Abstract:
An apparatus is provided for conveying electrical power and data signals between a first location and a second location in a well borehole. The apparatus comprises a first drill pipe disposed at the first location, and a second drill pipe disposed at the second location. A second end of the second drill pipe is coupled to a first end of the first drill pipe. A first plurality of conductive pathways such as insulated wires extend longitudinally through at least a portion of the first drill pipe and terminate at the first end. A second plurality of conductive pathways extend longitudinally through at least a portion of the second drill pipe and terminate at the second end. A verification device is operatively associated with the first and second pluralities of conductive pathways for verifying electrical continuity between the first and second pluralities of conductive pathways.

Description:
[0001]    This application is related to a U.S. provisional application titled “Integrated Modular Connector in a Drill Pipe” filed on Nov. 10, 2000, serial No. 60/247,092, the entire specification of which is hereby incorporated herein by reference and from which priority is claimed for the present application. 
     
    
     
       BACKGROUND OF THE INVENTION  
       RELATED APPLICATION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to oil well tools, and more particularly drill pipe electrical connectors for rig site applications.  
           [0004]    2. Description of the Related Art  
           [0005]    In the oil and gas industry, hydrocarbons are recovered from formations containing oil and gas by drilling a well borehole into the formation using a drilling system. The system typically comprises a drill bit carried at an end of a drill string. The drill string is comprised of a tubing which may be drill pipe made of jointed sections or a continuous coiled tubing and a drilling assembly that has a drill bit at its bottom end. The drilling assembly is attached to the bottom end of the tubing. To drill a borehole, a mud motor carried by the drilling assembly rotates the drill bit, or the bit is coupled to drill pipe, which is rotated by surface motors. A drilling fluid, also referred to as mud, is pumped under pressure from a source at the surface (mud pit) through the tubing to, among other things, drive the drilling motor (when used) and provide lubrication to various elements of the drill string.  
           [0006]    For many years drilling operations have included instrumentation disposed in one or more jointed pipe sections called a bottom-hole assembly (BHA) near the drill bit to measure various characteristics of the formation, the borehole and the drill string. These measurements are called measurement while drilling (MWD) or logging while drilling (LWD). Measurements from MWD and LWD include formation pressure, properties of hydrocarbons trapped in the formation, temperature and pressure of annulus fluids, drill bit direction, rotational speed and azimuth.  
           [0007]    Instruments housed in the BHA and used for the various measurements typically are powered by downhole generators located somewhere along the drill string, and signals from sensors are typically transferred to a mud-pulse telemetry subsystem also located along the drill string. These various components are usually electrically interconnected with insulated wiring also housed within the drill string.  
           [0008]    A particular difficult problem exists when wires must traverse more than one joint of a drill string. Achieving and maintaining a reliable electrical bond between pipe joints is very difficult considering the harsh environments encountered downhole, rugged handling of cumbersome pipe joints and time constraints placed on drilling operators at the surface. Prior art devices such as those described in U.S. Pat. No. 3,696,332 to Dickson, Jr. et al., and U.S. Pat. No. 5,251,708 to Perry et al. have tackled this problem using a ring connector with a single and substantially circular contact disposed at opposite ends of a pipe joint. These modular ring connectors are electrically connected together by a bus or wire in the pipe joint. When one pipe joint is connected to the next, a contact ring disposed on each of the mating modular ring connectors electrically mates with a like contact ring disposed a mating pipe or BHA sub thereby establishing an electrical path through the coupled pipe joints or between a pipe joint and BHA sub.  
           [0009]    Data acquisition in more recent MWD and LWD devices is becoming more and more sophisticated, and requires more and more power, bandwidth and channels. One of the drawbacks of ring connectors such as those described above is that a single contact and associated bus or wire is a limiting factor on the usefulness of instrumentation used today. Therefore, a need exists to provide a modular ring connector that has multiple contacts and multiple path wiring integrated into a drill pipe and the various BHA subs attachable thereto. Also, in providing an improved modular ring connector having multiple contacts, a further need exists to verify that the multiple contacts and associated conductors are mated properly.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention addresses the drawbacks discussed above by providing a drilling apparatus and method for transmitting an electrical signal between an uphole location and a downhole location using modular electrical connectors having multiple contacts and multiple wiring pathways integral to a drill string pipe joint.  
