RU2820265C2 - Threaded connection for pipes used in wells during exploration and production of hydrocarbons - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: threaded connection for pipes used in wells during exploration and production of hydrocarbons includes a connecting element, first and second pipe elements. Connecting element has an outer diameter of the COD connection and comprises a first coupling part, a second coupling part and a peripheral part. Peripheral part is located between the first coupling part and the second coupling part and has a radial thickness B and an axial length C. First coupling part and the second coupling part have radial thickness A located between the inner rim and the first internal threads and the second internal threads respectively. First tubular element contains the first non-threaded tubular part and the first nipple part. Second tubular element contains the second non-threaded tubular part and the second nipple part. First non-threaded tubular part and the second non-threaded tubular part have an outer diameter TOD and a radial wall thickness W. First tubular element and the second tubular elements have inner diameter TID. Threaded connection meets the following conditions: COD > TOD, B = approximately ((COD − TID)/2), C > 0, and A < W.

EFFECT: possibility of using threaded connection of pipes in wells of small diameter is provided.

14 cl, 10 dwg

Description

The invention relates to a threaded connection for exploration and production of hydrocarbon wells, which contains a connecting element, a first pipe element and a second pipe element. Such a threaded connection comprising a connecting member for through-connection of the first and second tubular elements is also referred to as a “threaded and mated” connection.

In a known threaded connection, the connecting element has a connection outer diameter (COD), a first coupling portion with first internal threads, and a second coupling portion with second internal threads. The first coupling portion and the second coupling portion have a radial coupling portion thickness A located between the first internal threads and the second internal threads. The first pipe element has a first non-threaded pipe portion and a first pin portion with first male threads. The second pipe element has a second non-threaded pipe portion and a second pin portion with second male threads. The first non-threaded pipe portion and the second non-threaded pipe portion have a tube outer diameter (TOD) and a radial tube wall thickness W. The joint outer diameter (COD) is larger than the tube outer diameter (TOD). The first internal threads, the second internal threads, the first external threads and the second external threads are dovetail shaped. The first internal threads and the first external threads form the first internal primary seal upon final engagement of the joint. The second internal threads and the second external threads form a second internal primary seal upon final engagement of the connection.

Upon final engagement of the connection, the first and second internal primary seals form the first line of defense against internal pressure in the threaded connection.

State of the art

In some cases, the known threaded connection has an outer diameter that is too large for use in exploration and production of hydrocarbon wells of a certain small diameter, for example, so-called thin profile wells, which are sometimes called small wells.

Threaded connections are known from the prior art according to documents US 8136846 B2, WO 2017/100026 A1, US 3989284 A1.

Disclosure of the Invention

The purpose of the invention is to provide an improved (or at least alternative) threaded connection that can be used in specified hydrocarbon wells of a certain small diameter.

The goal is achieved through a threaded connection for exploration and production of hydrocarbon wells, which contains:

- a connecting element having a connection outer diameter (COD) and containing a first coupling part containing first internal threads,

a second coupling portion comprising second internal threads, and

a peripheral portion comprising a radially projecting inner rim,

wherein the peripheral portion is located between the first coupling portion and the second coupling portion and has a radial thickness of the peripheral portion B and an axial length of the peripheral portion C, and

the first coupling part and the second coupling part have a radial thickness of the coupling part A located between the inner rim and, respectively, the first internal threads and the second internal threads,

- a first tubular element comprising a first non-threaded tubular portion, and a first pin portion comprising first male threads, and

- a second pipe element comprising a second non-threaded coupling portion, and a second nipple portion comprising second male threads, wherein

- the first non-threaded pipe part and the second non-threaded pipe part have a tube outer diameter TOD and a radial tube wall thickness W,

- the first pipe element and the second pipe element have an internal diameter of the TID tube,

- the first internal threads, the second internal threads, the first external threads, the second external threads have a dovetail shape,

- the first internal threads and the first external threads form the first internal primary seal upon final engagement of the connection,

- the second internal threads and the second external threads form a second internal primary seal upon final engagement of the connection, and

- the threaded connection meets the following conditions:

COD > TOD

B = approximately ((COD - TID) / 2)

C > 0, and

A < W.

COD > TOD indicates that the joint outer diameter (COD) of the connecting member is greater than the tube outer diameter (TOD) of the first non-threaded tubing portion of the first tubing member and the second non-threaded tubing portion of the second tubing member.

Compared with the known threaded connection, a peripheral part is added between the first coupling part and the second coupling part. The thickness of the peripheral portion B is measured in the radial direction relative to the longitudinal axis of the threaded connection, and the length of the peripheral portion A is measured in the axial direction.

B = (COD - TID)/2 indicates that the peripheral portion extends from the joint outer diameter (COD) of the connecting member to the tube inner diameter (TID) of the first tubular member and the second tubular member. This promotes fluid flow through the threaded connection. The fact that B is approximately (COD - TID) / 2 suggests that B can differ from the value of (COD - TID) / 2 in such a way that the difference does not interfere with the function of the rim and the operation of the connection. The difference may be due to processing tolerances.

C > 0 indicates that a peripheral portion with axial length C of the peripheral portion has been added to the threaded connection.

In accordance with the invention, a threaded connection comprising a connecting element for through-connection of the first and second pipe elements is also called a "threaded and mating" connection.

The operation of the first and second internal primary seals may be impaired when too high internal pressure of fluids flowing through the threaded connection separates the first internal threads from the first male threads and the second internal threads from the second external threads.

To withstand such high internal pressure, the coupling member of the known threaded joint has a relatively large radial thickness of the coupling portion A, which is measured between the first internal threads and the second internal threads of the coupling member. In the known threaded connection, the radial thickness of the coupling part A is greater than the radial wall thickness of the tube W of the first non-threaded pipe part of the first pipe element and the second non-threaded pipe part of the second pipe element. The result is a relatively large outer diameter of the connection.

The separation of the first internal threads from the first external threads and the second internal threads from the second external threads occurs due to radial deformation created by the internal pressure of the fluids flowing through the threaded connection. The invention is based on the fact that this radial deformation is associated with hoop stress in the threaded connection and that this stress can be reduced by adding a peripheral portion of the threaded connection in accordance with the present invention.

This means that by adding a peripheral portion to a known threaded connection, the radial thickness of the coupling portion A of the connecting member can be reduced, thereby providing a first internal primary seal between the first internal threads and the first external threads and a second internal primary seal between the second internal threads and the second external threads. . Therefore, according to the present invention, the radial thickness of the coupling portion A of the first and second coupling portions of the threaded joint connecting member is smaller than the radial thickness of the wall tube W of the first and second unthreaded pipe portions of the first and second pipe members. Therefore A < W.

A reduction in the radial thickness of the coupling portion A can be achieved by removing material from the outer connecting surface of the connecting element while maintaining the first and second internal threads of the connecting element and the pipe elements. Thus, the outer diameter of the COD connection is reduced, and the threaded connection can be used in these small diameter hydrocarbon wells, even if standard tubular elements are used.

