Note: Descriptions are shown in the official language in which they were submitted.
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WELLHEAD TUBING ROTATORS AND RELATED METHODS
FIELD
The present disclosure relates generally to wellhead equipment and, in
particular, to
wellhead tubing rotators.
BACKGROUND
Tubing rotators are used to prolong the service life of oilfield production
tubing. A
wellhead tubing rotator is a particular type of tubing rotator that is coupled
to a wellhead
or to other oilfield equipment at the surface of a production well. The
purpose of a
wellhead tubing rotator, like a downhole tubing rotator, is to prevent
excessive wear of a
production tubing string by slowly rotating the tubing string. This allows
wear, from
contact with a sucker rod string, for example, to be distributed around the
inside
circumference of the tubing string instead of the wear being concentrated at a
point of
contact.
In some conventional wellhead tubing rotators, a drive sub or other component
that is
driven to rotate production tubing also bears the weight of the tubing string.
In order to
support this weight while allowing rotation of the tubing string, a large
bearing is typically
installed between the drive sub and a housing of the tubing rotator, and the
housing
remains stationary during tubing rotation. A large bearing reduces the amount
of
available space inside the housing. This limits the outside diameter of the
drive sub and
therefore also limits the internal diameter of the drive sub.
In addition, the drive shaft and a gear mechanism with which the drive shaft
meshes are
often exposed to well fluids. This may necessitate the usage of corrosion-
resistant
materials for these components. Components that are exposed to well fluids may
also
require more frequent cleaning or servicing than other components that are not
in
contact with well fluids.
SUMMARY
In some embodiments, the weight of the tubing string is supported by a hanger
assembly resting against an inner shoulder inside the housing. A drive sub
assembly
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therefore does not support the full weight of the tubing string and does not
require as
large a bearing in order to be free to rotate the hanger assembly.
The drive sub assembly may also seal against an interior of the housing to
form a cavity
between the drive sub assembly and the housing. The drive sub assembly is
engaged
with the drive shaft inside the sealed housing.
According to one aspect of the present invention, a wellhead tubing rotator
includes: a
housing comprising an internal shoulder; a drive mechanism located in the
housing; a
drive sub assembly engaged with the drive mechanism and sealed against an
interior of
the housing to define a sealed cavity that isolates the drive mechanism
between the
housing and the drive sub assembly; and a hanger assembly, supported by the
internal
shoulder of the housing and engaged with the drive sub assembly, to be coupled
to
production tubing in a production well.
The hanger assembly may include: a hanger assembly housing, supported by the
internal shoulder of the housing; a hanger assembly bearing, supported by the
hanger
assembly housing; a hanger assembly gear, engaged with the drive sub assembly;
and
a mandrel, supported by the hanger assembly bearing and engaged with the
hanger
assembly gear, to be coupled to the production tubing.
The mandrel may seal against the hanger assembly housing, and the hanger
assembly
housing may seal against the housing.
The mandrel may engage with the hanger assembly gear by a hanger key that fits
into
slots in the mandrel and in the hanger assembly gear.
Alternatively, the hanger assembly may include: a hanger assembly housing,
supported
by the internal shoulder of the housing; a hanger assembly bearing, supported
by the
hanger assembly housing; a hanger assembly gear, engaged with the drive sub
assembly; an upper sub assembly, supported by the hanger assembly bearing and
engaged with the hanger assembly gear; and a mandrel, connected to the upper
sub
assembly, to be coupled to the production tubing.
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In this case, the mandrel may seal against the upper sub assembly, the upper
sub
assembly may seal against the hanger assembly housing, and the hanger assembly
housing may seal against the housing.
The upper sub assembly may engage with the hanger assembly gear by a hanger
key
that fits into slots in the upper sub assembly and in the hanger assembly
gear.
The upper sub assembly may include: an upper sub; and a fastener coupling the
upper
sub to the mandrel.
The hanger assembly gear is engaged with the drive sub assembly through lugs
on the
hanger assembly gear and on the drive sub assembly, in an embodiment.
The lugs of the hanger assembly gear and the lugs of the drive sub assembly
may be
tapered in a direction axial to the hanger assembly. The lugs of the hanger
assembly
gear and the lugs of the drive sub assembly may be tapered in a direction
radial to the
hanger assembly.
The drive sub assembly may include: a drive sub, engaged with the hanger
assembly; a
drive sub retainer, engaged with the housing and the drive sub; and a drive
sub gear,
engaged with the drive sub and the drive mechanism.
The drive sub retainer may seal against both the drive sub and a first portion
of the
interior of the housing, and the drive sub may seal against a second portion
of the
interior of the housing, the sealed cavity being defined between the housing,
the drive
sub retainer, and the drive sub.
The drive sub gear may be engaged with the drive sub by a drive sub key that
fits into
slots in the drive sub gear and in the drive sub.
The wellhead tubing rotator may include a pipe plug to prevent fluid
communication via
a channel between the sealed cavity and an exterior of the housing.
The wellhead tubing rotator may also include a locking pin installed in a bore
in the
housing to limit axial movement of the hanger assembly relative to the
housing.
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The locking pin may include: a locking bolt; and a first washer, packing, a
second
washer, and a locking nut arranged on the locking bolt.
The hanger assembly may further include: an auxiliary sub, engaged with the
mandrel
and the hanger assembly housing.
Alternatively, the hanger assembly may further include: an auxiliary sub,
engaged with
the upper sub assembly and the hanger assembly housing.
The wellhead tubing rotator may further include a locking pin installed in a
bore in the
housing to limit axial movement of the hanger assembly relative to the
housing, wherein
the locking pin is engaged with the auxiliary sub, in an embodiment.
According to another aspect of the present invention, a production assembly
for
producing a well includes: production tubing to be placed in the well; and the
wellhead
tubing rotator described herein, coupled to the production tubing.
According to still another aspect of the present invention, a method of using
the
wellhead tubing rotator described herein includes: securing the housing to a
wellhead;
coupling the hanger assembly to the production tubing; lowering the hanger
assembly
into the housing; and providing a force to the drive mechanism to rotate the
hanger
assembly.
According to still another aspect of the present invention, a kit includes: a
housing, a
drive mechanism, a drive sub assembly, and a hanger assembly as described
herein;
and instructions for assembling the housing, the drive mechanism, the drive
sub
assembly, and the hanger assembly to form the wellhead tubing rotator.
According to still another aspect of the present invention, a method of
manufacturing a
wellhead tubing rotator includes: providing a housing that includes an
internal shoulder;
sealing a drive mechanism in a sealed cavity between the housing and a drive
sub
assembly that is engaged with the drive mechanism and sealed against an
interior of
the housing; and placing a hanger assembly, which is to be coupled to
production
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tubing in a production well, on the internal shoulder of the housing and into
engagement
with the drive sub.
Other aspects and features of embodiments of the present disclosure will
become
apparent to those ordinarily skilled in the art upon review of the following
description.
BRIEF DESCRIPTION OF THE DRAWINGS
Examples of embodiments of the invention will now be described in greater
detail with
reference to the accompanying drawings.
FIG. 1 is an isometric view of a wellhead tubing rotator according to a first
embodiment.
FIG. 2 is a cross-section view of the wellhead tubing rotator of FIG. 1, along
line 2-2
shown in FIG. 1.
