BACKGROUND OF THE INVENTIONS
1. Field of the Inventions
[0002] The present invention relates to threaded and coupled connections
which either employ a torque ring or coupling shoulder to increase and maintain
torsional capacity and control stresses within said connection.
15 2. Description Of The Related Art
[0003] After a well has been drilled to a desired depth, large diameter and
relatively heavy pipe known as “casing” is frequently installed in the well. During
installation, such casing is typically inserted into the pre-drilled well bore in a number
of separate sections of substantially equal length commonly referred to as “joints.”
20 The joints, which generally include threaded connections at each end, are typically
joined axially in end-to-end orientation at the earth’s surface (typically from a drilling
rig) in order to form a substantially continuous “string” of pipe that reaches
downward into the well. After the casing is installed within the well bore, the pipe
string is usually cemented in place.
25 [0004] In addition to casing, drill pipe and other tubular goods used to drill,
complete and service subterranean wellbores are also commonly joined together in
end-to-end orientation using threaded connections. Many of these threaded
connections – and particularly those used with casing and certain types of tubing –
have tapered threads without shoulders. Frequently, such connections employ
3
internally threaded couplings installed between adjacent pipe joints in order to link or
join two externally threaded pipe sections together; during the “make up” or
connection process, a specified or predetermined amount of torque force is typically
applied to a pipe joint in order to mate the threaded connection of said pipe joint with
the threaded connection 5 of a coupling.
[0005] Such couplings typically have a somewhat larger outer diameter than
the outer diameter of the adjacent pipe joints being joined. Further, such couplings
generally have opposing tapered box threads designed to receive tapered, threaded
ends of the pipe sections to be joined (often referred to as “pins”). When joined
10 together, such threaded couplings structurally secure adjoining pipe sections together
in series, and form a fluid pressure seal between said joined pipe sections.
[0006] In many instances, torque forces are applied to an assembled pipe
string while such pipe string is at least partially disposed within a wellbore such as,
for example, to rotate said pipe string within said wellbore. Frequently, such
15 subterranean wellbores can include deviations from a true vertical path, at least to
some degree, which can result in additional torque being applied at the earth’s surface
in order to transmit such torque forces to the bottom of a wellbore. As a result, such
torque forces applied to a pipe string can sometimes exceed specification torque
required to “make up” or screw threaded connections together. In such situations,
20 excess torque forces may further drive the pin threads into the threaded connections
of the couplings. As such, there is a need to allow the couplings to accept more
torque without further running of the threads.
[0007] The oil and gas industry frequently employs floating shoulder rings
in order to increase the torque capacity of threaded connections employing threaded
25 couplings. Such floating shoulder rings are typically received within the internal bore
of a threaded coupling, and are relatively small compared to the couplings into which
they are installed. Functionally, a floating shoulder ring is installed inside the central
bore of a coupling between the two opposing pins (threaded ends) of adjacent pipe
joints, in an area frequently referred to as the “J space”. Such floating shoulder rings
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and couplings are described in detail in United States Patent No. 8,091,930, which is
incorporated herein by reference for all purposes.
[0008] Previously, there had been little need to rotate a casing string with
more torque than its assembly torque (that is, the torque required to add a threaded
joint to the existing pipe string); however lateral wells are now 5 being drilled into
relatively thin shale formations to produce gas and oil. Rotation of an assembled pipe
string can be required to get the assembled pipe string through a bend from a vertical
section of a well to a lateral section of a well; often, this requires application of more
torque forces to the assembled pipe string than the assembly torque. Further, axial
10 force is frequently applied to the assembled pipe string in order to “push” the
assembled pipe string within a wellbore, which increases axial stress on the inside of
the bend. Therefore, a need exists to increase the axial compressive force that a
casing threaded connection can withstand without leakage or damage.
[0009] As noted above, many threaded connections used on casing do not
15 employ a coupling shoulder to remain cost-effective, which leaves no shoulder to
abut the end of a pin for added torque. In such cases, said torque rings have been
inserted within couplings between the opposing ends of pipe joints to contact and
increase the torque the connection can withstand.
[00010] Similarly, tubing connections are frequently used for repeated trips
20 in and out of wellbores. Expensive tubing connections such as connections threaded
onto upset portions of the pipe ends are utilized in order to drill out corroded pipe,
packers or other obstructions within the wellbore. Remediation may require many
trips in and out of the well, before a replacement production string can begin to flow
anew and such operations dictate a reliable connection with enhanced torque and
25 sealability. Thus, there exists a need to increase mechanical capacity of pipe
connections while reducing costs to remain cost effective.
