Patent Publication Number: US-8115495-B2

Title: Wired pipe signal transmission testing apparatus and method

Description:
FIELD 
     The invention relates generally to borehole telemetry systems. More specifically, the invention relates to an apparatus and a method for testing the ability of a wired pipe or string of wired pipes to transmit a signal. 
     BACKGROUND 
     Wired pipe telemetry systems using a combination of electrical and magnetic principles to transmit data between a downhole location and the surface are described in, for example, U.S. Pat. Nos. 6,670,880 and 6,641,434. In these systems, inductive transducers are provided at the ends of wired pipes. The inductive transducers at the ends of each wired pipe are electrically connected by an electrical conductor running along the length of the wired pipe. Data transmission involves transmitting an electrical signal through an electrical conductor in a first wired pipe, converting the electrical signal to a magnetic field upon leaving the first wired pipe using an inductive transducer at an end of the first wired pipe, and converting the magnetic field back into an electrical signal upon entering a second wired pipe using an inductive transducer at an end of the second wired pipe. Several wired pipes are typically needed for data transmission between the downhole location and the surface. Before connecting a new wired pipe to existing wired pipes in a borehole, it is desirable to test that the new wired pipe can transmit a signal. After connecting a new wired to existing wired pipes in the borehole, it may also be desirable to test that the system can transmit a signal. An apparatus and a method for accomplishing such testing is desired. 
     SUMMARY 
     In one aspect, the invention relates to a wired pipe signal transmission testing apparatus. 
     In one embodiment, the apparatus comprises a core having a plurality of threads formed on a surface thereof and a plurality of slots cutting through crests and roots of at least a portion of the threads, thereby creating an escape route for debris that enter in between the threads. The apparatus further comprises an inductive transducer coupled to the core. 
     In another embodiment, the apparatus comprises a core having a plurality of threads formed on an external surface thereof and a plurality of slots cutting through crests and roots of at least a portion of the threads, thereby creating an escape route for debris that may enter in between the threads. The apparatus further comprises an inductive transducer mounted at an end face of the core. 
     In yet another embodiment, the apparatus comprises a core having an annular wall and a plurality of threads formed on an inner surface of the annular wall. The core is provided with a plurality of slots that cut through crests and roots of at least a portion of the threads and through the annular wall, thereby creating an escape route for debris that may enter in between the threads. The apparatus further includes an inductive transducer mounted within the core. 
     In another embodiment, the apparatus comprises at least one wired pipe having a pipe end with a surface on which a plurality of pipe threads are formed and a surface on which an inductive transducer is mounted. The apparatus includes a test plug carrying an inductive transducer. The test plug has a plurality of plug threads for engaging the pipe threads and a plurality of slots cutting through crests and roots of at least a portion of the pipe threads. When a threaded connection is formed between the core threads and the pipe threads, the inductive transducers are in a position to share magnetic fields. 
     In another aspect, the invention relates to a wired pipe signal transmission testing method. 
     In one embodiment, the method includes forming a threaded connection between a first end of a wired pipe including an inductive transducer and a test plug including an inductive transducer. The test plug comprises a plurality of threads for forming the threaded connection and a plurality of slots cutting through crests and roots of at least a portion of the threads. The method includes transmitting a signal to the inductive transducer included in the test plug and measuring a signal transmitted between the inductive transducer included at the first end of the wired pipe and an inductive transducer included at a second end of the wired pipe. Other features and advantages of the invention will be apparent from the following description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, described below, illustrate typical embodiments of the invention and are not to be considered limiting of the scope of the invention, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         FIG. 1  is a schematic of a wired pipe and an apparatus for testing the wired pipe for its ability to transmit a signal. 
         FIG. 2  is a schematic of a string of wired pipes and an apparatus for testing the string of wired pipes for its ability to transmit a signal. 
         FIG. 3  is a perspective view of the box-end test plug shown in  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the box-end test plug of  FIG. 3  along lines  4 - 4 . 
         FIG. 5  is an end view of the box-end test plug of  FIG. 3 . 
         FIG. 6  is a schematic of a threaded connection between a box end of a wired pipe and the box-end test plug of  FIG. 3 . 
         FIG. 7  is a cross-sectional view of a pin-end test plug. 
         FIG. 8  is an end view of the pin-end test plug of  FIG. 7 . 
