Universal carrier for grippers in a coiled tubing injector

Abstract

The gripping element of a coiled tubing injector has a carrier and a removable gripping shoe mounted to the carrier. The removable shoe slides onto slots formed on the carrier and is floated on the carrier by inserting an elastomeric pad sandwiched between the carrier and shoe. A manually depressible spring along ones side of the carrier prevents the shoe from sliding out of the slots during operation of the injector.

What is claimed is: 
     
       1. A tube conveying apparatus comprising:
 a frame;   a pair of continuous drive chains supported on the frame and revolving in a commom plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and   a plurality of grippers carried on each of the pair of drive chains;   wherein, each gripper includes a carrier mounted to the chain and a pipe gripping shoe mounted to the carrier, the shoe including a plurality of tongues for sliding, in directions generally perpendicular to the common plane, in corresponding grooves formed by the carrier for retaining the shoe on the carrier.   
     
     
       2. The apparatus of  claim 1  wherein the carrier includes a releasable retaining member for preventing the shoe from sliding out of the carrier along one of the directions perpendicular to the common plane. 
     
     
       3. The apparatus of  claim 1  further including a depressible spring extending from the carrier in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane, wherein depressing the spring allows sufficient clearance between the spring and the shoe to allow the shoe to slide out of carrier. 
     
     
       4. The apparatus of  claim 1  further wherein, in each gripper, the carrier includes a leaf spring having an arched portion between two end portions, each end portion extending into one of two slots formed in the carrier, the arched portion extending in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane; whereby manually depressing the arched portion toward the carrier causes each of the two end portions of the spring to slide further into the slots and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier. 
     
     
       5. The apparatus of  claim 4  wherein each of the slots have an opening opposite where the end of the leaf springs enter, whereby debris which may accumulate in each of the slots is forced out of the slots by depressing the leaf spring. 
     
     
       6. The apparatus of  claim 4  wherein, in each gripper,
 the carrier has an outer periphery, and the grooves are formed by ledges extending along opposites sides of the outer periphery of the carrier; and 
 the leaf spring is disposed along the periphery of the carrier, between the ledges. 
 
     
     
       7. The apparatus of  claim 6  wherein, in each gripper,
 the tongues on each shoe include four lugs; and 
 the ledges extending along opposite sides of the outer periphery of the carrier have openings through which an opposing pair of lugs may pass as the shoe is lowered toward the carrier during mounting, while the other lugs pass by to the side the ledges. 
 
     
     
       8. The apparatus of  claim 1  wherein the carrier further includes a fixed rail for retaining sliding movement of a shoe in one of the directions perpendicular to the common plane, and a releasable retaining member for preventing the shoe from sliding out of the carrier along the other of the directions perpendicular to the common plane. 
     
     
       9. The apparatus of  claim 1  further including an elastomeric pad positioned between the shoe and the carrier. 
     
     
       10. A tubing gripper comprising:
 a carrier having front and back sides, means for mounting the back side of the carrier to a chain, two opposing slots formed on the front side of the carrier, each of the slots having an open end and closed end; and   a pipe gripping shoe removably mounted to the carrier, the shoe including a base portion having lugs for sliding into the open ends of the slots, the slots and lugs thereby cooperating to retain the shoe on the carrier.   
     
     
       11. The gripper of  claim 10  further comprising manually-depressible means for blocking, in an extended position, movement of the lugs out of the open ends of the slots, and for allowing movement, when in a depressed position, of the lugs out of the open ends of the slots of the carrier. 
     
     
       12. The gripper of  claim 11  wherein the means for blocking movement includes a spring. 
     
     
       13. The gripper of  claim 12  wherein the spring is a leaf spring having an arched portion between two ends inserted into slits in the carrier, the arched portion extending in a plane generally perpendicular to the axis for blocking sliding of the shoe out of the carrier along one of the directions parallel to the axis; whereby, manually depressing the arched portion toward the carrier causes each of the two ends of the spring to slide further into the slits and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier. 
     
     
       14. The gripper of  claim 11  wherein the means for blocking movement incudes a leaf spring having an arched portion between two ends inserted into slits formed in the carrier, the arched portion extending in a plane generally perpendicular to the pivot axis of the carrier for blocking sliding of the shoe out of the carrier along one of the directions parallel to the axis; whereby manually depressing the arched portion toward the carrier causes each of the two ends of the spring to slide further into the slits and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier. 
     
     
       15. The gripper of  claim 10  wherein the carrier has an outer periphery, and wherein the slots are defined by ledges located along opposites sides of the side edges. 
     
     
       16. The gripper of  claim 10  further comprising an elastomeric pad positioned between the shoe and the carrier. 
     
     
       17. The gripper of  claim 10  further comprising a releasable retaining member for blocking movement of the lugs out of the open ends of the slots. 
     