In one embodiment of the threaded connection, the axial length of the peripheral portion C is: C ≤ 31.75 mm (1.25 inches), preferably C ≤ 27.94 mm (1.1 inches), even more preferably C ≤ 25.4 mm (1.0 inch).

In one embodiment of the threaded connection, the axial length of the peripheral portion C is: C ≤ 6.35 mm (0.25 inch), preferably C ≤ 10.16 mm (0.4 inch), even more preferably C ≤ 12.7 mm (0.5 inch).

In one embodiment of the threaded connection, the axial length of the peripheral portion C is: C ≤ 20.32 mm (0.8 inch), preferably C ≤ 27.94 mm (1.1 inch), even more preferably C ≤ 25.4 mm (1.0 inch).

In one embodiment of the threaded connection, the threaded connection meets the following conditions: A ≤ 0.9W, preferably A ≤ 0.8W. This means that the radial thickness of the coupling portion A is less than or equal to 90%, preferably 80%, of the radial wall thickness of the pipe.

In one embodiment, the threaded connection meets the following conditions:

A ≥ 0.7W. This means that the radial thickness of the coupling part is greater than 70% of the radial thickness of the pipe wall.

In one embodiment of the threaded connection, the radial thickness of the coupling portion A is located at a critical cross section of the first coupling portion and the second coupling portion.

In one embodiment of the threaded connection, the tube outer diameter TOD of the first and second unthreaded tubular portions of the first and second tubular members is: 114.3 mm (4.5 in.) ≤ TOD ≤ 244.5 mm (9 5/8 in.), preferably 114.3 mm (4.5 inches) ≤ TOD ≤ 193.7 mm (7.625 inches), even more preferably 114.3 mm (4.5 inches) ≤ TOD ≤ 139.7 mm (5.5 inches).

In one embodiment of the threaded connection, the radial wall thickness of the tube W of the first and second non-threaded tubular portions of the first and second tubular members is: 6.3 mm (0.250 inch) ≤ W ≤ 12.7 mm (0.500 inch), preferably 7.3 mm (0.290 in) ≤ W ≤ 11.1 mm (0.437 in).

In one embodiment, the threaded connection is characterized in that in the first direction from the inner rim towards the first internal primary seal, the first internal threads and the first external threads begin to have full contact in the initial position of the first seal, and in the opposite second direction from the inner rim towards of the second internal primary seal, the second internal threads and the second external threads begin to have full contact at the initial position of the second seal, wherein the initial position of the first seal is located at an axial distance of the seal D from the initial position of the second seal, and D > C.

In one embodiment, the threaded connection meets the following conditions:

3.6 mm (0.142 in) ≤ (D - C) / 2 ≤ 9.9 mm (0.392 in). This means that the first and second seal initial positions are located at an axial distance from the peripheral portion that is equal to or greater than 3.6 mm (0.142 inches) and less than or equal to 9.9 mm (0.392 inches). Preferably, the threaded connection meets the following conditions: 5 mm (0.2 in) ≤ (D - C) / 2 ≤ 7.7 mm (0.3 in), preferably (D - C) / 2 is 6.1 mm (0.242 inches).

In one embodiment, a radially projecting inner rim is located between the first nipple portion and the second nipple portion.

In one embodiment, the first tubular element (namely, the first nipple portion) includes a first nipple tip, the second tubular element (namely, the second nipple portion) includes a second nipple tip, and upon final engagement, the first nipple tip and the second nipple tip are spaced apart from the inner rim.

In one embodiment, a radially projecting inner rim is located between the first nipple tip and the second nipple tip.

In one embodiment, upon final engagement, the threaded connection does not have an additional internal seal (in addition to the first internal primary seal and the second internal primary seal).

In one embodiment, upon final engagement, the threaded connection does not have an additional secondary or metal-to-metal seal (in addition to the first internal primary seal and the second internal primary seal and full engagement of the threads).

In one embodiment, the first internal threads and the first external threads together form a first block of threads, and the second internal threads and the second external threads together form a second block of threads.

In one embodiment, the threaded connection does not have additional thread blocks (in addition to the first thread block and the second thread block). The first thread block and the second thread block are single thread blocks.

In one embodiment, the first thread block and the second thread block are tapered thread blocks.

According to one of the options for implementing a threaded connection:

- the threaded connection defines the longitudinal axis,

- the first internal threads have a constant cone angle of the first internal threads α ₁ relative to the longitudinal axis,

- the first external threads have a constant cone angle of the first external threads β ₁ relative to the longitudinal axis,

- the cone angle of the first internal threads α ₁ and the cone angle of the first external threads β ₁ are equal to each other,

- the second internal threads have a constant cone angle of the second internal threads α ₂ relative to the longitudinal axis,

- the second external threads have a constant taper angle of the second external threads β ₂ relative to the longitudinal axis, and

- the cone angle of the second internal threads α ₂ and the cone angle of the second external threads β ₂ are equal to each other.

According to one of the embodiments of the threaded connection, the cone angle of the first internal threads α ₁ , the cone angle of the first external threads β ₁ , the cone angle of the second internal threads α ₂ , the cone angle of the second external threads β ₂ have a diametrical cone from 0.36 to 0.86 mm /rev (0.014 and 0.034 in/rev) inclusive, preferably from 0.51 to 0.71 mm/rev (0.020 and 0.028 in/rev) inclusive.

In one embodiment of the threaded connection, the first internal threads and the first external threads have radial play of the first threads upon final engagement, and the second internal threads and the second external threads have radial play of the second threads upon final engagement.

According to one of the embodiments of the threaded connection:

- the threaded connection defines the longitudinal axis,

- the first internal threads have a constant cone angle of the first internal threads α ₁ relative to the longitudinal axis,

- the first external threads have a constant cone angle of the first external threads β ₁ relative to the longitudinal axis,

- the cone angle of the first internal threads α ₁ is greater than the cone angle of the first external threads β ₁ ,

- the second internal threads have a constant cone angle of the second internal threads α ₂ relative to the longitudinal axis,

- the second external threads have a constant taper angle of the second external threads β ₂ relative to the longitudinal axis, and

- the cone angle of the second internal threads α ₂ is greater than the cone angle of the second external threads β ₂ .

In one embodiment of the threaded connection, the taper angle of the first internal threads α ₁ and the taper angle of the second internal threads α ₂ have a diametrical internal taper of 0.41 to 0.91 mm/rev (0.016 and 0.036 in/rev), inclusive, preferably from 0.56 to 0.76 mm/rev (0.022 and 0.030 in/rev) inclusive, and the taper angle of the first male threads β ₁ and the taper angle of the second male threads β ₂ have a diametral taper of 0.36 to 0.86 mm/rev (0.014 and 0.034 in/rev) inclusive, preferably between 0.51 and 0.71 mm/rev (0.020 and 0.028 in/rev) inclusive.