         FIG. 9  is a schematic of a threaded connection between a pin end of a wired pipe and the pin-end test plug of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     The invention will now be described in detail with reference to a few embodiments, as illustrated in the accompanying drawings. In describing the embodiments, numerous specific details may be set forth in order to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the invention may be practiced without some or all of these specific details. In other instances, well-known features and/or process steps may not be described in detail so as not to unnecessarily obscure the invention. In addition, like or identical reference numerals may be used to identify common or similar elements. 
       FIG. 1  shows a wired pipe  100  that is to be tested for its ability to transmit an electrical signal. An apparatus for testing the wired pipe  100  includes a box-end test plug  102 , which is mounted at the box end  101  of the wired pipe  100 , and a pin-end test plug  104 , which is mounted at the pin end  103  of the wired pipe  100 . To test the wired pipe  100  for its ability to transmit an electrical signal, a signal diagnostics tool  106  is connected to the box-end test plug  102  and operated to transmit an electrical signal to the box-end test plug  106 . If the wired pipe  100  is working properly, the electrical signal will be coupled into the wired pipe  100  and then into the pin-end test plug  104 . The signal diagnostics tool  106  can be connected to the pin-end test plug  104  to measure the electrical signal coupled into the pin-end test plug  104 , and the output of the signal diagnostics tool  106  can be used to verify the ability of the wired pipe  100  to transmit a signal. 
     In another scenario, only one of box-end test plug  102  and pin-end test plug  104 , depending on the end of the wired pipe  100  available for connection to the test apparatus, may be used in the signal transmission testing. In  FIG. 2 , for example, a string  108  of wired pipes  100  is disposed in a borehole  110 . In this case, only the box-end test plug  102  is used to test the ability of the string  108  of wired pipes  100  to transmit a signal between a downhole tool  112  at the end of the string  108  of wired pipes  100  and the signal diagnostics tool  106  at the surface  114 . In the example shown in  FIG. 2 , the signal diagnostics tool  106  transmits an electrical signal to and receives an electrical signal from the downhole tool  112  through the box-end test plug  102 . As in the previous case, the output of the signal diagnostics tool  106  can be used to verify the ability of the string  108  of wired pipes  100  to transmit a signal. 
       FIG. 3  is a perspective view of the box-end test plug  102  (previously shown in  FIGS. 1 and 2 ). The box-end test plug  102  has a core or shaft  120  that terminates at one end in a head or flange  122 . The core  120  may have a generally cylindrical shape, which in some examples may be tapered. The head  122  may include a knob  124  having, for example, a hole  126  to facilitate insertion of a handling tool (not shown). Screw threads  128  are formed on the external surface  123  of the core  120 . In the example shown in  FIG. 3 , the threads  128  are formed in an upper portion  130  of the core  120 , the upper portion  130  being the portion of the core  120  closest to the head  122 . In other examples, the threads  128  may be formed in the lower portion  132  of the core  120 . The purpose of the threads  128  is to allow the box-end test plug  102  to be connected to the box end of a wired point joint that includes similar threads. Thus, only enough threads to form a threaded engagement between the box-end test plug  102  and a box end of a wired pipe need be formed on the core  120  of the box-end test plug  102 . The design of the threads  128  will be selected to match that of the box end of the wired pipe to be tested. 
     The screw threads  128  on the core  120  are segmented by a plurality of slots  134  that cut through the crests  125  and roots  127  of the threads  128  into the core  120 . The angle each slot  134  makes with the screw threads  128  is such that each slot  134  cuts through the crests  125  and roots  127  of a majority, preferably all, of the screw threads  128 . Each slot  134  cuts through the crests  125  and roots  127  of at least 50% of the screw threads  128  (measured from the lowermost screw thread  128 ), preferably greater than 75% of the screw threads  128  (measured from the lowermost screw thread  128 ), more preferably greater than 90% of the screw threads  128  (measured from the lowermost screw thread  128 ). The lowermost screw thread  128  is the screw thread  128  that is farthest from the head  122 . In one example, the slots  134  transversely intersect the crests  125  and roots  127  of the screw threads  128  at approximately 90° (i.e., substantially perpendicularly), e.g., as shown in  FIG. 3 . In other examples, the slots  134  may transversely intersect the crests  125  and roots  127  of the screw threads  128  at angles other 90° provided that the slots  134  cut through the crests  125  and roots  127  of a majority of the screw threads  128  as described above. The slots  134  are connected to the channels  129  between adjacent threads  128 . This allows the slots  134  to receive debris that fall into the channels  129  between adjacent threads  128 . Such debris may be encountered while making up a threaded connection between the box-end test plug  102  and a box end of a wired pipe. 
