Composite drill pipe and method of forming same

Abstract

A lightweight and durable drill pipe string capable of short radius drilling formed using a composite pipe segment formed to include tapered wall thickness ends that are each defined by opposed frustoconical surfaces conformed for self aligning receipt and intimate bonding contact within an annular space between corresponding surfaces of a coaxially nested set of metal end pieces and a set of nonconductive sleeves. The distal peripheries of the nested end pieces and sleeves are then welded to each other and the sandwiched and bonded portions are radially pinned. The composite segment may include imbedded conductive leads and the axial end portions of the end pieces are shaped to form a threaded joint with the next pipe assembly that includes contact rings in the opposed surfaces of the pipe joint assembly, the contact of which is effected by either piercing with a pointed contact from one end into the other to connect the corresponding leads across the joint or contacting opposed rings in each end.

1 . A drill pipe string forming a metal to composite interface, comprising:
 a plurality of longitudinally aligned filament wound composite pipe segments configured at their respective opposite extremities with tapered sections formed by cylindrical walls tapering distally to thin annular edges;   pairs of male and female couplers interposed between adjacent ends of respective pipe segments including inner and outer concentric cylindrical members formed by respective outer and inner walls, the respective walls formed with respective confronting bonding surfaces angling distally in one direction in conical fashion away from one another to cooperate in forming conical nesting cavities for complementary receipt of the respective tapered sections of the adjacent pipe segments of said string;   a bond bonding the pipe segment walls to the male and female couplers; and   said male and female couplers including respective threaded male nipples and female openings for screwable connection of respective adjacent male and female couplers together.   
   
   
       2 . The drill pipe string of  claim 1 , further comprising:
 at least one electrical lead conductor embedded within respective pipe segments including respective exposed connector portions protruding from respective pipe segment opposite extremities;   respective electrical contact surfaces positioned within respective male nipples and female openings disposed for electrical engagement to an adjacent electrical contact surface when adjacent male nipples and female openings are connected together; and wherein   the respective male and female couplers include lead passages configured for routing respective exposed portions into electrical contact with the respective contact surfaces of connected male nipples and female openings making said electrical contact therein.   
   
   
       3 . A drill pipe string forming a metal to composite interface, comprising:
 a plurality of filament wound composite pipe segments configured at their respective opposite extremities with tapered sections formed by cylindrical walls tapering distally to thin annular edges;   pairs of male and female couplers including respective proximate ends interposed between adjacent ends of respective pipe segments and further including inner and outer concentric cylindrical members formed by respective outer and inner walls, the respective walls formed with respective confronting bonding surfaces angling distally in one direction in conical fashion away from one another to cooperate in forming conical nesting cavities for complementary receipt of the respective tapered sections of the adjacent pipe segments of said string wherein one of the respective cylindrical members projects distally farther from its coupler proximate end than the other cylindrical member;   a bond bonding the pipe segment walls to the male and female couplers; and   said male and female couplers including respective threaded male nipples and females openings for screwable connection of respective adjacent male and female couplers together.   
   
   
       4 . The drill pipe string of  claim 3 , wherein:
 the inner cylindrical member projects distally farther than the outer cylindrical member.   
   
   
       5 . The drill pipe string of  claim 3 , wherein:
 the composite segments include a predetermined amount of carbon material.   
   
   
       6 . The drill pipe string of  claim 3 , further comprising:
 an electrical conductor mounted to respective pipe segments and routed through respective male and female couplers to effect an electrical connection between adjacent the adjacent ends of respective pipe segments.   
   
   
       7 . The drill pipe string of  claim 3 , wherein:
 respective pipe segment ends include a predetermined diameter and respective pipe segment walls taper narrowing in cross-section from the pipe segment ends to an intermediate point therefrom.   
   
   
       8 . The drill pipe string of  claim 3 , wherein:
 the female couplers include male bosses and the male couplers include female bosses configured for operative receipt of a male boss from an adjacent pipe segment end.   
   
   
       9 . A drill pipe string for end to end connection, comprising:
 composite walls forming elongated pipe segments having first and second extremities;   one or more conductor lead segments imbedded in the walls of respective pipe segments and extending between the respective first and second extremities therein and projecting distally therefrom to form mating connector links;   first and second connectors connected to the respective mating connector links and operative upon respective extremities of the pipe segments being connected together to form respective electrical couplings.   
   
   
       10 . The pipe string of  claim 9 , wherein:
 the respective connectors are formed with metallic male and female end fittings at the respective first and second extremities, including metallic walls with connector stems on the respective fitting proximal ends and on their respective distal ends with respective male and female bosses connected together.   
   
   
       11 . The pipe string of  claim 10 , wherein:
 the first connectors include respective electrically conductive contact rings in electrical contact with respective lead segments and constructed to be, when the respective male and female fittings are connected together, in operative electrical contact with one another.   
   
   
       12 . The pipe string of  claim 10 , wherein:
 the male and female bosses are threadably connected.   
   
