Multiple tapered threaded connection

Abstract

A plurality of connectors for forming a multiple tapered threaded connection has a first connector comprising a female connection end and a second connector comprising a male connection end. The female connection end has internal threads. The male connection end has external threads. The connectors comprise respective transitional threads provided between first and second tapers thereof for creating a continuous thread. The transitional threads are shorter in height than the internal threads of the female connection end and the external threads of the male connection end.

Description

[0001] Multiple Tapered Threaded Connection FIELD OF THE DISCLOSURE

[0002] The present application relates generally to threaded connections in drill tubulars and downhole tools, more specifically it relates to multiple tapered threaded connections in drill tubulars and downhole tools. BACKGROUND

[0003] This section provides background information to facilitate a better understanding of the various aspects of the invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

[0004] Drill string shouldered connections capable of carrying large torque loads are historically tapered double shoulder connections with a given threadform. The highest modern torque capabilities are generally seen with low taper thick-walled connections.

[0005] The largest issue with lower taper thick walled connections have been difficulties in the handling and threading together of adjoining tubulars. Due to the low taper, the male connection end does not stab deep into the female connection end. This results in many revolutions of the male connection end to fully engage into the female connection end. This can result in increased damage to the threads and a high repair cost.

[0006] To overcome this issue, a double or triple step / start thread on low taper connections have been used. The issue with this type of connection is that the male connection end only stabs on a pair of threads flanks instead of on multiple thread flanks. These connections are also notoriously difficult to manufacture and control leading to a high repair and service cost. BRIEF SUMMARY

[0007] There is provided a multiple tapered threaded connection. A female connection end has internal threads. The internal threads have a top end, a bottom end, a first portion and a second portion. The first portion of the internal thread is adjacent the top end of the internal thread and has a first taper. The second portion of the internal thread is adjacent the bottom end of the internal thread and has a second taper that is different from the first taper. A male connection end has external threads. The external threads have a top end, a bottom end, a first portion and a second portion. The first portion and the second portion of the male connection correspond to the first portion and the second portion of the female connection. The first portion of the external threads is adjacent the top end of the external threads and has a first taper corresponding to the first taper of the female connection. The second portion of the external threads is adjacent the bottom end of the external threads and has a second taper that corresponds to the second taper of the female connection.

[0008] In one embodiment, the second taper is steeper than the first taper. The first taper may have a taper of 0.75 inches per foot and the second taper may have a taper of 2 inches per foot.

[0009] In one embodiment, the first taper is steeper than the second taper.

[0010] In one embodiment, transitional threads are provided between the first taper and the second taper for creating a continuous thread. The transitional threads may be shorter in height than the internal threads of the female connection end and the external threads of the male connection end. This can help to prevent excessive damage to the threads during stabbing operations.

[0011] There is also provided a multiple tapered threaded connection. A female connection end has internal threads. The internal threads have a top end, a bottom end, a first portion with a first taper, a second portion with a second taper and a third portion with a third taper. The first portion is adjacent the top end of the internal threads. The second portion is adjacent to the first portion. The third portion is adjacent to the second portion and the bottom end of the internal threads. The taper of adjacent portions are different from each other. A male connection end has external threads. The external threads have a top end, a bottom end, a first portion with a first taper, a second portion with a second taper and a third portion with a third taper. The first portion is adjacent the top end of the external threads. The second portion is adjacent to the first portion. The third portion is adjacent to the second portion and the bottom end of the external threads. Each of the first taper, the second taper and the third taper correspond to the first taper, the second taper and the third taper of the female connection.

[0012] In one embodiment, transitional threads are provided between the first taper and the second taper and between the second taper and the third taper for creating a continuous thread. The transitional threads may be shorter in height than the internal threads of the female connection end and the external threads of the male connection end. This can help to prevent excessive damage to the threads during stabbing operations.

[0013] In one embodiment, the first taper is steeper than the second taper and the second taper is steeper than the third taper.

[0014] In one embodiment, the third taper is steeper than the second taper and the second taper is steeper than the first taper.

[0015] In one embodiment, the first taper and the third taper are the same and the first taper and the third taper are steeper than the second taper.

