U.S. patent application number 10/908794 was filed with the patent office on 2005-12-01 for apparatus and method for setting a tubing anchor and tensioning tubing string thereabove.
Invention is credited to Doyle, John P., Tessier, Lynn P., Weber, James L..
Application Number | 20050263293 10/908794 |
Document ID | / |
Family ID | 35450941 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050263293 |
Kind Code |
A1 |
Tessier, Lynn P. ; et
al. |
December 1, 2005 |
APPARATUS AND METHOD FOR SETTING A TUBING ANCHOR AND TENSIONING
TUBING STRING THEREABOVE
Abstract
A tensioning tool for connection with a tubing hanger and tubing
string suspended from the tubing hanger retained in a dognut by a
hanger retainer. Preferably the hanger retainer is temporarily
engaged to the top of the tensioning pup for release therefrom once
a lower end of the tubing has been fixed by a tubing anchor and the
tubing has been lifted a tensioning distance. The hanger retainer
is then engaged with the tubing hanger for suspending the tensioned
tubing from the dognut locked in the wellhead. The dognut and the
hanger retainer have co-operating locking faces which prevent
rotation of the hanger retainer in the dognut once the locking
faces are mated which assists in maintaining torque applied to the
tubing string which may have been applied to rotationally set the
tubing anchor. More preferably, the tensioning pup has a series of
gradations marked on the pup for measuring the amount of tension
applied to the tubing string.
Inventors: |
Tessier, Lynn P.; (Cochrane,
CA) ; Weber, James L.; (Calgary, CA) ; Doyle,
John P.; (Calgary, CA) |
Correspondence
Address: |
SEAN W. GOODWIN
237- 8TH AVE. S.E., SUITE 360
THE BURNS BUILDING
CALGARY
AB
T2G 5C3
CA
|
Family ID: |
35450941 |
Appl. No.: |
10/908794 |
Filed: |
May 26, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60574203 |
May 26, 2004 |
|
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Current U.S.
Class: |
166/382 ;
166/75.14 |
Current CPC
Class: |
E21B 33/04 20130101 |
Class at
Publication: |
166/382 ;
166/075.14 |
International
Class: |
E21B 023/00 |
Claims
What is claimed is:
1. A tensioning tool for tensioning a tubing string suspended in a
wellbore casing by a tubing hanger supported in a dognut in a
wellhead and anchored at a downhole end by a tubing anchor
comprising: means adapted for engaging the tubing hanger for
lifting the tubing hanger and tubing string suspended therefrom for
tensioning the tubing string; means for measuring a tensioning
distance applied for tensioning the anchored tubing string; and
means adapted for engaging the tubing hanger in the dognut when the
tubing string is in tension.
2. The tensioning tool as described in claim 1 wherein the means
adapted for engaging the tubing hanger and for measuring the
tensioning distance of the tubing hanger and anchored tubing string
is a tensioning pup adapted for connection to the tubing hanger at
a lower end and a lifting means at an upper end, the tensioning pup
having a series of evenly spaced gradations marked thereon for
measuring the amount of tension applied to the tubing hanger and
suspended tubing string.
3. The tensioning tool as described in claim 1 wherein the dognut
further comprises a bore for positioning the dognut about the
tensioning pup and being axially moveable thereon and having a
profiled inner circumferential locking face formed about an upper
inner edge; and the means adapted for engaging the top end of the
tubing hanger in the dognut comprises a hanger retainer adapted for
engagement with the top end of the tubing hanger and having an
outer circumferential locking face about an upper outer edge,
wherein, in a secured position the hanger retainer is moving
axially over the tensioning pup for connection to engagement means
at the top end of the tubing hanger, the hanger retainer, tubing
hanger and suspended tubing being lowered into and engaged in the
dognut for supporting the tubing hanger and tensioned tubing
therefrom and aligning and mating the circumferential locking faces
of the hanger retainer and the donut, preventing release of the
hanger retainer from the dognut.
4. The tensioning tool as described in claim 3 further comprising:
a temporary engagement means formed at an outer upper end of the
tensioning pup; and wherein in a connecting position, the hanger
retainer is temporarily engageable at the upper end of the
tensioning pup by the outer engagement means during connection of
the tensioning pup to the tubing hanger; and in the secured
position, the hanger retainer is releasable from the upper end of
the tensioning pup for moving axially thereover for connection to
the engagement means at the top end of the tubing hanger.
