the starting point will seldom result in maintaining a sufficiently accurate drill path and/or arriving reasonably close to the target destination.

While system 10 of FIG. 1 illustrates a "walk-over" type locating system using a steerable boring tool, it should be appreciated that "non-walkover" guidance/locating systems (not shown) are also useful in conjunction with steerable boring tools. The less commonly used non-walkover systems typically utilize an instrumentation/sensor package (not shown) located in the boring tool that is electrically connected directly to console 54 at the drill rig via the aforementioned insulated electrical conductor (not shown) located inside the through passage of the drill string. While batteries 50 may be used in the boring tool to power the instrumentation/sensor package, the insulated conductor may be used to supply electrical power to the instrumentation/sensor package, thus eliminating batteries 50 for reasons which will be seen. At the same time, data may be transmitted from the instrumentation/sensor package to console 54 on the insulated conductor. Data can also be sent to the instrumentation/sensor package for calibration, signal processing and programming.

In the instance of both walkover and non-walkover systems, the objective is to use information obtained from the locating system as a basis for making corrections and adjustments to the direction of steerable boring tool 30 in order to drill a bore hole that follows an intended drill path. Therefore, in most drilling scenarios, a walkover system is particularly advantageous since the origin of the locating signal leads directly to the position of the boring tool. Typically, the locating signal, in a walkover system, is also used to transmit to above ground locations encoded information including the roll and pitch orientation of boring tool 30 along with temperature and battery voltage readings. Battery powered transmitters often employ one to four replaceable internal "dry-cell" type batteries as a source for electric power.

Although internal battery powered transmitters perform satisfactorily under many conditions, there are a number of limitations associated with their use, most of which are due to the relatively low electric power available from dry-cell batteries. For example, battery life for a self-powered transmitter is relatively short and, under some circumstances, the exhaustion of batteries can result in the need to withdraw an entire drill string for the purpose of replacing batteries in order to complete a drill run. It should also be appreciated that the low power level available from dry-cell batteries, from a practical standpoint, limits the signal strength of locating signal 48. The available signal strength is of concern in relation to the depth at which the boring tool may be tracked. That is, the above ground signal strength of locating signal 48 decays relatively rapidly as depth increases. The maximum operating depth for reliable receipt of locating signal 48 using a dry-cell powered transmitter 46 is limited to approximately 100 feet, depending on the particular design and characteristics of boring tool transmitter 46 and the above ground detector(s) used. This distance may decrease in the presence of passive and active forms of magnetic field interference, such as metallic objects and stray magnetic signals from other sources.

As a result of these limitations, drill head transmitters for walkover systems have been developed that can be powered by an above ground external power source via the aforementioned electrical conductor. That is, the typical electrical conductor for this external power source is similar to that used with non-walkover systems, namely a single insulated wire that connects to the transmitter with the ground return for the electrical circuit including the metallic housing of boring tool 30, drill pipe 28 making up the drill string, and drill rig 18. Even in the case where a locating signal is transmitted from the boring tool, the electric conductor may be used to send information from boring tool 30 to the drill rig including, for example, the roll and pitch orientation of the boring tool, temperature and voltage, using a variety of data encoding and transmission methods. By using the insulated electrical conductor, reliable operational depth may be increased by increasing the output power of transmitter 46 without concern over depletion of internal battery power. Moreover, information encoded on the electrical conductor can be received at the drill rig essentially irrespective of the operating depth of the boring tool and background noise level.

The prior art practice (not shown) for using externally-powered electronic and electrical devices located in the boring tool has been to insert a piece of insulated electrical conducting wire of appropriate length inside each piece of drill pipe 28 and manually perform a physical splice of the electrical wire to the wire in the prior section of drill pipe 28 each time an additional drill pipe section is added to the drill string. The process typically entails the use of specialized and relatively expensive crimp-on connectors and various types of heat-shrinkable tubing or adhesive wrappings that are mechanically secure, waterproof, and resistant to the chemical and physical properties of drilling mud. The process of interrupting pipe joining operations to manually splice the electrical conductor is labor-intensive and results in significant reductions in drilling productivity. Care must also be taken by the person performing splicing to avoid twisting or pinching the electrical wire, and any failure to properly splice can result in wire breakage and the need to withdraw the drill string to make repairs. For drill rigs having the capability of adding/removing drill pipe automatically or semi-automatically, this otherwise useful time and labor saving function must be disabled or interrupted to allow a manual splice of the electric wire. After completing the drill run, a reverse process of withdrawing the drill string and removing each section of drill pipe 28 from the ground requires cutting the wire each time a section of drill pipe is removed, resulting in considerable waste due to the discard of these once-used electrical wires and splicing materials.

