Abstract:
A drill string section includes one or two tool joints that are removable from a body. Tool joints with different thread configurations may be interchangeably used with the same body. The tool joints have a compact construction that can facilitate making the drill string section short. The body overlaps with threads of one or both of the tool joints. The drill string section has non-exclusive application between a mud motor and a drill bit.

Description:
TECHNICAL FIELD 
       [0001]    This application relates to drill string sections. In particular, this application relates to drill string sections with interchangeable couplings. 
       BACKGROUND 
       [0002]    Recovering hydrocarbons from subterranean zones typically involves drilling wellbores. 
         [0003]    Wellbores are made using surface-located drilling equipment which drives a drill string that eventually extends from the surface equipment to the formation or subterranean zone of interest. The drill string can extend thousands of feet or meters below the surface. The terminal end of the drill string includes a drill bit for drilling (or extending) the wellbore. Drilling fluid, usually in the form of a drilling “mud”, is typically pumped through the drill string. The drilling fluid cools and lubricates the drill bit and also carries cuttings back to the surface. Drilling fluid may also be used to help control bottom hole pressure to inhibit hydrocarbon influx from the formation into the wellbore and potential blow out at surface. 
         [0004]    Bottom hole assembly (BHA) is the name given to the equipment at the terminal end of a drill string. In addition to a drill bit, a BHA may comprise elements such as: apparatus for steering the direction of the drilling (e.g. a steerable downhole mud motor or rotary steerable system); sensors for measuring properties of the surrounding geological formations (e.g. sensors for use in well logging); sensors for measuring downhole conditions as drilling progresses; one or more systems for telemetry of data to the surface; stabilizers; heavy weight drill collars; pulsers; and the like. The BHA is typically advanced into the wellbore by a string of metallic tubulars (drill pipe). 
         [0005]    Modern drilling systems may include any of a wide range of mechanical/electronic systems in the BHA or at other downhole locations. Such electronics systems may be packaged as part of a downhole probe. A downhole probe may comprise any active mechanical, electronic, and/or electromechanical system that operates downhole. A probe may provide any of a wide range of functions including, without limitation: data acquisition; measuring properties of the surrounding geological formations (e.g. well logging); measuring downhole conditions as drilling progresses; controlling downhole equipment; monitoring status of downhole equipment; directional drilling applications; measuring while drilling (MWD) applications; logging while drilling (LWD) applications; measuring properties of downhole fluids; and the like. A probe may comprise one or more systems for: telemetry of data to the surface; collecting data by way of sensors (e.g. sensors for use in well logging) that may include one or more of vibration sensors, magnetometers, inclinometers, accelerometers, nuclear particle detectors, electromagnetic detectors, acoustic detectors, and others; acquiring images; measuring fluid flow; determining directions; emitting signals, particles or fields for detection by other devices; interfacing to other downhole equipment; sampling downhole fluids; etc. 
         [0006]    A downhole probe may communicate a wide range of information to the surface by telemetry. Telemetry information can be invaluable for efficient drilling operations. For example, telemetry information may be used by a drill rig crew to make decisions about controlling and steering the drill bit to optimize the drilling speed and trajectory based on numerous factors, including legal boundaries, locations of existing wells, formation properties, hydrocarbon size and location, etc. A crew may make intentional deviations from the planned path as necessary based on information gathered from downhole sensors and transmitted to the surface by telemetry during the drilling process. The ability to obtain and transmit reliable data from downhole locations allows for relatively more economical and more efficient drilling operations. 
         [0007]    There are several known telemetry techniques. These include transmitting information by generating vibrations in fluid in the bore hole (e.g. acoustic telemetry or mud pulse (MP) telemetry) and transmitting information by way of electromagnetic signals that propagate at least in part through the earth (EM telemetry). Other telemetry techniques use hardwired drill pipe, fibre optic cable, or drill collar acoustic telemetry to carry data to the surface. 
         [0008]    A typical arrangement for electromagnetic telemetry uses parts of the drill string as an antenna. The drill string may be divided into two conductive sections by including an insulating joint or connector (a “gap sub”) in the drill string. The gap sub is typically placed such that metallic drill pipe in the drill string above the BHA serves as one antenna element and metallic sections in the BHA serve as another antenna element. Electromagnetic telemetry signals can then be transmitted by applying electrical signals between the two antenna elements. The signals typically comprise very low frequency AC signals applied in a manner that codes information for transmission to the surface. (Higher frequency signals attenuate faster than low frequency signals.) The electromagnetic signals may be detected at the surface, for example by measuring electrical potential differences between the drill string or a metal casing that extends into the ground and one or more ground rods. 