5. The tensioning tool as described in claim 4 wherein the
engagement means at the outer upper end of the tensioning pup and
the top end the tubing hanger are a plurality of threads formed
thereon and the hanger retainer is threaded for engagement
therewith.
6. The tensioning tool as described in claim 1 further comprising a
seal formed about the hanger retainer for sealing between the
hanger retainer and the dognut in the secured position.
7. A tensioning tool for tensioning a tubing string suspended in a
wellbore casing by a dognut supported in a wellhead, the tubing
string being anchored at a downhole end by a tubing anchor
comprising: a tubing hanger having a top end movable through the
dognut; a tensioning pup adapted at a lower end for supportable
connection to the tubing hanger and tubing string suspended
therefrom and adapted for connection to a lifting means at an upper
end for lifting the tubing hanger and suspended tubing string for
tensioning the tubing string; and a retainer for engaging the top
end of the tubing hanger in the dognut once the subbing string is
in tension.
8. The tensioning tool as described in claim 7 further comprising a
series of gradations marked on the tensioning pup for measuring the
amount of tension placed on the tubing string.
9. The tensioning tool as described in claim 7 wherein the dognut
further comprises a bore for positioning the dognut about the
tensioning pup and being axially moveable thereon and having a
profiled inner circumferential locking face formed about an upper
inner edge; and the means adapted for engaging the top end of the
tubing hanger in the dognut comprises a hanger retainer adapted for
engagement with the top end of the tubing hanger and having an
outer circumferential locking face about an upper outer edge,
wherein, in a secured position the hanger retainer is moving
axially over the tensioning pup for connection to engagement means
at the top end of the tubing hanger, the hanger retainer, tubing
hanger and suspended tubing being lowered into and engaged in the
dognut for supporting the tubing hanger and tensioned tubing
therefrom and aligning and mating the circumferential locking faces
of the hanger retainer and the donut, preventing release of the
hanger retainer from the dognut.
10. The tensioning tool as described in claim 9 further comprising:
a temporary engagement means formed at an outer upper end of the
tensioning pup; and wherein in a connecting position, the hanger
retainer is temporarily engageable at the upper end of the
tensioning pup by the outer engagement means during connection of
the tensioning pup to the tubing hanger; and in the secured
position, the hanger retainer is releasable from the upper end of
the tensioning pup for moving axially thereover for connection to
the engagement means at the top end of the tubing hanger.
11. The tensioning tool as described in claim 10 wherein the
engagement means at the outer upper end of the tensioning pup and
the top end the tubing hanger are a plurality of threads formed
thereon and the hanger retainer is threaded for engagement
therewith.
12. The tensioning tool as described in claim 7 further comprising
a seal formed about the hanger retainer for sealing between the
hanger retainer and the dognut in the secured position.
13. A method of tensioning a tubing string suspended in a wellbore,
the tubing string having an upper end at a wellhead and a lower end
having a tubing anchor, the wellhead having a bowl for lockably
supporting a dognut therein, the method comprising: supporting the
tubing string at the wellhead with the upper end of the tubing
string projecting from the wellhead; fitting the upper end of the
tubing string with a tubing hanger for suspending the tubing string
therefrom, the tubing hanger having a threaded top end; fitting a
dognut over the top end of the tubing hanger, the dognut having a
bore and a top end having a first circumferential locking face
extending radially outwards from the bore; releasing the tubing
string at the wellhead; lowering the tubing hanger and the tubing
string so as to engage the dognut in the wellhead bowl; continuing
to lower the tubing hanger and tubing string so that the top end of
the tubing hanger is below the top end of the dognut by a
tensioning distance, the lower end of the tubing string being
substantially at a target depth; setting the tubing anchor to fix
the position of the lower end of the tubing string at the target
depth in the wellbore; pulling up the tubing hanger and tubing
string at least the tensioning distance to tension the tubing
string and expose the top end of the tubing hanger; engaging a
hanger retainer having a second circumferential locking face
extending radially outwards therefrom to the top end of the tubing
hanger for supporting the tubing string therefrom; aligning the
first and second circumferential locking faces; and lowering the
hanger retainer supporting the tubing hanger and tubing string into
the dognut for suspending the tensioned tubing string therefrom,
the first and second circumferential locking faces being mated
together for preventing rotation of the hanger retainer within the
dognut.