     
       18. A tube conveying apparatus comprising:
 a frame;   a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and   a plurality of grippers carried on each of the first and second drive chains;   wherein, each gripper includes,
 a carrier mounted to the chain, 
 a pipe gripping shoe retained on the carrier, the pipe gripping shoe having a gripping portion having a rigid shape that fits around substantially one-half of an outer circumference of tubing to be injected, and 
   an elastomeric pad positioned between the carrier and shoe for floating the shoe on the carrier;   wherein,   the carrier has two opposing slots, each of the slots having an open end and closed end; and   the pipe gripping shoe has lugs for sliding into the open ends of the slots, the slots and lugs thereby cooperating to retain the shoe on the carrier.   
     
     
       19. A tube conveying apparatus comprising:
 a frame;   a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and   a plurality of grippers carried on each of the pair of drive chains;   wherein, each gripper includes a carrier mounted to the chain and a gripping shoe connected to the carrier by means of tongues that slide into corresponding grooves in directions generally perpendicular to the common plane for retaining the shoe on the carrier.   
     
     
       20. The apparatus of  claim 19  wherein the carrier includes a retaining member for preventing the shoe from sliding out of the carrier alone one of the directions perpendicular to the common plane. 
     
     
       21. The apparatus of  claim 19  further including a depressible spring extending from the carrier in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane, wherein depressing the spring allows sufficient clearance between the spring and the shoe to allow the shoe to slide out of carrier. 
     
     
       22. The apparatus of  claim 19  further wherein each gripper includes a leaf spring having an arched portion between two end portions, each end portion extending into one of two slots formed in the carrier, the arched portion extending in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane; whereby manually depressing the arched portion toward the carrier causes each of the two ends of the spring to slide further into the slots and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier. 
     
     
       23. The apparatus of  claim 22  wherein each of the slots have an opening opposite where the end of the leaf springs enter, whereby debris which may accumulate in each of the slots is forced out of the slots by depressing the leaf spring. 
     
     
       24. The apparatus of  claim 19  further including an elastomeric pad positioned between the shoe and the carrier. 
     
     
       25. A coiled tubing injector for inserting coil tubing into, and removing coiled tubing from, a well bore comprising:
 a frame;   a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and   a plurality of grippers carried on each of the pair of drive chains;   wherein, each gripper is comprised of a carrier mounted to the chain and a pipe gripping shoe of unitary construction mounted to the carrier, the shoe including a plurality of tongues for sliding in corresponding grooves formed by the carrier for retaining the shoe on the carrier, the gripper further comprising an elastomeric pad positioned between the carrier and the shoe for floating the shoe on the carrier.   
     
     
       26. The coiled tubing injector for inserting coil tubing into, and removing coiled tubing from, a well bore of claim 25 wherein the carrier includes a releasable retaining member for preventing the tongues from sliding out of the grooves. 
     
     
       27. A coiled tubing injector for inserting coil tubing into, and removing coiled tubing from, a well bore comprising:
 a carrier comprising means for mounting the back side of the carrier to a chain and two opposing slots formed on the carrier for mounting pipe gripping shoes;   a pipe gripping shoe of unitary construction removably mounted to the carrier, the shoe including a base portion having lugs for sliding into the slots, the slots and lugs thereby cooperating to retain the shoe on the carrier; and   an elastomeric pad positioned between the shoe and the carrier for floating the shoe on the carrier.   
     
     
       28. A coiled tubing injector for inserting coil tubing into, and removing coiled tubing from, a well bore comprising:
 a frame;   a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and   a plurality of grippers carried on each of the first and second drive chains;   wherein, each gripper includes,
 a carrier mounted to the chain, 
 a pipe gripping shoe retained on the carrier, the pipe gripping shoe having a gripping portion having a unitary construction and a rigid shape that fits around a portion of an outer circumference of tubing to be injected, and 
 an elastomeric pad positioned between the carrier and shoe for floating the shoe on the carrier; and 
   wherein,
 the carrier has two opposing slots; and 
 the pipe gripping shoe has lugs for sliding into the slots, the slots and lugs thereby cooperating to retain the shoe on the carrier. 
   
     
     
       29. A coiled tubing injector for inserting coil tubing into, and removing coiled tubing from, a well bore comprising:
 a frame;   a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and   a plurality of grippers carried on each of the pair of drive chains;   wherein, each of the plurality of grippers is comprised of a carrier mounted to the chain, a gripping shoe of unitary construction connected to the carrier by means of tongues that slide into corresponding grooves, and an elastomeric pad positioned between the carrier and the gripping shoe for floating the gripping shoe on the carrier.   
     
     
       30. The coiled tubing injector for inserting coiled tubing into, and removing coiled tubing from, a well bore of claim 19 wherein the carrier includes a retaining member for preventing the tongues from sliding out of the grooves.