METHODS FOR REPLACING PIN ENDS AND REPAIRING COATINGS ON COATED CONTINUOUS SUCKER RODS

Abstract

hi a method for repairing a fractured coated continuous sucker rod, the pin end segment of the broken rod is discarded, the remaining rod is cut off; and the existing rod coating is trimmed back from the rod cut-off point. A replacement pin end, incorporating a rod portion and an upset pin end, is welded to the cut-off end of the sucker rod. A resilient cylindrical repair sleeve with a longitudinal slit is spread open and urged by radial force over and around the rod portion of the replacement pin end and the adjoining exposed portion of the sucker rod. Using an appropriate fusing apparatus, the edges of the repair sleeve's longitudinal slit are then fused together, and one end of the sleeve is circumferentially fused to the trimmed-back existing coating. Repair sleeves can also be used to repair damaged sections of coating on unfractured sucker rods.

Claims

1. A method for repairing a fractured continuous sucker rod, where the continuous sucker rod prior to fracture comprised an elongate rod section contiguous with a pin end, plus a circumferential plastic coating on the rod section, and where the fracture has resulted in the sucker rod being divided into a broken end segment including the upset pin and an attached remnant of the rod section, plus a remaining rod portion, said method comprising: discarding the broken end segment; cutting off the remaining rod portion at a selected rod cut-off point; trimming the existing coating on the remaining rod portion back to a coating trim point a selected distance from the rod cut-off point; providing a replacement pin end incorporating a replacement rod portion and a pin end portion, said replacement rod portion having a free end; positioning the replacement pin end in alignment with the remaining rod portion with the replacement rod portion's free end adjacent to the cut-off end of the remaining rod portion; welding the replacement rod portion's free end to the cut-off end of the remaining rod portion; providing a repair sleeve having a longitudinal slit; spreading said longitudinal slit and installing the repair sleeve over and around the replacement rod portion of the replacement pin end and an exposed portion of the remaining rod portion; and fusing the edges of the longitudinal slit together.

2. The method as in claim 1 further comprising fusing an end of the repair sleeve to the existing coating on the remaining rod portion at the coating trim point.

3. A method for repairing a plastic coating on a sucker rod, said method comprising: removing a damaged portion of the plastic coating between a first coating cut-off point and a second coating cut-off point, thereby exposing a portion of the sucker rod; providing a repair sleeve having a longitudinal slit, said repair sleeve being of a length to fit between said first and second coating cut-off points; spreading said longitudinal slit and installing the repair sleeve over the exposed portion of the sucker rod; and fusing the edges of the longitudinal slit together.

4. The method as in claim 3 further comprising fusing an end of the repair sleeve to the existing coating on the sucker rod at a selected one of the first coating cut-off point and the second coating cut-off point.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Embodiments in accordance with the present disclosure will now be described with reference to the accompanying Figures, in which numerical references denote like parts, and in which:

[0042] FIG. 1 is schematic illustration of a prior art pump jack reciprocating a sucker rod to operate a downhole pump to produce hydrocarbon fluids from a subsurface formation.

[0043] FIGS. 2-4 illustrates sequential steps in one embodiment of a method for replacing an upset pin end of a sucker rod in accordance with the present disclosure.

[0044] FIG. 5 is a cross-section through a replacement pin end in accordance with the method step illustrated in FIG. 4, showing a repair sleeve in the process of being mounted around the rod portion of the replacement pin end.

[0045] FIG. 6 is a cross-section similar to FIG. 5, showing the repair sleeve fully disposed over and around the rod portion of the replacement pin end.

[0046] FIGS. 7-8 illustrate sequential steps in one embodiment of a method for repairing a damaged section of coating on a coated sucker rod in accordance with the present disclosure.

DETAILED DESCRIPTION

[0047] FIG. 2 illustrates the pin end region of a coated continuous steel sucker rod comprising a steel rod 10 (having a coating 20) and an upset pin end 30 (having threads 32, wrench flats 34, and a transition section 36), where rod 10 has experienced a fracture at a point X near upset pin end 30. FIG. 2 also conceptually illustrates steps in one embodiment of a method for replacing the pin end of a fractured coated continuous sucker rod and for repairing the coating after the pin end has been replaced.

[0048] As illustrated in FIG. 2, the rod fracture at point X has created a broken end segment outboard of the fracture comprising upset pin end 30 and an attached remnant section 10X of rod 10. One step in the method is to discard the broken end segment. Additional steps are to cleanly cut off the remaining portion of rod 10 at a cut-off point Y a selected distance from fracture point X (discarding the rod portion 10A between fracture point X and cut-off point Y), and to trim coating 20 back to a point Z away a selected distance from cut-off point Y (discarding the trimmed portion 20X of coating 20). The step of trimming coating 20 can be performed either before or after the step of cutting off rod 10 at cut-off point Y.

