Patent Publication Number: US-2003222409-A1

Title: Non-rotating expandable connection with collapsing type seal

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09/457,997, filed on Dec. 9, 1999. That application is incorporated by reference in its entirety. 
    
    
     
       BACKGROUND OF INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The invention is related to threaded tubular joints usable in oil and gas well drilling and production, such as tubing, casing, line pipe, and drill pipe, commonly known collectively as oilfield tubular goods. More particularly, the invention relates to a seal for tubular joints for connecting male (pin) and female (box) members.  
       [0004] 2. Background Art  
       [0005] Threaded tubular connections are used for joining segments of conduits end-to-end to form a continuous conduit for transporting fluid under pressure. Oilfield tubular goods generally use such threaded connections for connecting adjacent sections of conduit or pipe. Examples of such threaded end connections designed for use on oilfield tubular goods are disclosed in U.S. Pat. Nos. 2,239,942; 2,992,019; 3,359,013; RE 30,647; and RE 34,467, all of which are assigned to the assignee of this invention.  
       [0006] In U.S. Pat. No. RE 30,647 issued to Blose, a particular thread form or structure is disclosed for a tubular connection that provides an unusually strong joint while controlling the stress and strain in connected “pin” (male thread) and “box” (female thread) members to within acceptable levels. The pin member has at least one generally dovetail-shaped external thread whose width increases in one direction along the pin, while the box member has at least one matching generally dovetail-shaped internal thread whose width increases in the other direction. The mating set of helical threads provide a wedge-like engagement of opposing pin and box thread flanks that limit the extent of relative rotation between the pin and box members, and define a forcible make-up condition that completes the connection. In this thread structure, the angles of the flank shoulder, as well as the thread width, can be used to control the stress and strain preload conditions induced in the pin and box members for a given make-up torque. Thus, by tailoring the thread structure to a particular application or use, the tubular connection or joint is limited only by the properties of the materials selected.  
       [0007] As shown in FIG. 1, a prior art tubular connection  10  includes a pin member  11  and a box member  12 . Box member  12  has a tapered, internal, generally dovetail-shaped thread structure  14  formed thereon which is adapted for engaging complementary tapered, external, generally dovetail-shaped thread structure  15  formed on pin member  11  to mechanically secure the box  12  and pin  11  members in a releasable manner.  
       [0008] Internal thread  14  on the box member  12  has stab flanks  18 , load flanks  16 , roots  20 , and crests  24 . The thread  14  increases in width progressively at a uniform rate in one direction over substantially the entire helical length of thread  14 . External thread  15  of pin member  11  has stab flanks  19 , load flanks  17 , roots  21 , and crests  25 . The thread  15  increases in width progressively at a uniform rate in the other direction over substantially the entire helical length of thread  15 . The oppositely increasing thread widths and the taper of threads  14  and  15 , cause the complementary roots and crests of the respective threads  14  and  15  to move into engagement during make-up of the connection  10  in conjunction with the moving of complementary stab and load flanks into engagement upon make-up of the connection.  
       [0009] The pin member  11  or the box member  12  defines the longitudinal axis  13  of the made-up connection  10 . The roots and crests of the box and pin members are flat and parallel to the longitudinal axis of the connection and have sufficient width to prevent any permanent deformation of the threads when the connection is made up.  
       [0010] An important part of any connection is a seal for keeping the conduit fluid pressure-tight at the connections. Typically connections will be designed to include metal-to-metal seals therein. Metal-to-metal seals have the advantage of not requiring gaskets or other additional sealing devices, which would typically have to be replaced periodically as the connections are coupled and uncoupled. Metal seals are created when contact pressure between two metal surfaces exceeds the fluid pressure to be sealed. Typically the contact pressures are created during make up of the connection.  
       [0011] More recently, oilfield tubular goods have been developed which can be plastically radially expanded from their initial diameters after being installed for the intended application. See for example, R. D. Mack et al,  How in situ Expansion Affects Casing and Tubing Properties,  World Oil, July 1999, Gulf Publishing Co., Houston, Tex., for a description of plastically radially expanding oilfield tubular goods. This article is incorporated by reference in its entirety. In particular, this article discusses the use of plastically radially expandable tubular goods. Plastically radially expandable tubular goods have particular application as casing in oil and gas producing wells. It has been difficult to seal plastically radially expandable tubular connections using metal-to-metal seals known in the art.  