According to one of the options for implementing a threaded connection:

- the first internal threads and the first external threads have radial play of the first threads upon final engagement,

- the radial play of the first threads between the first internal threads and the first external threads is reduced in a first direction from the inner rim towards the first internal primary seal,

- the second internal threads and the second external threads have radial play of the second threads upon final engagement, and

- the radial play of the second threads between the second internal threads and the second external threads is reduced in a second direction from the inner rim towards the second internal primary seal.

“The first direction from the inner rim towards the first inner primary seal” means a direction along the first direction. This does not mean that the first direction begins at the inner rim and/or ends at the first inner primary seal. “The second direction from the inner rim towards the second inner primary seal” means a direction along the second direction. This does not mean that the second direction begins at the inner rim and/or ends at the second inner primary seal.

According to one of the options for implementing a threaded connection:

- the radial play of the first threads between the first internal threads and the first external threads is reduced in the first direction until the radial play of the first threads reaches zero, and

- the radial play of the second threads between the second internal threads and the second external threads is reduced in the second direction until the radial play of the second threads reaches zero.

According to one of the options for implementing a threaded connection:

- the first internal threads and the first external threads have a first direction and are located beyond the location of the first threads where zero radial play of the first threads is achieved, without radial play of the first threads between the first internal threads and the first external threads, and

- the second internal threads and the second external threads have a second direction and are located outside the location of the second threads, where zero radial play of the second threads is achieved, without radial play of the second threads between the second internal threads and the second external threads.

According to one of the options for implementing a threaded connection:

- the first internal threads and the first external threads have, in a first direction and beyond the location of the first threads where zero radial play of the first threads is achieved, a radial play of the first threads between the first internal threads and the first external threads, and

- the second internal threads and the second external threads have, in a second direction beyond the location of the second threads where zero radial play of the second threads is achieved, a radial clearance of the second threads between the second internal threads and the second external threads.

According to one embodiment of the threaded connection, the connecting element contains a first relief groove between the first internal threads and the internal rim and a second relief groove between the second internal threads and the internal rim. Specifically, the first relief groove has an axial direction along the longitudinal axis between the first internal threads and the inner rim, and the second relief groove has an axial direction along the longitudinal axis between the second internal threads and the internal rim. During production of the connecting member, the first and second relief slots are used by turning tools to move away from the first and second internal threads and out of the connecting member without damaging the radially projecting internal rim after the first and second internal threads are formed.

According to one embodiment of the threaded connection, the radial thickness of the coupling part A of the first coupling part and the second coupling part are located at the location of the first relief groove and the second relief groove, respectively.

According to one embodiment of the threaded connection, the outer diameter of the COD connection is the largest diameter of the threaded connection.

According to one embodiment of the threaded connection, the peripheral part has an internal rim diameter RID and the threaded connection meets the conditions: RID = approximately TID. This indicates that the peripheral portion, namely the inner rim, is flush or substantially flush with the first and second tubular members. The fact that the RID is approximately equal to the TID suggests that the RID can differ from the TID value in such a way that the difference does not interfere with the function of the rim and the operation of the connection. The difference between RID and TID may be due to processing tolerances. Preferably, RID = TID ± 0.127 mm (0.050 inch). Even more preferably, RID = TID.

According to one of the embodiments of the threaded connection, the peripheral part has the outer diameter of the rim ROD and the threaded connection meets the conditions: B = (ROD - RID)/2. This indicates that the radial thickness of the peripheral portion B projects from the outer diameter of the rim ROD toward the inner diameter of the rim RID.

In one embodiment of the threaded connection, the threaded connection meets the following conditions: COD = ROD. This indicates that the outer diameter of the COD joint and the outer diameter of the ROD rim are equal.

According to one embodiment of the threaded connection, the first coupling part has an outer diameter FBOD, the second coupling part has an outer diameter SBOD, and the threaded connection meets the following conditions: COD = FBOD = SBOD. This indicates that the outer diameter of the COD connection, the diameter of the first coupling portion FBOD and the second coupling portion SBOD are equal.

In one embodiment, the threaded connection defines a longitudinal axis.

In one embodiment of the threaded connection, the radial thickness of the coupling portion A of the first coupling portion and the second coupling portion is located in the axial direction along the longitudinal axis between the inner rim and the first and second internal threads, respectively.

In one embodiment of the threaded connection, the radial thickness of the coupling portion A of the first coupling portion and the second coupling portion is measured in the radial direction relative to the longitudinal axis.

In one embodiment of the threaded connection, the connection member includes an outer connection surface that defines an outer diameter of the COD connection, and the radial thickness of the coupling portion A of the first coupling portion and the second coupling portion is measured from the outer surface of the connection.

According to one embodiment of the threaded connection, the outer surface of the connection forms the boundary between the outer thickness of the radial thickness of the coupling part A of the first coupling part and the second coupling part.

According to one of the embodiments of the threaded connection, the first pin part of the first pipe element is located in the axial direction along the longitudinal axis between the inner rim and the first unthreaded pipe part, and the second pin part of the first pipe element is located in the axial direction along the longitudinal axis between the inner rim and the second unthreaded pipe part.

In one embodiment of the threaded connection, the peripheral portion and the inner rim completely surround the longitudinal axis.

In one embodiment of the threaded connection, the peripheral portion includes an inner surface of the rim that is substantially flush, and preferably flush, with the inner surface of the first tube of the first tube element and the inner surface of the second tube of the second tube element.

One skilled in the art will appreciate that a threaded connection in accordance with the present invention may have several features of any of the above threaded connection embodiments.

Brief description of drawings

Embodiments of a threaded connection in accordance with the present invention are described by way of example only, with reference to the accompanying schematic drawings, which indicate the relevant parts, namely:

Figure 1A is a schematic perspective view of an embodiment of a threaded connection in accordance with the present invention,

Figure 1B shows a schematic cross-section of the threaded connection of Figure 1A,

Figure 2 shows a schematic enlarged view of part II of Figure 1,

Figure 3 shows a schematic enlarged view of part III of Figure 2.

Figure 4 shows graph 1, which shows hoop stresses in different embodiments of a threaded connection (b-n) having the design of Figure 1, and a threaded connection (a) without a peripheral part,

Figure 5 shows graph 2, which shows the hoop stresses at the initial position of the first seal of the threaded connections (a-n) according to graph 1,

Figure 6 shows graph 3, which shows the hoop stresses at the initial position of the first seal of alternative implementations of a’-n’ threaded connections according to graph 2,

Figure 7 schematically shows the angles of the cone of the threaded connection from Figure 1,

Figure 8 schematically shows the taper angles of a first alternative embodiment of a threaded connection in accordance with the present invention, and

Figure 9 schematically shows the cone angles of a second alternative embodiment of a threaded connection in accordance with the present invention.