FIG. 3 is a side view of the wellhead tubing rotator of FIG. 1, with a hanger
assembly
shown above a housing.
FIG. 4 includes cross-section views of the hanger assembly and the housing of
FIG. 3,
and a drive sub assembly in the housing.
FIG. 5 is an exploded, isometric view of the hanger assembly of FIG. 3.
FIG. 6 is an isometric view of the wellhead tubing rotator of FIG. 1, with a
drive sub
assembly and a locking pin exploded therefrom.
FIG. 7 is an exploded, isometric view of the drive sub assembly shown in FIG.
6.
FIG. 8A is a side view of the wellhead tubing rotator of FIG. 1.
FIG. 8B is a cross-section view along line 8B-8B shown in FIG. 8A.
FIG. 8C is a cross-section view along line 8C-8C shown in FIG. 8A.
FIG. 8D is a cross-section view along line 8D-8D shown in FIG. 8A.
FIG. 8E is a detail view of window 8E shown in FIG. 8B.
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FIG. 8F is an isometric view of the wellhead tubing rotator of FIG. 1, with a
drive
mechanism exploded therefrom.
FIG. 9 is a cross-section view of the locking pin shown in FIG. 6, installed
in the
housing.
FIG. 10 is an exploded view of the locking pin shown in FIG. 6.
FIG. 11 is an isometric view of a wellhead tubing rotator according to a
second
embodiment, with a shear sub exploded therefrom.
FIG. 12 is a cross-section view of the wellhead tubing rotator of FIG. 11,
along line 12-
12 shown in FIG. 11.
FIG. 13 is a cross-section view of the hanger assembly shown in FIG. 12.
FIG. 14 is an exploded, isometric view of the hanger assembly of FIG. 13.
FIG. 15 is a cross-section view of a hanger assembly according to another
embodiment.
FIG. 16 is a cross-section view of a hanger assembly according to a further
embodiment.
FIGS. 17A-E show cross-section views of the wellhead tubing rotator of FIG. 11
at
different stages of removing portions of the hanger assembly of FIG. 13.
FIG. 18 is a flow chart of a method of manufacturing a wellhead tubing
rotator.
FIG. 19 is a flow chart of a method of using a wellhead tubing rotator.
DETAILED DESCRIPTION
It should be appreciated that the drawings are intended solely for
illustrative purposes,
and that the present invention is in no way limited to the particular example
embodiments explicitly shown in the drawings and described herein.
Many of the features of the wellhead tubing rotators discussed below are
cylindrical or
ring-shaped, and therefore these features have both inner and outer surfaces.
For
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example, an axis 25 is shown in FIG. 2 along a centerline of a mandrel 21. An
"inner
surface" would be a surface that faces toward the axis 25 and an "outer
surface" would
be a surface that faces away from the axis 25. This also applies to other
embodiments,
including embodiments with other shapes that are not entirely cylindrical.
Many of the features also have first and second ends, and reference may also
be made
to certain directions, with respect to a typical operating orientation of the
wellhead
tubing rotators disclosed herein. For example, there could be "top" or "upper"
ends
and/or "bottom" or "lower" ends, and upward and/or downward directions.
However,
wellhead tubing rotators could be shipped, stored, serviced, or assembled, and
possibly
even operated, in non-vertical orientations or in orientations opposite to
those described
herein.
FIG. 1 is an isometric view of a wellhead tubing rotator according to a first
embodiment.
A wellhead tubing rotator 1 has a housing 3, which is shaped for being placed
on a
wellhead. The housing 3 has an upper face 11, which may have one or more axial
bores or holes 13, such that the housing 3 may be coupled to other wellhead
equipment
using bolts and nuts or other types of fasteners, for example. There are
multiple bores
13 in the example shown.
The housing 3 may also have one or more radial bores or holes 15 on its side,
to
accommodate one or more locking pins 7, four in the example shown. The housing
3
also has one or more radial bores or holes 17 to allow access to the interior
of the
housing. For example, the radial bores 17 may provide access to different
internal
components of the wellhead tubing rotator 1. The radial bores 17 could also or
instead
be used to inject grease into the housing 3. A plug 9 may be used to seal each
of the
radial bores 17 after each greasing operation.
The housing 3 is configured to receive a drive mechanism 5a, which may be
coupled to
a manual drive, or to an electric or hydraulic motor. A drive shaft 5, which
is a part of the
drive mechanism 5a, is coupled to a hanger assembly 19, which is shown in more
detail
in FIG. 2 and described below. A mandrel 21, which is also part of the hanger
assembly
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19, is located inside the housing 3 as shown during operation of the wellhead
tubing
rotator 1.
The wellhead tubing rotator 1 may be coupled to production tubing 23 via the
mandrel
21. The production tubing 23 is not part of the wellhead tubing rotator 1, but
is shown in
FIG. 1 to illustrate how the wellhead tubing rotator is coupled to a
production tubing
string in an embodiment.
The housing 3 may be made of any material(s) sufficiently rigid to withstand
the weight
of the production tubing 23, to withstand wellbore pressures, and to support
any other
wellhead equipment that rests on the housing upper face 11. Rigid materials
that are
resistant to corrosion or deterioration when exposed to well fluids, and
possibly also
industrial chemicals, may be preferred. In an embodiment, the housing 3 is
constructed
using 4130 steel in conformance with specifications from The National
Association of
Corrosion Engineers (NACE) for H2S corrosive environments and having a
Rockwell C
Hardness between 18 and 22, stainless steel, or other alloys.
The drive shaft 5 may be made of any material(s) with sufficient torsional
strength to
resist breakage or significant buckling when a force is used to turn the drive
shaft 5. The
drive shaft 5 may be made of, for example, NACE-compliant 4130 steel or
stainless
steel. The drive shaft 5 could be made of the same material as the housing 3,
or of a
different material. For example, corrosion or deterioration from well fluids
or industrial
chemicals used in well operations might not be as much of a concern for the
drive shaft
as for the housing 3.
The mandrel 21 may be made of any rigid material(s) that may be coupled to the
production tubing 23, such as NACE-compliant 4130 steel or stainless steel. In
an
embodiment, the mandrel 21 is made of material(s) resistant to corrosion or
deterioration from well fluids and/or industrial chemicals used in well
operations.
Most of the components of the wellhead tubing rotator 1 are housed in the
housing 3.
The radial bores 15 allow the locking pins 7 to pass through the housing 3 as
noted
above, and the locking pins 7 limit axial movement of the hanger assembly 19,
as
described in further detail below.
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Rotation of the drive shaft 5 causes the mandrel 21 to turn, thereby rotating
the
production tubing 23. The coupling between the mandrel 21 and the production
tubing
23 could be a threaded connection, for example. Tubing rotators typically turn
the
tubing string to the right (right hand rotation), and right hand threading is
also used for
threaded connections so that rotation of the production tubing 23 does not
loosen the
threaded connections. There could also or instead be threaded connections
elsewhere,
between segments of the production tubing 23, for example.
Further details of the wellhead tubing rotator 1 are shown in FIGS. 2 to 10
and
described below.