Electrical conductors have been described by the prior art for use in applications other than horizontal directional drilling. One specific field of application resides in extraction of underground resources such as, for example, oil and natural gas. The need for an electrical communication path arises, in many instances, for the purpose of monitoring, controlling and/or providing operational power to in-ground devices such as valves and data acquisition modules. One such approach is exemplified by U.S. Pat. No. 6,257,332 entitled WELL MANAGEMENT SYSTEM (hereinafter the '332 patent). The problem being solved may be different, in some instances, than that encountered with respect to HDD, however, since HDD drill strings generally rotate. The objective, in the instance of a pre-existing wellbore such as an oil or gas well, may be to install an electrical cable in a pre-existing wellbore. Thus, a drill string type arrangement may simply be dropped or pushed into the pre-existing wellbore without the need for rotation or actual drilling. In this regard, the '332 patent and its related background art contemplates simply attaching an electrical cable to the exterior of the drill string as it is extended into the wellbore or, alternatively, threading the cable through the interior passage of the drill string. This latter approach is quite inconvenient unless a continuous (i.e. non-sectioned) pipe is used to house the cable since a cable splice must generally be performed whenever additional pipe is added to the drill string. Where the cable is attached to the exterior of the drill string, it is so exposed as to quite readily be damaged in any number of situations. As one example, the cable may be crushed between the drill string and the casing of the wellbore. As another example, the need even for limited rotation of the drill string such as for the purpose of steering could cause the cable to detach from the drill string. It should be appreciated that either type of cable installation is primarily possible due to the general non-rotation of the drill string.

The present invention provides a heretofore unseen and highly advantageous arrangement and associated method which automatically forms an isolated electrically conductive pathway between a drill rig and boring tool or other in-ground device as the drill string extending between the drill rig and the boring tool is either extended or shortened.

SUMMARY OF THE INVENTION

As will be described in more detail hereinafter, there are disclosed herein arrangements and an associated method of providing an isolated electrically conductive path in a system in which a boring tool is moved through the ground in a region. The system includes a drill rig and a drill string which is connected between a boring tool, or other in-ground device, and the drill rig and is configured for extension and/or retraction from the drill rig such that, when the drill string is extended, the boring tool moves in a forward direction through the ground and, when the drill string is retracted, the boring tool moves in a reverse direction approaching the drill rig. The drill string is made up of a plurality of electrically conductive drill pipe sections, each of which includes a section length and all of which are configured for removable attachment with one another to facilitate the extension and retraction of the drill string by one section length at a time. The improvement comprises an arrangement associated with each drill pipe section for providing part of at least one electrically conductive path along the section length of each drill pipe section, which electrically conductive path is electrically isolated from its associated drill pipe section and extends from the boring tool to the drill rig such that the electrically conductive path is extended by the section length when the drill string is extended by attachment of an additional drill pipe section to the drill string at the drill rig and the electrically conductive path is shortened by the section length when the drill string is shortened by detaching the additional drill pipe section from the drill string at the drill rig.

