Abstract:
A drill pipe for an oil or gas well is provided that includes a generally cylindrical hollow drill pipe having a length; and a conductive coating connected to the drill pipe to define an electrical pathway that extends along at least a portion of the length of the drill pipe.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application is a continuation of U.S. patent application Ser. No. 10/279,717 entitled “Drill Pipe Having an Internally Coated Electrical Pathway,” filed Oct. 23, 2002, the entire content of which is incorporated by reference herein. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to a drill pipe for an oil or gas well and more particularly to a drill pipe having an internally coated conductive material for providing an electrical pathway for electronic data obtained down hole to be efficiently transmitted to the surface of an oil or gas well.  
         BACKGROUND OF THE INVENTION  
         [0003]    Currently there exist tools in the oil and gas well industry that are specifically designed to obtain drilling and geological parameters downhole, near the drill bit. In some instances, the information obtained by these tools is stored in memory devices. In such cases, the stored information can be retrieved when the memory devices are returned to the surface of the well. This system, however, produces an undesirable lag time between the initial collection and storing of the downhole information and the retrieval of the downhole information at the surface of the well.  
           [0004]    As an alternative, the downhole information can be transmitted to the surface of the well using pressure pulses in the drilling fluid. However, this method also produces an undesirable lag time caused by the time a pressure pulse takes to reach the surface. Accordingly, a need exists for a method and a system of transmitting data instantaneously and efficiently to the surface of a well.  
         SUMMARY OF THE INVENTION  
         [0005]    In one embodiment, the present invention is a drill pipe for an oil or gas well that includes a generally cylindrical hollow drill pipe having a length; and a conductive coating connected to the drill pipe to define an electrical pathway that extends along at least a portion of the length of the drill pipe.  
           [0006]    In another embodiment, the present invention is a method of communicating to downhole oil or gas well equipment that includes providing a generally cylindrical hollow drill pipe having a length; and applying a conductive coating on the drill pipe to define an electrical pathway that extends along at least a portion of the length of the drill pipe. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:  
         [0008]    [0008]FIG. 1 is a cross-sectional view of a lower end of a first drill pipe and a cross-sectional view of an upper end of a second drill pipe;  
         [0009]    [0009]FIG. 2 is a cross-sectional view of the drill pipes of FIG. 1 threadingly connected, wherein each drill pipe has a conductive coating electrically connected by a connector;  
         [0010]    [0010]FIG. 3 is a cross-sectional view of the drill pipes of FIG. 1 threadingly connected, wherein each drill pipe has a first conductive coating and a second conductive coating, and wherein the corresponding first conductive coatings and the corresponding second conductive coatings are electrically connected by a connector;  
         [0011]    [0011]FIG. 4A is a longitudinal cross-section of the connector of FIG. 2;  
         [0012]    [0012]FIG. 4B is a transverse cross-section of the connector of FIG. 2, taken from line  4 B- 4 B of FIG. 4A;  
         [0013]    [0013]FIG. 5 is a cross-sectional view of the drill pipes of FIG. 1 threadingly connected, wherein each drill pipe has a conductive coating electrically connected to an upper and a lower conductive sleeve and wherein a lower conductive sleeve of the first drill pipe is connected to the upper conductive sleeve of the second drill pipe by the connector of FIGS. 4A and 4B; and  
         [0014]    [0014]FIG. 6 is a cross-sectional view of the drill pipes of FIG. 1 threadingly connected, wherein each drill pipe has a first conductive coating electrically connected to a first upper and a first lower conductive sleeve and a second conductive coating electrically connected to a second upper and a second lower conductive sleeve, and wherein the first sleeve and the second sleeve are electrically connected by a connector. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    As shown in FIGS. 1-6, the present invention is directed a drill pipe having an internally coated conductive material for forming an electrical pathway from an upper end of the drill pipe to a lower end of the drill pipe. The drill pipe of the current invention allows for communication between a well head and downhole equipment in an oil or gas well so that drilling parameters and geological parameters may be obtained downhole and transmitted to the well head for analysis.  
         [0016]    [0016]FIG. 1 shows a lower end  10  of a first drill pipe  12  and an upper end  14  of a second drill pipe  16 . Although omitted for clarity, the first drill pipe  12  comprises an upper end that is similar to the upper end  14  of a second drill pipe  16  and the second drill pipe  16  comprises a lower end that is similar to the lower end  10  of the first drill pipe  12 . As such, reference to the lower end  10  and the upper end  14  in the following description is to be understood to apply equally to the first drill pipe  12  and to the second drill pipe  16 . In addition, the first drill pipe  12  and the second drill pipe  16  are shaped and formed similarly, such that reference to a drill pipe  22  in the following description is to be understood to apply equally to the first drill pipe  12  and to the second drill pipe  16 .  
