1. Field of the Disclosure
The present disclosure relates to couplings for an expandable tubular.
2. Description of the Related Art
In the oil and gas exploration and production industry, expandable tubing has been developed and has a variety of uses. Expandable tubing offers a number of advantages over conventional borehole tubing, as the expandable tubing can be run into a borehole in an unexpanded state and subsequently expanded downhole. This allows the tubing to be run through existing tubing and then expanded to a larger diameter within the borehole.
There exists a need in the art for an expandable connection which maintains sealing integrity before, during, and after expansion.
The present disclosure relates to couplings for an expandable tubular. In one embodiment, an expandable tubular for use in a wellbore includes: a pin formed at a first longitudinal end of the expandable tubular; a box formed at a second longitudinal end of the expandable tubular; a tubular body connecting the pin and the box; and an elastomeric seal disposed in a groove of the box. Each of the pin and box has: a torque shoulder; and a thread. The pin has an asymmetric protrusion formed on an inner surface thereof.
In another embodiment, an expandable tubular connection for use in a wellbore includes: a pin made from a ductile steel or ductile corrosion resistant alloy and having a torque shoulder, a thread, a seal groove, a seal receptacle, a metallic seal face, and an asymmetric protrusion formed on an inner surface thereof; an elastomeric seal disposed in the pin seal groove; a box made from a ductile steel or ductile corrosion resistant alloy and having a torque shoulder, a thread, a seal groove, a seal receptacle, and a metallic seal face; and an elastomeric seal disposed in the box seal groove. A second end of the protrusion is adjacent to the box seal groove. A first end of the first protrusion is adjacent to an end of the box metallic seal face.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.
Each expandable tubular 5 may include the pin 6 formed at an upper longitudinal end thereof, the box 7 formed at a lower longitudinal end thereof, a body 8 connecting the pin and the box, and one or more seals, such as an o-ring 9p carried by the pin and an o-ring 9b carried by the box. The pin 6, the box 7, and the body 8 may each be made of a ductile material capable of sustaining plastic deformation, such as a metal or alloy (i.e., steel). The seals 9p,b may each be made from an elastomeric material, such as an elastomer, an engineering thermoplastic, or a copolymer thereof. The pin 6, box 7, and body 8 may be integrally formed from a blank tubular (not shown). The box 7 may be formed by expanding, such as by swaging, an end of the blank tubular. The swaged end may then be stress relieved and the box profile machined into an inner surface of the blank tubular.
Alternatively, the pin and/or box may be welded to the body. Alternatively, the metal or alloy may be corrosion resistant, such as stainless steel or a nickel based alloy.
The expandable tubulars 5u,b may be connected together at a surface of a wellbore according to normal stab-in and threading procedures to form a string of expandable tubing. The stab-in procedures can be performed with tubulars arranged in a pin up and a box down configuration. The made up expandable tubulars 5u,b may then be deployed into the wellbore to a desired depth on a workstring 20 (
Alternatively, each tubular 5 may have pins at both ends thereof and a separate coupling (not shown) having two box ends may be used to assemble the tubulars 5u,b. Alternatively, the tubulars may be connected in a box up and pin down configuration. Alternatively, the expander may be a rotary expansion tool having pressure actuated rollers. Alternatively, coiled tubing may be used instead of the drill pipe.
The connection 5c may include the pin 6b of the lower tubular 5b screwed together with the box 7u of the upper tubular 5u and one or more extrusion gaps, such as a leading gap 18f and a trailing gap 18t. Each box 7 may include a metallic seal face 10b, a seal groove 11b, a thread 12b, a seal receptacle 13b, a torque shoulder 14b, and an extrusion taper 17b. Each pin 6 may be complementary to the respective box 7 and may include a metallic seal face 10p, a seal groove 11p, a thread 12p, a seal receptacle 13p, a torque shoulder 14p, a protrusion 15, and an extrusion taper 17p.
The metallic seal face 10p may be formed in an outer surface of the pin 6 and be located at end thereof distal from the body 8. The metallic seal face 10b may be formed in an inner surface of the box 7 and may form an end thereof adjacent to the body 8. The seal faces 10b,p may be sized to form a radial interference fit during makeup for providing pressure integrity during deployment into the wellbore and during expansion. Each metallic seal face 10b,p may taper such that the respective pin and box thickness increases from the respective distal end thereof the toward the body 8.
Each torque shoulder 14b,p may be formed in an outer surface of the respective box 7 and pin 6 and be perpendicular to a longitudinal axis of the tubulars 5u,b. The torque shoulder 14b of the box 7 may be located at an end thereof distal from the body 8 and the torque shoulder 14p of the pin 6 may form an end thereof adjacent to the body 8. External location of the torque shoulders 14b,p may allow for visual inspection of the engaged shoulders after makeup.
The pin groove 11p may be formed in an outer surface of the pin 6 and located between the torque shoulder 14p and the thread 12p. The box groove 11b may be formed in an inner surface of the box 7 and located between the thread 12b and the metallic seal face 10b. The box groove 11b may further have a trapezoidal cross section to retain the o-ring 9b therein. The pin receptacle 13p may be formed in an outer surface of the pin 6 and located between the metallic seal face 10p and the thread 12p. The box receptacle 13b may be formed in an inner surface of the box 7 and located between the torque shoulder 14b and the thread 12b.
Each thread 12b,p may have a tapered form such that the respective pin and box thickness increases from a respective end thereof distal from the body 8 toward the body. The tapered threadform may facilitate stabbing and makeup and maximize compressive and/or tensile strength of the connection 5c. Each thread 12b,p may also have a hooked tension flank form to discourage separation during expansion and deployment into the wellbore. Each thread 12b,p may also have a multi-start form, such as a double start 16a,b form, to reduce wear on the o-rings 9b,p during makeup of the connection 5c.
The extrusion taper 17p may be formed in an outer surface of the pin 6 and located between the seal receptacle 13p and the thread 12p. The extrusion taper 17b may be formed in an inner surface of the box 7 and located between the groove 11b and the thread 12b. Each extrusion taper 17b,p may taper such that the respective pin and box thickness increases from the respective distal end thereof the toward the body 8. The leading extrusion gap 18f may be formed between the pin extrusion taper 17p and the box seal groove 11b. The trailing extrusion gap 18t may be formed between an engaged portion of the metallic seal faces 10b,p and the box seal groove 11b.
The protrusion 15 may be formed on an inner surface of the pin 6 located adjacent to the trailing extrusion gap 18t and adjacent to the distal end thereof. A lower/leading end of the protrusion 15 may be aligned with a lower end of the metallic seal face 10p and a centerline of the box groove 11b. An upper/trailing end of the protrusion 15 may be aligned with a lower end of the box seal face 10b. The protrusion may be asymmetric and formed by a leading taper 15f, a mid taper 15m, and a trailing taper 15t. The leading and trailing tapers 15f,t may each be sharp and the mid taper 15m may be gradual. The mid taper 15m may have a length substantially greater than respective lengths of the leading and trailing tapers 15f,t. The trailing taper 15t may taper such that the pin thickness increases from the distal end thereof toward the body 8 and the mid and leading tapers 15f,m may taper such that the pin thickness decreases from the distal end thereof toward the body 8. Alternatively, the leading taper 15f may be omitted.
Alternatively, for some applications, a unidirectional seal may be sufficient and the pin o-ring and groove may be omitted. Alternatively, the metallic seal faces of the pin and box may be omitted.
The connection 5c may be especially beneficial for larger expandable tubulars, i.e. having a nominal size greater than or equal to six inches.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow.
Number | Date | Country | |
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61789901 | Mar 2013 | US |