In one aspect of the present invention, a system is disclosed including a drill string for underground use. The drill string includes a length which is extendable and/or retractable through being made up of a plurality of pipe sections having opposing first and second ends and a section length defining an innermost passage and all of which pipe sections are configured for removable attachment with one another by physically connecting the first end of one pipe section with the second end of another pipe section to facilitate extension of the drill string by one section length at a time in a way which aligns the interior passage of attached ones of the pipe sections. As a portion of the system, an assembly is provided for use with each of the pipe sections including a pair of adapters for installation of a first one of the adapters in a first end of the innermost passage of each one of the pipe sections and installation of a second one of the adapters in a second end of the innermost passage of each one of the pipe sections. The first adapter defines a first electrical contact area and the second adapter defines a second electrical contact area. The first and second adapters are configured for resiliently biasing the first and second contact areas against one another between attached ones of the pipe sections to establish an electrical connection between the pair of adapters. An electrically conductive arrangement is located in the innermost passage of each pipe section and extends between and electrically connects each one of the pair of adapters so as to provide an electrically conductive path interconnecting the pair of adapters of each pipe section in electrical isolation from the pipe sections and cooperating with the adapters to form an electrically isolated path through the drill string.

In another aspect of the present invention, the first one of the pair of adapters is configured to resiliently bias the first electrical contact area against the second electrical contact area defined by the second adapter to provide electrical contact between the first and second electrical contact areas while adjacent ones of the pipe sections are attached to one another.

In still another aspect of the present invention, the first adapter includes a first electrically conductive member having a resilient section including a free end defining the first electrical contact area and having an opposing end configured for electrical communication with the electrically conductive arrangement. The free end is configured for engaging the second adapter in a way which brings the first and second electrical contact areas into electrical contact as adjacent ones of the pipe sections are attached to one another and, thereafter, resiliently biases the first electrical contact area against the second electrical contact area. In one feature, the first adapter is configured to apply a resilient bias in a direction generally along the length of the drill string between attached ones of the pipe sections to bias the first electrical contact area against the second electrical contact area. In another feature, the first adapter includes a first electrically conductive member having a resilient section including a free end defining the first electrical contact area and having an opposing, first connection end for electrical connection to the electrically conductive arrangement with a first conductive length defined between the first connection end and the resilient section. The first connection end is supported within the innermost passage of its associated pipe section with the resilient section extending outwardly from the innermost passage. In still another feature, the first conductive member is integrally formed using a resiliently flexible electrically conductive material. In yet another feature, the resilient section is in the form of a helical compression spring defining an axis generally oriented along the axis of the drill string. In a further feature, the first electrical contact surface is defined on the free end of the first conductive member facing away or outwardly from each pipe section in which the first adapter is installed.

In a further aspect of the present invention, the first and second adapters, along with the electrically conductive arrangement, may be installed in pipe sections in conjunction with the manufacturing process of the pipe sections. Alternatively, the first and second adapters may be provided as an after market kit for use with pipe sections already in field use.

In a continuing aspect of the present invention, one or more drill strings configured in accordance with the present invention so as to define an electrically isolated conductive path may be used as part of an electrical communication and/or power supply arrangement installed, for example, in a well in a way which forms a multiplexed data and power supply network. Such drill strings may be used, for instance, in horizontal directional drilling or in underground resource extraction.

In another aspect of the present invention, a system includes a drill string having a length which is configured for extension and/or retraction. The drill string is made up of a plurality of pipe sections having opposing first and second ends and a section length having an inner wall defining an innermost passage and all of which pipe sections are configured for removable attachment with one another by physically connecting the first end of one pipe section with the second end of another pipe section to facilitate extension of the drill string by one section length at a time. An assembly and associated method are provided for use with each one of the pipe sections including contact means for forming an isolated electrical connection between attached ones of the pipe sections that is located within the innermost passage at each opposing end of each pipe section. The assembly further includes an electrically conductive arrangement located in the innermost passage of each pipe section and in electrical communication with the contact means at each opposing end each pipe section to extend therebetween in a way which provides an electrically conductive path that is arranged against the inner wall of the innermost passage of each pipe section. The electrically conductive path cooperates with the contact means to form an overall electrically isolated conductive path through the drill string. In one feature, the electrically conductive arrangement resiliently biases the electrically conductive path against the inner wall. In another feature, the electrically conductive path at least generally forms a helix that is biased against the inner wall. The helix includes opposing helix ends that are electrically attached to the contact means at opposing ends of each pipe section. In still another feature, the electrically conductive path includes a coil spring having a coiled length that is extended along the innermost passage of each pipe section and having opposing spring ends that are electrically attached to the contact means at the opposing ends of each pipe section and the coiled length is configured to resiliently bias against the inner wall of the innermost passage. In yet another feature, the coil spring is a helical coil spring.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be understood by reference to the following detailed description taken in conjunction with the drawings briefly described below.