With reference to FIGS. 2 to 4, FIG. 2 is a cross-section view of the wellhead
tubing
rotator of FIG. 1, along line 2-2 shown in FIG. 1, FIG. 3 is a side view of
the wellhead
tubing rotator 1 with the hanger assembly 19 shown above the housing 3, and
FIG. 4
includes cross-section views of the hanger assembly 19 and the housing of FIG.
3. A
section line is not shown in FIG. 3, but FIG. 4 is a cross-section in the
plane of the
drawing sheet of FIG. 3, through the center of the hanger assembly 19 and the
housing
3.
The hanger assembly 19 includes the mandrel 21, a hanger assembly housing 43
and a
hanger assembly gear 33. The mandrel 21 is supported by a bearing assembly 57.
The
bearing assembly 57 is supported by the hanger assembly housing 43, which
rests
against a housing internal shoulder 68a of the housing 3. As shown perhaps
most
clearly in FIG. 4, the hanger assembly housing 43 includes a shoulder 68b,
which
engages the housing internal shoulder 68a when the hanger assembly 19 is
installed in
the housing 3. Although these shoulders are flat and sloped in the example
shown,
different surface shapes and/or slope angles may be used in other embodiments.
The hanger assembly housing 43 may be made of any material(s) sufficiently
rigid to
support the weight of the tubing string. Rigid material(s) resistant to
corrosion or
deterioration when exposed to well fluids, and possibly also industrial
chemicals, may
be preferred. In an embodiment, the hanger assembly housing 43 is constructed
of
NACE-compliant 4130 steel or stainless steel.
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The hanger assembly 19 is coupled to a drive sub assembly 45 via the hanger
assembly gear 33. The hanger assembly gear 33 is connected to the mandrel 21
by one
or more hanger keys 35.
The components of the hanger assembly 19 are held in place on the mandrel 21
by a
retainer 53.
As shown in FIGS. 2 and 4, the drive sub assembly 45 includes a drive sub 37,
a drive
sub retainer 39 and a drive sub gear 41. The drive sub retainer 39 is
connected to the
housing 3 and also engages the drive sub 37. The drive sub retainer 39 is
rotatively
coupled to the drive sub 37. The drive sub gear 41 is connected to the drive
sub 37 by
one or more drive sub keys 42. The drive sub gear 41 is coupled to a worm gear
31,
which is connected to, and could be formed as part of, the drive shaft 5.
The hanger assembly gear 33, the hanger keys 35, the drive sub 37 and the
drive sub
retainer 39 may be made of any material(s) sufficiently rigid to handle
expected loads.
Material(s) resistant to corrosion or deterioration from well fluids and/or
industrial
chemicals used in well operations may be preferred. For example, NACE-
compliant
4130 steel or stainless steel could be used.
The worm gear 31, the drive sub gear 41 and the drive sub keys 42 may
similarly be
made of any rigid material(s) capable of handling expected loads, and may be
made of
the same material(s) as the hanger assembly gear 33, the hanger keys 35,
and/or the
drive sub 37, or of different material(s). For example, corrosion
deterioration from well
fluids and industrial chemicals used in well operations might not be as much
of a
concern for the worm gear 31, the drive sub gear 41 and the drive sub keys 42
as these
parts are not exposed to well fluids.
A plug 27 and a plug 29 are received in radial bores 17, and are illustrative
examples of
types of plugs generally designated at 9 in FIGS. 1 and 3. The plug 27 is
located in a
radial bore 17 that connects the exterior of the housing 3 with a generally
annular cavity
70 formed between the housing 3 and the drive sub assembly 45. In FIGS. 2 and
4, the
plug 27 is a bleeder. The plug 29 is located in a radial bore 17 that connects
the exterior
of the housing 3 with a part of the cavity 70 that contains the worm gear 31.
In FIGS. 2
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and 4, the plug 29 is a grease-fitting vent cap. As shown, the radial bores 17
may have
different shapes and sizes, and a single bore may have different diameters.
Plugs,
such as the plugs 27, 29, or other components such as fittings, could instead
be
installed in the radial bores 17, and could similarly have different shapes,
sizes, and/or
purposes.
The plugs 27, 29 may be any plugs that permanently or temporarily prevent
fluid
communication between the exterior of the housing 3 and the interior of the
housing 3.
For example, the plugs 27, 29 could be pipe plugs instead of a bleeder and a
grease
fitting vent cap as shown.
In operation, the worm gear 31 indirectly drives the mandrel 21. The worm gear
31
meshes with the drive sub gear 41, which as noted above is connected to the
drive sub
37. The drive sub 37 is engaged with the hanger assembly gear 33, which is
connected
to the mandrel 21 by the hanger keys 35. Rotation of the worm gear 31, by
driving the
drive shaft 5 (FIG. 1), thus rotates the mandrel 21 and any production tubing
coupled
thereto.
The engagement between the hanger assembly 19 and the drive sub 37 can perhaps
best be seen with reference to the side view of the hanger assembly 19 in FIG.
3 and
the cross-section view of the housing in FIG. 4. As shown in FIG. 3, the
hanger
assembly gear 33 has one or more tapered lugs 33a. The tapered lugs 33a could
be
formed on the hanger assembly gear 33 by machining such as turning, milling or
broaching, for example. Other processes could also or instead be used to
provide the
tapered lugs 33a on the hanger assembly gear 33. As shown in the cross-section
of the
housing in FIG. 4, tapered lugs 37a, facing inwards, are also formed or
otherwise
provided on an inner surface of the drive sub 37. In the embodiment shown,
both the
hanger assembly gear 33 and the drive sub 37 have multiple lugs 33a, 37a and
the lugs
fully mesh, with each lug being received in each slot between adjacent lugs
when the
wellhead tubing rotator 1 is assembled. In other embodiments, more or fewer
lugs
could be provided on one of the hanger assembly gear 33 and the drive sub 37,
to
mesh with slots that are provided on the other.
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Each of the lugs 33a on the hanger assembly gear 33 has tapered corners 33h,
33c at
its lower end, to aid the meshing or inter-locking of the lugs 33a of the
hanger assembly
gear 33 with the lugs 37a of the drive sub 37 when the hanger assembly 19 is
lowered
or otherwise placed inside the drive sub 37. Each of the lugs 37a on the drive
sub 37
similarly has tapered corners 37b, 37c at its upper end, which may further aid
in
meshing or interlocking the lugs 37a with the lugs 33a. FIGS. 3 and 4 also
show
tapered ends 33d, 37d on the lugs 33a, 37a, respectively, which may also aid
in
meshing or interlocking the lugs. In other embodiments, lugs 33a, 37a may have
different shapes than those shown.
The tapered corners 33b, 33c, 37b, 37c taper the lugs 33, 37 along an axial
direction.
Without the tapered ends 33d, 37d, a width of the lugs 33 tapers along the
downward
axial direction in FIG. 3 and a width of the lugs 37 tapers along the upward
axial
direction in FIG. 4. The tapered ends 33d, 37d could be considered a form of
radial
tapering in that a radial thickness of the lugs 33d, 37d is tapered. Thus, the
lugs 33 of
the hanger assembly gear 33 and the lugs 37a of the drive sub assembly 45 may
be
tapered in an axial direction and/or a radial direction.