14. The method as described in claim 13 wherein the tubing anchor
is set rotationally, further comprising: applying torque to the
tubing string for setting the tubing anchor; maintaining at least
some of the torque on the tubing string while tensioning the tubing
string, engaging the hanger retainer in the dognut, wherein the
mated first and second locked circumferential locking faces
maintain the at least some of the torque by preventing rotation of
the hanger retainer within the dognut.
15. The method as described in claim 13, following fitting the
dognut over the tubing hanger, further comprising: engaging a
tensioning pup with the tubing hanger for supportably lifting and
lowering the tubing hanger and tubing string suspended
therefrom.
16. The method as described in claim 15 further comprising:
lowering the tubing hanger a tensioning distance by lowering the
tensioning pup as measured against a series of gradations at evenly
spaced intervals along the tensioning pup for measuring the
relative tensioning distance.
17. The method as described in claim 16 wherein the gradations are
spaced at one inch intervals.
18. The method as described in claim 15 wherein the tensioning pup
has outer engagement means formed at a top end for temporarily
retaining the hanger retainer thereon prior to engaging the hanger
retainer with the tubing hanger.
19. The method as described in claim 18 wherein the hanger retainer
is a hanger nut and wherein the top end of the tubing hanger is a
plurality of threads for threadably engaging the hanger nut
thereon.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a regular application claiming priority
of U.S. Provisional Patent application Ser. No. 60/574,203 filed on
May 26, 2004, the entirety of which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] Embodiments of the invention relate to production of oil and
gas from a wellbore and more particularly to apparatus for
tensioning production tubing to prevent wear due to compression of
at least a portion of the tubing string during production.
BACKGROUND OF THE INVENTION
[0003] In conventional oil and gas production, once a wellbore has
been drilled, cased and perforated, a production tubing string is
lowered into the wellbore to produce the hydrocarbons therethrough.
A rod string extends through the production tubing string to either
a reciprocating pump or a progressive cavity pump (PCP), positioned
at a downhole end of the production tubing. In the case of a PCP,
the rod string is used to rotate a rotor within a stator in the PC
pump, to pump the hydrocarbons to surface. A top drive is typically
used to rotate the rod string. In the case of a reciprocating pump,
the rod string is reciprocated axially within the tubing string,
typically by a pumpjack. Further, in the case of the reciprocating
pump, an anchor is set at the lower end of the production tubing to
prevent a corresponding axial movement of the pump barrel during
reciprocation of the rod string.
[0004] The length of the production tubing may be greater than 1000
ft and, more typically, is at least 3000-4000 ft long, depending
upon the depth of the wellbore. Typically, the weight of the tubing
string hanging in the wellbore places at least the portion of the
tubing string closest to surface, in tension. In such long strings
of jointed tubing and particularly when using a reciprocating pump,
it is not unusual that the production tubing string closest to the
tubing anchor rests on the anchored pump barrel causing a portion
of the tubing string to go into compression and buckle slightly.
Buckling of the tubing string may result in contact with the rod
string resulting in wear as the rod string is actuated. Excessive
wear may eventually compromise the structural integrity of the
production tubing necessitating frequent replacement. Tripping the
production tubing string in and out of the wellbore to effect said
replacements results in cessation of production and costly downtime
and servicing.
[0005] Typically, the tubing string may be tensioned approximately
1 inch for every one thousand feet of tubing in order to alleviate
buckling. Conventional methods of tensioning tubing include
lowering the tubing string to a desired depth, setting a tubing
anchor at a lower end of the tubing to fix the position of the
lower end of the tubing string and then pulling up to stretch the
tubing. Once the tubing is stretched, a set of shorty slips are
used to hold the tubing string in place. The pulling apparatus is
disconnected so that a dognut can be threaded onto the tubing
string. The pulling apparatus must then be reinserted in order to
lift the tubing string to release the shorty slips. The tubing
string must be lifted at least 3 inches, and more typically 5-6
inches to effectively release the shorty slips. In the case of
shallow wells, there is not enough stretch in the tubing string to
permit sufficient lifting and therefore attempts to straighten the
tubing may result in tearing out the threaded joints.
[0006] Further, even in deeper wellbores where there is sufficient
slack to permit lifting high enough to set and release the slips,
the methods are fairly crude and inaccurate and do not always have
a successful outcome, the tubing string being tensioned too much or
not enough.