FIG. 1 is a diagrammatic elevational view of a drilling operation being performed in a region in accordance with the prior art.

FIG. 2 is a diagrammatic cross-sectional view of adjacent ends of a pair of drill pipe sections shown here to illustrate a first embodiment of an arrangement manufactured in accordance with the present invention for automatically forming a continuous, isolated electrically conductive path between a drill rig and in-ground device.

FIG. 3A is a diagrammatic cross-sectional view of a box adapter fitting forming part of the arrangement of FIG. 2 shown here to illustrate details of its construction.

FIG. 3B is a diagrammatic cross-sectional view of a pin adapter fitting forming part of the arrangement of FIG. 2 shown here to illustrate details of its construction and which is configured to mate with the box adapter fitting of FIG. 3A when the fittings are installed in adjacent drill pipe sections.

FIG. 3C is an end view of the pin adapter fitting of FIG. 3B shown here to illustrate further details of its construction.

FIG. 4 is a diagrammatic cross-sectional view showing mated, adjacent ends of the pair of drill pipe sections of FIG. 2 illustrating mated pin and box adapter fittings of FIGS. 3A 3C which automatically form a continuous, isolated electrically conductive path in accordance with the present invention.

FIG. 5 is a diagrammatic partially cut-away view of adjacent ends of a pair of drill pipe sections shown here to illustrate a second embodiment of an arrangement manufactured in accordance with the present invention for automatically forming a continuous, isolated electrically conductive path between a drill rig and in-ground device.

FIG. 6A is a diagrammatic plan view of a box adapter tube fitting forming part of the arrangement of FIG. 5 shown here to illustrate details of its construction.

FIG. 6B is a diagrammatic plan view of a pin adapter tube fitting forming part of the arrangement of FIG. 5 shown here to illustrate details of its construction and which is configured to mate with the box adapter tube fitting of FIG. 6A when the adapter tube fittings are installed in adjacent drill pipe sections.

FIG. 6C is an end view of the pin adapter fitting of FIG. 6B shown here to illustrate further details of its construction.

FIG. 7 is a diagrammatic cross-sectional view showing mated, adjacent ends of the pair of drill pipe sections of FIG. 5 illustrating mated pin and box adapter tube fittings according to FIGS. 6A 6C which automatically form a continuous, isolated electrically conductive path in accordance with the present invention.

FIG. 8 is a diagrammatic cross sectional view of adjacent ends of the pair of adjacent drill pipe sections shown here to illustrate a third embodiment of an arrangement manufactured in accordance with the present invention for automatically forming a continuous, isolated electrically conductive path between a drill rig and in-ground device.

FIG. 9 is a diagrammatic cross sectional view of a tool used in installing adapter fittings which form part of the embodiment illustrated in FIG. 8.

FIG. 10 is diagrammatic cross-sectional view showing mated, adjacent ends of the pair of drill pipe sections of FIG. 8 illustrating mated pin and box adapter fittings according to the third embodiment of the invention which automatically form a continuous, isolated electrically conductive path.

FIG. 11 is a diagrammatic cross sectional view of adjacent ends of the pair of adjacent drill pipe sections shown here to illustrate a fourth third embodiment of an arrangement manufactured in accordance with the present invention for automatically forming a continuous, isolated electrically conductive path between a drill rig and in-ground device.

FIG. 12 is a diagrammatic cross sectional view of adjacent ends of the pair of adjacent drill pipe sections shown here to illustrate a multi-conductor embodiment of an arrangement manufactured in accordance with the present invention for automatically forming two continuous, isolated electrically conductive paths between a drill rig and in-ground device.

FIG. 13 is a diagrammatic cross sectional view of another embodiment of the present invention for providing an electrically isolated conductor within a drill string including first and second adapters shown here representatively installed in adjacent ends of two drill pipe sections which make up a portion of the overall drill string, the drill pipe sections and adapters are illustrated only partially engaged.