       SUMMARY OF INVENTION  
       [0012] The invention is a plastically radially expansible conduit connection or coupling. The connection includes a first sealing surface disposed proximal to an end of a pin member of the connection, and it includes a corresponding second sealing surface disposed proximal to an end of a box member of the connection. The first and said second sealing surfaces are substantially opposite each other upon connection of the pin and box members. The connection also includes a first locking surface proximal to the sealing surface on the pin member and a second locking surface proximal to the second sealing surface on the box member. The first and second sealing surfaces and the first and second locking surfaces each having a diameter such that prior to plastic radial expansion of the box member and the pin member the locking surfaces are proximal to each other and do not contact each other, and after plastic radial expansion the first and the second sealing surfaces develop a contact pressure, and the first and second locking surfaces are engaged. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0013]FIG. 1 shows a prior art tubular threaded connection.  
     [0014]FIG. 2 shows one embodiment of a connection seal of the invention prior to plastic radial expansion of the tubular joints and connection.  
     [0015]FIG. 3 shows one embodiment of a connection seal of the invention after plastic radial expansion of the tubular joints and connection.  
     [0016]FIG. 4 shows one embodiment of a connection of the invention that is being plastically radially expanded.  
     [0017]FIG. 5 shows one embodiment of a casing string that is being plastically radially expanded.  
     [0018]FIG. 6A shows a top view cross-section of one embodiment of clearance surfaces of the invention prior to plastic radial expansion.  
     [0019]FIG. 6B shows a top view cross-section of one embodiment of clearance surfaces of the invention after plastic radial expansion.  
     [0020]FIG. 7A shows one embodiment of clearance surfaces of the invention prior to plastic radial expansion  
     [0021]FIG. 7B shows one embodiment of clearance surfaces of the invention after plastic radial expansion.  
     [0022]FIG. 8 shows one embodiment of clearance surfaces of the invention after plastic radial expansion. 
    
    
     DETAILED DESCRIPTION  
     [0023]FIG. 2 shows one example of a tubular connection  10 A as used on plastically radially expandable tubular goods. The example shown in FIG. 2 is for a threaded coupling. FIG. 2 is a cross-section through only one side of the threaded tubular connection  10 A, and the view shown in FIG. 2 should therefore be thought of as rotationally symmetric about the axis (not shown) of the tubular connection  10 A. The tubular connection  10 A is formed by joining a male-threaded “pin” member  30  to a female-threaded “box” member  32 . The pin  30  and box  32  members have thereon corresponding threads  36  and  34 , respectively, which when engaged provide axial coupling force to join tubular joints together. The threads  34 ,  36  can be any type known in the art for coupling together tubular goods, and may be a sealing type or a non-sealing type. The particular type of threads selected will depend, as is known in the art, on the intended use of the tubular goods being joined by the connection  10 A. The type of threads is not intended to limit the invention. It should also be noted that the connection  10 A can be formed wherein segments of conduit (not shown separately) include a pin at both ends and are connected by a short segment having box members at both ends, the short segment being known as a “collar”. The connection  10 A can also be formed wherein each segment of conduit includes therein a pin at one end and a box at the other. Either conduit connection will work with this invention.  