[0016] In one embodiment, the first taper and the third taper are the same and the second taper is steeper than the first taper and the third taper.

[0017] In one embodiment, the first taper is steeper than the third taper and the third taper is steeper than the second taper.

[0018] In one embodiment, the third taper is steeper than the first taper and the first taper is steeper than the second taper.

[0019] In one embodiment, the second taper is steeper than the first taper and the first taper is steeper than the third taper.

[0020] In one embodiment, the second taper is steeper than the third taper and the third taper is steeper than the first taper.

[0021] There is also provided a multiple tapered threaded connection. A female connection end has internal threads. The internal threads have a top end, a bottom end and at least three portions. Each of the at least three portions have a taper such that the taper of adjacent portions are different from each other. A male connection end has external threads. The external threads have a top end, a bottom end and at least three portions corresponding to the at least three portions of the female connection. Each of the at least three portions have a taper corresponding to the taper of the at least three portions of the female connection. The taper of adjacent portions are different from each other.

[0022] In one embodiment, transitional threads are provided between the at least three portions for creating a continuous thread. The transitional threads may be shorter in height than the internal threads of the female connection end and the external threads of the male connection end. This can help to prevent excessive damage to the threads during stabbing operations.

[0023] There is also provided a multiple tapered threaded connection. A female connection end has internal threads. The internal threads have a top end, a bottom end and at least two portions. Each of the at least two portions has a taper such that the taper of adjacent portions are different from each other. A male connection end has external threads. The external threads have a top end, a bottom end and at least two portions. Each of the at least two portions having a taper such that the taper of adjacent portions are different from each other. At least a portion of at least one portion of the internal threads of the female connection end corresponds to at least a portion of at least one portion of the external threads of the male connection end such that a threaded connection is made between the at least one portion of the internal threads and the at least one portion of the external threads.

[0024] In one embodiment, the internal threads of the female connection end have two portions and the external threads of the male connection end have three portions. At least a portion of at least one of the two portions of the internal threads correspond to at least a portion of at least one of the three portions of the external threads.

[0025] In another embodiment, the internal threads of the female connection end have three portions and the external threads of the male connection end have two portions. At least a portion of at least one of the two portions of the external threads corresponds to at least a portion of at least one of the three portions of the internal threads.

[0026] In one embodiment, transitional threads are provided between the at least two portions for creating a continuous thread. The transitional threads may be shorter in height than the internal threads of the female connection end and the external threads of the male connection end. This can help to prevent excessive damage to the threads during stabbing operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and other features will become more apparent from the following description in which references are made to the following drawings, in which numerical references denote like parts. The drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiments shown.

[0028] FIG. 1 is a side elevation view of a male connection end of a multiple tapered threaded connection.

[0029] FIG. 2 is a detailed side elevation view, in section, of the threads of the male connection end shown in FIG. 1.

[0030] FIG. 3 is a perspective view of the male connection end shown in FIG. 1

[0031] FIG. 4 is a side elevation view, in section, of a female connection end of the multiple tapered threaded connection.

[0032] FIG. 5 is a detailed side elevation view, in section, of the female connection end of the multiple tapered threaded connection shown in FIG. 4.

[0033] FIG. 6 is a perspective view, in section, of the female connection end of the multiple tapered threaded connection shown in FIG. 4.

[0034] FIG. 7 is a detailed side elevation view, in section, of the female connection end and the male connection end with connected threads.

[0035] FIG. 8 is a detailed side elevation view, in section, of the female connection end of the multiple tapered threaded connection with tapers having an alternative steepness.

[0036] FIG. 9 is a detailed side elevation view, in section, of the male connection end of the multiple tapered threaded connection with tapers corresponding to the tapers of the female connection end shown in FIG. 8.

[0037] FIG. 10 is a detailed side elevation view, in section, of the male connection end of FIG. 9 and the female connection end of FIG. 8 with connected threads.

[0038] FIG. 11 is a side elevation view of the male connection end of a multiple tapered threaded connection.