FIG. 14 is diagrammatic plan view of a first electrically conductive member forming part of the first adapter shown in FIG. 13, shown here to illustrate details of the construction of the first electrically conductive member in accordance with the present invention.

FIG. 15 is a diagrammatic end view of the first electrically conductive member of FIG. 14 taken from a line 15--15 and shown here to further illustrate details of its structure.

FIG. 16 is a diagrammatic end view of a first electrically insulative sleeve forming a portion of the first adapter as shown in FIG. 13 and configured for supporting the first electrically conductive member of FIGS. 14 and 15.

FIG. 17 is a diagrammatic view of the first insulative sleeve of FIG. 16, in cross section, taken along a line 17--17 and shown here to further illustrate details of the structure of the first insulative sleeve including a configuration for supporting a base coil of the first electrically conductive member of FIGS. 14 and 15.

FIG. 18 is a diagrammatic view of the first insulative sleeve of FIG. 16, in cross section, taken along a line 18--18 and shown here to further illustrate details of the structure of the first insulative sleeve including a receiving arm hole for supporting the first electrically conductive member of FIGS. 14 and 15.

FIG. 19 is diagrammatic plan view of a second electrically conductive member forming part of the second adapter shown in FIG. 13, shown here to illustrate details of the construction of the second electrically conductive member in accordance with the present invention.

FIG. 20 is a diagrammatic end view of the first electrically conductive member of FIG. 14 taken from a line 20--20 and shown here to further illustrate details of its structure.

FIG. 21 is a diagrammatic end view of a second electrically insulative sleeve forming a portion of the second adapter as shown in FIG. 13 and configured for supporting the second electrically conductive member of FIGS. 19 and 20.

FIG. 22 is a diagrammatic view of the second insulative sleeve of FIG. 21, in cross section, taken along a line 22--22 and shown here to further illustrate details of the structure of the second insulative sleeve including a configuration for supporting a contact coil and arm of the second electrically conductive member of FIGS. 19 and 20.

FIG. 23 is a diagrammatic view of the second insulative sleeve of FIG. 21, in cross section, taken along a line 23--23 and shown here to further illustrate details of the structure of the second insulative sleeve of FIGS. 21 and 22.

FIG. 24 is a diagrammatic cross sectional view of the embodiment of FIG. 13 of the present invention, shown here to illustrate the first and second adapters of the present invention in a fully engaged state.

FIG. 25 is an enlarged partial view, in cross-section, of a portion of the assembly of FIG. 24, shown here to illustrate details of the first and second adapters and, in particular, the function of an elastomeric seal forming part of the first adapter.

FIG. 26 is a diagrammatic illustration, in elevation, of a portion of a multilateral well having a plurality of drill strings incorporating electrically isolated conductors as taught by the present invention and used to interface a number of in-ground devices for data and/or power transfer.

FIG. 27 is a diagrammatic side view of a pipe section shown here to illustrate the installation of a highly advantageous isolated conductor assembly including a helical coil conductor installed in the inner passage of the pipe section in accordance with the present invention.

FIG. 28a is a diagrammatic side view showing the helical coil conductor of FIG. 27 in a pre-installation, relaxed state.

FIG. 28b is a diagrammatic end view of the helical coil conductor of FIGS. 27 and 28a, in the pre-installation state.

FIG. 29 is a diagrammatic view, in perspective, of the highly advantageous isolated conductor assembly of FIG. 27, showing the assembly as it appears in its installed state, but without showing a pipe section for purposes of illustrative clarity.

FIG. 30 is a diagrammatic view, in perspective, showing an alternative embodiment of the isolated conductor assembly of the present invention incorporating a conductor that is separate from a helical coil spring.

FIG. 31 is a diagrammatic end view of a spring member supported against an insulated electrical conductor using heat shrink tubing.

DETAILED DESCRIPTION OF THE INVENTION

Having previously described FIG. 1, attention is immediately directed to FIG. 2 which illustrates a first embodiment of an arrangement manufactured in accordance with the present invention and generally indicated by the reference numeral 100 for automatically extending and retracting electrically isolated conductors provided in a segmented drill string. It should be noted that like reference numbers refer to like components throughout the various figures. Moreover, dimensions in the figures have been exaggerated with respect to component sizes and relative spacing for illustrative purposes.