[0049] As illustrated in FIG. 3, the cut-off end 10Y of the remaining rod portion 10 (i.e., at cut-off point Y) is prepared for welding as appropriate. Then, a replacement upset pin end 100, incorporating a steel replacement rod portion 110 (with a free end 110Y) and an upset pin end 130 (with threads 132, wrench flats 134, and a transition section 136), is positioned in alignment with rod 10 as shown, with free end 110Y of replacement rod portion 110 positioned closely adjacent to cut-off end 10Y of rod 10, and with free end 110Y also having been prepared for welding as appropriate. Existing rod end 10Y and replacement rod end 110Y are then welded together to restore required structural strength, and the resultant weld zone 115 is ground down as necessary to match the diameter of the steel rods, as seen in FIG. 4.

[0050] With the rod repair phase of the method thus being completed, the next step is to restore or extend the integrity of coating 20 along the full length of the repaired rod. This is achieved by first providing a cylindrical repair sleeve 120, made from a suitable resilient material preferably (but not necessarily) corresponding to the material of coating 20, and having an inside diameter matching the diameter of the uncoated rod(s). (In cases where the sucker rod has a semi-elliptical or other non-circular cross-section, the repair sleeve would have a corresponding configuration.) As illustrated in cross-section in FIGS. 5 and 6, repair sleeve 120 is formed or provided with a longitudinal slit 122, such that repair sleeve 120 can be spread open (using suitable known tools and methods) to temporarily take on a generally C-shaped cross-section so that it can be urged over and around replacement rod 110 (and the exposed portion of existing rod 10 between point Y and point Z) by the application of radial force F as conceptually illustrated in FIG. 5. This results in repair sleeve 120 becoming circumferentially disposed around replacement rod 110 and the exposed portion of existing rod 10 as shown in FIG. 6 (and FIG. 4).

[0051] With repair sleeve 120 thus in position, longitudinal slit 122 in sleeve 120 may be sealed by fusing the edges of slit 122 using an appropriate fusing apparatus (such as an Injectiweld device or other suitable plastic welding apparatus). Preferably, the repair sleeve 120 and the trimmed-back existing coating 20 will also be fused together by similar means at point Z. In preferred embodiments of the method, longitudinal slit 122 will be formed so as to define a gap G120 after the installation of repair sleeve 120 around replacement rod 110, as shown in FIG. 6, to facilitate deposition or injection of molten welding rod material or other fusing material during the slit-fusing step. For similar reasons, repair sleeve 120 will preferably be positioned so as to create a circumferential gap G22 between sleeve 120 and the trimmed-back end 22 of existing coating 20.

[0052] To this point, the present disclosure has addressed coating repair primarily in the context of replacing a pin end on a fractured sucker rod. However, the coating repair methodology previously described herein can be readily adapted for repairing damaged coatings on otherwise serviceable coated sucker rods (including coated jointed sucker rods), as illustrated in FIGS. 7 and 8. In the event that a damaged section of coating 20 is identified during well maintenance and servicing operations, the damaged coating section 20X can be cut out between undamaged coating ends 22A and 22B, as shown in FIG. 7. Then, one or more repair sleeves 120 can be disposed around the exposed section of sucker rod 10 as shown in FIG. 8 (and in FIG. 6), preferably so as to form circumferential gaps G22A and G220 between sleeve(s) 120 and undamaged coating ends 22A and 22B to facilitate effective fusing or sealing between sleeve(s) 120 and the undamaged original coating 20.

[0053] It will be readily appreciated by persons skilled in the art that various modifications of embodiments in accordance with the present disclosure may be devised without departing from the scope and teaching of the present disclosure, including modifications which may use materials and apparatus hereafter conceived or developed (such as but not limited to coating materials, sleeve materials, and apparatus and materials for bonding thermoplastics. It is to be especially understood that the disclosure is not intended to be limited to any described or illustrated embodiment, and that the substitution of a variant of a claimed element, step, or feature, without any substantial resultant change in operation or functionality, will not constitute a departure from the intended scope of the claim.

[0054] In this patent document, any form of the word comprise is to be understood in its non-limiting sense to mean that any item or step following such word is included, but items or steps not specifically mentioned are not excluded. A reference to an element by the indefinite article a does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of the word typical is to be understood in the non-limiting sense of common or usual, and not as suggesting essentiality or invariability.