Force that is applied to the hanger assembly gear 33 is transferred to the
mandrel 21
through the hanger keys 35. In an embodiment shown in the exploded, isometric
view
of the hanger assembly 19 in FIG. 5, the hanger keys 35 are placed into
respective key
slots 35a in the mandrel 21, and engage with slots 35b in an inner surface of
the hanger
assembly gear 33. The slots 35a, 35b could be machined or otherwise provided
in the
outer surface of the mandrel 21 and the inner surface of the hanger assembly
gear 33.
In the example shown, three hanger keys 35 are visible in FIG. 5, but there
may be
more or fewer keys in other embodiments. For instance, a fourth hanger key and
key
slot, which are not visible in FIG. 5, could be provided, such that each of
the four keys
engages one of the slots 35b in the inner surface of the hanger assembly gear
33.
Hanger keys and slots could be symmetrically distributed or otherwise arranged
around
the mandrel 21 and the hanger assembly gear 33.
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A key structure could also or instead be used in transferring force from the
drive sub
gear 41 to the drive sub 37. As shown in the exploded, isometric view of the
drive sub
assembly in FIG. 7, for example, drive sub keys 42 are placed into respective
key slots
42a in the drive sub 37, and engage with slots 42b in an inner surface of the
drive sub
gear 41. The slots 42a, 42b could be machined or otherwise provided in the
outer
surface of the drive sub 37 and the inner surface of the drive sub gear 41.
Although three drive sub keys 42 are visible in FIG. 7, there may be more or
fewer keys
in other embodiments. The drive sub gear 41 includes four slots 42b, for
example, and
a fourth drive sub key could be provided. There would then be one drive sub
key to
engage each of the four slots 42b in the inner surface of the drive sub gear
41. Like the
hanger keys and slots described above, drive keys and slots could be
symmetrically or
otherwise distributed, around the drive sub 37 and the drive sub gear 41.
The key-based connection structures between the hanger assembly gear 33 and
the
mandrel 21, and between the drive sub gear 41 and the drive sub 37 are
illustrative
examples. Other structures such as fasteners, or techniques such as welding,
could be
used to connect these components together in other embodiments. The hanger
assembly gear 33 and/or the drive sub gear 41 could instead be machined or
otherwise
provided in a surface of the mandrel 21 or a surface of the drive sub 37. For
example,
the lugs 33a (FIG. 3) could be machined into the outer surface of the mandrel
21, and/or
the lugs 37a could be machined into the inner surface of the drive sub 37.
When the wellhead tubing rotator 1 is installed and coupled to the production
tubing 23
(FIG. 1), the housing internal shoulder 68a (most clearly visible in FIG. 4)
bears the
weight of the production tubing string via the corresponding shoulder 68b cut
or milled
into the hanger assembly housing 43. Therefore, the drive sub assembly 45 does
not
bear the weight of the production tubing 23.
The bearing assembly 57 allows the mandrel 21 to rotate relative to the hanger
assembly housing 43, which remains stationary relative to the housing 3 during
tubing
rotation. The bearing assembly 57 not only supports the mandrel 21, but also
carries
side loading between the mandrel 21 and the hanger assembly housing 43. Side
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loading between the mandrel 21 and the hanger assembly housing 43 may be
created,
for example, in slant wells and deviated wells.
The bearing assembly 57, in an example shown in more detail in FIG. 5,
includes ball
bearings in a bearing race 59. The bearing race 59 may be made of any
material(s)
sufficiently rigid to support the expected weight of the tubing string. For
example, in one
embodiment the ball bearings and the bearing race 59 are made of stainless
steel.
The drive sub 37 is similarly supported by a bearing ring 69, which as shown
in FIG. 4 is
supported by the drive sub retainer 39 that is coupled to the housing 3. The
drive sub 37
abuts a shoulder 3h on the inner surface of the housing 3. Another bearing
ring 67 may
be provided between the drive sub gear 41, the drive sub 37 and the housing 3,
since
the drive sub gear 41 and the drive sub 37 rotate relative to the housing 3
during tubing
rotation. The bearing rings 67, 69 are made of material(s) sufficiently rigid
to withstand
expected loading. For example the bearing rings 67, 69 may be made of bearing
bronze. Since the bearing rings 67, 69 are isolated from well fluids as
described below,
resistance to corrosion might not be of concern in material selection.
The bearing rings 67, 69 are illustrative of a type of bearing that could be
used between
components that move relative to each other, and other types of bearings,
fewer
bearings, or additional bearings may be provided in other embodiments. For
example,
a single bearing such as the bearing ring 69 could be used between the drive
sub 37
and the drive sub retainer 39 to support vertical loads and still permit
rotation of the
drive sub 37. The bearing ring 67 or another type of bearing between the drive
sub
gear 41, the drive sub 37 and the housing 3 may be provided for additional
side load
support, but need not be provided in all embodiments.
A bushing 55 located between the hanger assembly housing 43 and the mandrel 21
could be used in some embodiments to provide additional load support, for side
loading
of the mandrel 21 for instance. The bushing 55 allows the mandrel 21 to rotate
inside
the hanger assembly housing 43, even under significant side loading. Side
loading may
occur when the wellhead is employed in a slant well application, in particular
with a slant
wellhead at the surface. The bushing 55, like other load carrying components,
is made
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of material(s) such as bearing bronze, having sufficient rigidity to withstand
expected
loads.
Various seals are also shown in FIGS. 2 to 5 and 7. The purposes or effects of
these
seals can perhaps best be understood with reference to FIGS. 2 and 4.
Seals 47, 49, 51, 61, 65 may be exposed to wellbore pressures, and therefore
are made
of material(s) that can withstand such pressures. A seal 63 may be made of the
same
material(s) as the seals 47, 49, 51, 61, 65, but the seal 63 may be exposed to
lower
pressures and therefore may be made of different materials. Seal materials may
also or
instead be selected based on whether the seals are between parts that are
stationary or
movable relative to each other. The seals 49, 51, 61, 65 are moveable seals,
whereas
the seals 47, 63 are stationary. Another factor that may be used in seal
material
selection is expected fluid exposure. For example, the seals 47, 49, 61, 65
may have
the greatest exposure to well fluids, and material(s) resistant to corrosion
or
deterioration from well fluids and/or industrial chemicals used in well
operations may be
preferred for at least these seals. In an embodiment, all of the seals 47, 49,
51, 61, 63,
65 are rubber 0-Rings. In another embodiment, at least the movable seals 49,
51, 61,
65 are PolypakTm rings.
The seals 47 allow the hanger assembly 19 to seal against the housing 3. The
seals
49, 51 allow the mandrel 21 to seal against the hanger assembly housing 43.
The seals
61, 65 seal the cavity 70 from well fluids. The seal 63 is a backup or safety
seal to seal
the drive sub retainer 39 against the housing 3, to help prevent leakage of
well fluids to
the atmosphere if either or both of the seals 61, 65 are leaking.
There may also be other seals in a complete wellhead equipment installation.
For
example, a groove 73 (FIG. 7) may be formed in the drive sub retainer 39 to
accommodate an additional seal to permit the wellhead tubing rotator 1 to be
sealed to
other wellhead equipment. In an embodiment, a metal ring gasket may be placed
in the
groove 73.