[00011] Due to varying tolerances or the use of a used pipe string, significant
variations may exist between a “field end” of a coupling as compared to a “mill end”
of the coupling. In a case where the mill end pin has a higher diametrical interference
5
than its field end counterpart, the mill end pin will build up high hoop stresses and
the field end will begin to yield the pin nose to attain prescribed torque. Conversely
when the mill end pin is loose, it will tend to yield the pin nose in order to attain the
prescribed torque and the field end will build up high hoop stresses.
[00012] In the case of a loose pin, in which the threads are 5 unable to provide
sufficient torsional resistance, the pin nose is in compression, even before the
theoretical shoulder torque is reached. Therefore, the connection will begin yielding
at the pin nose prior to reaching its intended total torque. The side wherein the pin
nose has yielded will decrease torsion resistance and shear strength of the threads due
10 to stress preloading; further, the threads will fail to generate their potential torque and
as a result, total torque will be reduced in an amount equal to reduced shoulder
torque.
[00013] A properly dimensioned torque ring can be placed at the mill end
nose of sufficient thickness to allow the field end pin have proper standoff based
15 upon the diametrical interference between field pin and coupling thread thereby
equalizing hoop stresses within the connection.
[00014] Each time a tubing connection is made up and broken out, the
threaded members undergo some plastic deformation and thread surfaces begin to
wear. This reduces radial interference between box and pin members and, ultimately,
20 the torque forces that the connection can withstand. When a torque ring is inserted in
the J space, the mid-length area of the coupling or box starting after the connections
make-up loss, as measured from each coupling end, overall torsional capacity is
increased due to contact between pin face and ring face. Since the ring acts as a
barrier to further ingress of the pin into the box, each successive make-up lowers
25 shoulder torque due to plastic yield and wear of the threads. Higher shoulder torques,
those torques derived from thread interference, could be maintained if the pin could
travel further into the connection by a prescribed amount before reaching the torque
ring.
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[00015] The use of a torque ring as described herein include enhanced
sealability of a threaded connection by means of a controlled bearing load between
the pin face and ring face. With a torque ring dimensioned to optimize the crosssectional
area of the face, the bearing pressure between pin faces and ring faces will
exceed the internal pressure rating of the pipe, and thereby provide 5 reliable sealing
surfaces. This feature further provides protection against thread corrosion and thread
washout. The smooth bore provided by means of abutment between pin faces and
ring faces increases flow within the bore and the bearing load between said faces
reduces overall bending stresses.
10 [00016] Thus, there is a need for a robust shoulder ring that can structurally
support torque forces applied to threaded pipe connections, and particularly coupled
threaded pipe connections.

We Claim:
1. A coupled pipe connection 5 system comprising:
a coupling having a bore therethrough defining an inner surface having
a plurality of tapered inner threads disposed on opposite ends of the coupling, and
tapering toward a central portion of the coupling where an inner diameter of the
coupling is smaller than inner diameters of the coupling at its opposite ends;
10 a first pipe having a first pin, the first pipe having an inner cylindrical
surface and an outer cylindrical surface, the outer cylindrical surface including a
plurality of tapered outer threads disposed therearound, the tapered outer threads on
the first pipe being threadably engaged with the tapered inner threads on a left mill
side of the coupling;
15 a second pipe having a second pin, the first pipe having an inner
cylindrical surface and an outer cylindrical surface, the outer cylindrical surface
including a plurality of tapered outer threads disposed therearound, the tapered outer
threads on the second pipe being threadably engaged with the tapered inner threads
on a right field side of the coupling; and
20 a torque ring disposed within the coupling and between the first pin
and the second pin, the torque ring having an inner cylindrical surface, an outer
cylindrical surface, and an outer tapered threaded surface having a plurality of tapered
threads engaged with and tapered to match a mid-length axial section of the inner
threads of the coupling.
25 2. The coupled pipe connection system of claim 1, wherein inner
diameters of the first pin, the second pin, and the torque ring are substantially equal.
3. The coupled pipe connection system of claim 1, wherein the first pin,
the second pin, and the torque ring are in co-axial alignment so that the inner
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cylindrical surfaces of the torque ring, the first pipe and the second pipe form a
continuous inner cylindrical surface within the connection system.
4. The coupled pipe connection system of claim 1, wherein a major
diameter of the tapered threads on the torque ring are adjacent a field end face of the
torque ring, and the field end face of the torque ring is in contact with 5 a field end face
of the second pin.