     The slots  134  are distributed about the circumference of the core  120  at selected offsets. In some examples, the slots  134  are equally spaced about the circumference of the core  120 . In other examples, the slots  134  are unequally spaced about the circumference of the core  120 . As shown in  FIG. 4 , in one example, four slots  134  are distributed about the circumference of the core  120  at 90° offsets. In other examples, more of fewer slots  134  may be distributed about the circumference of the core  120 . In some examples, the sidewalls  131  of the slots  134  are slanted outwardly relative to the external surface  123  of the core  120 . The slant angles may be between 20° and 80°, preferably between 30° and 60°, and more preferably approximately 45°, where the slant angles are measured from the external surface  123 . The slots  134  cut through the lowermost screw thread  128 , thereby creating an escape route for debris received in the slots  134 , i.e., debris received in the slots  134  can fall down the external surface  123  of the core  120 . 
     Weight-reducing slots  136  may be formed in the core  120  and head  122  to reduce the overall weight of the box-end test plug  102 . In one example, as shown more clearly in  FIG. 4 , four weight-reducing slots  136  are formed in the core  120 . The weight-reducing slot  136  at the center, indicated at  137 , extends into the knob  124  of the head  122 . In general, as many weight-reducing slots  136  as desired without hampering the structural integrity of the box-end test plug  102  may be used. Referring to  FIG. 5 , an annular groove  138  is provided at the bottom face  140  of the core  120 . Inside the groove  138  is disposed an inductive transducer  142 . Any suitable inductive transducer  142  for converting an electrical signal to a magnetic field may be used, such as described, for example, in U.S. Pat. No. 6,670,880 issued to Hall et al. In the Hall et al. patent, the inductive transducer  142  included a magnetically-conductive electrically insulating element (MCEI) having a U-shaped trough in which is located an electrically conducting coil. A varying current applied to the electrically conducting coil generates a varying magnetic field in the MCEI. The core  120  includes a conduit  144  (shown in  FIG. 4 ) that extends from the head  122  (shown in  FIG. 3 ) to the groove  138  and through which an electrical wire (not shown) can be connected to an electrically conducting coil (not shown separately) in the inductive transducer  142 . 
       FIG. 6  shows a threaded connection  141  between the box-end test plug  102  and the box end  101  of the wired pipe  100 . The box end  101  of the wired pipe  100  includes an inner chamber  146  defined by an annular wall  148 . The shape of the box-end test plug  102  is such that it can be received in the inner chamber  146 . Threads  149  are formed on the annular wall  148 . The bottom surface  145  of the inner chamber  146  includes a groove  147  in which an inductive transducer  143  is mounted. The inductive transducer  143  may be as described above for the box-end test plug. To test the wired pipe  100 , it is necessary for the inductive transducer  143  in the box end  101  of the wire pipe joint  100  to come into close proximity with the inductive transducer  142  in the box-end test plug  102  so that the inductive transducers  142 ,  143  can share magnetic field. Thus, the location of the threads  128  on the box-end test plug  102  is such that when a threaded connection is formed between the box-end test plug  102  and the box end  101  of the wired pipe  100 , the inductive transducers  142 ,  143  are in close proximity. To allow such a threaded connection to be successfully made up, slots  134  are provided in the box-end test plug  102 , as described above, to clean out any debris that fall into the channels between the threads  128  of the box-end test plug  102  from between the threads  128 ,  149 . 
       FIG. 7  is a cross-sectional view of the pin-end test plug  104  (previously shown in  FIG. 1 ). The pin-end test plug  104  has a core or shaft  150  that terminates at one end in a head or flange  152 . The core  150  may have a generally cylindrical shape, which in some examples may be tapered. The head  152  may include a knob  154  having, for example, a hole  156  to facilitate insertion of a handling tool (not shown). The core  150  has an annular wall  160  defining an inner chamber  158 . Screw threads  162  are formed on the inner surface  159  of the annular wall  160 . The purpose of the screw threads  162  is to allow the pin-end test plug  104  to be connected to the pin end of a wired pipe that includes similar threads. Only enough threads to form a threaded engagement between the pin-end test plug  104  and a pin end of a wired pipe need to be formed on the internal surface  159  of the annular wall  160 . That is, threads may be formed on a portion of the length or the entire length of the internal surface  159  as deemed necessary. The design of the screw threads  162  will be selected to match that of the pin end of the wired pipe to be tested. 