SUMMARY OF THE INVENTION
[0007] In one embodiment, a tensioning tool engages a form of
tubing hanger, hanger retainer and dognut from which a tubing
string is suspended, to permit lowering of the tubing, setting of a
tubing anchor and lifting of the tubing hanger and tubing string to
be stretched or tensioned. Measuring means are provide to determine
a tensioning distance to which the tubing string and hanger are
lowered such that when lifted, adequate tensioning of the tubing is
achieved without over-stretching the tubing. A retainer is provided
for engaging between the tubing hanger and the dognut, lockingly
supported in a wellhead bowl, for supporting the tubing string in
the dognut following tensioning of the tubing string. The form of
tubing hanger and retainer minimize over tensioning and enable
support and anti-rotation of the tubing hanger and tubing
string.
[0008] Preferably, the tool comprises a tensioning pup that engages
the tubing hanger and which is marked with a series of evenly
spaced gradations for measuring the tensioning distance. A hanger
retainer or nut is engaged with a top of the tubing hanger once the
tubing has been tensioned permitting the tensioned tubing to be
suspended from the hanger nut in the dognut.
[0009] In the case where the tubing anchor is rotationally set, at
least some of the torque applied to the tubing string to set the
anchor is maintained by the tubing hanger and retainer in order to
keep the tubing anchor actuated. Mating circumferential locking
faces are machined on an inner radial face of the dognut and an
outer face of the hanger retainer which, when aligned and mated,
rotationally lock the hanger nut in the dognut preventing release
of at least some of the torque applied to the tubing string.
[0010] Thus in a broad aspect of the invention a tensioning tool
for tensioning a tubing string suspended in a wellbore casing by a
tubing hanger supported in a dognut in a wellhead and anchored at a
downhole end by a tubing anchor comprises: a tensioning pup adapted
for engaging the tubing hanger for lifting the tubing hanger and
tubing string suspended therefrom for tensioning the tubing string;
means for measuring a tensioning distance applied for tensioning
the anchored tubing string; and a retainer adapted for re-engaging
the tubing hanger in the wellhead dognut when the tubing string is
in tension. Preferably, a tensioning pup is engaged with the tubing
hanger for supportably lifting and lowering the tubing hanger and
tubing string suspended therefrom, the tensioning pup being marked
with a series of gradations at evenly spaced intervals for
measuring the tensioning distance therewith. The hanger retainer is
preferably a nut for threaded engagement with the top end of the
tubing hanger. More preferably, the hanger nut has a
circumferential locking face which engages a circumferential
locking face formed in the dognut for rotationally locking the
tubing hanger and tubing string from rotation once tensioned.
[0011] Further, a method of tensioning a tubing string suspended in
a wellbore is provided wherein the tubing string has an upper end
at a wellhead and a lower end having a tubing anchor, the wellhead
having a bowl for lockably supporting a dognut therein, the method
comprising: supporting the tubing string at the wellhead with the
upper end of the tubing string projecting from the wellhead;
fitting the upper end of the tubing string with a tubing hanger for
suspending the tubing string therefrom, the tubing hanger having a
threaded top end; fitting a dognut over the top end of the tubing
hanger, the dognut having a bore and a top end having a first
circumferential locking face extending radially outwards from the
bore; releasing the tubing string at the wellhead; lowering the
tubing hanger and the tubing string so as to engage the dognut in
the wellhead bowl; continuing to lower the tubing hanger and tubing
string so that the top end of the tubing hanger is below the top
end of the dognut by a tensioning distance, the lower end of the
tubing string being substantially at a target depth; setting the
tubing anchor to fix the position of the lower end of the tubing
string at the target depth in the wellbore; pulling up the tubing
hanger and tubing string at least the tensioning distance to
tension the tubing string and expose the top end of the tubing
hanger; engaging a hanger retainer having a second circumferential
locking face extending radially outwards therefrom to the top end
of the tubing hanger for supporting the tubing string therefrom;
aligning the first and second circumferential locking faces; and
lowering the hanger retainer supporting the tubing hanger and
tubing string into the dognut for suspending the tensioned tubing
string therefrom, the first and second circumferential locking
faces being mated together for preventing rotation of the hanger
retainer within the dognut.