The drive sub assembly 45, with its seals 61, 65 defines the sealed cavity 70
(FIG. 4)
that isolates the worm gear 31, the drive sub gear 41 and other components
such as the
CA 02941404 2016-09-09
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drive sub keys 42 in the example shown, from well fluids. Removal of the
hanger
assembly 19 from the housing 3 does not affect the sealed cavity 70. The
sealed cavity
70 could be accessible through the radial bores 17 to apply grease into the
cavity, for
example, but remains sealed from well fluids. Pipe plugs could be used instead
of the
plug 27, which is shown as a bleeder (FIG. 2), and the plug 29, which is shown
as a
grease-fitting vent cap (FIG. 2), to seal the cavity 70 from the exterior of
the housing 3,
between grease applications and/or other servicing for instance.
Holes 75 (FIG. 4) allow the drive sub retainer 39 to be coupled to the drive
sub 37 as
described with reference to FIG. 7, herein.
The housing 3 may also have one or more axial bores or holes 77 (FIG. 4) that
may
allow the wellhead tubing rotator 1 to be coupled to other wellhead equipment
using, for
example, bolts and nuts. Other means of connecting the wellhead tubing rotator
1 to
other wellhead equipment, such as a clamping system, could also or instead be
used.
Most of the components of the wellhead tubing rotator 1 that are involved in
rotation of
production tubing are described above. Other components may also be provided.
FIG. 5 is an exploded, isometric view of the hanger assembly 19. With
reference to
FIG. 5, the following operations are performed to assemble the hanger assembly
19 in
an embodiment:
the seal 49 is positioned in a groove 21a in the mandrel 21;
the bearing assembly 57 is slid onto the mandrel 21 to abut a bottom surface
of a
top flange 21d of the mandrel;
the bushing 55 is slid onto the mandrel 21 to abut a shoulder 21b on the
mandrel;
the hanger keys 35 are placed into the key slots 35a;
the seals 47 are placed into grooves 43a, 43b in the outer surface of the
hanger
assembly housing 43;
16
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the seal 51 is placed into a groove in the inner surface of the hanger
assembly
housing 43;
the hanger assembly housing 43 is slid onto the mandrel 21 to position the
bearing assembly 57 between an internal shoulder 43c of the hanger assembly
housing
43 and the bottom surface of the top flange 21d of the mandrel;
the hanger assembly gear 33 is slid onto the mandrel 21;
the slots 35b in the inner surface of the hanger assembly gear 33 are aligned
with the hanger keys 35;
the hanger assembly gear 33 is slid further along the mandrel 21 to abut the
hanger assembly housing 43; and
the retainer 53, illustratively a stainless steel snap ring, is installed into
the
groove 21c on the mandrel 21 to hold components of the hanger assembly 19 on
the
mandrel 21.
These operations may be performed in a different order in other embodiments.
There
could also be additional operations, such as applying lubricants and/or
sealing
compounds during assembly. Fewer operations could be involved in embodiments
that
have fewer components, such as embodiments in which the lugs 33a on the hanger
assembly gear 33 are machined into the mandrel 21.
The housing 3 may also have components assembled or installed therein. With
reference to the isometric view of the wellhead tubing rotator 1 in FIG. 6,
components
such as the locking pins 7 (four in the example shown) and the plugs 9 could
be
installed before or after the hanger assembly 19 is installed in the housing
3. The drive
sub assembly 45 is installed in the housing 3, before or possibly after the
hanger
assembly 19 is installed.
FIG. 7 is an exploded, isometric view of the drive sub assembly 45. With
reference to
FIGS. 4 and 7, the following operations are performed to assemble the drive
sub
assembly 45 and install it into the housing 3 in an embodiment:
17
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the drive sub keys 42 are placed into the key slots 42a in the drive sub 37;
the drive sub gear 41 is slid onto the drive sub 37;
the key slots 42b in the inner surface of the drive sub gear 41 are aligned
with
the drive sub keys 42;
the drive sub gear 41 is slid further along the drive sub 37 to abut a
shoulder 37e
on the drive sub 37;
a retainer 71, illustratively a stainless steel snap ring, is installed into a
groove
37f on the drive sub 37 to hold the drive sub gear 41 on the drive sub 37;
the bearing ring 67 is slid onto the drive sub 37 to abut the drive sub gear
41;
the seal 61 is placed into a groove 37g in the outer surface of the drive sub
37;
the drive sub 37 is slid into the housing 3 to abut the shoulder 3b (FIG. 4)
on the
inner surface of the housing 3;
the bearing ring 69 is slid onto the drive sub 37 to abut a shoulder 37h on
the
outer surface of the drive sub 37;
the seal 65 is placed into a groove 39a in the inner surface of the drive sub
retainer 39;
the seal 63 is placed into a notch 3c (FIG. 4) in the inner surface of the
housing 3
or around an outer surface of the drive sub retainer 39; and
the drive sub retainer 39 is connected to the housing 3 such that the drive
sub
retainer 39 abuts the bearing ring 69.
In an embodiment, the holes 75 in the drive sub retainer 39 (FIG.4) allow a C-
wrench to
be used in threadedly connecting the drive sub retainer 39 to the housing 3 by
engaging
threads on an outer surface of the drive sub retainer with threads on an inner
surface of
the housing.
18
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5484p-20
These operations may be performed in a different order in other embodiments.
There
could also be additional operations, such as applying lubricants and/or
sealing
compounds during assembly. Fewer operations could be involved in embodiments
that
have fewer components, such as embodiments in which the drive sub gear 41 is
machined into the drive sub 37.
FIGS. 8A to 8E show additional internal details of the wellhead tubing rotator
1. FIG. 8A
is a side view of the wellhead tubing rotator 1. FIGS. 8B to 8D are cross-
section views
of the wellhead tubing rotator 1 along lines 8B-8B, 8C-8C, and 8D-8D,
respectively,
shown in FIG. 8A, and FIG. 8E is a detail view of window 8E as shown in FIG.
8B.
Referring to FIG. 8B, this drawing shows the worm gear 31 formed as part of
the drive
shaft 5, but in other embodiments the worm gear 31 could be a separate
component
that is connected to the drive shaft 5. The worm gear 31 is held in place by a
bearing 79
and a bearing 81. The bearings 79, 81 may be made of any material(s) having
sufficient
compressional strength to support expected loading. For example, the bearings
79, 81
are thrust bearings made of bearing bronze in an embodiment.
FIG. 8B also illustrates that the plug 29 in this embodiment provides access
to the worm
gear 31, for applying grease to the gear for example. The drive sub keys 42
are also
shown.
FIG. 8C is a cross-section view through the bearing assembly 57, and
individual ball
bearings are visible in this view.
Referring now to FIG. 8D, the coupling of the drive sub 37 to the hanger
assembly gear
33 and the hanger assembly gear 33 to the mandrel 21 is shown. In the example
shown, four hanger keys connect the mandrel 21 to the hanger assembly gear 33,
and
ten lugs on the hanger assembly gear 33 mesh with ten lugs on the drive sub
37.
Referring now to FIG. 8E, a seal is created between the drive shaft 5 and the
housing 3
by seals 83, 85, 87. A seal retainer 91 holds the seal 85 in place. A retainer
nut 93 is
held in place with a nut 89. Both the retainer nut 93 and the nut 89 are
threadedly
coupled to the housing 3. The seals 83, 85, 87 may be made of material(s)
similar to
19
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the seal material(s) of the seals 47, 49, 51, 61, 63, 65. For example, the
seals 83, 87
are rubber 0-rings and the seal 85 is a PolypakTM ring in an embodiment. The
nut 89,
the seal retainer 91, and the retainer nut 93 may be made of any material(s)
with
sufficient strength to retain the drive shaft 5, the seals 83, 85, 87, and the
bearing 81 in
place, such as stainless steel.