     [0024] In the example shown in FIG. 2, the box member  32  includes at its thread start end a clearance surface  42  and a sealing surface  44 . The pin member  30  includes thereon at the end of the threads  36  a corresponding clearance surface  38  and sealing surface  40 . The clearance surfaces  38  and  42  on the pin member  30  and box member  32 , respectively, each may be parallel to the axis (not shown) of the connection  10 A each so as to define a generally cylindrical surface, or they may be tapered. Similarly, the sealing surfaces  40  and  44  may be parallel, but the sealing surfaces  40 ,  44  are preferably tapered as shown in FIG. 2. In the invention, the clearance between the clearance surfaces  38 ,  42  is greater than the clearance between the sealing surfaces  40 ,  44  prior to plastically radial expansion of the pin member  30  and box member  32 . The additional clearance between the clearance surfaces  38 ,  42  results in a radially-inward deformation of the seal surface area (particularly seal surface  44 ) on the box  32  when the box  32  is plastically radially expanded, which results in a high contact pressure between the sealing surfaces  40 ,  44 . In the embodiment shown in FIG. 2, the clearance surface  42  on the box  32  has a larger internal diameter than does the seal surface  40  on the box  32  to provide the larger clearance between corresponding clearance surfaces  38 ,  42  than the corresponding seal surfaces  40 ,  44 . It is also possible to provide larger clearance between the clearance surfaces  38 ,  42  by making the clearance surface  42  on the pin  30  with a smaller external diameter than the sealing surface  44  on the pin  30 . Any other combination of internal diameters on the box surfaces  38 ,  40  and external diameters on the pin surfaces  42 ,  44  which provides larger clearance between corresponding clearance surfaces  38 ,  42  will also work with the invention.  
     [0025] Although FIG. 2 shows the sealing surfaces  40 ,  44  as having a small amount of clearance between them prior to radial expansion of the pin  30  and box  32 , the sealing surfaces  40 ,  44  may also be in interference contact with each other. Where the sealing surfaces  40 ,  44  are in interference contact prior to plastically radial expansion, after radial expansion the sealing surfaces  40 ,  44  will contact each other at a higher contact pressure than prior to expansion as long as the clearance surfaces  38 ,  42  remain out of contact after expansion.  
     [0026] The amount of clearance between the clearance surfaces  38 ,  42  prior to plastically radial expansion will depend on, among other factors, the amount of radial expansion to be applied to the pin  30  and box  32  and the pre-expansion diameter of the pin  30  and box  32 . Generally, large clearance where the amount of expansion is small, or small clearance where the amount of expansion is to be large are not highly desirable. A preferred amount of clearance between the sealing surfaces is about 30 to 40 percent of the amount of plastic expansion to be applied, although other clearances will work with the invention, including an interference fit, as previously explained. A preferred pre-expansion clearance for the clearance surfaces is about 50 to 55 percent of the amount of plastic radial expansion, although other clearances will work with the invention. The important aspect is that the clearance surfaces  38 ,  42  retain some clearance therebetween after radial expansion of the box  32  and pin  30 .  
     [0027]FIG. 3 shows the connection  10 A after plastic radial expansion of the pin  30  and box  32 . As can be seen in FIG. 3, the sealing surfaces  40 ,  44  have been put into sealing contact with each other by reason of the plastic radial expansion of the pin  30  and box  32 . The clearance surfaces  38 ,  42  do not come into contact with each other as a result of the plastic radial expansion of the pin  30  and box  32 .  
     [0028] While the embodiment of the invention described herein includes a threaded coupling for joining segments of conduit, the invention does not require the use of threaded couplings. For example, J-slot connectors including locking pins on the pin end, with corresponding slots on the box end could provide axial coupling force to hold the pin and box together. Other types of couplings which do not use mating threads can also be devised by those skilled in the art.  
     [0029] In general, there are two primary types of methods for plastically radially expanding tubular goods. The first is a “cone” or “pig” type expansion, and the second is a “rotary” type expansion.  
     [0030] “Cone” or “pig” type expansion includes using a forming die that is moved through a tubular member in an axial direction. The forming die is larger than the inside diameter of the tubular member, and the forming die causes the tubular member to plastically radially expand as the die moves through the tubular member.  
     [0031] “Rotary” type expansion methods use a forming die that includes rotatable rollers. A rotary type die is also larger than the inside diameter of the tubular member, and it is rotated as it is forced through the tubular member in an axial direction. The combination of axial and torsional forces causes the tubular member to plastically radially expand as the die moves through the tubular member.  
     [0032] With rotary expansion, the forming die typically is rotated “to the right,” which means in a clockwise direction looking down the hole. Right-handed rotation is the standard direction for oilfield drillstrings. During rotary expansion, the right-hand rotation of the forming die will tend to loosen, or “break-out,” right-handed threads in the tubular connections, such as well casing. For this reason, expandable casing that is to be expanded using rotary methods typically are connected using left-handed threads.  