Arrangement 100 is configured for use with standard drill pipe sections such as drill pipe section 28 described above. FIG. 2 illustrates drill pipe sections 28a and 28b having arrangement 100 installed therein. It should be appreciated that arrangement 100 may be provided as an after market kit for installation in commercially available drill pipe sections which may already be in service or for installation in new drill pipe sections. Alternatively, manufacturers may produce new drill pipe sections having arrangement 100 incorporated therein at the time of manufacture. Drill pipe sections 28 each define through hole 102, indicated by the reference numbers 102a and 102b, respectively, for drill pipe sections 28a and 28b. Through holes 102 include a diameter D and define an interior surface 103. Drill pipe section 28a includes a threaded pin (male) end fitting 104a while drill pipe section 28b includes a threaded box (female) end fitting 104b. As is typical in the prior art, these end fittings are designed to threadably engage one another, for example, by rotating pin end fitting 104a of drill pipe section 28a into box end fitting 104b of drill pipe section 28b during a drilling operation so as to extend the drill string, as described above with regard to FIG. 1. It should be appreciated that the configurations of these end fittings cooperate to produce self alignment as they engage one another, yet produce a suitably strong connection between the drill pipe sections once the end fittings are fully engaged with one another. Moreover, as described with regard to FIG. 1, drilling mud (not shown) is pumped down the drill string and through holes 102a and 102b. The connection formed between drill pipe sections 28a and 28b should also prevent the escape of the drilling fluid from the drill string.

Referring now to FIGS. 3A and 3B in conjunction with FIG. 2, arrangement 100 includes a box adapter fitting 108 which preferably is positioned in through hole 102a of drill pipe section 28a and a pin adapter fitting 110 which preferably is positioned in through hole 102b of drill pipe section 28b for reasons to be described below. FIG. 3A illustrates box adapter fitting 108 while FIG. 3B illustrates pin adapter fitting 110. While only one pair of end fittings of adjacent drill pipe sections have been illustrated, it should be appreciated that each drill pipe section includes opposing ends having a box end fitting at one end and a pin end fitting at its other end. Thus, each drill pipe section in an overall drill string (not shown) receives pin adapter fitting 110 in its box end fitting 104b and box adapter fitting 108 in its pin end fitting 104. A length of insulated conductor 112 (only partially shown in FIG. 2) is used to electrically interconnect the pin and adapter fittings associated with each drill pipe section.

Referring primarily to FIG. 3A, box adapter fitting 108 includes a first cylindrically shaped electrically conductive body 114 having a threaded end portion 116, an outwardly projecting peripheral collar 118, having an outer diameter d1, at its opposing end defining a step 119 and an outer peripheral surface 120, having a diameter d2, disposed between peripheral collar 118 and threaded end portion 116. An electrical connection tab 122 extends outwardly from an area of peripheral collar 118 for use in electrical connection with conductor 112 (FIG. 2). The interior surface of conductive body 114 includes a diameter d3 configured to allow the passage of drilling fluid and comprises an electrical contact surface 123. Conductive body 114 may be formed from suitable electrically conductive materials including, but not limited to stainless steel or beryllium copper. A cylindrical electrical insulating sleeve 124 includes a length L and outer diameter D'. Sleeve 124 includes an inwardly projecting peripheral collar 126 defining an entrance diameter approximately equal to d2. The remaining extent of length L of sleeve 124 includes an inner diameter that is slightly greater than d1. Sleeve 124 may be formed from suitable materials such as, for example, Delrin.RTM. (acetal). A compression collar 130 is captured between peripheral collar 126 of sleeve 124 and a locking ring 132. The latter is designed to threadably engage threaded end portion 116 of conductive body 114 and is produced from an electrically non-conductive material such as, for example, Delrin.RTM.. Alternatively (not shown), locking ring 132 may include a conductive, threaded inner body surrounded on its exterior by an electrical insulating material. Compression collar 130 may be formed from elastomeric materials such as, for example, polyurethane. Locking ring 132 also includes a pair of opposing notches 134 (as shown by a dashed line) which may be utilized in rotating the locking ring relative to conductive body 114. Specific details regarding the installation and operational use of box adapter fitting 108 will be provided at an appropriate point hereinafter following a description of pin adapter fitting 110.