[0039] FIG. 12 is a side elevation view, in section, of the female connection end of the multiple tapered threaded connection.

[0040] FIG. 13 is a side elevation view of a variation of a male connection end of a multiple tapered threaded connection.

[0041] FIG. 14 is a detailed side elevation view, in section, of the variation of a male connection end shown in FIG. 13.

[0042] FIG. 15 is a perspective view of the variation of a male connection end shown in FIG. 13.

[0043] FIG. 16 is a side elevation view, in section, of a variation of a female connection end of a multiple tapered threaded connection.

[0044] FIG. 17 is a detailed side elevation view, in section, of the variation of a female connection end of a multiple tapered threaded connection shown in FIG. 16.

[0045] FIG. 18 is a perspective view, in section, of the variation of a female connection end shown in FIG. 16.

[0046] FIG. 19 is a detailed side elevation view, in section, of a variation of a male connection end and a variation of a female connection end with connected threads.

[0047] FIG. 20 is a detailed side elevation view, in section, of a variation of a male connection end with threads having tapers with alternative steepness.

[0048] FIG. 21 is a detailed side elevation view, in section, of a variation of a male connection end with threads having tapers with another alternative steepness.

[0049] FIG. 22 is a side elevation view of a variation of the male connection end of a multiple tapered threaded connection.

[0050] FIG. 23 is a side elevation view, in section, of a variation of a female connection end of the multiple tapered threaded connection.

[0051] FIG. 24 is a side elevation view, in section, of another variation of a multiple tapered threaded connection.

[0052] FIG. 25 is a side elevation view, in section, of another variation of a multiple tapered threaded connection. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] A multiple tapered threaded connection, generally identified by reference numeral 10, will now be described with reference to FIG. 1 through FIG. 12.

[0054] Referring to FIG. 7, a multiple tapered thread connection 10 has a female connection end 12 and a male connection end 14. Referring to FIG. 4 through 6, female connection end 12 has internal threads 16. Referring to FIG. 1, male connection end 14 has external threads 18 that correspond to internal threads 16 of female connection end 12, shown in FIG. 4. Referring to FIG. 5, internal threads 16 have a top end 20, a bottom end 22, a first portion 24 and a second portion 26. First portion 24 is adjacent top end 20 of internal threads 16 and has a first taper 28. Second portion 26 is adjacent bottom end 22 of internal threads 16 and has a second taper 30. In the embodiments shown, first portion 24 and second portion 26 appear to be substantially the same length, however it will be understood by a person skilled in the art that first portion 24 and second portion 26 may be different lengths. In the embodiment shown in FIG. 4 through 6, second taper 30 is steeper than first taper 28. In the embodiment shown in FIG. 8 and 10, first taper 28 is steeper than second taper 30. By providing different tapers, the stress distribution within the connection may be altered in a desirable fashion.

[0055] Referring to FIG. 3, male connection end 14 has external threads 18 that have a top end 32, a bottom end 34, a first portion 36 and a second portion 38. First portion 36 and second portion 38 of male connection end 14 correspond to first portion 24 and second portion 26 of female connection end 12, shown in FIG. 7. Referring to FIG. 1, first portion 36 is adjacent top end 32 of external threads 18 and has a first taper 40 corresponding to first taper 28 of female connection end 12. Second portion 38 is adjacent bottom end 34 of external threads 18 and has a second taper 42 that corresponds to second taper 30 of female connection end 12. In the embodiments shown, first portion 36 and second portion 38 appear to be substantially the same length, however it will be understood by a person skilled in the art that first portion 36 and second portion 38 may be different lengths. In the embodiment shown in FIG. 1 through 3, second taper 42 is steeper than first taper 40. In the embodiment shown in FIG. 9 and 10, first taper 40 is steeper than second taper 42. By providing different tapers, the stress distribution within the connection may be altered in a desirable fashion.

[0056] Referring to FIG. 7, in the embodiment shown, first tapers 28 and 40 create a connection that is thick walled to maximize torque capability in higher stressed regions of connections 10. Second tapers 30 and 42 have a steeper taper to permit deep stabbing in lower stressed regions of connections 10. This can allow for a quick make-up and reduce damage without compromising the overall torque carrying capabilities of the connections 10.