           [0011]    An apparatus is provided for conveying electrical power and data signals between a first location and a second location in a well borehole. The apparatus comprises a first drill pipe disposed at the first location, and a second drill pipe disposed at the second location. A second end of the second drill pipe is coupled to a first end of the first drill pipe. A first plurality of conductive pathways such as insulated wires extend longitudinally through at least a portion of the first drill pipe and terminate at the first end. A second plurality of conductive pathways extend longitudinally through at least a portion of the second drill pipe and terminate at the second end. A verification device is operatively associated with the first and second pluralities of conductive pathways for verifying electrical continuity between the first and second pluralities of conductive pathways.  
           [0012]    The present invention also provides a method for conveying electrical power and data signals between a first location and a second location in a well borehole via multiple conductive pathways. The method comprises coupling a first end of a first drill pipe to a second end of a second drill pipe. The two pipes are conveyed such that the first drill pipe is conveyed to the first location and the second drill pipe is conveyed to the second location. The first and second drill pipes have corresponding pluralities of conductive pathways extending longitudinally through at least a portion of each drill pipe and terminating respectively at the first and second ends. The method provides for verifying electrical continuity between the first and second pluralities of conductive pathways with a verification device operatively associated with the first and second pluralities of conductive pathways to ensure the pathways are electrically connected.  
           [0013]    A modular ring connector provided by the present invention connects multiple independent electrical wireways upon coupling of pipe joints or of a pipe joint and BHA sub. The ring connectors may include four segments made of conductive material, and with segments centers at an angle of 45°. Segments made of non conductive material are disposed between the conductive segments, and the nonconductive segments also have centers at an angle of 45°.  
           [0014]    The alignment of conductive segments or contacts may be accomplished by various embodiment options including time cut thread, ring alignment and electrical selection. A time cut embodiment includes a pipe joint and/or a BHA sub having all threads of a pin and/or box end with modular connector cut to precise specifications. The multiple contacts on the connector ring will then always align when the threads are connected to a like-threaded connector.  
           [0015]    A ring alignment embodiment includes an alignment gauge. During assembly of the modular ring the position of the thread to the shoulder will be measured by the gauge. The gauge will show the correct position of the segments, and when assembled into the sub, the ring will be positioned with respect to this measured position.  
           [0016]    The third and most viable option is electrical selection where the segments are aligned by an electrical switching device. When the system is powered, the electronics will automatically measure the position of each independent modular ring at each thread and will align the contacted wires according to the measurement. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    For detailed understanding of the present invention, references should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings described below, in which like elements have been given like numerals.  
         [0018]    [0018]FIG. 1A is a plan view of a drill pipe joint  100  with a box end cross-sectioned and partial plan view of a second pipe joint  102 .  
         [0019]    [0019]FIG. 1B is an enlarged view of mated pipes such as in FIG. 1A.  
         [0020]    [0020]FIG. 1C is an end view of the lower end of the first pipe of FIG. 1B.  
         [0021]    [0021]FIG. 2A is an isometric view of a ring assembly according to the present invention showing multiple contacts.  
         [0022]    [0022]FIG. 2B is an isometric view of the ring assembly of FIG. 2A shown from another angle.  
         [0023]    [0023]FIG. 3A is a plan view of a coupled pair of drill pipe joint sections.  
         [0024]    [0024]FIG. 3B is a cross-section view of a coupled pair of drill pipe joint sections according to another embodiment of the present invention.  
         [0025]    [0025]FIG. 3C is a cross-sectioned elevation view of another embodiment of the present invention showing a section of drill string.  
         [0026]    [0026]FIG. 4A and 4B are cross-sectioned isometric views of another embodiment of the present invention showing alternative locations for the ring connectors.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    [0027]FIG. 1A is a plan view of a drill pipe joint  100  with a box end cross-sectioned and partial plan view of a second pipe joint  102 . The first drill pipe  100  has a central bore  104  extending from a first or upper end  106  to a second or lower end  108 . The upper end  106  has an internally threaded box  110 . The box  110  is usually tapered and has an end shoulder  112  extending from the box inner edge to the outer edge  114  of the pipe. The lower end  108  has an externally threaded pin  116  tapered and threaded to mate with a second pipe  102  having a box  118  substantially identical to the box  110  of the first pipe  100 . The pin  116  has a base shoulder  120  extending from the threaded edge  122  to the outer edge of the pipe  124 . A plurality of insulated wires  126   a,    126   b,    126   c,  etc. are integrally disposed within the pipe to make an electrically conductive pathway between the pin base shoulder  120  to the box end shoulder  112 . Electrical contacts are disposed at each of the shoulders  120  and  112  to receive the electrical wires. The pin  116  and box  110  typically have threads  128  conforming to American Petroleum Institute (API) standards. Whatever thread standard is used, the threads must be compatible for proper mating. The pipes are typically produced substantially identical to each other to allow interchangeability between pipes. Thus, the second pipe may have a pinned end to mate with a cupped end of the first pipe. Furthermore, the lengths of pipe may vary between joints without adversely affecting the mating.  