[0012] Preferably, a tensioning pup is engaged with the tubing
hanger for supportably lifting and lowering the tubing hanger and
tubing string suspended therefrom, the tensioning pup being marked
with a series of gradations at evenly spaced intervals for
measuring the tensioning distance therewith. The hanger retainer is
preferably a nut for threaded engagement with the top end of the
tubing hanger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1a is an exploded schematic view of a tensioning tool
according to an embodiment of the invention, the tool being adapted
for use to tension production tubing suspended from a tubing
hanger, to remove buckling therein;
[0014] FIG. 1b is a cross-sectional view according to FIG. 1a,
along section lines A-A, illustrating mating circumferential
locking faces of a hanger retainer and a modified dognut;
[0015] FIG. 2a-c are partial longitudinal sectional views of the
tensioning tool according to FIG. 1, in use to tension the
production tubing, and more particularly,
[0016] FIG. 2a illustrates a first step of engaging the tensioning
tool according to FIG. 1 into a top end of a tubing string, the
tensioning tool and tubing string being lowered to a predetermined
position prior to fixing the position of the lower end of the
production tubing;
[0017] FIG. 2b illustrates a second step wherein the dognut has
been locked into place in the wellhead and the production tubing is
tensioned by lifting the tubing at a top end to position the
tensioning tool at a predetermined position;
[0018] FIG. 2c illustrates a third step wherein a hanger retainer
carried on the tensioning tool engages a modified dognut for
locking the production tubing into the tensioned position;
[0019] FIG. 3 is a longitudinal sectional view of the wellhead
illustrating the engaged hanger retainer and modified dognut
positioned in the wellhead following tensioning of the production
tubing suspended therefrom;
[0020] FIG. 4a is a partial longitudinal sectional view according
to FIG. 2b illustrating the second step in tensioning the tubing
string;
[0021] FIG. 4b is a partial longitudinal sectional view according
to FIG. 2c illustrating the third step in tensioning the tubing
string; and
[0022] FIG. 4c is a partial perspective sectional view according to
FIG. 4b.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] As shown in FIG. 1a, an embodiment of a tensioning tool 1
comprises a tubing hanger 2 from which production tubing (not
shown) is suspended, a tensioning pup 3, threadably connected to
the tubing hanger 2, a modified dognut 4 positioned about the
tensioning pup 3 and being axially moveable thereover and a hanger
retainer 5, preferably a hanger nut, positioned on the tensioning
pup 3 and being axially moveable over the tensioning pup 3.
[0024] In the preferred embodiment and in a connecting position,
the hanger nut 5 is threaded for operational engagement in a
secured position with an upper, outer threaded surface 66 at the
top end 6 of the tubing hanger 2. The top end 6 of the tubing
hanger 2 is sized to fit axially upwardly through the dognut 4 for
exposing the outer threaded surface 66 above the dognut 4 for
engagement with the hanger nut 5. When engaged, the nut 5 may seat
on a shoulder 16.
[0025] Further, the tensioning pup 3 is threaded at an upper
portion 7, adjacent a top end 8 of the tensioning pup 3, for
temporarily retaining the hanger nut 5 thereon during connection of
the tensioning tool 1 to the tubing hanger 2. The tensioning pup 3
has a threaded portion 17 adjacent a bottom end 18 for connection
to a threaded bore 19 of the tubing hanger 2. The production tubing
(not shown) is suspended from the tubing hanger 2.
[0026] As shown in FIGS. 1a and 1b, the hanger retainer 5 is
machined with an radially outward extending outer circumferential
locking face 11 about an upper outer edge 12. The dognut 4 is
machined having an inner circumferential locking face 13 formed to
extend radially outwards from an upper, inner edge 14. One
embodiment of the locking faces 11,13 is a form of compatible
spline having a variable radial extent to lock relative rotation.
Once the circumferential locking faces 11,13 are engaged, the
hanger retainer 5 and dognut 4 are fixed to prevent independent
rotation of the hanger retainer 5, and supported tubing hanger 2
and tubing string 20, within the dognut 4 and to suspend the tubing
hanger 2 and string 20 from the hanger retainer 5, supported in the
dognut 4.
[0027] The tensioning pup 3 is conveniently marked along a length
with a series of gradations 10 used to measure the amount of
tension or stretching applied to the tubing string 20. Typically,
the gradations 10 are marked in 1 inch intervals.