Referring now to FIGS. 8B and 8E, when the drive shaft 5 turns the worm gear
31, a
force is created on one or both of the bearings 79, 81. The bearings 79, 81
allow the
drive shaft 5 to rotate, and retain the worm gear 31 in an appropriate
position in which it
meshes with the drive sub gear 41.
The seals 83, 85, 87 seal the cavity 70 that is formed between the housing 3
and the
drive sub assembly 45 from the exterior of the housing 3.
The drive mechanism 5a is perhaps most clearly shown in FIGS. 8B, 8E and 8F.
FIG.
8F is an isometric view of the wellhead tubing rotator 1, with the drive
mechanism 5a
exploded therefrom. The drive mechanism 5a includes the drive shaft 5, the
worm gear
31 and the bearings 79, 81.
The drive mechanism 5a may be installed before or after the drive sub assembly
45 is
installed in the housing 3. With reference to FIGS. 8B, 8E and 8F the
following
operations are performed to assemble the drive mechanism 5a in an embodiment:
the bearing 79 is placed into the housing 3 to abut a shoulder 3d on the
housing
3;
the drive shaft 5 is slid into a bore 5b and the bearing 79, and may also be
rotated to mesh with the drive sub gear 41;
the bearing 81 is slid onto the drive shaft 5 to abut a shoulder 3e on the
housing
3;
the seal 87 is placed against a shoulder 93a on the retainer nut 93, and the
retainer nut 93 is then slid onto the drive shaft 5 and threaded into the
housing 3 to abut
the bearing 81;
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the seal 85 is slid onto the drive shaft 5 to abut a shoulder 93h of the
retainer nut
93;
the seal retainer 91 is slid onto the drive shaft 5 to abut the seal 85; and
the seal 83 is placed into a groove 89a in the nut 89 and the nut 89 is slid
onto
the drive shaft 5 and threaded into the housing 3 to abut the retainer nut 93
and the seal
retainer 91.
These operations may be performed in a different order in other embodiments.
There
could also be additional operations, such as applying lubricants and/or
sealing
compounds during assembly. For example, LoctiteTM could be placed onto threads
of
the nut 89 before it is threadedly connected to the housing 3. Fewer
operations could be
involved in embodiments that have fewer components.
FIG. 9 is a cross-section view of the locking pin shown 7 in FIG. 6, and FIG.
10 is an
exploded view of the locking pin 7. As shown, washers 99, 103, packing 101,
and the
locking nut 97 are fitted onto the locking bolt 95. The locking bolt 95 is
threaded into a
threaded bore the housing 3. The washers 99, 103 and the packing 101 are then
also
installed into the bore, and the locking nut 97 is then threadedly coupled to
the housing
3. The extent to which the locking bolt 95 protrudes from an interior surface
3a of the
rotator housing is controllable by turning the locking bolt 95. The washers
99, 103 and
the packing 101 are held in place against a shoulder in the bore by the
locking nut 97.
In the embodiment shown in FIG. 9, the locking nut 97 is threaded into the
housing 3
until the packing 101 seals between the bore and the locking bolt 95. The
locking bolt
95 can then be safely moved while under pressure. The locking bolt 95 moves
between
a locked position, where a shoulder 95a of the locking bolt 95 protrudes from
the bore
and contacts a shoulder of the hanger assembly housing 43 in the embodiment
shown,
and an unlocked position, where the shoulder 95a of the locking bolt no longer
protrudes from the bore and a second shoulder 95b of the locking bolt 95 may
be in
contact with the washer 103. In the locked position shown, the locking bolt 95
abuts the
hanger assembly housing 43 such that further upwards movement of the hanger
assembly housing 43 is limited by the locking bolt 95.
21
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The locking nut 97 and the locking bolt 95 are made of stainless steel in an
embodiment. The washers 99, 103 are also made of stainless steel and the
packing
101 is rubber in an embodiment.
FIG. 11 is an isometric view of a wellhead tubing rotator according to a
second
embodiment, with a shear sub exploded therefrom.
A wellhead tubing rotator 105 shares many features with the wellhead tubing
rotator 1
described above. However, the wellhead tubing rotator 105 also has an upper
sub 109,
which is a part of a hanger assembly 115.
The upper sub 109 allows for the mandrel 107 to be detached from other parts
of the
hanger assembly 115 as is described in more detail below with reference to
FIGS. 15A
to 15E.
The upper sub 109 has one or more axial bores or holes 111. For example, two
bores
111 are shown in FIG. 11. The bores 111 in the upper sub 109 allow for the
upper sub
109 to be assembled with or dissembled from the mandrel 107 by means of a C-
wrench.
The upper sub 109 and the mandrel 107 may be made of any material(s)
sufficiently
rigid to support expected loading. For example, NACE-compliant 4130 steel or
stainless
steel is used in an embodiment.
The wellhead tubing rotator 105 may be coupled to the production tubing 23 via
the
mandrel 107. The production tubing 23 is not part of the wellhead tubing
rotator 105, but
is shown in FIG. 11 to illustrate how the wellhead tubing rotator 105 is
coupled to the
production tubing 23 in an embodiment.
The drive shaft 5 may be coupled to a shear sub 139. The shear sub 139 is
constructed
to limit force transfer such that the drive shaft 5 is not overtorqued. The
shear sub 139 is
also not part of the wellhead tubing rotator 105, but is shown in FIG. 11 to
illustrate how
the drive shaft 5 may be coupled to the shear sub 139.
22
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With reference to FIGS. 12 to 14, FIG. 12 is a cross-section view of the
wellhead tubing
rotator 105, along line 12-12 shown in FIG. 11, FIG. 13 is a cross-section
view of the
hanger assembly 115 shown in FIG. 12, and FIG. 14 is an exploded, isometric
view of
the hanger assembly 115 of FIG. 13.
The hanger assembly 115 includes the mandrel 107, an upper sub assembly 119, a
hanger assembly housing 117 and a hanger assembly gear 127. The upper sub
assembly 119 includes the upper sub 109 and one or more fasteners 113.
The mandrel 107 is supported by the upper sub 109. The upper sub 109 is
supported by
a bearing assembly 123. The bearing assembly 123 is supported by the hanger
assembly housing 117, which rests against the housing internal shoulder 68a of
the
housing 3. As shown perhaps most clearly in FIG. 13, the hanger assembly
housing 117
includes the shoulder 68b, which engages the housing internal shoulder 68a
when the
hanger assembly 115 is installed in the housing 3. Other embodiments of these
shoulders are contemplated, as described above with reference to the housing 3
and
the hanger assembly 19.
The hanger assembly 115 is coupled to the drive sub assembly 45 via the hanger
assembly gear 127. The hanger assembly gear 127 is connected to the upper sub
109
by one or more hanger keys 129. The upper sub 109 is attached to the mandrel
107 by
a connection between threads 114a on an inner surface of the upper sub 109 and
threads 114b on an outer surface of the mandrel 107, and by the fasteners 113.