Carrying out the invention

Figure 1A shows a perspective view of an embodiment of a threaded connection 1 in accordance with the present invention after final engagement 20. The threaded connection 1 for exploration and production of hydrocarbon wells includes a connecting element 2, a first tubular element 9 and a second tubular element 13. Details of the connecting element 2, the first pipe element 9 and the second pipe element 13 are shown separately to more accurately describe the threaded connection 1. Figure 1B shows a cross-section of the threaded connection from Figure 1A. Figure 2 shows an enlarged view of part II of Figure 1A. Figure 3 shows an enlarged view of part III of Figure 2.

The threaded connection 1 defines the longitudinal axis 31. The connection element 2 has a connection outer diameter COD defined by the outer connection surface 35, a first coupling portion 3 containing first internal threads 4, a second coupling portion 5 containing second internal threads 6, and a peripheral portion 7, comprising a radially projecting inner rim 8. The first coupling portion 3 has the length of the first coupling portion FBL. The second coupling part 5 has the length of the second coupling part SBL. The peripheral portion 7 is located between the first coupling portion 3 and the second coupling portion 5 and has a radial thickness of the peripheral portion B and an axial length of the peripheral portion C. The first coupling portion 3 and the second coupling portion 5 have a radial thickness of the coupling portion A between the inner rim 8 and the first inner threads 4 and second internal threads 6, respectively. This means that the first coupling portion 3 and the second coupling portion 5 have a radial thickness of the coupling portion A. The radial thickness of the coupling portion A of the first coupling portion 3 is located between the first internal threads 4 and the inner rim 8. The radial thickness of the coupling portion A of the second coupling portion 5 is located between the second internal threads 6 and the internal rim 8.

Specifically, the radial thickness of the coupling portion A of the first coupling portion 3 and the second coupling portion 5 is located in the axial direction along the longitudinal axis 31 between the inner rim 8 and the first internal threads 4 and the second internal threads 6, respectively. The radial thickness of the coupling portion A of the first coupling portion 3 and the second coupling portion 5 is measured in the radial direction relative to the longitudinal axis 31. The radial thickness of the coupling portion A of the first coupling portion 3 and the second coupling portion 5 is measured from the outer surface 35 of the joint. The outer joint surface 35 defines a boundary 36 between the outer radial thickness of the coupling portion A of the first coupling portion 3 and the second coupling portion 5.

Specifically, the connecting member 2, including the peripheral portion 7 with the inner rim 8, rotates about the longitudinal axis 31. In this regard, the peripheral portion 7 containing the inner rim 8 is located at an axial distance from the first internal threads 4 and from the second internal threads 6. Accordingly, the radial thickness of the coupling portion A of the first coupling portion 3 and the second coupling portion 5 is located between the inner rim 8 and the first internal threads 4 and the second internal threads 6.

The first pipe element 9 has a first non-threaded pipe part 10 and a first pin part 11 containing first male threads 12.

The second pipe element 13 has a second non-threaded pipe part 14 and a second pin part 15 containing second male threads 16.

The first nipple part 11 of the first pipe element 9 is located in the axial direction along the longitudinal axis 31 between the inner rim 8 and the first unthreaded pipe part 10, and the second nipple part 15 of the first pipe element 13 is located in the axial direction along the longitudinal axis 31 between the inner rim 8 and the second unthreaded pipe part 14.

The first non-threaded tube portion 10 and the second non-threaded tube portion 14 have an outer diameter TOD and a radial tube wall thickness W.

The first pipe element 9 and the second pipe element 13 have an inner diameter TID.

The first internal threads 4, the second internal threads 6, the first external threads 12 and the second external threads 16 are dovetail-shaped wedge threads 17.

17 dovetail wedge threads are characterized by threads that have a negative profile angle of the embedded sides and the supporting sides. The 17 dovetail wedge threads increase in width in opposite directions on the pin part and the corresponding coupling part. The degree of change in the width of 17 dovetail wedge threads is determined by a variable called the wedge ratio. The wedge ratio (though not technically a ratio) refers to the difference between the pitch of the embedded side and the pitch of the supporting side, causing the width of the dovetail wedge threads 17 to vary in the thread direction. The "pitch" of a thread is the differential distance between a portion of a thread on successive threads. Therefore, the pitch of the embedded side is the distance between the embedded sides of successive thread pitches along the axial length of the threaded pipe connection.

The first internal threads 4 and the first external threads 12 form a first internal primary seal 19 at final engagement 20. The second internal threads 6 and the second external threads 16 form a second internal primary seal 18 at final engagement 20.

The term "engagement" means engaging the first and second pin parts 11, 15 into the first and second coupling parts 3, 5 and threading these parts together by applying torque. By final engagement 20 is meant a situation where engagement is accomplished by threading together the first and second pin parts 11, 15 and the first and second coupling parts 3, 5 at the required moment or until the first and second pin parts 11, 15 reach a certain position relative to the first and second coupling parts 3, 5.

The first internal primary seal 19 is formed by complete contact between the first internal threads 4 and the first external threads 12, and the second internal primary seal 18 is formed by complete contact between the second internal threads 6 and the second external threads 16.

Upon final engagement 20, the first and second internal primary seals 18, 19 form a first line of defense against internal pressure in the threaded connection 1.

Threaded connection 1 meets the following conditions:

COD > TOD

B = (COD - TID) / 2

C > 0, and

A < W.

COD > TOD indicates that the connection outer diameter (COD) of the connecting member 2 is larger than the outer diameter (TOD) of the first unthreaded pipe portion 10 and the second unthreaded pipe portion 14.

Compared with the known threaded connection, a peripheral part 7 is added between the first coupling part 3 and the second coupling part 5. The peripheral part 7 has the same outer dimensions as the first and second coupling parts 3, 5, and has an inner rim 8 projecting inside in the radial direction towards the longitudinal axis 31 and located between the first nipple part 11 of the first pipe element 9 and the second nipple part 15 of the second pipe element 13. The peripheral part 7 surrounds the longitudinal axis 31 completely and has a thickness B, measured in the radial direction, and a length C , measured in the axial direction. The inner rim 8 is a circular rim surrounding the longitudinal axis 31.

B = (COD - TID) / 2 indicates that the inner rim 8 extends from the connection outer diameter (COD) of the connecting element to the tube inner diameter (TID). This promotes fluid flow through threaded connection 1.

The peripheral part 7 contains an inner surface of the rim 34, which is flush with the inner surface 32 of the first pipe element 9 and the inner surface 33 of the second pipe element 13.

C > 0 indicates that the inner rim 7 with the axial length of the peripheral portion C has been added to the threaded connection.

The axial length of the peripheral portion C is: C ≤ 31.75 mm (1.25 inches), preferably C ≤ 27.94 mm (1.1 inches), even more preferably C ≤ 25.4 mm (1.0 inches).

The axial length of the peripheral portion C is: C ≤ 6.35 mm (0.25 inch), preferably C ≤ 10.16 mm (0.4 inch), even more preferably C ≤ 12.7 mm (0.5 inch).