[0028] In Use
[0029] Having reference to FIGS. 2a-c and in use, a tubing string
20 of production tubing is lowered into the wellbore 21 to the
final section of tubing 20 with the lower end of the string at
about a target depth. The string 20 is hung in a wellhead 9 from
slips (such as shorty slips not shown). The tubing hanger 2 is
threaded onto the final piece of tubing 20. The dognut 4 is then
set onto the tubing string 20 over the tubing hanger 2. The hanger
nut 5 is temporarily suspended above the dognut such as by threaded
connection to threads 7 at the top end 8 of the tensioning pup 3. A
seal 15, typically an O-ring, is placed over the tensioning pup 3
for sealing between the tubing hanger 2 and the dognut 4 when
installed. The tensioning pup 3 is then threaded into internal
threads 17 in the tubing hanger 2.
[0030] The tensioning pup 3 and tubing string 20 are lifted to
release and remove the slips (not shown), after which the tubing
string 20 is lowered. The dognut 4 is landed into the bowl in the
wellhead 9 and preferably that his time the dognut 4 is locked into
place in the wellhead 9 by setting a plurality of dogs 22. The
tubing string 20 is further lowered a tensioning distance (FIG. 2a)
as measured on the series of gradations 10 on the tensioning pup 3.
One approach is to mark the tensioning distance from 0" as the top
end 6 of the tubing hanger 2 when the tensioning pup 3 is threaded
thereto. For example, as the tensioning pup 3 is typically graded
in 1 inch intervals, in order to stretch the tubing by 5 inches the
tubing string 20 is lowered a relative tensioning distance from 0"
to the 5 inch gradation on the tensioning pup 3 as viewed above the
top end 6 of the tubing hanger 2 and relative to some datum such as
the dognut 4.
[0031] A tubing anchor 30 is set at a lower end 31 of the tubing
string 20 to fix the position of the lower end 31 of the tubing
string 20 in the wellbore 21 at the target depth.
[0032] In the case of a rotationally actuated tubing anchor 30, the
tensioning pup 3 is rotated to set the tubing anchor 30. It may be
necessary, depending upon the type of tubing anchor 30 used to hold
at least some of the torque on the tubing anchor 30 to keep the
tubing anchor 30 engaged with the wellbore 21 until the tensioning
operation is completed or thereafter.
[0033] As shown in FIG. 2b, and once the tubing anchor 30 has been
set, the tubing string 20 is lifted or pulled up to stretch the
tubing string 20 suspended therefrom. The tubing 20 is pulled
upwards the tensioning distance and a further distance sufficient
to expose the threaded top end 6 of the tubing hanger 2 through the
dognut 4. The O-ring 15 and hanger nut 5, which is released from
the threads 7 at the top end 8 of the tensioning pup 3, are pushed
down to the dognut 4. The hanger nut 5 is threaded onto the top end
of the tubing hanger 2.
[0034] As shown in FIG. 4a, the hanger nut 5 is tightened onto the
tubing hanger 2, preferably until the hanger nut 5 is adjacent or
stops against shoulder 16 on the tubing hanger 2. Typically, at
this point the circumferential locking face 11 of the hanger nut 5
sit a small distance of approximately .+-.4" above the dognut 4. In
other words the top end 6 of the tubing hanger 2 is slightly
over-tensioned more than the tensioning distance to facilitate
engaging the hanger retainer. The outer circumferential locking
face 11 of the hanger nut 5 is aligned to mate with the inner
circumferential locking face 13 of the dognut 4.
[0035] As shown in FIGS. 2c, 3 and 4b-c, the tubing hanger 2 and
string 20 is lowered the last small distance downwards through the
dognut 4, compressing the O-ring 15 to seal against the tubing
hanger 2. The circumferential locking faces 11,13 on the hanger
retainer or nut 5 and the dognut 4 mate and act to rotationally
lock the tubing hanger 2 into the dognut 4, retaining at least some
of the torque applied to the tubing string 20 in the case where
rotation is used to set the tubing anchor 30 and to suspend the
tubing string 20 from the hanger nut 5 supported in the dognut 4.
There may be some residual rotation of the top end 6 of the tubing
hanger 2 to seat the shoulder 16 into the hanger nut 5.
[0036] Once the tensioning operation is completed, the pulling tool
is removed and the tensioning pup 3 is unthreaded and removed from
the tubing hanger 2 and such production equipment as is required is
connected thereto.
* * * * *