[0057] As an example, first tapers 28 and 40 may have a taper of 0.75 inches per foot while second tapers 30 and 42 have a steeper taper of 2 inches per foot. The steeper taper of second tapers 30 and 42 allows for deeper stabbing of male connection end 14 into female connection end 12 while the less steep taper of first tapers 28 and 40 provide a thicker wall for each of male connection end 14 and female connection end 12.

[0058] Referring to FIG. 5, transitional threads 44 connect the threads of first taper 28 and second taper 30 of internal threads 16 to create a continuous thread. Generally, transitional threads 44 comprise between two and four thread rotations, however it will be understood by a person skilled in the art that more or fewer transitional thread rotations may be used. The number of transitional threads 44 can vary based upon the diameter, connection length and pitch of the threads. Referring to FIG. 2, transitional threads 46 connect the threads of first taper 40 and second taper 42 of external threads 18 to create a continuous thread. Transitional threads 46 of external threads 18 correspond to transitional threads 44 of internal threads 16. Generally, transitional threads 46 comprise two to four thread rotations, however it will be understood by a person skilled in the art that more or fewer transitional thread rotations may be used. The number of transitional threads 46 can vary based upon the diameter, connection length and pitch of the threads.

[0059] Referring to FIG. 11, first taper 40 and second taper 42 of external threads 18 may be spaced apart from each other by a relatively blank space 35. In this embodiment, there are no continuous threads. The size of blank space 35 may vary. Referring to FIG. 12, first taper 28 and second taper 30 of internal threads 16 may be spaced apart from each other by a relatively blank space 37. In this embodiment, there are no continuous threads. The size of blank space 37 may vary. In the embodiment shown in FIG. 11, first taper 40 has a taper of zero inches per foot and second taper 42 has a taper of two inches per foot. In the embodiment shown in FIG. 12, first taper 28 has a taper of zero inches per foot and second taper 30 has a taper of two inches per foot. A person of skill in the art will understand that different tapers may be used.

[0060] Referring to FIG. 7 and FIG. 10, in the embodiment shown, transitional threads 44 and 46 are stubbed or shortened such that transitional threads 44 and 46 are shorter in height than unshortened internal threads 16 and external threads 18. Transitional threads 44 and 46 generally bear the brunt of stabbing damage. By stubbing the threads, it is possible to restrict damage to transitional threads 44 and 46 and to mitigate damage to internal threads 16 and external threads 18.

[0061] A variation of the multiple tapered threaded connection, generally identified by reference numeral 100, will now be described with reference to FIG. 13 through FIG. 23.

[0062] Referring to FIG. 19, in the embodiment shown, a multiple tapered threaded connection 100 has a female connection end 102 and a male connection end 104. Referring to FIG. 16 through 18, female connection end 102 has internal threads 106. Referring to FIG. 13 through 15, male connection end 104 has external threads 108 that correspond to internal threads 106 of female connection end 102, shown in FIG. 16. Referring to FIG. 16, internal threads 106 have a top end 120, a bottom end 122, a first portion 124, a second portion 126 and a third portion 127. First portion 124 is adjacent top end 120 of internal threads 106 and has a first taper 128. Third portion 127 is adjacent bottom end 122 of internal threads 106 and has a third taper 131. Second portion 126 is positioned between first portion 124 and third portion 127 and has a second taper 130. The taper of adjacent portions are different from each other, therefore first taper 128 and second taper 130 must be different and second taper 130 and third taper 131 must be different. In the embodiment shown in FIG. 16 and 17, each of first taper 128, second taper 130 and third taper 131 have different tapers from each other. In this embodiment, third taper 131 is steeper than second taper 130, and second taper 130 is steeper than first taper 128. In the embodiments shown, first portion 124, second portion 126 and third portion 127 appear to be of different lengths, it will be understood by a person skilled in the art that first portion 124, second portion 126 and third portion 127 may be of the same or different lengths.