Other
types of connections could be used in other embodiments to connect the upper
sub 109
and the mandrel 107 to each other.
The upper sub 109 has one or more radial holes or bores 109b and the mandrel
107
has one or more radial bores or holes 107a. For example, in FIG. 14, two
radial bores
109b and two radial bores 107a are visible, and radial bores 109b, 107a are
aligned.
The fasteners 113 are threadedly engaged with a radial bore 109b, which allows
the
fasteners to be extended into and retracted from the radial bores 107a. The
fasteners
113 could have different shapes, sizes, and/or engagements with the radial
bores 109b,
107a in other embodiments.
23
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The fasteners 113 may be made of any material(s) sufficiently rigid to
withstand
expected loading between the upper sub 109 and the mandrel 107. For example,
the
fasteners 113 could be stainless steel bolts.
The drive sub assembly 45, the housing 3, the drive mechanism 5a, the locking
pins 7
and the plugs 9, 27, 29 have similar parts, configurations and preferred
materials to
those identified above in association with the first embodiment.
The hanger assembly housing 117; the bearing assembly 123, illustratively
including
ball bearings in a bearing race 121 (FIGS. 13 and 14); the hanger assembly
gear 127;
and the hanger keys 129 may be made of similar materials and have similar
configurations as those described above in association with the first
embodiment.
Various seals are also shown in FIGS. 12 to 14. The purposes or effects of
these seals
can perhaps best be understood with reference to FIGS. 12 and 13. The seals
47,133,135,137 may be exposed to wellbore pressure, and therefore are made of
material(s) that can withstand such pressures. The seals 133, 135 are moveable
seals,
whereas the seals 47, 137 are stationary. In an embodiment, the seals 47, 137
are 0-
rings, and the seals 133, 135 are PolypakTM rings. The seals 47 allow the
hanger
assembly housing 117 to seal against the housing 3, as in the first embodiment
described above. The seals 133, 135 allow the upper sub 109 to seal against
the
hanger assembly housing 117. These seals 133, 135 are similar to the seals
51,49
(FIG. 4) in the first embodiment, but in the first embodiment the seals 51, 49
allow the
mandrel 21, instead of an upper sub 109 as in FIG. 12, to seal against the
hanger
assembly housing 43. The seal 137 does not have a counterpart in the first
embodiment, but allows the mandrel 107 to seal against the upper sub 109 in
the
second embodiment, as shown in FIG. 12, for example.
A bushing 125 located between the hanger assembly housing 117 and the upper
sub
109 could be used in some embodiments to provide additional load support in a
similar
manner to the bushing 55 described herein. The bushing 125, like other load
carrying
components, is made of material(s) having sufficient rigidity to withstand
expected
loads.
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An opening 117f is provided in the hanger assembly housing 117 allows for the
equalization of pressure between the seals 47 during installation or
disassembly of the
hanger assembly 115.
The hanger keys 129 and the hanger assembly gear 127 are held in place on the
upper
sub 109 by a retainer 131. Although the hanger assembly gear 127 is carried by
the
upper sub 109 in the second embodiment, the hanger assembly gear 127 may be
the
same as or substantially similar to the hanger assembly gear 33 of the first
embodiment,
and includes tapered lugs 127a (FIG. 14) to mesh with tapered lugs in the
drive sub 37
in the housing 3.
With reference to FIGS. 13 and 14, the following operations are performed to
assemble
the hanger assembly 115 in an embodiment:
the seals 47 are positioned in grooves 117e on the hanger assembly housing
117;
the bearing assembly 123 is placed on a shoulder 117b of the hanger assembly
housing 117;
the bushing 125 is placed on a shoulder 117a on the hanger assembly housing
117;
the seal 133 is positioned in a groove 117d in an inner surface of the hanger
assembly housing 117;
the seal 135 is positioned in a groove 109c in the upper sub 109, and the
upper
sub 109 is slid into the hanger assembly housing 117 to abut the bearing
assembly 123
and the bushing 125;
the hanger keys 129 are placed into hanger key slots 129a in the outer surface
of
the upper sub 109;
the hanger assembly gear 127 is slid onto the upper sub 109;
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the slots 129b in the inner surface of the hanger assembly gear 127 are
aligned
with the hanger keys 129;
the hanger assembly gear 127 is slid further along the upper sub 109 to abut
an
end 117c of the hanger assembly housing 117;
the retainer 131, illustratively a stainless steel snap ring, is installed
into a groove
109d on the upper sub 109 to hold the hanger keys 129 and the hanger assembly
gear
127 on the upper sub 109;
the seal 137 is positioned in a groove 107b in the mandrel 107;
the mandrel 107 is inserted into the upper sub 109;
the threads 114b of the mandrel 107 are threaded into the threads 114a in the
inner surface of the upper sub 109 so that a shoulder 107c on the mandrel 107
abuts
the upper sub 109;
the fasteners 113 are inserted into the bores 109b in the upper sub 109; and
the fasteners 113 are threadedly tightened into the bores 109b so that the
fasteners 113 extend into the bores 107a in the mandrel 107.
These operations may be performed in a different order in other embodiments.
There
could also be additional operations, such as applying lubricants and/or
sealing
compounds during assembly. Fewer operations could be involved in embodiments
that
have fewer components, such as embodiments in which the lugs 127a of the
hanger
assembly gear 127 are machined into the upper sub 109.
Threaded connections are also shown in FIG. 13 between the mandrel 107 and the
upper sub 109, and the upper sub 109 and the fasteners 113. Other connection
methods, such as lock-and-key connections, could also or instead be used.
The second embodiment is similar to the first embodiment in that the housing 3
bears
the weight of the production tubing 23 via the housing internal shoulder 68a.
Therefore,
in the second embodiment the drive sub assembly 45 also does not bear the
weight of
26
CA 02941404 2016-09-09
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the production tubing 23. Also like the first embodiment, in the second
embodiment the
drive sub gear 41 and the worm gear 31 are sealed from well fluids by the
drive sub
assembly 45.
The upper sub assembly 119 allows for the mandrel 107 to be released from
other parts
of the hanger assembly housing 117. For example, the mandrel 107 may be
detached
from the upper sub 109 by removing the fasteners 113 and unthreading the
threads114a, 114b. Detaching the mandrel 107 from the upper sub 109 may allow
for
the production tubing 23, and the mandrel 107 that is attached to the
production tubing
23, to be moved further down into the well to wash or clear material that has
deposited
onto downhole equipment in the well. This may be especially useful in
horizontal wells.
Two illustrative embodiments are shown in FIGS. 1 to 14 and described in
detail above.
Other embodiments are also contemplated. For example, FIG. 15 is a cross-
section
view of a hanger according to another embodiment.
A hanger assembly 179 shares many features with the hanger assembly 19 (FIGS.
1 to
4), and such shared features are labelled in FIG. 15 with the same reference
numbers
as above. However, the hanger assembly 179 also has additional components.
As shown, an upper auxiliary sub 172 is threadedly connected to a hanger
assembly
housing 170 and rests on a bearing 176. The bearing 176 allows the mandrel 21
to
rotate relative to the upper auxiliary sub 172.
The upper auxiliary sub 172 seals against the mandrel 21 and the hanger
assembly
housing 170 by means of seals 178,174, respectively.