         [0017]    As depicted in FIG. 1, the drill pipe  22  comprises a body portion  20  that is generally cylindrical in shape and has a hollow center defined by an inner diameter  24 . The upper and lower ends  10  and  14  of the drill pipe  22  each comprise threads  18 . The threads  18  allow the upper end  10  of one drill pipe  22  to be connected to the lower end  14  of another drill pipe  22 . Drill pipes  22  that are connected in this way (as is shown in FIGS. 2-3 and  5 - 6 ) are typically collectively referred to as a drill string  26 . Although FIGS. 2-3 and  5 - 6  show the drill string  26  as having only two drill pipes  22 , the drill string may comprise any number of connected drill pipes  22 .  
         [0018]    In an exemplary embodiment, the threads  18  are special tapered threads that, when engaged, provide a connection that is almost as strong as the body portion  20  of the drill pipe  22  and also provides a very reliable pressure seal for drilling fluids that are pumped through the drill string  26  during the drilling process.  
         [0019]    In one embodiment, as depicted in FIG. 2, each drill pipe  22  in the drill string  26  comprises an outer insulative coating  28  attached to the inner diameter  24  of the drill pipe  22 , a conductive coating  30  attached to the outer insulative coating  28 , and an inner insulative coating  32  attached to the conductive coating  30 . As such, the outer insulative coating  28 , the conductive coating  30  and the inner insulative coating  32  of each drill pipe  22  together form an insulated electrical pathway from the upper end  14  of the drill pipe  22  to the lower end  10  of the drill pipe  22 , i.e. the outer insulative coating  28  insulates the conductive coating  30  from the body  20  of the drill pipe  22 , which is typically comprised of a metal material, and the inner insulative coating  32  insulates the conductive coating  30  from the drilling fluids.  
         [0020]    As shown in FIGS. 2-3 and  5 - 6  when two drill pipes  22  are connected, a small gap  34  exists between the lower end  10  of one drill pipe  22  and the upper end  14  of the adjacent drill pipe  22 . In one embodiment, a connector  36  is attached to the drill string  26  in the small gap  34  between adjacent drill pipes  22  to electrically connect the insulated electrically pathways of the adjacent drill pipes  22 . For example, in the depicted embodiment of FIG. 2, the connector  36  comprises a protruding section  38  that has a larger diameter than the inner diameter  24  of the drill pipes  22 , such that when the connector  36  is disposed between the lower end  10  of one drill pipe  22  and the upper end  14  of the adjacent drill pipe  22  and the drill pipes  22  are connected, the connector  36  is trapped in the small gap  34  between the drill pipes  22 .  
         [0021]    In one embodiment, the protruding section  38  of the connector  36  comprises a protruding shoulder  40  that mates with or abuts against a shoulder  42  in the upper end  14  of the drill pipe  22  to secure the connector to the drill string  26  when the connector  36  is disposed between the lower end  10  of one drill pipe  22  and the upper end  14  of the adjacent drill pipe  22 .  
         [0022]    To establish the electrical connection between the insulated electrically pathways of the adjacently connected drill pipes  22 , the connector  36  comprises a conducting material  44  that has a body portion  45 , an upper conducting contact  46  and a lower conducting contact  48 . When the connector  36  is disposed between the lower end  10  of one drill pipe  22  and the upper end  14  of the adjacent drill pipe  22 , the upper conducting contact  46  establishes an electrical connection  50  with the conductive coating  30  in the lower end  10  of one drill pipe  22  and the lower conducting contact  48  establishes an electrical connection  52  with the conductive coating  30  in the upper end  14  of the adjacent drill pipe  22 . As such, an electrical pathway is established from the conductive coating  30  in the lower end  10  of one drill pipe  22 , to the upper conducting contact  46 , then to the connector conducting material body portion  45 , then to the lower conducting contact  48 , and then to the upper end  14  of the adjacent drill pipe  22 .  