[0063] Referring to FIG. 13, male connection end 104 has external threads 108 that have a top end 132, a bottom end 134, a first portion 136, a second portion 138 and a third portion 139. First portion 136, second portion 138 and third portion 139 of male connection end 104 corresponds to first portion 124, second portion 126 and third portion 127 of female connection end 102, shown in FIG. 16. Referring to FIG. 13, first portion 136 is adjacent top end 132 of external threads 108 and has a first taper 140 corresponding to first taper 128 of female connection end 102. Third portion 139 is adjacent bottom end 134 of external threads 108 and has a third taper 143 that corresponds to third taper 131 of female connection end 102. Second portion 138 is positioned between first portion 136 and third portion 139 and has a second taper 142 that corresponds to second taper 130 of female connection end 102. In the embodiment shown in FIG. 13 and 14, each of first taper 140, second taper 142 and third taper 143 have different tapers from each other. In this embodiment, third taper 143 is steeper than second taper 142, and second taper 142 is steeper than first taper 140. In the embodiment shown in FIG. 20 and 21, the taper of first taper 140 and third taper 143 are the same and the taper of second taper 142 is different. The taper of first taper 140 and third taper 143 are steeper in the embodiment shown in FIG. 20 than in the embodiment shown in FIG. 21. In the various embodiments shown, first portion 136, second portion 138 and third portion 139 appear to be of different lengths, it will be understood by a person skilled in the art that first portion 136, second portion 138 and third portion 139 may be of the same or different lengths.

[0064] Referring to FIG. 19, first tapers 128 and 140 create a connection that is thick walled to maximize torque capability in higher stressed regions of connections 100. Second tapers 130 and 142 and third tapers 131 and 143 have a steeper taper to permit deep stabbing in lower stressed regions of connections 100. This can allow for a quick make-up and reduce damage without compromising the overall torque carrying capabilities of the connections 100.

[0065] As an example, first tapers 128 and 140 may have a taper of 0.75 inches per foot while second tapers 130 and 142 have a steeper taper of 1.25 inches per foot and third tapers 131 and 143 have a steeper taper of 2 inches per foot. The steeper taper of second tapers 130 and 142 and third tapers 131 and 143 allows for deeper stabbing of male connection end 104 into female connection end 102 while the less steep taper of first tapers 128 and 140 provide a thicker wall for each of male connection end 104 and female connection end 102. By providing different tapers, the stress distribution within the connection may be altered. By providing different tapers, the stress distribution within the connection may be altered in a desirable fashion.

[0066] Referring to FIG. 17, transitional threads 144 connect the threads of first taper 128 and second taper 130 of internal threads 106 to create a continuous thread. Transitional threads 145 connect the threads of second taper 130 and third taper 131 of internal threads 106 to create a continuous thread. Generally, transitional threads 144 and 145 comprise two to four thread rotations, however it will be understood by a person skilled in the art that more or fewer transitional thread rotations may be used. The number of transitional threads 144 and 145 can vary based upon the diameter, connection length and pitch of the threads. Referring to FIG. 14, transitional threads 146 connect the threads of first taper 140 and second taper 142 of external threads 108 to create a continuous thread. Transitional threads 146 of external threads 108 correspond to transitional threads 144 of internal threads 106. Transitional threads 147 connect the threads of second taper 142 and third taper 143 of external threads 108 to create a continuous thread. Transitional threads 147 of external threads 108 correspond to transitional threads 145 of internal threads 106. Generally, transitional threads 146 and 147 comprise two to four thread rotations, however it will be understood by a person skilled in the art that more or fewer transitional thread rotations may be used. The number of transitional threads 146 and 147 can vary based upon the diameter, connection length and pitch of the threads. In the event that a significant number of transitional threads are required, the threads of second portion 126 may act as transitional threads between first portion 124 and third portion 127 and the threads of second portion 138 may act as transitional threads between first portion 136 and third portion 139.

[0067] In the embodiment shown in FIG. 19, transitional threads 144, 145, 146 and 147 are stubbed or shortened. Transitional threads 144, 145, 146 and 147 generally bear the brunt of the stabbing damage. By stubbing the threads, it is possible to restrict damage to transitional threads 144, 145, 146 and 147 and to mitigate damage to internal threads 106 and external threads 108.