   
       13 . The pipe string of  claim 9 , further comprising:
 respective hollow sleeve walls including proximate extremities and distal extremities, the sleeve walls positioned between the respective composite wall first and second extremities and respective connectors.   
   
   
       14 . The pipe string of  claim 13 , wherein:
 skirts formed on the respective sleeve walls proximate extremities define a first pair of sockets receiving the respective composite wall first and second extremities;   a second pair of sockets formed on the respective sleeve wall distal extremities receive the respective connectors, the sleeve walls further include respective passages for routing of respective mating connector links into operative electrical contact upon respective extremities of the pipe segments being connected together.   
   
   
       15 . The pipe string of  claim 11 , wherein:
 the metallic walls of respective fittings incorporate connector passages receiving the respective mating connector links disposed in electrical contact to respective contact rings.   
   
   
       16 . The pipe string of  claim 15 , wherein:
 the metallic fittings are formed at their respective distal ends with flanges incorporating shoulders and circumscribing the base of the respective bosses;   the respective connector passages are configured to pass through respective metallic fitting flanges; and   the sleeves incorporate flanges on respective distal extremities configured for abutment against the shoulders of respective end fittings, the sleeve flanges incorporating the passage for routing respective connector mating links.   
   
   
       17 . The pipe string of  claim 13 , wherein:
 the composite walls are formed with an exterior surface tapering narrowingly from an intermediate point on the exterior surface toward the pipe first and second extremities and an interior surface tapering expandingly from an intermediate point of the walls toward the pipe first and second extremities;   the sleeves are formed with a tapered interior surface on their respective proximate extremities configured to receive the respective pipe segment extremities and indexed to fittingly match the tapered exterior surface of respective pipe segment first and second extremities; and   the connectors are formed with a tapering exterior surface narrowing from an intermediate point along a connector exterior surface to the connector proximal ends and configured for receipt within the sleeves and indexed to the interior surface of respective pipe segment extremities.   
   
   
       18 . The pipe string of  claim 11 , further comprising:
 insulator rings made of an electrically insulative material positioned adjacent respective bosses; and   the connector mating links projecting through respective insulator rings in electrical engagement with respective contact ring.   
   
   
       19 . The pipe string of  claim 18 , wherein:
 the insulator rings are made from an elastomeric material.   
   
   
       20 . The pipe string of  claim 18 , further comprising:
 piercing means incorporated within the flanges of the respective female boss for piercing the insulator ring of the male boss.   
   
   
       21 . The pipe string of  claim 18 , wherein:
 the insulator rings include one or more axially projecting pockets;   the conductive contact ring incorporates one or more legs projecting in electrical connection from the contact ring configured for receipt within the respective pockets;   respective fittings include an abutment surface incorporating one or more bores operative for receipt of the insulator ring pockets; and   at least one mating connector link projecting longitudinally through the bores of the respective abutment surfaces and through the respective insulator ring pockets in conductive contact with the contact ring legs.   
   
   
       22 . The pipe string of  claim 20 , wherein:
 the insulative material is constructed to flow out from the respective insulator rings when pierced and fills voids surrounding the contact rings of adjacent fittings.   
   
   
       23 . The pipe string of  claim 9 , wherein:
 the mating connector links are optical fibers.   
   
   
       24 . The pipe string of  claim 13 , wherein:
 the composite pipe segments, sleeve walls, and connectors are formed with respective sets of holes configured to be aligned upon receipt of the composite pipe segment through the sleeve and connectors; and   further comprising a set of fasteners configured for receipt within the respective holes for cooperating in coupling the pipes, sleeves, and connectors together.   
   
   
       25 . The pipe string of  claim 13 , wherein:
 the sleeves further include respective longitudinal grooves on their exterior surface aligned with the respective passages for routing the respective connector mating links projecting longitudinally within respective grooves through the respective sleeve shoulders.   
   
   
       26 . A method for fixing the ends of composite pipe segments within metal end fitting assemblies, comprising the steps of:
 forming the exterior and interior surface portions of each end of said segment ends to define opposed frustoconical surfaces;   inserting each end of said composite pipe segment into an annular gap formed between concentrically nested exterior and interior tubular end pieces conformed to thereby center the nested end pieces along the corresponding ones of said frustoconical surfaces on each said pipe segment end;   bonding the interior and exterior end surfaces of each end of said pipe segment to the corresponding surfaces of said exterior and interior end pieces;   welding together the peripheral edges of said interior and exterior end pieces distal of said interior and exterior surfaces while concurrently cooling those portions of said end pieces that are bonded to the ends of said segment; and   pressing in interference fit a plurality of radially aligned pins through the bonded combination of said segment ends received between said exterior and interior end pieces.   
   
   
       27 . A method according to  claim 26  wherein:
 the step of bonding includes the further step of aligning the adjacent portions of said interior and exterior pieces into intimate contact with the corresponding ones of said frustoconical surfaces.   
   
   
       28 . A method according to  claim 26  wherein:
 said step of forming further includes wrapping graphite fibers together with imbedded conductors; and   said step of bonding further includes conveying the ends of said conductors through said interior pieces.