         [0009]    The joints between drill string sections (sometimes called ‘tool joints’) are made up and taken apart frequently. Over time, this results in the tool joints becoming worn. Eventually the tool joints need to be refurbished. For example, a drill string section may be sent to a machine shop where threaded couplings can be remachined. Drill string sections may be made with extra length so that they can be remachined. 
         [0010]    Drill string sections that have replaceable tool joints are described in U.S. Pat. No. 4,240,652; U.S. Pat. No. 4,445,265; U.S. Pat. No. 6,305,723; U.S. Pat. No. 6,845,826; U.S. Pat. No. 7,390,032; and WO2013037058. Such replaceable tool joints can make it easier to repair the tool joints and may permit field repair of tool joints. A modular drill bit having a replaceable pin coupling is described in US20110120269. 
       SUMMARY 
       [0011]    The invention has a number of aspects. Some aspects provide drill string sections having at least one coupling that is removable so that the coupling can be replaced with other interchangeable couplings. Other aspects provide methods for assembling and installing drill string sections having at least one coupling that is removable and kits comprising drill string sections having at least one coupling that is removable so that the coupling can be replaced and interchangeable couplings having different coupling configurations. 
         [0012]    In some embodiments the drill string section comprises a body having an uphole connector and a downhole connector. A coupling such as a pin may be connected to the uphole connector and a coupling such as a box may be connected to the downhole connector. In some embodiments, the pin may comprise male threads and/or the box may comprise female threads. 
         [0013]    In some embodiments, the pin and/or the box may each comprise a bore for receiving a part of the body of the drill string section. The pin and/or the box may be attached to the body of the drill string section by one or more a ball and channel connection, male and female threads, a pinned connection or the like. 
         [0014]    In some embodiments, the pin and/or the box may be installed without increasing the axial length of the body of the drill string section. In other embodiments, the pin and/or the box may be increase the axial length of the body when installed. 
         [0015]    Further aspects of the invention and features of example embodiments are illustrated in the accompanying drawings and/or described in the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The accompanying drawings illustrate non-limiting example embodiments of the invention. 
           [0017]      FIG. 1  is a schematic view of an example prior art drilling operation. 
           [0018]      FIGS. 2A and 2B  are a schematic views of a prior art section of drill string. 
           [0019]      FIG. 3  is a cross-sectional view of a section of drill string according to an example embodiment of the invention. 
           [0020]      FIG. 4A  is a cross-sectional view of the pin and uphole connector shown in  FIG. 3  in an unconnected configuration.  FIG. 4B  is a cross-sectional view of the pin and uphole connector shown in  FIG. 3  in a connected configuration. 
           [0021]      FIG. 5A  is a cross-sectional view of the box shown in  FIG. 3 .  FIG. 5B  is a cross-sectional view of the box and downhole connector shown in  FIG. 3  in a connected configuration. 
       
    
    
     DESCRIPTION 
       [0022]    Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. The following description of examples of the technology is not intended to be exhaustive or to limit the system to the precise forms of any example embodiment. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
         [0023]      FIG. 1  shows schematically an example prior art drilling operation. A drill rig  10  drives a drill string  12  which includes sections of drill pipe that extend to a drill bit  14 . The illustrated drill rig  10  includes a derrick  10 A, a rig floor  10 B and draw works  10 C for supporting the drill string. Drill bit  14  is larger in diameter than the drill string above the drill bit. An annular region  15  surrounding the drill string is typically filled with drilling fluid. The drilling fluid is pumped through a bore in the drill string to the drill bit and returns to the surface through annular region  15  carrying cuttings from the drilling operation. As the well is drilled, a casing  16  may be made in the well bore. A blow out preventer  17  is supported at a top end of the casing. The drill rig illustrated in  FIG. 1  is an example only. The methods and apparatus described herein are not specific to any particular type of drill rig. 
         [0024]      FIG. 2A  is a schematic view of a prior art drill string section  100 . Section  100  has an uphole coupling component  101  and a downhole coupling component  102 . Uphole coupling component  101  can be coupled to uphole drill string section  121 . Downhole coupling component can be coupled to downhole drill string section  122 . 
         [0025]    Different parts of a drill string may have different sizes and different types of couplings. The coupling components of section  100  may not match with the coupling components of adjacent sections of drill string. In this case adapters may be used to couple section  100  to the adjacent sections of drill string. 
         [0026]      FIG. 2B  is a schematic view of prior art section  100  coupled to drill string sections with prior art adapters (also known as “cross-over subs”). An adapter  111  is used to form a coupling between uphole coupling component  101  and uphole drill string section  131 . An adapter  112  is used to form a coupling between downhole coupling component  102  and downhole drill string section  132 . 