     [0033] During the expansion process, the forming die typically passes through each connection from pin to box. FIG. 4 shows a forming die, or “roller”  403 , as it passes through a threaded connection  405 . The roller  403  passes through the connection  405 , which, in this embodiment, is comprised of a pin member  415  and a box member  416 . In this embodiment, the roller  403  passes from the pin member to the box member  416 . This direction of movement is called “pinto-box.”  
     [0034] As the roller  403  moves pin-to-box, a pin member threaded section  409  is plastically radially expanded. This expansion pushes the pin member threaded section  409  into a box member threaded section  407 , causing the box member threaded section  407  to also plastically radially expand. Expansion also tends to axially stretch the tubular members  415 ,  416  and the connections (e.g.,  405  in FIG. 4). The pin member threaded section  409 , because it has a smaller diameter than the box member threaded section  407 , tends to stretch in the axial direction more than the box member threaded section  407  does. As a result, gaps develop between the threads (not shown), and the torsional preload on the connection  405  is reduced.  
     [0035] When the roller  403  moves axially into contact with the inside diameter of the box member  416 , the rotation of the roller  403  along with the reduced preload in the connection may cause the box member  416  to rotate with respect to the pin member  415 . In a right-handed connection, the right-handed rotation of the roller  403  would cause the box member  416  to unscrew, or “back off.” In a left-handed connection, the rotation of the roller  403  would cause the box member  416  to screw together, or “make-up.” 
     [0036] Connections in a casing string that have already been plastically radially expanded also may be susceptible to relative rotation. The gaps created between the threads during the expansion process, along with the rotation of the roller as it moves away from an expanded connection, may cause undesirable relative rotation in connections after the expansion process.  
     [0037]FIG. 5 shows a roller  501  that is being run downward through a casing string  511  in a borehole. A drillstring  502  is used to rotate the roller  501  in a right-handed direction (shown by arrow  504 ). FIG. 5 shows the roller  501  as a lower connection  514  is expanded.  
     [0038] As described above, an upper connection  512  that has been previously expanded by the roller  501  also may experience relative rotation between the pin and box member of that connection  512 . In particular, this may occur when the casing  511  is trapped by an obstruction  522  in the formation that prevents the free rotation of the casing string  511 . In contrast to the above, where a left-handed threaded connection that is being presently expanded will make-up due to the right-hand rotation of a roller, a previously expanded left-handed threaded connection will tend to back-off due to the rotation of the roller. Thus, in this embodiment, if the upper connection  512  is a left-handed connection, the rotation of the roller  501  will cause the upper connection to back-off. On the other hand, if the upper connection  512  is a right-handed connection, the rotation of the roller  501  will cause the upper connection  512  to make-up.  
     [0039]FIG. 5 shows a roller  501  that moves downward through a casing string  511 . Those having ordinary skill in the art will realize that the roller  501 , in certain embodiments, could move upward through the casing string  511 . In that case, a lower connection may experience relative rotation as the roller  501  moves upward through the casing string  511  and upper connections. No limitation is intended by a description of the direction of roller movement.  
     [0040]FIG. 6A shows one embodiment of an anti-rotation device  601  in accordance with an embodiment of the invention. FIG. 6A shows a cross-section taken through section A-A in FIG. 7A. The box member  611  and the pin member  621  are shown prior to plastic radial expansion. The box member  611  has a locking surface  613 . In the embodiment shown, the box member locking surface  613  is knurled so that it includes peaks  617  and grooves  615 . The pin member  621  also includes a locking surface  613 . The pin member locking surface  623  is similarly knurled to include corresponding peaks  625  and grooves  627 .  
     [0041] Prior to expansion, the peaks  625  on the pin member locking surface  623  and the peaks  617  on the box member locking surface  613  have diameters selected such that they will not contact each other. This enables the pin member  612  and the box member  611  to rotate with respect to each other during, for example, initial make-up of the connection.  