[0068] Referring to FIG. 22, first taper 140, second taper 142 of external threads 108 may be spaced apart from each other by a relatively blank space 135a. Second taper 142 and third taper 143 of external threads 108 may be spaced apart from each other by a relatively blank space 135b. In this embodiment, there are no continuous threads. The size of blank spaces 135a and 135b may vary. Referring to FIG. 23, first taper 128 and second taper 130 of internal threads 106 may be spaced apart from each other by a relatively blank space 137a. Second taper 130 and third taper 131 of internal threads 106 may be spaced apart from each other by a relatively blank space 137b. In this embodiment, there are no continuous threads. The size of blank space 137a and 137b may vary.

[0069] A variation of the multiple tapered threaded connection, generally identified by reference numeral 200, will now be described with reference to FIG. 24.

[0070] Referring to FIG. 24, a multiple tapered threaded connection 200 has a female connection end 212 and a male connection end 214. Female connection end 212 has internal threads 216 and male connection end 214 has external threads 218. Internal threads 216 have a top end 220, a bottom end 222, a first portion 224 and a second portion 226. First portion 224 is adjacent top end 220 of internal threads 216 and has a first taper 228. Second portion 226 is adjacent bottom end 222 of internal threads 216 and has a second taper 230. In the embodiments shown, first portion 224 and second portion 226 appear to be substantially the same length, however it will be understood by a person skilled in the art that first portion 224 and second portion 226 may be different lengths. In the embodiment shown second taper 230 is steeper than first taper 228.

[0071] Referring to FIG. 24, male connection end 214 has external threads 218 that have a top end 232, a bottom end 234, a first portion 236, a second portion 238 and a third portion 239. In the embodiment shown, first portion 236 is adjacent top end 232 of external threads 218 and has a first taper 240 corresponding to first taper 228 of female connection end 212. Third portion 239 is adjacent bottom end 234 of external threads 218 and has a third taper 243 that corresponds to second taper 230 of female connection end 212. Second portion 238 is positioned between first portion 236 and third portion 239 and has a second taper 242 that does not correspond to either first taper 228 or second taper 230 of female connection end 212. In the embodiment shown, first portion 236 of male connection end 214 corresponds to a portion of first portion 224 of female connection end 212 and third portion 239 of male connection end 214 corresponds to second portion 226 of female connection end 212. Second portion 238 of male connection end 214 does not correspond to either first portion 224 or second portion 226 of female connection end 212 and there is, therefore, no threaded connection between external threads 218 and internal threads 216 occurs between second portion 238 of male connection end 214 and any of internal threads 216 of female connection end 212. It will be understood by a person skilled in the art that any combination of corresponding portions between male connection end 214 and female connection end 212 may occur without departing from the scope of the invention. In the embodiment shown, each of first taper 240, second taper 242 and third taper 243 have different tapers from each other. In this embodiment, third taper 243 is steeper than second taper 242, and second taper 242 is steeper than first taper 240. In the embodiment shown, first portion 236, second portion 238 and third portion 239 appear to be of different lengths, it will be understood by a person skilled in the art that first portion 236, second portion 238 and third portion 239 may be of the same or different lengths.

[0072] A variation of the multiple tapered threaded connection, generally identified by reference numeral 300, will now be described with reference to FIG. 25.

[0073] Referring to FIG. 25, in the embodiment shown, a multiple tapered threaded connection 300 has a female connection end 312 and a male connection end 314. Female connection end 312 has internal threads 316 and male connection end 314 has external threads 318. Internal threads 316 have a top end 320, a bottom end 322, a first portion 324, a second portion 326 and a third portion 327. First portion 324 is adjacent top end 320 of internal threads 316 and has a first taper 328. Third portion 327 is adjacent bottom end 322 of internal threads 316 and has a third taper 331. Second portion 326 is positioned between first portion 324 and third portion 327 and has a second taper 330. The taper of adjacent portions are different from each other, therefore first taper 328 and second taper 330 must be different and second taper 330 and third taper 331 must be different. In the embodiment shown, each of first taper 328, second taper 330 and third taper 331 have different tapers from each other. In this embodiment, third taper 331 is steeper than second taper 330, and second taper 330 is steeper than first taper 328. In the embodiments shown, first portion 324, second portion 326 and third portion 327 appear to be of different lengths, it will be understood by a person skilled in the art that first portion 324, second portion 326 and third portion 327 may be of the same or different lengths.