         [0027]      FIG. 3  is a cross-sectional view of a drill string section  200  according to an example embodiment of the invention. Section  200  may have any of a variety of functions. For example, section  200  may comprise a mud motor, gap sub, electronics package, cross-over sub, combinations of these, or the like. Section  200  is adaptable to couple to uphole and/or downhole drill string components having different types of couplings. Section  200  has at least one coupling that is removable so that the coupling can be replaced with other interchangeable couplings having different coupling configurations.  FIG. 3  shows section  200  in an unassembled configuration. Section  200  comprises a body  210 . 
         [0028]    The uphole end of body  210  comprises an uphole connector  230 . The downhole end of body  210  comprises a downhole connector  240 . 
         [0029]    A coupling such as a pin  250  may be connected to uphole connector  230 . Uphole connector  230  and pin  250  are shown in greater detail in an unconnected configuration in  FIG. 4A  and in a connected configuration in  FIG. 4B . 
         [0030]    Uphole connector  230  comprises a protrusion  233 . Pin  250  comprises a bore  253 . Pin  250  may be connected to uphole connector  230  by inserting protrusion  233  into bore  253  and then locking pin  250  into place on protrusion  233 . In the illustrated embodiment, pin  250  is connected to uphole connector  230  by a “ball and channel” connection. Balls  235  may be placed within channels  255  to prevent pin  250  from being removed from uphole connector  230 . Balls  255  may also prevent pin  250  from rotating relative to uphole connector  230 . In some embodiments balls  255  are made of an electrically-insulating material and electrically insulate pin  250  from uphole connector  230 , thereby forming an insulating gap. For example, balls  255  may be made of a ceramic. 
         [0031]    In other embodiments, pin  250  may be connected to uphole connector  230  by another type of connection, for example, a threaded connection or a pinned connection. 
         [0032]    Pin  250  may comprise threads  257 . Threads  257  may correspond to a particular type of threaded coupling used on a particular section of drill string to which it is desired to attach section  200 . A set of different pins  250  may be provided, each with a different thread  257  for coupling to a different type of threaded coupling. Threads  257  of different pins  250  may have different diameter, taper, pitch, cross-sectional shape, etc. Threads  257  may be API threads, ACME threads, etc. 
         [0033]    When section  200  needs to be coupled to a particular section of drill string with a particular type of coupling, a pin  250  with appropriate threads may be selected and connected to uphole connector  230  of section  200 . Pin  250  may be removed from uphole connector  230  and replaced with a different pin when section  200  needs to be coupled to a different section of drill string with a different type of coupling. Pin  250  may be removed from uphole connector  230 , for example, by removing balls  235  from channels  255 . 
         [0034]    Pin  250  may be replaced if it becomes damaged (e.g. if threads  257  become overly worn or otherwise damaged). Pin  250  may be made of a material that is resistant to galling (e.g. beryllium copper) for enhanced wear-resistance. 
         [0035]    In some embodiments, a portion of threads  257  (or all of threads  257 ) overlap with bore  253  in the axial direction. The overlapping of threads  257  and bore  253  may allow pin  250  to be very compact in the axial direction. In some embodiments, pin  250  is dimensioned so that when it is connected to protrusion  233  it does not extend beyond protrusion  233  in the axial direction (see  FIG. 4B , for example). In some embodiments, pin  250  is dimensioned so that when it is connected to protrusion  233  it extends beyond protrusion  233  by no more than ½, ⅓, or ¼ of its length in the axial direction. In some embodiments, when pin  250  is connected to protrusion  233 , a portion of threads  257  (or all of threads  257 ) overlap with protrusion  233  in the axial direction. 
         [0036]    A coupling such as a box  260  may be connected to downhole connector  240 . Box  260  is shown in greater detail in  FIG. 5A . Box  260  and downhole connector  240  are shown in a connected configuration in  FIG. 5B . 
         [0037]    Box  260  may be inserted into a bore  242  of downhole connector  240 . Box  260  may be connected to downhole connector  240  by engaging threads  265  of box  260  with corresponding threads  245  of downhole connector  240 . In other embodiments, box  260  may be connected to downhole connector  240  by another type of connection, for example, a “ball and channel” connection or a pinned connection. 
         [0038]    Box  260  comprises a bore  267  and threads  268 . Threads  268  may correspond to a particular type of threaded coupling used on a particular section of drill string to which it is desired to couple section  200 . A set of different boxes  260  may be provided, each with different threads  268  for coupling to a different type of threaded coupling. Different threads  268  of different boxes  260  may have different diameter, taper, pitch, cross-sectional shape, etc. Threads  268  may be API threads, ACME threads, etc. 