Turning now to FIG. 3B, pin adapter fitting 110 includes a second cylindrically shaped electrically conductive body 140 having threaded end portion 116, peripheral collar 118, including its outer diameter d1, defining step 119 and outer peripheral surface 120, having a diameter d2, disposed between peripheral collar 118 and threaded end portion 116. Electrical connection tab 122 extends outwardly from an area of peripheral collar 118. Conductive body 140, like previously described conductive body 114, may be formed from suitable electrically conductive materials including, but not limited to beryllium copper and defines a through opening 135 for the passage of drilling fluid. Installation of cylindrical electrical insulating sleeve 124, locking collar 130 and locking ring 132 will be described below.

Referring to FIGS. 3B and 3C, second conductive body 140 includes a contact finger arrangement 142 formed as an outermost part of threaded end portion 116. Contact finger arrangement 142 includes an opposing pair of elongated electrical contact fingers 144. Each contact finger includes an elongated contact arm 146 and an end contact 148. Elongated contact arms 146 are preferably integrally formed with conductive body 140. End contacts 148 may be integrally formed with contact arms 146 (not shown) or may be produced separately and attached by any suitable method (as shown) such as, for example, welding. Separately produced end contacts may be formed from suitable electrically conductive materials such as, for example, stainless steel or high strength copper alloy. FIG. 3C shows locking ring 132 threadably engaged with second conductive body 140 using threads 148 of the locking ring and conductive body, where these threads are indicated diagrammatically by a zigzag line. It should be noted that the configuration of contact fingers 144 allows the contact fingers to be biased towards one another such that the contact fingers exert a resilient, outward force against applied inward biasing forces.

Referring to FIGS. 2, 3A and 3B, having generally described the structure of arrangement 100, its installation will now be described. Each adapter fitting is initially assembled by first sliding insulating sleeve 124 onto either conductive body 114 of box adapter fitting 108 or conductive body 140 of pin fitting adapter 110 such that outwardly projecting peripheral collar 118 is received against inwardly projecting peripheral collar 126 of sleeve 124. Compression collar 130 is then positioned on either of the conductive bodies, as shown. Because compression collar 130 is generally formed from elastomeric materials, its inner diameter may be slightly less than d2 so long as the compression collar is positionable as shown. Following installation of the compression collar, locking ring 132 is installed with notches 134 exposed for access thereto.

Following initial assembly of the adapter fittings, installation in a drill pipe section may proceed. Outer diameter D' of box adapter fitting 108 and pin adapter fitting 110 are configured to be less than diameter D of through hole 102 in one of drill pipe sections 102. Therefore, the pin and box adapters are slidably receivable in through hole 102. As illustrated in FIG. 2, box fitting adapter 108 is preferably installed at pin end fitting 104a of each drill pipe section while pin fitting adapter 110 is preferably installed at box end fitting 104b of each drill pipe section for reasons to be described below.

Installation of the adapters may be performed by first connecting electrical conductor 112 between connection tabs 122 of one box fitting adapter 108 and of one pin fitting adapter 110. Thereafter, for example, pin fitting adapter 110 is inserted, contact finger arrangement 142 first, into through hole 102 at pin end fitting 104a of a drill pipe section. Pin fitting adapter 110, with electrical conductor 112 attached, is allowed to slide in the through hole until positioned at box end fitting 104b as shown in FIG. 2. At this point, notches 134 of locking ring 132 the pin fitting adapter may be engaged using a specifically configured socket tool (not shown). The locking ring is rotated to compress compression collar 130 between inwardly projecting peripheral collar 126 of insulation sleeve 124 and locking ring 124. As the compression collar is compressed, it expands radially between and against peripheral surface 120 of conductive body 114 or 140 and interior surface 102 (FIG. 2) of a drill pipe section 28. The compression collar is designed to seal against the interior of the drill pipe in order to achieve a tight and secure fit by this radial expansion. In addition, compression collar 130 will allow adapter fittings 108 and 110 to accommodate normal manufacturing variations in the inside diameter of the drill pipe through hole to avoid the need for additional precision machining of the drill pipe. It should be appreciated that use of a threaded engaging configuration permits the removal and/or replacement of the pin and box adapter fittings and/or of other components, such as compression collars 130, by a reverse process and results in a reusable adapter fitting.