         [0023]    In one embodiment, the connector  36  is comprised of an insulative material, such that the electrical pathway from the upper conducting contact  46 , to the conducing material body portion  45 , to the lower conducting contact  48 , is insulated. For instance, the connector  36  may be formed in a molding process, such as injection molding, with the conducting material  44  being molded into the insulative material of the connector  36 . In one embodiment, the conducting material  44  is elastic, such that the upper conducting contact  46  and the lower conducting contact  48  compress when the electrical connections  50  and  52  are established between the adjacent drill pipes  22 .  
         [0024]    The connector  36  may also comprise an upper annular groove  54  and a lower annular groove  56 . For instance, in the embodiment depicted in FIG. 2, the upper annular groove  54  is disposed above the upper conducting contact  46 , and hence above the electrical connection  50 , while the lower annular groove  56  is disposed below the lower conducting contact  48 , and hence below the electrical connection  52 . Disposed within each annular groove  54  and  56  is an elastomeric o-ring  58 . The o-ring  58  in the upper annular groove  54  creates a seal against the conductive coating  30  in the lower end  10  of one drill pipe  22  to prevent the drilling fluids from contaminating the electrical connections  50  and  52  from above, while the o-ring  58  in the lower annular groove  56  creates a seal against the conductive coating  30  in the upper end  14  of the adjacent drill pipe  22  to prevent the drilling fluids from contaminating the electrical connections  50  and  52  from below.  
         [0025]    The connector  36  may comprise one conducting material  44 , or, as depicted in FIGS. 4A and 4B, the connector  36  may comprise a plurality of conducting materials  44 . For instance, in the depicted embodiment of FIGS. 4A and 4B, the connector  36  comprises six conducting materials  44 , each attached to the connector  36  and forming the electrical connections  50  and  52  as described above.  
         [0026]    The drill string  26  may comprise a plurality of adjacently connected drill pipes  22 , wherein each adjacently connected drill pipe  22  has a the connector  36  disposed therebetween as described above, such that each connector  36  electrically connects the conductive coating  30  of one drill pipe  22  to the conductive coating  30  of its adjacent drill pipe  22  to establish an insulated electrical pathway from an upper end of the drill string  26  to a lower end of the drill string  26 .  
         [0027]    As depicted in FIG. 3, each drill pipe  22  in the drill string  26  may comprise a second conductive coating  60  attached to the inner insulative coating  32 , and a second inner insulative coating  62  attached to the second conductive coating  60 , such that the inner insulative coating  32 , the second conductive coating  60  and the second inner insulative coating  62  together form a second insulated electrical pathway.  
         [0028]    In such an embodiment, the connector  36  may have an inwardly stepped section  63 , containing a second conducting material  64  having a body portion  65 , an upper conducting contact  66  and a lower conducting contact  68 . The second conducting material  64  may be formed and attached to the conductor  36  as described above with respect to the conducting material  44 .  
         [0029]    When the connector  36  is disposed between the lower end  10  of one drill pipe  22  and the upper end  14  of the adjacent drill pipe  22 , the upper conducting contact  66  establishes an electrical connection  70  with the conductive coating  60  in the lower end  10  of one drill pipe  22  and the lower conducting contact  68  establishes an electrical connection  72  with the conductive coating  60  in the upper end  14  of the adjacent drill pipe  22 . As such, an electrical pathway is established from the conductive coating  60  in the lower end  10  of one drill pipe  22 , to the upper conducting contact  66 , then to the connector conducting material body portion  65 , then to the lower conducting contact  68 , and then to the upper end  14  of the adjacent drill pipe  22 . As described above and as shown in FIGS. 4A and 4B, the connector  36  may comprise one second conducting material  64 , or the connector  36  may comprise a plurality of second conducting materials  64 .  
         [0030]    The drill string  26  may comprise a plurality of adjacently connected drill pipes  22 , wherein each adjacently connected drill pipe  22  has the connector  36  disposed therebetween as described above, such that each connector  36  electrically connects the conductive coating  60  of one drill pipe  22  to the conductive coating  60  of its adjacent drill pipe  22  to establish a second insulated electrical pathway from an upper end of the drill string  26  to a lower end of the drill string  26 . O-rings may be used, as described above, to prevent the drilling fluids from contaminating the electrical connections  70  and  72 .  
         [0031]    Each drill pipe  22  in the drill string  26  may comprise a plurality of conductive coatings and each connector may comprise a corresponding plurality of inwardly stepped sections and conducting materials, such that the drill string  26  comprises a plurality of insulated electrical pathways from an upper end of the drill string  26  to a lower end of the drill string  26 .  