         [0039]    When section  200  needs to be coupled to a particular section of drill string with a particular type of coupling, a box  260  with appropriate threads may be selected and connected to downhole connector  240  of section  200 . Box  260  may be removed from section  200  and replaced with a different box if section  200  needs to be coupled to a different section of drill string with a different type of coupling. Box  260  may be removed from downhole connector  240 , for example, by unscrewing box  260  from downhole connector  240 . 
         [0040]    Box  260  may be replaced if it becomes damaged (e.g. if threads  265  or threads  268  become overly worn or otherwise damaged). Box  260  may be made of a material that is resistant to galling (e.g. beryllium copper) for enhanced wear-resistance. 
         [0041]    In some embodiments, a portion of threads  265  (or all of threads  265 ) overlap with threads  268  in the axial direction. The overlapping of threads  265  and threads  268  may allow box  260  to be very compact in the axial direction. In some embodiments, box  260  is dimensioned so that when it is connected to downhole connector  240  it does not extend beyond bore  242  in the axial direction. In some embodiments, box  260  is dimensioned so that when it is connected to downhole connector  240  it extends beyond bore  242  by no more than ½, ⅓, or ¼ of its length in the axial direction (see  FIG. 5B , for example). In some embodiments, when box  260  is connected to downhole connector  240  a portion of threads  268  (or all of threads  268 ) overlap with bore  242  in the axial direction. 
         [0042]    Body  210  of section  200  may comprise a housing for an equipment package  220 . Equipment package  220  may be inserted into body  210  and secured therein. Equipment package  220  may comprise any type of downhole equipment, including sensors, telemetry tools, etc. Before box  260  is connected to downhole connector  240 , equipment package  220  may be inserted into body  210 . Box  260  may secure equipment package  220  within body  210 . O-rings or other seals may be provided to seal equipment package  220  within body  210 . These seals may prevent drilling fluid from entering the space between equipment package  220  and box  260 . Box  260  may be removed in order to remove equipment package  220  from body  210  (for repair, replacement, etc.). 
         [0043]    In the embodiment illustrated in  FIG. 3 , uphole connector  230  comprises a protrusion  233  and downhole connector  240  comprises a bore  242 . In other embodiments, uphole connector  230  comprises a bore and downhole connector  240  comprises a protrusion. In other embodiments, both uphole connector  230  and downhole connector  240  comprise protrusions. In other embodiments, both uphole connector  230  and downhole connector  240  comprise bores. 
         [0044]    In the embodiment illustrated in  FIG. 3 , section  200  comprises a pin at its uphole end and a box at its downhole end. In other embodiments, section  200  comprises pins at both ends or boxes at both ends. In other embodiments, section  200  comprises a box at its uphole end and a pin at its downhole end. 
         [0045]    Section  200  may be provided with sets of pins  250  and boxes  260  with different types of threads for coupling to different types of threaded connectors of sections of drill string. A section and a set of two or more pins and/or two or more boxes may be provided as a kit. 
         [0046]    Pin  250  and box  260  may be significantly shorter than prior art adapters  111  and  112 , and thus section  200  may be shorter than section  100 . In directional drilling applications where section  200  forms a part of the drill string between the drill bit and the bend in the drill string, it is advantageous for section  200  to be relatively short to permit greater control of the drilling direction. It is particularly beneficial for drill string section  200  to be short when section  200  is coupled between a mud motor and a drill bit. 
         [0047]    In some embodiments a section like section  200  has an overall length that does not exceed 2 feet (about 60 cm) or 3 feet (about 90 cm) for example. 
         [0048]    While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. 
       Interpretation of Terms 
       [0049]    Unless the context clearly requires otherwise, throughout the description and the claims:
       “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.   “connected,” “coupled,” or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof.   “herein,” “above,” “below,” and words of similar import, when used to describe this specification shall refer to this specification as a whole and not to any particular portions of this specification.   “or,” in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.   the singular forms “a,” “an,” and “the” also include the meaning of any appropriate plural forms.       
 
         [0055]    Words that indicate directions such as “vertical,” “transverse,” “horizontal,” “upward,” “downward,” “forward,” “backward,” “inward,” “outward,” “vertical,” “transverse,” “left,” “right,” “front,” “back”, “top,” “bottom,” “below,” “above,” “under,” and the like, used in this description and any accompanying claims (where present) depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly. 
         [0056]    Where a component (e.g. a circuit, module, assembly, device, drill string component, drill rig system, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention. 
         [0057]    Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and/or acts with equivalent features, elements and/or acts; mixing and matching of features, elements and/or acts from different embodiments; combining features, elements and/or acts from embodiments as described herein with features, elements and/or acts of other technology; and/or omitting combining features, elements and/or acts from described embodiments. 
         [0058]    It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.