5. The coupled pipe connection system of claim 1, wherein the torque
ring is centrally positioned radially and axially with the mid-length axial section of
the coupling.
10 6. The coupled pipe connection system of claim 1, wherein an axial
length of each of the threads on the outer surface of the torque ring is less than an
axial length of each of the outer threads on the first and second pins.
7. The coupled pipe connection system of claim 1, wherein the threads
on the outer surface of the torque ring are truncated.
15 8. The coupled pipe connection system of claim 1, wherein the torque
ring includes at least one bevel formed towards a center outer diameter of the torque
ring.
9. The coupled pipe connection system of claim 1, wherein the torque
ring includes at least one bevel formed away from a center outer diameter of the
20 torque ring.
10. The coupled pipe connection system of claim 1, wherein each of
opposed faces of the torque ring includes a planar face section and a beveled surface
extending downwardly from the planar face section and away from a central inner
diameter of the torque ring to form opposed first and second beveled surfaces adapted
25 for engagement with corresponding internal chamfers on the internal cylindrical
surfaces of the first and second pipes.
11. The coupled pipe connection system of claim 1, wherein each of
opposed faces of the torque ring includes a planar face section and a beveled surface
extending upwardly from the planar face section and away from a central outer
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diameter of the torque ring to form opposed first and second beveled surfaces adapted
for engagement with corresponding external chamfers on the outer cylindrical
surfaces of the first and second pipes.
12. A coupled pipe connection system including interchangeable torque
5 rings comprising:
a coupling having a bore therethrough defining an inner surface having
a plurality of tapered inner threads disposed on opposite ends of the coupling, and
tapering toward a central portion of the coupling where an inner diameter of the
coupling is smaller than inner diameters of the coupling at its opposite ends;
10 a first pipe having a first pin, the first pipe having an inner cylindrical
surface and an outer cylindrical surface, the outer cylindrical surface including a
plurality of outer threads disposed therearound, the outer threads on the first pipe
being threadably engaged with the inner threads on a left mill side of the coupling;
a second pipe having a second pin, the first pipe having an inner
15 cylindrical surface and an outer cylindrical surface, the outer cylindrical surface
including a plurality of outer threads disposed therearound, the outer threads on the
second pipe being threadably engaged with the inner threads on a right field side of
the coupling; and
at least a first torque ring, and a second torque ring, each of the torque
20 rings being adapted to be sequentially disposed within the coupling and between the
first pin and the second pin, each torque ring having an inner cylindrical surface and
an outer cylindrical surface, at least a portion of the outer cylindrical surface of each
torque ring including a plurality of threads engaged with and dimensioned to match a
mid-length axial section of the inner threads of the coupling, the mid-length axial
25 section having a J-space length, the first torque ring having an axial length not greater
than the J-space length, and the second torque ring having an axial length less than
the axial length of the first torque ring.
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13. The coupled pipe connection system of claim 12, wherein the threads
on the outer cylindrical surface of the torque ring are cylindrical threads partially
extending across an axial length of the torque ring.
14. The coupled pipe connection system of claim 12, wherein the threads
on the outer cylindrical surface of the torque ring are cylindrical 5 threads fully
extending across an axial length of the torque ring.
15. The coupled pipe connection system of claim 12, wherein the threads
on the outer cylindrical surface of the torque ring are tapered threads partially
extending across an axial length of the torque ring.
10 16. The coupled pipe connection system of claim 12, wherein each of the
first torque ring and the second torque ring is simultaneously disposed within the
coupling and between the first pin and the second pin.
17. The coupled pipe connection system of claim 12, wherein an axial
length of each of the threads on the outer surface of the torque ring is less than an
15 axial length of each of the outer threads on the first and second pins.
18. The coupled pipe connection system of claim 12, wherein the threads
on the outer surface of the torque ring are truncated.
19. The coupled pipe connection system of claim 12, wherein the torque
ring includes at least one bevel formed towards a center outer diameter of the torque
20 ring.
20. The coupled pipe connection system of claim 12, wherein the torque
ring includes at least one bevel formed away from a center outer diameter of the
torque ring.
21. The coupled pipe connection system of claim 12, wherein each of
25 opposed faces of the torque ring includes a planar face section and a beveled surface
extending downwardly from the planar face section and away from a central inner
diameter of the torque ring to form opposed first and second beveled surfaces adapted
for engagement with corresponding internal chamfers on the internal cylindrical
surfaces of the first and second pipes.