         [0028]    [0028]FIG. 1B is an enlarged view of mated pipe joints such as in FIG. 1A. The first pipe  100  is mated to the second pipe  102  at a coupling  130  with an externally threaded pin  116  screwed into a complementary internally threaded box  118 . A base shoulder  120  on the first pipe  100  is juxtaposed to an end shoulder  132  on the second pipe  102  when the two pipes are fully mated. Each shoulder includes a ring assembly  134  and  140  extending in a circular path around a central axis of the pipe.  
         [0029]    Multiple electrically conductive contacts  142  are disposed in a groove  136  on the ring assembly of the first pipe  100 . A similar groove  138  in a similar ring assembly  140  of the second pipe  102  has a corresponding contact  144  for each contact  142  on the first pipe. The contacts may be any suitable conductive material and the preferred material is gold-plated copper berrillium. A spring  146  associated with each contact on each pipe provides force to ensure each contact from the first pipe remains electrically connected to its mated contact on the second pipe.  
         [0030]    [0030]FIG. 1C is an end view of the lower end of the first pipe of FIG. 1B. The base shoulder  120  extends around the pin  118 , and the central bore  104  is at the center of the pipe. The groove  136  is shown disposed in the ring assembly  134 , and the contacts  142   a,    142   b,    142   c  and  142   d  are mounted in the groove and separated by high-temperature polymide inserts  148   a,    148   b,    148   c  and  148   d  to protect and insulate the contacts from each other. The preferred insulating insert is polyetheretherketone, commonly known by the acronym PEEK, although Arlon is another known material found suitable for this invention.  
         [0031]    [0031]FIG. 2A is an isometric view of a ring assembly  200  according to the present invention showing contacts and insulating inserts alternatingly disposed in the ring assembly. The ring assembly  200  is attached to a drill pipe (not shown) via suitable fasteners such as press-fit dowel pins  202   a,    202   b,    202   c,  and  202   d.  The ring may also be fastened to the drill pipe shoulder by screws, epoxy, keeper ring, by having a thread on the inner diameter to mate with a male fitting, a thread on the outer diameter to mate with a female fitting, and/or by welding or soldering.  
         [0032]    It should be noted here that the groove  204  might be cut directly into the shoulder of the drill pipe. In this case, the ring assembly  200  is not necessary. The ring assembly provides the added benefit of maintainability when contacts become worn or broken.  
         [0033]    Still referring to FIG. 2A, contacts  206   a,    206   b,    206   c  and  206   d  are disposed at 45 angles with PEEK inserts  208   a,    208   b,    208   c  and  208   d  disposed at 45. Angles and between the contacts. The length of each contact arc along with the length of the PEEK inserts spacing the contacts apart allow for proper connection with a similar mating ring assembly with a substantial safety margin to ensure contacts are not misaligned. More contacts in the assembly will reduce the available safety margin by requiring a reduction of the contact length, spacing between contacts or both. Reducing the number of contacts will provide the ability to increase the margin of safety by allowing for larger contact size, more space between contacts or both.  
         [0034]    [0034]FIG. 2B is an isometric view of the ring assembly  200  of FIG. 2A from another angle. In this view, the fasteners  202   a - 202   d  are shown extending upward, which would be toward a pipe shoulder (not shown) on which the ring assembly would be anchored. Each contact  206   a - 206   d  has an associated conductor  210   a - 210   d  leading from the contact. The conductor is preferably an insulated wire having a current and voltage rating suitable for a particular desired application. Each wire is conductively bonded to its associated contact by typical known methods such as soldering or wire-wrap. Leading from the contact, each wire extends to the opposite end of the drill pipe, and as described above and shown in FIG. 1A, each wire passes through a conduit or wire groove cut into the pipe.  