The axial length of the peripheral portion C is: C ≤ 20.32 mm (0.8 inch), preferably C ≤ 27.94 mm (1.1 inch), even more preferably C ≤ 25.4 mm (1.0 inch).

The radial thickness A of the first and second coupling parts 3, 5 is less than the radial wall thickness W of the first and second unthreaded pipe parts 10, 14 of the first and second pipe elements 9, 13.

In order to withstand high internal pressure, known threaded connections 1 usually have a radial thickness of the coupling portion A greater than the radial thickness of the pipe portion W. The result is a large outer diameter of the COD connection.

According to the present invention, the peripheral portion 7 of the threaded connection 1 allows the radial thickness of the coupling portion A to be reduced while maintaining the first and second internal primary seals 18, 19 under high internal pressure. As a result, it is possible to obtain a threaded connection 1 with a smaller outer diameter of the COD connection, due to which the threaded connection 1 can be used in hydrocarbon wells of smaller diameter, for example, so-called thin profile wells, which are sometimes called small wells.

The largest diametrical dimension of this type of threaded connection 1 is usually formed by the connection outer diameter (COD) of the connecting element 2. For this type of threaded connection 1 for exploration and production of hydrocarbon wells, tubular elements with a standard tube outer diameter (TOD) are usually used for the first and second pipe element 9, 13. To reduce the largest diametrical dimension of the threaded connection 1, it is necessary to reduce the radial thickness of the coupling part A of the connecting element 2.

The radial thickness of the coupling portion A and the radial thickness of the pipe portion W may meet the following conditions: A ≤ 0.9W, preferably A ≤ 0.8W.

The radial thickness of the coupling part A and the radial thickness of the pipe part W can meet the following conditions: A ≥ 0.7W.

The radial thickness of the coupling part A is located at the critical cross section of the first coupling part 3 and the second coupling part 5.

The outer diameter of the TOD tube can meet the following conditions: 114.3 mm (4.5 in) ≤ TOD ≤ 244.5 mm (9 5/8 in), preferably 114.3 mm (4.5 in) ≤ TOD ≤ 193, 7 mm (7.625 inches), preferably 114.3 mm (4.5 inches) ≤ TOD ≤ 139.7 mm (5.5 inches).

The radial thickness of the pipe portion W can meet the following conditions: 6.3 mm (0.250 inch) ≤ W ≤ 12.7 mm (0.500 inch), preferably 7.3 mm (0.290 inch) ≤ W ≤ 11.1 mm (0.437 inch) .

In the first direction 21 from the inner rim 8 toward the first inner primary seal 19, the first internal threads 4 and the first external threads 12 begin to have full contact at the initial position 22 of the first seal. In the opposite direction 23 from the inner rim 8 toward the second inner primary seal 18, the second inner threads 6 and the second outer threads 16 begin to make full contact at the initial position 24 of the second seal. The initial position 22 of the first seal is located at an axial distance of the seal D from the initial position 24 of the second seal. The axial distance of the seal D is greater than the axial length of the coupling part C. In other words, the axial distance of the seal D and the axial length of the coupling part C meet the following conditions: D > C.

"First direction 21 from the inner rim 8 towards the first inner primary seal 19" denotes the direction of the first direction 21. This does not mean that the first direction 21 begins at the inner rim 8 and/or ends at the first inner primary seal 19. "Second direction 23 from the inner rim 8 toward the second inner primary seal 18" denotes the direction of the second direction 23. This does not mean that the second direction 23 begins at the inner rim 8 and/or ends at the second inner primary seal 18.

The axial length of the peripheral part C and the axial distance of the seal D can meet the following conditions: 3.6 mm (0.142 inch) ≤ (D - C) / 2 ≤ 9.9 mm (0.392 inch), preferably 5 mm (0.2 inch) ≤ (D - C) / 2 ≤ 7.7 mm (0.3 in), preferably (D - C) / 2 = 6.1 mm (0.242 in).

The radially protruding inner rim 8 is located between the first nipple part 11 and the second nipple part 15.

The first tubular element 9 (namely the first nipple part 11) includes a first nipple tip 25, the second tubular element 13 (namely the second nipple part 15) contains a second nipple tip 26, and upon final engagement 20, the first nipple tip 25 and the second nipple tip 26 located at a distance from the inner rim 8 (see Figure 3).

A radially projecting inner rim 8 is located between the first nipple tip 26 and the second nipple tip 26.

At final engagement 20, the threaded connection 1 has no additional internal seal in addition to the first internal primary seal 19 and the second internal primary seal 18.

The first internal threads 4 and the first external threads 12 together form a first block of threads 27. The second internal threads 6 and the second external threads 16 together form a second block of threads 28. The threaded connection 1 does not have any other blocks of threads. This means that there are no thread blocks in addition to the first thread block 27 and the second thread block 28. The first thread block 27 and the second thread block 28 are single threads.

The connecting element 2 includes a first relief groove 29 between the first internal threads 4 and the internal rim 8 and a second relief groove 30 between the second internal threads 6 and the internal rim 8. In particular, the first relief groove 29 is located in the axial direction along the longitudinal axis 31 between the first internal threads 4 and the inner rim 8, and the second relief groove 30 is located in the axial direction along the longitudinal axis 31 between the second internal threads 6 and the inner rim 8. The radial thickness A of the first coupling part 3 and the second coupling part 5 is located at the location of the first relief groove 29 and the second unloading groove is 20, respectively.

In this embodiment, the peripheral portion 7 has an inner diameter of the rim RID equal to the inner diameter of the tube TID. In other words, the inner diameter of the tube TID and the inner diameter of the rim RID meet the following conditions: TID = RID. In other embodiments, the inside diameter of the TID tube and the inside diameter of the RID rim may differ by, for example, ±0.127 mm (0.050 inch).

The peripheral portion 7 has an outer diameter of the rim ROD, and the radial thickness of the peripheral portion B is equal to the difference between the outer diameter of the rim ROD and the inner diameter of the rim RID divided by two. In other words, the radial thickness of the peripheral portion B, the outer diameter of the rim ROD and the inner diameter of the rim RID correspond to the following conditions: B = (ROD - RID)/2.

The outer diameter of the COD connection is equal to the outer diameter of the ROD rim. In other words, the joint outer diameter COD and the rim outer diameter ROD meet the following conditions: COD = ROD.

The first coupling part 3 has an outer diameter of the first coupling part FBOD, the second coupling part 5 has an outer diameter of the second coupling part SBOD, which are equal to the outer diameter of the connection COD. In other words, the outer diameter of the connection COD, the diameter of the first coupling part FBOD and the second coupling part SBOD correspond to the following conditions: COD = FBOD = SBOD.

Figure 4 shows graph 1, which shows hoop stresses in different embodiments of a threaded connection (b-n) having the structure of Figure 1, and a threaded connection (a) without peripheral part 7.