[0074] Referring to FIG. 25, male connection end 314 has external threads 318 that have a top end 332, a bottom end 334, a first portion 336 and a second portion 338. First portion 336 is adjacent top end 332 of external threads 318 and has a first taper 340. Second portion 338 is adjacent bottom end 334 of external threads 318 and has a second taper 342. In the embodiment shown, first taper 340 of first portion 336 of external threads 318 corresponds to first taper 328 of female connection end 312. Second taper 342 of second portion 338 of external threads 318 corresponds to third taper 331 of female connection end 312. Second taper 330 of second portion 326 of female connection end 312 does not correspond to either first taper 340 or second taper 342 of male connection end 314. In the embodiment shown, a portion of first portion 336 of male connection end 314 corresponds to first portion 324 of female connection end 312 and second portion 338 of male connection end 314 corresponds to third portion 327 of female connection end 312. Second portion 326 of female connection end 312 does not correspond to either first portion 336 or second portion 338 of male connection end 314 and there is, therefore, no threaded connection between external threads 318 and internal threads 316 occurs between second portion 326 of female connection end 312 and any of external threads 318 of male connection end 314. It will be understood by a person skilled in the art that any combination of corresponding portions between male connection end 314 and female connection end 312 may occur without departing from the scope of the invention. In the embodiments shown, first portion 336 and second portion 338 appear to be substantially the same length, however it will be understood by a person skilled in the art that first portion 336 and second portion 338 may be different lengths. In the embodiment shown, second taper 342 is steeper than first taper 340.

[0075] Any use herein of any terms describing an interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between the elements such as through secondary or intermediary structure unless specifically stated otherwise.

[0076] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items 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 of the elements.

[0077] It will be apparent that changes may be made to the illustrative embodiments, while falling within the scope of the invention. As such, the scope of the following claims should not be limited by the preferred embodiments set forth in the examples and drawings described above, but should be given the broadest interpretation consistent with the description as a whole.

Claims

1. A plurality of connectors for forming a multiple tapered threaded connection, comprising: a first connector comprising a female connection end having internal threads, the internal thread having a top end located proximal to a free end thereof, a bottom end located distal to the free end, a first portion and a second portion, the first portion being adjacent the top end of the internal thread and having a first taper, the second portion being adjacent the bottom end of the internal thread and having a second taper, the second taper being different from the first taper; and a second connector comprising a male connection end having external threads, the external threads having a top end located distal to a free end thereof, a bottom end located proximal to the free end, a first portion and a second portion corresponding to the first portion and the second portion of the female connection, the first portion being adjacent the top end of the external threads and having a first taper corresponding to the first taper of the female connection, the second portion being adjacent the bottom end of the external threads and having a second taper corresponding to the second taper of the female connection, wherein the first connector and the second connector comprise respective transitional threads provided between the first taper and the second taper thereof for creating a continuous thread, and wherein the transitional threads are shorter in height than the internal threads of the female connection end and the external threads of the male connection end.