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22. The coupled pipe connection system of claim 12, wherein each of
opposed faces of the torque ring includes a planar face section and a beveled surface
extending upwardly from the planar face section and away from a central outer
diameter of the torque ring to form opposed first and second beveled surfaces adapted
for engagement with corresponding external chamfers on the 5 outer cylindrical
surfaces of the first and second pipes.
23. A coupled pipe connection system including interchangeable
couplings comprising:
at least a first coupling and a second coupling adapted to be
10 sequentially used as part of the coupled pipe connection system, each coupling having
a bore therethrough defining an inner surface having a centrally disposed internal
shoulder, each coupling including a first plurality of tapered inner threads disposed on
a left side of the shoulder and a second plurality of tapered inner threads disposed on
a right side of the shoulder, the internal shoulder of the first coupling having a first
15 axial length, the internal shoulder of the second coupling having a second axial length
less than the first axial length;
a first pipe having a first pin, the first pipe having an inner cylindrical
surface and an outer cylindrical surface, the outer cylindrical surface including a
plurality of outer threads disposed therearound, the outer threads on the first pipe
20 being threadably and sequentially engaged with a first plurality of tapered inner
threads on one of the first coupling and the second coupling; and
a second pipe having a second pin, the first pipe having an inner
cylindrical surface and an outer cylindrical surface, the outer cylindrical surface
including a plurality of outer threads disposed therearound, the outer threads on the
25 second pipe being threadably and sequentially engaged with a first plurality of tapered
inner threads on one of the first coupling and the second coupling.
24. A coupled pipe connection system comprising:
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a first pipe having a first pin, the first pin having an inner cylindrical
surface and an outer cylindrical surface, the outer cylindrical surface including a
plurality of outer threads disposed therearound;
a second pipe having an upset box and a main body, the upset box
including an internal annular surface having a plurality of tapered 5 box threads
disposed therein, the internal annular surface terminating in an annular abutment
joining the internal annular surface of the upset box to a main cylindrical bore within
the main body, the plurality of outer threads on the first pipe being threadably
engaged to the tapered box threads; and
10 at least one torque ring disposed within the upset box and between a
distal end of the first pipe and the annular abutment within the second pipe, each
torque ring having an inner cylindrical surface,an outer cylindrical surface, and an
outer threaded surface at least a portion of the outer cylindrical surface including a
plurality of tapered threads engaged with the box threads.
15 25. The coupled pipe connection system of claim 24, wherein inner
diameters of the first pin, the second pipe, and the torque ring are equal.
26. The coupled pipe connection system of claim 24, wherein the first pin,
the second pipe, and the torque ring are in co-axial alignment so that the inner
cylindrical surfaces of the torque ring, the first pin and the second pipe form a
20 continuous inner cylindrical surface within the connection system.
27. The coupled pipe connection system of claim 24, wherein an axial
length of each of the threads on the outer surface of the torque ring is less than an
axial length of each of the outer threads on the first pin.
28. The coupled pipe connection system of claim 24, wherein the threads
25 on the outer cylindrical surface of the torque ring are cylindrical threads partially
extending across an axial length of the torque ring.
29. The coupled pipe connection system of claim 24, wherein the threads
on the outer cylindrical surface of the torque ring are cylindrical threads fully
extending across an axial length of the torque ring.
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30. The coupled pipe connection system of claim 24, wherein the threads
on the outer surface of the torque ring are truncated.
31. The coupled pipe connection system of claim 24, wherein the torque
ring includes at least one bevel formed towards a center outer diameter of the torque
5 ring.
32. The coupled pipe connection system of claim 24, wherein the torque
ring includes at least one bevel formed away from a center outer diameter of the
torque ring.
33. The coupled pipe connection system of claim 24, wherein each of
10 opposed faces of the torque ring includes a planar face section and a beveled surface
extending downwardly from the planar face section and away from a central inner
diameter of the torque ring to form opposed first and second beveled surfaces adapted
for engagement with corresponding internal chamfers on the internal cylindrical
surfaces of the first and second pipes.
15 34. The coupled pipe connection system of claim 24, wherein each of
opposed faces of the torque ring includes a planar face section and a beveled surface
extending upwardly from the planar face section and away from a central outer
diameter of the torque ring to form opposed first and second beveled surfaces adapted
for engagement with corresponding external chamfers on the outer cylindrical
20 surfaces of the first and second pipes.