For all a-n threaded connections, TOD tube OD is 139.7 mm (5.5 in), TID tube ID is 121.3 mm (4.776 in), W tube radial wall thickness is 9.2 mm (0.361 in), The outer diameter of the COD connection is 148.6 mm (5.852 in.) and the radial thickness of the coupling portion A is 6.9 mm (0.271 in.).

Graph 1 shows the hoop stresses in a-n threaded connections along a normalized length at an internal pressure of 555 bar (8050 psi). The length of the threaded connections a-n is normalized from 0 to 1. The normalization length includes the distance between the distal end of the fully formed first threads and the distal end of the fully formed second threads. The end of the fully formed threads is located in such a place that the fully formed threads merge into incomplete threads. The near end of fully formed threads is the end next to the rim, and the far end of fully formed threads is the farthest end from the rim.

The vertical lines a-n show the respective starting positions 22, 24 of the first and second seals of the threaded connections a-n.

Threaded connection a is not part of the invention, since it does not have a peripheral part 7 containing a radially protruding inner rim 8.

Threaded connections b-n have the same structure as threaded connection a, except that a peripheral part 7 containing a radially projecting inner rim 8 is added between the first and second coupling parts 3, 5.

Threaded connections b-n differ from each other in that they have a differential axial length of the peripheral part C. The axial length of the peripheral part C of threaded connections b-n is indicated in Table 1.

All b-n threaded connections have a radial peripheral thickness B of 13.64 mm (0.537 in).

Threaded connection Axial length of peripheral part C Hoop stress at the initial position of the first seal a 0.00 mm (0.00 in) 5426.2 bar (78700 psi) b 2.54 mm (0.10 in) 5157.3 bar (74800 psi) c 5.08 mm (0.20 in) 4805.6 bar (69700 psi) d 6.35 mm (0.25 in) 4660.9 bar (67600 psi) e 7.62mm (0.30 inch) 4591.9 bar (66600 psi) f 10.16 mm (0.40 in) 4378.17 bar (63500 psi) g 12.7 mm (0.50 in) 4205.8 bar (61000 psi) h 15.24 mm (0.60 in) 4067.9 bar (59000 psi) i 20.32 mm (0.80 in) 3930.0 bar (57000 psi) j 25.4 mm (1.0 in) 3743.9 bar (54300 psi) k 27.94 mm (1.10 in) 3737.0 bar (54200 psi) l 31.75 mm (1.25 in) 3688.7 bar (53500 psi) m 38.1 mm (1.50 in) 3716.3 bar (53900 psi) n 43.18 mm (1.70 in) 3688.7 bar (53500 psi)

Table 1:

The different initial positions 22, 24 of the first and second seals, shown in graph 1 by vertical lines a-n, are due to the different axial length C of the peripheral parts 7 of the threaded connections b-n.

Peripheral parts 7 of threaded connections b-n are added between the first and second coupling parts 3, 5 of threaded connection a. Compared to threaded connection a, the length of threaded connections b-n is increased (in the axial direction) by an amount equal to their axial length of the peripheral part C.

Figure 5 shows graph 2, which shows the hoop stresses at the initial position 22 of the first seal of the threaded connections (a-n) from graph 4. The indicated hoop stresses are also shown in table 1. Graph 1 shows that the hoop stresses at the initial positions 24 of the second seal equal to the hoop stresses in the initial positions 22 of the first seal.

If the radial strain (and associated hoop stresses) at the initial positions 22, 24 of the first and second seals is too high, then the first and second internal primary seals 18, 19 are weakened due to the separation of the first internal threads 4 from the first external threads 12 at the initial position 22 of the first seal and separation of the second internal threads 6 from the second external threads 16 in the initial position 24 of the second seal. After separation at the initial positions 22, 24 of the first and second seal, due to radial deformation caused by internal pressure, the rest of the first internal threads 4 will be more easily separated from the rest of the first external threads 12, and the rest of the second internal threads 6 will be more easily separated from the rest. second external threads 16.

Comparison of threaded connection a (without peripheral part 7) with threaded connections b-n (with peripheral part 7) in graphs 1 and 2 shows that peripheral parts 7 reduce hoop stresses in threaded connections b-n.

Of particular importance is the value of the hoop stress in the initial positions 22, 24 of the first and second seals, since too high hoop stresses (and associated radial deformations) in the specified initial positions 22, 24 of the first and second seals weaken the first and second internal primary seals 18 19. Beyond the initial first and second seal positions 22, 24, hoop stresses (and associated radial strains) are much less important since the internal pressure does not extend beyond the initial first and second seal positions 22, 24 while maintaining the first and second internal primary seals 18, 19. Higher hoop stresses beyond the initial positions 22, 24 of the first and second seals can be reduced using alternative embodiments of the threaded connection in accordance with the invention shown in figures 8 and 9.

Graphs 1 and 2 also show that the size of the axial length of the peripheral part C affects the degree of reduction of hoop stresses in the threaded connections b-n, in particular in the initial positions 22, 24 of the first and second seals. Initially, the contraction in the initial positions 22, 24 of the first and second seal increases with increasing axial length of the peripheral part C, but such contraction stops with a further increase in the axial length of the peripheral part C.

The disadvantage of too long an axial length of the peripheral part C is that the total length of the connecting element 2 (the sum of the length of the first coupling part FBL 3, the length C of the peripheral part 7 and the length of the second coupling part SBL 5) increases without the additional benefit of reducing hoop stresses in initial positions 22, 24 of the first and second seals. In addition, increasing the overall length of the connection increases material costs. Exceeding a certain total length may reduce the ability to use certain field equipment to make the connection. The disadvantage of too short an axial length of the peripheral part C is the possibility of damage to the inner rim 8.

Figure 6 shows graph 3, which shows the hoop stresses at the initial position 22 of the first seal of alternative embodiments of the a'-n' threaded connections according to graph 2.

For all a'-n' threaded connections, TOD tube OD is 114.3 mm (4.5 in), TID tube ID is 99.6 mm (3.920 in), and W tube radial wall thickness is 7.4 mm ( 0.290 in.), the outside diameter of the COD connection is 122 mm (4.803 in.), and the radial thickness of the coupling portion A is 5.4 mm (0.213 in.).

In addition, the threaded connection a' is not part of the invention, since it does not have a peripheral part 7 containing a radially projecting inner rim 8.

The b'-n' threaded connections differ from each other in that they have a differential axial length of the peripheral part C. The axial length of the peripheral part C of the b'-n' threaded connections is shown in Table 2. All b'-n' threaded connections have a radial thickness peripheral part B 11.2 mm (0.442 inches).

The hoop stresses at the initial position 22 of the first seal of the a'-n' threaded connections for an internal pressure of 555 bar (8050 psi) are also given in Table 2. The hoop stresses at the initial positions 24 of the second seal are equal to the hoop stresses at the initial positions 22 of the first seals.