     The screw threads  162  on the internal surface  159  of the annular wall  160  are segmented by a plurality of slots  164  that cut through the crests  166  and roots  168  of the threads  162  and through the annular wall  160 . The slots  164  are through slots in that they extend from the external surface  170  of the core  150  to the inner chamber  158  of the core  150 . In one example, the slots  150  transversely intersect the crests  166  and roots  168  of the threads  162  at approximately 90° (i.e., substantially perpendicularly). In other examples, the slots  150  may transversely intersect the crests  166  and roots  168  of the threads  162  provided that the slots  150  cut through the crests  166  and roots  168  of a majority of the threads  162 . Each slot  150  cuts through the crests  166  and roots  168  of at least 50% of threads  162  (measured from the lowermost thread  162 ), preferably greater than 75% of the screw threads  162  (measured from the lowermost screw thread  162 ), more preferably greater than 90% of the screw threads  162  (measured from the lowermost screw thread  162 ). The lowermost screw thread  162  is the screw thread  162  that is farthest from the head  152 . 
     In the disclosed example, two diametrically-opposed slots  164  (see also  FIG. 8 ) as described above are formed in the pin-end test plug  104 . In general, any number of slots  164  may be formed in the pin-end test plug  104  provided there is enough thread surface remaining on the core  150  to form a threaded connection with a wire pipe joint (not shown) and the pin-end test plug  104  has sufficient structural strength. In one example, the sidewalls  163  of the slots  164  are slanted inwardly relative to the external surface  170  of the core  150 . That is, the angle between the sidewalls  163  and the external surface  170  (measured from the external surface  170 ) is greater than 90°. In one example, the sidewalls  163  of the slots  164  form an angle of 95° with the external surface  170  of the core  150 , where the slant angle is measured from the external surface  170 . The slots  164  function similarly to the cleaning slots ( 134  in  FIG. 3 ) described for the box-end test plug ( 102  in  FIG. 3 ). That is, debris in the channels  172  between adjacent threads  162  and fall into the slots  164 . When the pin-end test plug  104  is being made up with a pin end of a wired pipe, the debris falling into the slots  164  will be able to fall down the wired pipe and away from the threaded connection that is being made up between the pin-end test plug  104  and the pin end of the wired pipe. 
     Weight reducing slots  153  may be formed in the portion of the core  150  above the inner chamber  158  and in the head  152 . An annular groove  180  is formed in the core  150  above the inner chamber  158 . As shown in  FIG. 8 , the groove  180  holds an inductive transducer  182  as described above for the box-end test plug ( 102  in  FIG. 5 ). Referring to  FIG. 7 , a conduit  184  runs from the head  152  to the groove  180  and is used to pass an electrical wire  185  to an electrical conducting coil (not shown separately) of the inductive transducer  182  as described above for the box-end test plug. 
       FIG. 9  shows a threaded connection  190  between the pin-end test plug  104  and a pin end  103  of the wire pipe joint  100  (previously shown in  FIG. 1 ). The external surface of the pin end  103  of the wire pipe joint  100  is provided with threads  192 . The end face  194  of the pin end  103  of the wire pipe joint  100  includes a groove  195  in which an inductive transducer  196  is mounted. The inductive transducer  194  may be as described above for the pin-end test plug  104  and box-end test plug. For completeness, it should be noted that an electrical conductor  198  runs from the inductive transducer  194  in the pin end  103  of the wire pipe joint  100  to the inductive transducer ( 143  in  FIG. 6 ) in the box end ( 101  in  FIG. 6 ) of the wire pipe joint  100 . To test the wire pipe joint  100 , it is necessary for the inductive transducer  196  in the pin end  103  of the wire pipe joint  100  to come into close proximity with the inductive transducer  182  in the pin-end test plug  104  so that the inductive transducers  182 ,  196  can share magnetic fields. Thus, the location of the threads  162  on the pin-end test plug  104  is such that when the threaded connection  190  is formed between the pin-end test plug  104  and the pin end  103  of the wired pipe  100 , the inductive transducers  182 ,  196  are in close proximity. To allow such a threaded connection to be successfully made up, slots  164  are provided in the pin-end test plug  104 , as described above, to clean out any debris that fall into the channels between the threads  162  of the pin-end test plug  104  from between the threads  162 ,  192 . 
     While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.