Following installation of the pin fitting adapter, as described immediately above, box adapter fitting 108, also connected to conductor 112, is positioned in pin end fitting 104a of the drill pipe section and fixed in position in essentially the same manner as pin adapter fitting 110. It should be appreciated that this installation technique may be modified in any suitable manner so long as the illustrated configuration of the adapter fittings and conductor 112 is achieved in the through hole of the drill pipe section. For example, box adapter fitting 108 may be installed first. As another example, conductor 112 may initially be connected to only the adapter fitting to be installed first and, after its installation, with the conductor extending through the drill pipe section, the conductor may be connected to the other adapter fitting prior to its installation.

Turning again to FIG. 2, attention is now directed to the operational use of arrangement 100. FIG. 2 illustrates drill pipe sections 28a and 28b as these sections are about to be attached with one another. As can be seen in this figure, pin end fitting 104a of drill pipe section 28a is partially extending within box end fitting 104b of drill pipe section 28b. In this regard, it should be appreciated that drill pipe sections 28a and 28b will be brought into substantial alignment by the box and pin end fittings prior to pin adapter fitting 110 engaging box adapter fitting 108. Thus, the possibility of damage to the adapter fittings resulting from misalignment of the drill pipe sections is greatly reduced. With regard to avoiding damage to the adapter fittings, it should be appreciated that installation of pin adapter fitting 110 in box end fitting 104b of each drill pipe section affords substantial protection to contact fingers 142 extending outwardly from the through hole of the drill pipe section. That is, installation of pin adapter fitting 110 in pin end fitting 104 of the drill pipe sections (not shown) would cause contact fingers 142 to extrude in a highly exposed manner from the drill pipe section risking damage during virtually any handling of the drill pipe section.

Referring to FIGS. 2 and 4, as attachment of drill pipe sections 28a and 28b proceeds from the pre-aligned situation of FIG. 2, pin adapter fitting 110 and box adapter fitting 108 contact one another at a predetermined point (not shown) when substantial alignment has already been achieved between drill pipe sections 28a and 28b. At this predetermined point, contacts 148 of contact fingers 144 engage electrical contact surface 123 of box adapter fitting 108. As a result, contact finger arms 146 are resiliently biased towards one another in a way which maintains electrical contact between contacts 148 and electrical contact surface 123. Thus, each time an additional drill pipe section is attached to a drill string (not shown) electrical contact is formed between the pin adapter fitting and box adapter fitting, as arranged in the drill pipe section which defines an above ground end of the drill string and the end of the additional drill pipe section to be connected therewith. At the same time, drilling fluid may readily pass through the central through openings defined by the mated box and pin adapter fittings in adjacent drill pipe sections. In accordance with the present invention, arrangement 100 produces an electrically conductive path between a boring tool and a drill rig (such as shown in FIG. 1) in an essentially automatic manner. Arrangement 100 is highly advantageous in this regard since drilling operations need not be interrupted for purposes of maintaining an electrical connection with the boring tool. Therefore, the full advantages attendant to drill rigs configured for automatically adding drill pipe sections to the drill string will be realized while still maintaining a continuous, isolated electrically conductive path between the drill rig and the boring tool. Moreover, this advantage is realized in retraction of the drill string as well as in its advancement. That is, removal of a drill pipe section from the above ground end of the drill string automatically disconnects arrangement 100 within that drill pipe section from the overall continuous, electrically conductive path being maintained between the boring tool and the drill rig. Arrangement 100 is suitable for any application requiring an isolated electrical conductive pathway between the drill rig and the underground end of the drill string. For example, the arrangement may be used with a boring tool to carry electrical power from the drill rig to the boring tool and/or carrying data to and/or from the boring tool. Alternatively, arrangement 100, and other arrangements described below, are useful in utility pullback operations during which it may be useful to send data from the un