Threaded connection Axial length of peripheral part C Hoop stress at initial seal position a' 0.00 mm (0.00 in) 5191.8 bar (75300 psi) b' 2.54 mm (0.10 in) 4726.4 bar (68550 psi) c' 5.08 mm (0.20 in) 4429.9 bar (64250 psi) d' 6.35 mm (0.25 in) 4309.2 bar (62500 psi) e' 7.62mm (0.30 inch) 4267.9 bar (61900 psi) f' 10.16 mm (0.40 in) 4088.6 bar (59300 psi) g' 12.7 mm (0.50 in) 3957.6 bar (57400 psi) h' 15.24 mm (0.60 in) 3881.7 bar (56300 psi) i' 20.32 mm (0.80 in) 3792.1 bar (55000 psi) j' 25.4 mm (1.0 in) 3668.0 bar (53200 psi) k' 27.94 mm (1.10 in) 3681.8 bar (53400 psi) l' 31.75 mm (1.25 in) 3688.7 bar (53500 psi) m' 38.1 mm (1.50 in) 3778.3 bar (54800 psi) n' 43.18 mm (1.70 in) 3757.6 bar (54500 psi)

Table 2:

The effects described in relation to graphs 1 and 2 of threaded connections a-n are shown in graph 3 of threaded connections a’-n’.

Figure 7 shows the cone angles of the threaded connection 1 of Figure 1 at final engagement 20. A view similar to Figure 2 is used to represent the average diameter of the first pin portion PPD1 of the first male threads 12 of the first pin portion 11, the average diameter of the first box portion BPD1 of the first internal threads 4 of the first coupling part 3, the average diameter of the second nipple part PPD2 of the second external threads 16 of the second nipple part 15, the average diameter of the second coupling part BPD2 of the second internal threads 46 of the second coupling part 5.

Line I shows the change in the average diameter of the first nipple part of PPD1 along the longitudinal axis 31.

Line II shows the change in the average diameter of the first coupling part BPD1 along the longitudinal axis 31.

Line III shows the change in the average diameter of the second nipple portion of PPD2 along the longitudinal axis 31.

Line IV shows the change in the average diameter of the second coupling part BPD2 along the longitudinal axis 31.

The cone angle of the first internal thread α1 is the angle between the average diameter line I of the first nipple part of PPD 1 and the longitudinal axis 31. The cone angle of the first external thread β1 is the angle between the average diameter line II of the coupling part BPD1 and the longitudinal axis 31. The cone angle of the second internal thread thread α2 is the angle between line III of the average diameter of the second nipple part PPD 2 and the longitudinal axis 31. The cone angle of the second external thread β2 is the angle between line IV of the average diameter of the coupling part BPD2 and the longitudinal axis 31.

Figure 7 shows that the first internal threads 4 have a constant taper angle of the first internal thread α ₁ relative to the longitudinal axis 31. The first external threads 12 have a constant taper angle of the first external threads β ₁ relative to the longitudinal axis 31. The second internal threads 6 have a constant taper angle the first internal threads α ₂ relative to the longitudinal axis 31. The second external threads 16 have a constant cone angle of the second external threads β ₂ relative to the longitudinal axis 31.

The cone angle of the first internal threads α ₁ and the cone angle of the first external threads β ₁ are equal to each other. The cone angle of the second internal threads α ₂ and the cone angle of the second external threads β ₂ are equal to each other.

The first internal threads 4 and the first external threads 12 have a radial play of the first threads 37. The second internal threads 6 and the second external threads 16 have a radial play of the second threads 38.

The cone angle of the first internal threads α ₁ , the cone angle of the first external threads β ₁ , the cone angle of the second internal threads α ₂ , the cone angle of the second external threads β ₂ have a diametrical cone from 0.36 to 0.86 mm/revolution (0.014 and 0.034 inches /rev) inclusive, preferably from 0.51 to 0.71 mm/rev (0.020 and 0.028 in/rev) inclusive.

To determine the taper angle of the first internal threads α ₁ , it is possible to measure the diametral taper on the first coupling portion 3, which represents the change in the average diameter of the coupling portion BPD1 of the first internal threads 4 per revolution along the first internal threads 4, and the pitch, which represents the displacement in the axial direction by revolution along the first internal threads 4. Therefore, the cone angle can be calculated as follows:

This applies similarly to the taper angle of the first male threads β ₁ , the taper angle of the second female threads α ₂ and the taper angle of the second male threads β _{2 .}

Figure 8 shows the cone angles of a first alternative embodiment of a threaded connection 1 according to the invention. The first alternative embodiment differs from the threaded connection in figure 7 only in that the taper angle of the first internal threads α ₁ is greater than the taper angle of the first external threads β ₁ , and the taper angle of the second internal threads α ₂ is greater than the taper angle of the second external threads β _{2 .}

The taper angle of the first internal threads α ₁ and the taper angle of the second internal threads α ₂ have a diametrical internal taper of 0.41 to 0.91 mm/rev (0.016 and 0.036 in/rev) inclusive, preferably 0.56 to 0.76 mm /rev (0.022 and 0.030 in/rev) inclusive, and the taper angle of the first external threads β ₁ and the cone angle of the second external threads β ₂ have a diametral taper of 0.36 to 0.86 mm/rev (0.014 and 0.034 in/rev ) inclusive, preferably from 0.51 to 0.71 mm/rev (0.020 and 0.028 in/rev) inclusive.

The first internal threads 4 and the first external threads 12 have a radial play 37 of the first threads upon final engagement 20. The radial play 37 of the first threads between the first internal threads 4 and the first external threads 12 decreases in the first direction 21 from the inner rim 8 towards the first internal primary seal. 18 (see Figure 1A). The second internal threads 6 and the second external threads 16 have a radial play 38 of the second threads upon final engagement 20, and the radial play 38 of the second threads between the second internal threads 6 and the second external threads 16 decreases in the opposite direction 23 from the inner rim 8 towards the second internal primary seals 18 (see Figure 1A). The decreasing radial play 37 of the first threads and the decreasing radial play 38 of the second threads reduce the higher hoop stresses that occur outside the initial positions 22, 24 of the first and second seals when viewed in the first and second directions 21, 23, respectively (see graph at Figure 4).

Specifically, the radial play 37 of the first threads between the first internal threads 4 and the first external threads 12 is reduced in the first direction 21 until the radial play of the first threads reaches zero, and the radial play 38 of the second threads between the second internal threads 6 and the second external threads 16 is reduced. in the second direction 23 until the radial play of the second threads reaches zero. The first internal threads 4 and the first external threads 12 extend in the first direction 21 and outside the first threads arrangement 39, where the radial play of the first threads equal to zero is achieved without the radial play of the first threads (see position 41, Figure 9) between the first internal threads 4 and the first male threads 12. The second internal threads 6 and the second male threads 16 extend in the second direction 23 and outside the second thread location 40, where the radial play of the second threads equal to zero is achieved without the radial play of the second threads (see position 42, Figure 9) between the second internal threads 6 and the second external threads 16.