         [0032]    In one embodiment, as depicted in FIG. 5, the lower end  10  and the upper end  14  of each drill pipe  22  in the drill string  26  comprises a lower annular recess  76  and an upper annular recess  78 . In such an embodiment, the outer insulative coating  28  is attached to the inner diameter  24 , the upper annular recess  78  and the lower annular recess  76  of each drill pipe  22 . An upper and a lower conducting sleeve  82  and  80  are attached to the outer insulative coating  28  in the upper annular recess  78  and the lower annular recess  76 , respectively. For instance, the upper and lower conducting sleeves  82  and  80  may be press fit into the upper and lower annular recesses  78  and  76 , respectively.  
         [0033]    In this embodiment, the conductive coating  30  is attached to the outer insulative coating  28  and to the upper and lower conducting sleeves  82  and  80  to establish an electrical pathway from the upper end  14  to the lower end  10  of each drill pipe  22 . The inner insulative coating  32  is attached to the conductive coating  30  such that the conductive coating  30  is insulated.  
         [0034]    As described above, to establish an electrical connection between the insulated electrically pathways of the adjacently connected drill pipes  22 , the connector  36  is disposed between the lower end  10  of one drill pipe  22  and the upper end  14  of the adjacent drill pipe  22 . When so positioned, the upper conducting contact  46  establishes an electrical connection  90  with the lower conducting sleeve  80  and the lower conducting contact  48  establishes an electrical connection  92  with the upper conducting sleeve  82 , such that an insulated electrical pathway is established from the conductive coating  30  in the lower end  10  of one drill pipe  22 , to the lower conducting sleeve  80 , then to the upper conducting contact  46 , then to the connector conducting material body portion  45 , then to the lower conducting contact  48 , then to the upper conducting sleeve  82 , and then to the upper end  14  of the adjacent drill pipe  22 .  
         [0035]    The conducting sleeves  80  and  82  provide a more robust contact surface than the conductive coating. Hence the addition of the conducting sleeves  80  and  82  produces more secure electrical connection  90  and  92  with the connector  36 . O-rings may be used, as described above, to prevent the drilling fluids from contaminating the electrical connections  90  and  92 . In addition, rather than extending the outer insulative coating  28  into the upper and lower annular recesses  78  and  76 , the contact sleeves  82  and  80  may each comprise an insulative material on its outer surface.  
         [0036]    In the embodiment depicted in FIG. 6, each drill pipe  22  in the drill string  26  comprises a second lower annular recess  86  and a second upper annular recess  88 . In this embodiment, a second lower conducting sleeve  100  and a second upper conducting sleeve  102  are attached to the second lower annular recess  86  and the second upper annular recess  88 , respectively, such as by press fitting. The second conductive coating  60  is attached to the inner insulative coating  32  and to the second upper and lower conducting sleeves  102  and  100  to establish a second electrical pathway from the upper end  14  to the lower end  10  of each drill pipe  22 . The second inner insulative coating  62  is attached to the second conductive coating  60  such that the second conductive coating  60  is insulated.  
         [0037]    In this embodiment, the connector  36  may comprise the inwardly stepped portion  63  comprising the second conducting material  64 , such that the upper conducting contact  66  and a lower conducting contact  68  establish electrical contacts  110  and  112 , respectively, with the second lower conducting sleeve  100  and the second upper conducting sleeve  112 .  
         [0038]    Each drill pipe  22  in the drill string  26  may comprise a plurality of conductive coatings and a plurality of corresponding upper and lower conducting sleeves; and each connector may comprise a corresponding plurality of inwardly stepped sections and conducting materials, such that the drill string  26  comprises a plurality of insulated electrical pathways from an upper end of the drill string  26  to a lower end of the drill string  26 .  
         [0039]    In each of the embodiments described above, each coating may have a thickness in the range of approximately 0.006 inches to approximately 0.030 inches. In addition, each insulative coating may comprise a plastic polymer such as an epoxy, phenolic, teflon, or nylon. The insulative coatings may be spray applied. The conductive coatings may comprise a metal material, such as copper, aluminum, silver or gold, or a mixture of metal particles and a polymer. The conductive coatings may be applied by plating or spraying.  
         [0040]    The preceding description has been presented with references to presently preferred embodiments of the invention. Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, spirit and scope of this invention. Specifically, although drill strings having only one or two conductive pathways are described herein, it should be understood that the principles of the invention may be applied to form drill pipe and therefore drill strings having any arbitrary number of conductive pathways. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.