The seal 178 is a moveable seal and the seal 174 is a stationary seal. The
seals
178,174 may be exposed to well pressure, and therefore are made of material(s)
that
can withstand such pressures. The seals 178,174 may be made of similar
materials to
the seals 49,47, respectively.
The bearing 176 may be made of material(s) having sufficient rigidity to
withstand
expected loads.
27
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The upper auxiliary sub 172, and the hanger assembly housing 170 may be made
of
any material(s) with sufficient rigidity and resistance to corrosion.
In operation, the shoulder 95a of the locking pin 7 (FIG. 9) abuts a shoulder
172a of the
upper auxiliary sub 172. The larger thickness in the radial direction of the
upper auxiliary
sub 172 relative to that of the hanger assembly housing 43 may help reduce the
likelihood that overtightening of the locking pin 7 will prevent the mandrel
21 from
turning. The thicker upper auxiliary sub 172 is less likely to be deformed
than the
hanger assembly housing 43 by overtightening of the locking pin 7.
Further embodiments are also contemplated. FIG. 16 is a cross-section view of
a
hanger assembly according to a further embodiment.
A hanger assembly 180 shares many features with the hanger assembly 115 (FIGS.
11
to 14) and such shared features are labelled in FIG. 16 with the same
reference
numerals as above. However, similar to the hanger assembly 179 (FIG. 15), the
hanger
assembly 180 also has additional components.
As shown, an upper sub 152 is threadedly connected to the mandrel 107 and an
upper
auxiliary sub 154 is threadedly connected to a hanger assembly housing 150 and
rests
on a bearing 156. The bearing 156 is identical to the bearing 176 except that
the
bearing 156 is supported by the upper sub 152.
The upper auxiliary sub 154 seals against the hanger assembly housing 150 and
the
upper sub 152 by means of seals 158, 160, respectively.
The seal 160 is a moveable seal and the seal 158 is a stationary seal. The
seals 160,
158 may be exposed to well pressure, and therefore are made of material(s)
that can
withstand such pressures. The seals 160, 158 may be made of similar materials
to the
seals 178, 174, respectively.
The bearing 156 may be made of material(s) having sufficient rigidity to
withstand
expected loads.
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The upper auxiliary sub 154, the upper sub 152 and the hanger assembly housing
150
may be made of any material(s) with sufficient rigidity and resistance to
corrosion.
In operation, the shoulder 95a of the locking pin 7 (FIG. 9) abuts a shoulder
154a of the
upper auxiliary sub 154. The larger thickness in the radial direction of the
upper auxiliary
sub 154 relative to that of the hanger assembly housing 117 (FIG. 13) may help
reduce
the likelihood that overtightening of the locking pin 7 will prevent the
mandrel 107 from
turning. The thicker upper auxiliary sub 154 is less likely to be deformed
than the
hanger assembly housing 117 by overtightening of the locking pin 7.
Different stages of removing portions of the hanger assembly are depicted in
the cross-
section views in FIGS. 17A to 17E. FIG. 17A shows the wellhead tubing rotator
105 in
an assembled position in which the mandrel 107 is connected to the production
tubing
23. In FIG, 17B, a connector 138, which may also be referred to as a pick up
sub, is
coupled to the mandrel 107, by threading the connector to the mandrel 107 for
example.
The connecter 138 may be made of any rigid material(s) that can carry expected
loads,
such as a stub or section of production tubing. The locking pins 7 may be
backed off or
otherwise retracted from protruding inside the housing 3 before or after the
connector
138 is coupled to the mandrel 107. FIG. 17C shows the connector 138 being
lifted, by
using wellhead equipment to apply a lifting force for example, to remove the
hanger
assembly 115 from the housing 3. At this stage, the drive sub assembly 45
remains in
the housing 3.
Referring now to FIG. 17D, the fasteners 113 are removed, thereby partially
releasing
the upper sub 109 from the mandrel 107. FIG. 17E shows the mandrel 107 after
it has
been decoupled from the upper sub assembly 119, by unthreading the upper sub
assembly from the mandrel 107 for example. At this point the mandrel 107,
which is
coupled to the production tubing 23, is free to be moved upwards and/or
downwards.
Examples of wellhead tubing rotators are described in detail above. Wellhead
tubing
rotators may be implemented in conjunction with, and coupled to, the
production tubing
23 that is to be placed in a well, a manual drive or an electric or hydraulic
motor to drive
the drive shaft 5, and other wellhead or surface production equipment.
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The embodiments described above relate primarily to examples of wellhead
tubing
rotators. Methods are also contemplated.
FIG. 18 is a flow chart of a method of manufacturing a wellhead tubing
rotator. The
example method 1800 involves providing, at 1802, a housing that includes an
internal
shoulder. This could involve machining or otherwise manufacturing the housing,
or
purchasing the housing from a manufacturer, for example. A drive mechanism is
sealed
in a sealed cavity between the housing and a drive sub assembly that is
engaged with
the drive mechanism and sealed against an interior of the housing, at 1804. At
1806, a
hanger assembly, which is to be coupled to production tubing in a production
well, is
installed in the housing by placing the hanger assembly on the internal
shoulder of the
housing and into engagement with the drive sub.
FIG. 19 is a flow chart of a method of using a wellhead tubing rotator. The
example
method 1900 involves securing, at 1902, a housing of a wellhead tubing rotator
to a
wellhead of a production well. The housing has an internal shoulder. The
wellhead
tubing rotator also has: a drive mechanism located in the housing; a drive sub
assembly
engaged with the drive mechanism and sealed against an interior of the housing
to
define a sealed cavity that isolates the drive mechanism between the housing
and the
drive sub assembly; and a hanger assembly, supported by the internal shoulder
of the
housing and engaged with the drive sub assembly, to be coupled to production
tubing in
the production well, as described above. The hanger assembly is coupled to the
production tubing, at 1904. The hanger assembly is lowered into the housing,
at 1906.
At 1908, a force is provided to the drive mechanism to rotate the hanger
assembly.
The methods 1800, 1900 are illustrative embodiments. Other embodiments could
involve performing the illustrated operations in a similar or different order,
and/or
performing additional operations. For example, other embodiments could involve
providing and assembling other components of a wellhead tubing rotator. For
instance,
one embodiment could involve a kit including a housing, such as 3, a drive
mechanism,
such as 5a, a drive sub assembly, such as 45, and a hanger assembly, such as
19 or
115, along with instructions for assembling the housing, the drive mechanism,
the drive
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sub assembly and the hanger assembly to form a wellhead tubing rotator, such
as 1 or
105. Assembly of hanger assemblies and a housing are described above. Other
variations may also be or become apparent to a skilled person.
What has been described is merely illustrative of the application of
principles of
embodiments of the present disclosure. Other arrangements and methods can be
implemented by those skilled in the art.
For example, the hanger assembly housings 43 and 117 are described above as
being
supported on the housing internal shoulder 68a. However, other means for
supporting
the hanger assembly housings 43 and 117 are possible, such as a locking pin
system.
As another example, the mandrels 21 and 107 are described above as being
support by
the bearing assemblies 57 and 123. However, other options to support the
mandrels 21
and 107 while allowing them to rotate could also or instead be used, such as a
sleeve
bearing or magnetic support.
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