         [0035]    Referring now to FIGS. 3A through 3C, three embodiments of the present invention for verifying and ensuring proper connection will be described. FIG. 3A is a plan view of a coupled pair of drill pipe joint sections  300  and  302 . Each pipe joint has a ring assembly (not shown) as described above and shown in FIGS. 2A and 2B. Each ring assembly has a plurality of contacts, and each contact is attached to a wire that extends through the respective pipe as described and shown above. For simplicity, only a single conducting wire  304   a  and  304   b  and single contact pair  306   a  and  306   b  are shown in each pipe.  
         [0036]    The contacts  306   a  and  306   b  must align properly so that current will flow across the contact junction and through the conductors  304   a  and  304   b.  Furthermore, a circuit configuration of instruments in a tool (not shown) housed in the drill string typically requires that specific contacts be mated together. Therefore, a mechanical alignment gauge comprising an indicator  308  stamped, engraved or painted on one pipe  300 , and a corresponding indicator  310  similarly disposed on the joining pipe  302 . A very simple, yet effective indicator pair is shown in FIG. 3A. The indicator  308  for the first pipe  300  is a longitudinal line or bar marking, while the indicator  310  on the joining pipe  302  is a vertical arrow or line.  
         [0037]    The length of the line  308  is proportional to the length of each contact  306   a  or the line may be proportional to the distance between contacts. The arrow  310  is located on the second pipe  302  such that each contact  306   b  on that pipe aligns with a corresponding contact  306   a  on the first pipe  300  whenever the arrow  310  aligns with any portion of the line  308 . This alignment feature will ensure that the same pair of contacts  306   a  and  306   b  are mated every time the two pipes  300  and  302  are joined. Any variation due to wear or thread deformation is taken into account when defining the length of contacts, space between contacts and the length of the horizontal indicator line  308 .  
         [0038]    The embodiment shown in FIG. 3A is a mechanical configuration of an indicator used when pipe joints are mated at the surface by a drilling crew. The intent of the present invention is to also include non-mechanical indicators for use by the drilling crew to assure contacts are properly mated. A not-shown electrical embodiment includes a typical multimeter adapted for measuring contact alignment and/or continuity. The multimeter is preferably located at the surface and should be accessible to the drilling crew. A crew member attaches the multimeter at the contacts exposed at a distal end of the drill pipe being joined, and a meter indicator such as a continuity light or audible signal provides confirmation that contacts are mated when the piped are joined.  
         [0039]    [0039]FIG. 3B is a cross section view of a coupled pipe pair according to another embodiment of the present invention. A first pipe joint  320  includes a pin  322  and a ring assembly  324 . Multiple contacts  326 , one of which is shown are disposed in the ring assembly  324 . Each contact  326  is electrically bonded to a corresponding conductor  328 , and each conductor extends from the corresponding contact through at least a portion of the second pipe  320 . A second pipe joint  330  is shown mated to the first pipe  320 . The second pipe has a box  332  and a ring assembly  334 . Multiple contacts  336 , of which one is shown are disposed in the ring assembly  334 . Each contact  336  is electrically bonded to a corresponding conductor  338 , and each conductor extends from the corresponding contact through at least a portion of the second pipe  330 . These components are substantially identical to the similarly-named components described above and shown in FIGS. 1A through 2B.  
         [0040]    The pin  322  includes externally located threads  340  that are compatible with internal threads  342  of the box  332 . The threads are time cut, meaning that they are precision cut such that a predetermined number of turns results in precise positioning of the contacts  326  and  336  each time the pipes  320  and  340  are mated. The advantage of this embodiment is that there are no actions required by the drilling crew other than the typical actions associated with mating pipe joints during drilling operations.  
         [0041]    [0041]FIG. 3C is a cross-section elevation view of another embodiment of the present invention showing a section of drill string  350 . An uphole pipe joint  352  having an externally-threaded pin  354  is shown coupled to a downhole pipe joint  356  having an internally threaded box  358 . This coupling is as described above and is a typical pipe coupling configuration known in the art.  
         [0042]    As described above and shown in FIGS. 1A through 2B, a modular ring assembly  360  is disposed on the uphole pipe joint  352  on a base shoulder  362  at the base of the pin. The ring assembly  360  includes multiple contacts  364  with one contact being shown. The contacts are housed in a groove  365  and have nonconducting inserts (not shown) separating the contacts as described above and shown in FIGS. 1B and 1C. Each contact  364  is connected to one of multiple conductor wires  366  and each wire  366  leads to an electronic switching unit (ESU)  368  to be described in more detail later. A typical downhole controller  370  well known in the art is disposed in the uphole pipe joint  352  at a suitable location. The controller is electrically connected to the ESU  368  via conductor wires  372 , each of which should correspond to one of the ESU-to-contact wires  366 .  