2. The connectors of claim 1 wherein the second taper is steeper than the first taper.

3. The connectors of claims 1 or 2 wherein the first taper has a taper of 0.75 inches per foot.

4. The connectors of claims 1, 2 or 3 wherein the second taper has a taper of 2 inches per foot.

5. The connectors of claim 1 wherein the first taper is steeper than the second taper.

6. A plurality of connectors for forming a multiple tapered threaded connection, comprising: a first connector comprising a female connection end having internal threads, the internal threads having a top end located proximal to a free end thereof, a bottom end located distal to the free end, a first portion having a first taper, a second portion having a second taper and a third portion having a third taper, the first portion being adjacent the top end of the internal threads, the second portion being adjacent to the first portion and the third portion being adjacent to the second portion and the bottom end of the internal threads, the taper of adjacent portions being different from each other; and a second connector comprising a male connection end having external threads, the external threads having a top end located distal to a free end thereof, a bottom end located proximal to the free end, a first portion with a first taper, a second portion having a second taper and a third portion having a third taper, the first portion being adjacent the top end of the external threads, the second portion being adjacent to the first portion and the third portion being adjacent to the second portion and the bottom end of the external threads, the first taper of the external threads corresponding to the first taper of the internal threads, the second taper of the external threads corresponding to the second taper of the internal threads and the third taper of the external threads corresponding to the third taper of the internal threads, wherein the first connector and the second connector comprise respective transitional threads provided between the first taper and the second taper thereof and between the second taper and the third taper thereof for creating a continuous thread, and wherein the transitional threads are shorter in height than the internal threads of the female connection end and the external threads of the male connection end.

7. The connectors of claim 6 wherein the first taper is steeper than the second taper and the second taper is steeper than the third taper.

8. The connectors of claim 6wherein the third taper is steeper than the second taper and the second taper is steeper than the first taper.

9. The connectors of claim 6 wherein the first taper and the third taper are the same and the first taper and the third taper are steeper than the second taper.

10. The connectors of claim 6 wherein the first taper and the third taper are the same and the second taper is steeper than the first taper and the third taper.

11. The connectors of claim 6 wherein the first taper is steeper than the third taper and the third taper is steeper than the second taper.

12. The connectors of claim 6wherein the third taper is steeper than the first taper and the first taper is steeper than the second taper.

13. The connectors of claim 6wherein the second taper is steeper than the first taper and the first taper is steeper than the third taper.

14. The connectors of claim 6 wherein the second taper is steeper than the third taper and the third taper is steeper than the first taper.

15. A plurality of connectors for forming a multiple tapered threaded connection, comprising: a first connector comprising a female connection end having internal threads, the internal threads having a top end located proximal to a free end thereof, a bottom end located distal to the free end, and at least three portions, each of the at least three portions having a taper such that the taper of adjacent portions are different from each other; and a second connector comprising a male connection end having external threads, the external threads having a top end located distal to a free end thereof, a bottom end located proximal to the free end, and at least three portions corresponding to the at least three portions of the female connection, each of the at least three portions having a taper corresponding to the taper of the at least three portions of the female connection, wherein the first connector and the second connector comprise respective transitional threads provided between the at least three portions thereof for creating a continuous thread, and wherein the transitional threads are shorter in height than the internal threads of the female connection end and the external threads of the male connection end.

16. A plurality of connectors for forming a multiple tapered threaded connection, comprising: a first connector comprising a female connection end having internal threads, the internal threads having a top end located proximal to a free end thereof, a bottom end located distal to the free end, and at least two portions, each of the at least two portions having a taper such that the taper of adjacent portions are different from each other; and a second connector comprising a male connection end having external threads, the external threads having a top end located distal to a free end thereof, a bottom end located proximal to the free end, and at least two portions, each of the at least two portions having a taper such that the taper of adjacent portions are different from each other, wherein at least a portion of the at least two portions of the internal threads of the female connection end corresponds to at least a portion of the at least two portions of the external threads of the male connection end such that a threaded connection is made between the at least one portion of the internal threads and the at least one portion of the external threads, wherein the first connector and the second connector comprise respective transitional threads provided between the at least two portions for creating a continuous thread, and wherein the transitional threads are shorter in height than the internal threads of the female connection end and the external threads of the male connection end.

17. The multiple tapered threaded connection of claim 16 wherein the internal threads of the female connection end have two portions and the external threads of the male connection end have three portions, at least a portion of at least one of the two portions of the internal threads corresponding to at least a portion of at least one of the three portions of the external threads.

18. The multiple tapered threaded connection of claim 16 wherein the internal threads of the female connection end have three portions and the external threads of the male connection end have two portions, at least a portion of at least one of the two portions of the external threads corresponding to at least a portion of at least one of the three portions of the internal threads.