     [0042]FIG. 6B shows one embodiment of an anti-rotation device  601  after plastic radial expansion. The peaks  625  and grooves  627  of the pin member locking surface  623  engage with corresponding peaks  617  and grooves  615  of the box member locking surface  613 . This engagement prevents relative rotation between the pin member  621  and the box member  611 . It is noted that in some embodiments, such as the one shown in FIG. 6B, although the peaks  625  and grooves  627  of the pin member locking surface  623  are “engaged” with corresponding peaks  617  and grooves  615  of the box member locking surface  613 , the pin member locking surface  623  is not in contact with the box member locking surface  613 . If the box member  611  were to be rotated, it would cause rotational contact between the peaks  617 ,  625  of the locking surfaces  613 ,  623 . The contact between the peaks  625  of the pin member locking surface  623  and the peaks  617  of the box member locking surface  613  would prevent relative rotation. Such contact would be caused by relative rotation of the pin member  621  and the box member  611  and not by the radial expansion of the connection. In some other embodiments, there is contact between the locking surfaces  613 ,  623  after plastic radial expansion.  
     [0043]FIG. 7A shows a cross-section of a connection  700  with a collapsible seal  701  and an anti-rotation device  702  prior to plastic radial expansion. The pin member  730  includes a first sealing surface  740  and a first clearance surface  738 . The pin member also includes a first locking surface  711  disposed proximal the first sealing surface and the first clearance surface. The first locking surface  711  is knurled, and the section shown in FIG. 7A includes a groove. Likewise, the box member  732  has a second sealing surface  744  and a second clearance surface  742 . A second locking surface  721  is disposed proximal to the second sealing surface  744  and the second clearance surface  742 . The second locking surface  721  is also knurled, and the section shown in FIG. 7A includes a peak.  
     [0044] It is notes that the knurled locking surfaces  711 ,  721  each contain peaks and grooves. In the embodiment shown in FIG. 7A, the cross-section is taken at a point where there is a groove in the first locking surface  711  and a peak in the second locking surface  721 . A cross-section at a different point may show a peak in the first locking surface and a groove in the second locking surface.  
     [0045]FIG. 7B shows a cross-section of an embodiment a connection  700  after plastic radial expansion of the pin member  730  and the box member  732 . As was discussed above with reference to FIG. 3, the second sealing surface  744  on the box member  732  has collapsed to be in sealing contact with the first sealing surface  740  on the pin member  730 . In the embodiment shown, the clearance surfaces  738 ,  742  remain out of contact.  
     [0046]FIG. 7B shows that the first locking surface  711  in engaged with the second locking surface  721 . Because the locking surfaces  711 ,  721 , in the embodiment shown, have an alternating peak/groove pattern, the engagement between them prevents relative rotation between the pin member  730  and the box member  732 .  
     [0047] In other embodiments, an anti-rotation device may comprise flutes on the locking surfaces or high friction coatings on the locking surfaces, such as a plasma-spray carbide. Those having ordinary skill in the art will realize that anti-rotation devices other than a knurled surface may be used without departing from the scope of the invention.  
     [0048] In some embodiments the locking surfaces may include coatings that are in contact after plastic radial expansion. FIG. 8, for example, shows a cross-section of an embodiment of a threaded connection  800  with a collapsible type seal  801  and locking surfaces  811 ,  821  with coatings  851 ,  852  that contact each other after plastic radial expansion. A first sealing surface  840  is in sealing contact with a second sealing surface  844 , and the first clearance surface  838  and the second clearance surface  842  remain out of contact. The first coating  852  on the first locking surface  811  and the second coating  851  on the second locking surface  821  are in contact with each other. In some embodiments, the coatings  851 ,  852  are high friction coatings that resist relative rotation between the pin member  830  and the box member  832 .  
     [0049] Those having ordinary skill in the art will be able to devise other embodiments of locking surfaces and anti-rotation devices that do not depart from the scope of the present invention. For example, In some embodiments, a connection with a anti-rotation device does not include clearance surfaces. While the embodiments shown include clearance surfaces, those having ordinary skill in the art will realize the they are not required by the present invention.  
     [0050] Advantageously, embodiments of the present invention that include an anti-rotation device enable the plastic radial expansion of tubular goods using rotary expansion techniques without relative rotation between the pin member and the box member. Further, certain embodiments prevent the relative rotation of previously expanded connections by the rotation of a rotary expansion tool, such as a roller.  
     [0051] While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.