In another alternative embodiment, the radial play 37 of the first threads between the first internal threads 4 and the first external threads 12 is reduced in the first direction 21 until the radial play of the first threads is greater than zero, and the radial play 38 of the second threads between the second internal threads 6 and the second external threads 16 decreases in the second direction 23 until the radial play of the second threads is above zero.

Figure 9 shows the taper angles of a first alternative embodiment of a threaded connection in accordance with the present invention. The second alternative embodiment differs from the threaded connection in Figure 8 only in that the first internal threads 4 and the first external threads 12 have in a first direction 21 beyond the location 39 of the first threads where zero radial play 37 is achieved, the radial play 41 of the first threads between the first internal threads 4 and the first external threads 12, and the second internal threads 6 and the second external threads 16 have in a second direction 23 outside the location 40 of the second threads, where zero radial play of the second threads is achieved, the second radial play 42 between the second internal threads 6 and second external threads 16.

This application discloses in detail embodiments of the present invention; however, it is understood that the disclosed embodiments are provided to illustrate the present invention, which can be implemented in various ways. Therefore, the structural and functional features disclosed in this application are not limiting, but serve as the basis for the claims and represent special cases for specialists in the art, taking into account the various applications of the invention in almost any design having the corresponding parts. Moreover, the terms and phrases used in this application are not intended to be limiting, but rather provide a clear description of the invention.

The articles used in the text mean “one” or “more than one.” The plural used in the text means "two" or "more than two." The term "other" as used herein means at least a second or more. The terms “including” and/or “having” as used herein mean “comprises” (namely, without excluding other elements or steps). Any reference positions in the claims should not be considered limiting the claims or the invention.

It will be apparent to those skilled in the industry that the threaded connection can be made in various modifications without deviating from the scope of the claims.

Claims (55)

1. Threaded connection for pipes used in wells for exploration and production of hydrocarbons, which contains: - a connecting element having an outer diameter of the COD connection and containing: a first coupling portion comprising first internal threads, a second coupling portion comprising second internal threads, and a peripheral portion comprising a radially projecting inner rim, wherein the peripheral portion is located between the first coupling portion and the second coupling portion and has a radial thickness B and an axial length C, the first coupling portion and the second coupling portion have a radial thickness A located between the inner rim and the first internal threads and the second internal threads, respectively, - a first tubular element comprising a first non-threaded tubular portion, and a first pin portion comprising first male threads, and - a second tubular element comprising a second non-threaded tubular portion, and a second pin portion comprising second male threads, wherein - the first non-threaded pipe part and the second non-threaded pipe part have an outer diameter TOD and a radial wall thickness W, - the first pipe element and the second pipe element have an internal diameter TID, - the first internal threads, the second internal threads, the first external threads, the second external threads have a dovetail shape, - the first internal threads and the first external threads form the first internal primary seal upon final engagement of the connection, - the second internal threads and the second external threads form a second internal primary seal upon final engagement of the connection, and - the threaded connection meets the following conditions: COD > TOD B = approximately ((COD – TID) / 2) C > 0, and A < W. 2. Threaded connection according to claim 1, which meets the following conditions: C ≤ 31.75 mm (1.25 inches), preferably C ≤ 27.94 mm (1.1 inches). 3. Threaded connection according to claim 1 or 2, which meets the following conditions: C ≤ 6.35 mm (0.25 inch), preferably C ≤ 10.16 mm (0.4 inch). 4. A threaded connection according to claim 1, which meets the following conditions: 20.32 mm (0.8 inch) ≤ C ≤ 27.94 mm (1.1 inch), preferably C ≤ 25.4 mm (1.0 inch). 5. Threaded connection according to one of the previous paragraphs, which meets the following conditions: A ≤ 0.9W, preferably A ≤ 0.8W and/or A ≥ 0.7W. 6. Threaded connection according to one of the previous paragraphs, characterized in that the radial thickness A of the coupling part is located at the critical cross section of the first coupling part and the second coupling part. 7. Threaded connection according to one of the previous paragraphs, characterized in that: - in a first direction from the inner rim towards the first internal primary seal, the first internal threads and the first external threads come into full contact in the initial position of the first seal, - in the opposite second direction from the inner rim towards the second internal primary seal, the second internal threads and the second external threads come into full contact in the initial position of the second seal, - the initial position of the first seal is located at the axial distance of the seal D from the initial position of the second seal, and - the threaded connection meets the following conditions: D>C. 8. Threaded connection according to clause 7, which meets the following conditions: 3.6 mm (0.142 in) ≤ (D – C) / 2 ≤ 9.9 mm (0.392 in), preferably 5 mm (0.2 in) ≤ (D – C) / 2 ≤ 7.7 mm (0 .3 inches), preferably (D – C) / 2 = 6.1 mm (0.242 inches). 9. Threaded connection according to one of the previous paragraphs, characterized in that: - the first internal threads and the first external threads together form a first block of threads, - the second internal threads and the second external threads together form a second thread block, and - the first block of threads and the second block of threads are blocks of single-thread threads. 10. Threaded connection according to any of the previous paragraphs, characterized in that: - the threaded connection defines the longitudinal axis, - the first internal threads have a constant cone angle of the first internal threads α ₁ relative to the longitudinal axis, - the first external threads have a constant cone angle of the first external threads β ₁ relative to the longitudinal axis, - the cone angle of the first internal threads α ₁ is greater than the cone angle of the first external threads β ₁ , - the second internal threads have a constant cone angle of the second internal threads α ₂ relative to the longitudinal axis, - the second external threads have a constant taper angle of the second external threads β ₂ relative to the longitudinal axis, and - the cone angle of the second internal threads α ₂ is greater than the cone angle of the second external threads β ₂ . 11. Threaded connection according to claim 11, characterized in that: - the first internal threads and the first external threads have radial play of the first threads upon final engagement, - the radial play of the first threads between the first internal threads and the first external threads is reduced in a first direction from the inner rim towards the first internal primary seal, - the second internal threads and the second external threads have radial play of the second threads upon final engagement, and - the radial play of the second threads between the second internal threads and the second external threads is reduced in a second direction from the inner rim towards the second internal primary seal. 12. Threaded connection according to one of the previous paragraphs, in which the outer diameter of the connection COD is the largest diameter of the threaded connection. 13. Threaded connection according to one of the previous paragraphs, in which the peripheral part has the inner diameter of the rim RID and the threaded connection meets the conditions: RID = TID ±0.127 mm (0.050 in), preferably RID = TID. 14. Threaded connection according to one of the previous paragraphs, which meets the following conditions: COD = ROD and/or wherein the first coupling portion has an outer diameter FBOD, the second coupling portion has an outer diameter SBOD, and the threaded connection meets the following conditions: COD = FBOD = SBOD.