         [0043]    A primary purpose of the controller  370  is to control at least one electronic instrument  374  disposed in the downhole pipe joint  356 . In a typical downhole tool having electronic instruments interconnected via wiring conductors, the conductors leading from one instrument such as the controller  370  shown in FIG. 3C must lead to a particular input of a second instrument. Downhole tools such as the prior art described above typically include instruments disposed in two pipe joints are interconnected via a single conductor leading from the first instrument in an uphole pipe joint to a single ring connector contact. A corresponding single ring connector contact in the downhole pipe joint mates with the contact in the uphole ring connector and a conductor leads from the downhole ring connector to an instrument disposed in the downhole pipe joint.  
         [0044]    A major advantage of the present invention is realized when, as shown in FIG. 3C, a downhole pipe joint  356  includes an instrument  374  requiring multiple input wires  376 . The instrument shown is disposed in the downhole pipe joint  356 . Multiple wires  376  lead from the instrument  374  to corresponding multiple contacts  378 , of which only one is shown.  
         [0045]    When the uphole pipe  352  is coupled to the downhole pipe  356 , the contacts  364  in the uphole pipe  352  interface with the contacts  378  disposed in the downhole pipe  356 . The ESU  368  includes a measuring device  380  such as an ohm, current or voltage meter that senses the position of the uphole contacts  364  with respect to the downhole contacts  378  once the instrument is activated by typical methods known in the art. There are several circuits known that have the capability of sensing position of contacts. The ESU also includes a switching circuit  382  such as an array of relays or electronic switches. Once the ESU determines the initial position of contacts, the switching circuit reroutes the wiring paths using the switch array so that there is a continuous electrical pathway leading from the uphole electrical device  370 , through the ESU  368 , crossing the junction of the contacts  364  and  378 , and on to predetermined input/out channels  384  of the instrument  374  disposed in the downhole pipe  356 .  
         [0046]    It should be understood that the downhole pipe shown in FIG. 3C may also be a tool disposed at the end of a drill pipe, the tool having a box connector substantially identical to the box shown in FIG. 3C. The pipes may also be two joint sections of a wireline apparatus having a coupling substantially as described and shown in FIG. 3C.  
         [0047]    The coupling configuration described thus far and shown in FIGS.  1 A- 3 C is known as a flush joint connection with male and female threads cut directly into the pipe. This provides the same inner diameter (ID) and outer diameter (OD) clearances at the pipe coupling as in the middle of the pipe joint once lengths are joined. The invention provided herein may also be incorporated in drill pipes with other coupling schemes such as a threaded and coupled (T&amp;C) joint or tool joint. These alternate coupling configurations are well known in the art.  
         [0048]    [0048]FIGS. 4A and 4B are cross-sectioned isometric views of another embodiment of the present invention showing alternative locations for the ring connectors disposed on a pin and box respectively. The pin  402  has external threads  404  helically disposed around the exterior of the pin and extending from a base shoulder  406  to an end shoulder  408 . A modular ring connector  410  having multiple contacts  412  disposed in a ring groove  413  is mounted and anchored on the end shoulder  406  as described above and shown in FIGS. 1B through 2B for a ring connector mounted on a base shoulder. Each contact  412  is separated from the other contacts by a nonconductive insert  414  such as PEEK. A wire  416  is connected to each contact and is routed through a conduit  418  cut in the pipe wall  420 .  
         [0049]    [0049]FIG. 4B is a cross-sectioned isometric view of a box end of a a pipe section capable of mating with the pin  402 . The box  422  has internal threads  424  helically disposed around the interior of the box  422  and extending from a base shoulder  426  to an end shoulder  428 . When the pin  402  is screwed into the box  422 , the pin base shoulder  406  meets the box end shoulder  428 . The pin end shoulder  408  housing the pin ring connector meets the box base shoulder  426 . A compatible box ring connector  430  is disposed in a groove found in the box base shoulder  426 .  
         [0050]    The box ring connector is substantially identical to the pin ring connector. The box ring connector  430  includes multiple contacts  432  and a conducting wire  434  for each contact  432  is routed through a conduit  436  extending longitudinally through the pipe wall  434 . Suitable high pressure breakout connectors (not shown) well known in the art are used wherever the wires in either pipe must exit the conduit to connect with components such as those described above and shown in FIG. 3C.  
         [0051]    The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes.