Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CASING HANGER LOCKDOWN TOOLS
BACKGROUND
[0001] This section is intended to introduce the reader to various aspects
of art that
may be related to various aspects of the presently described embodiments. This
discussion is believed to be helpful in providing the reader with background
information to facilitate a better understanding of the various aspects of the
present
embodiments. Accordingly, it should be understood that these statements arc to
be read
in this light, and not as admissions of prior art.
[0002] In order to meet consumer and industrial demand for natural
resources,
companies often invest significant amounts of time and money in finding and
extracting oil, natural gas, and other subterranean resources from the earth.
Particularly,
once a desired subterranean resource such as oil or natural gas is discovered,
drilling
and production systems arc often employed to access and extract the resource.
These
systems may be located onshore or offshore depending on the location of a
desired
resource. Further, such systems generally include a wellhead assembly mounted
on a
well through which the resource is accessed or extracted. These wellhead
assemblies
may include a wide variety of components, such as various casings, valves,
hangers,
pumps, fluid conduits, and the like, that facilitate drilling or production
operations.
[0003] As will be appreciated, various tubular strings can be run into
wells through
wellhead assemblies. For instance, wells are often lined with casing that
generally serves
to stabilize the well and to isolate fluids within the wellbore from certain
formations
penetrated by the well (e.g., to prevent contamination of freshwater
reservoirs). Such
casing is frequently hung in a well from a hanger in the wellhead assembly and
cemented into place within the well. During a cement job, cement can be pumped
down a casing string in a well, out the bottom of the casing string, and then
up the
annular space surrounding the casing string. The cement is then allowed to set
in the
annular space.
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SUMMARY
[0004] Certain aspects of some embodiments disclosed herein are set
forth below. It should be understood that these aspects are presented merely
to provide the reader with a brief summary of certain forms the invention
might take and that these aspects are not intended to limit the scope of the
invention. Indeed, the invention may encompass a variety of aspects that may
not be set forth below.
[0005] Embodiments of the present disclosure generally relate to tools
for selectively locking down hangers within wellheads. In some instances, a
lockdown tool can also function as a running tool and a cementing tool. That
is, the tool can be used to run the wellhead hanger (e.g., a casing hanger)
into
a wellhead, to secure the wellhead hanger and restrain its movement within
the wellhead by locking the tool in place with a locking mechanism, and to
then facilitate cementing of a tubular string (e.g., a casing string) within
the
well. In certain embodiments, the lockdown tool includes a collapsible
retaining ring that can be released to engage a wellhead housing and lock the
tool in place. The retaining ring can also be collapsed to unlock the tool and
allow it to be removed from the wellhead housing. In one embodiment, an
outer body of the lockdown tool can be rotated in one direction with respect
to
an inner body of the tool to release the retaining ring and lock the tool in
place. The outer body can later be rotated in the opposite direction to
collapse
the retaining ring, unlocking the tool from the wellhead housing. Further
rotation of the outer body in the opposite direction can also cause the inner
body of the tool to rotate and unthread from the casing hanger, allowing the
tool to then be removed from the wellhead housing.
[0005a] Some embodiments of the present disclosure relate to a system
comprising: a lockdown tool for inhibiting movement of a casing hanger within
a wellhead housing, the lockdown tool including: an inner body; an outer body
coupled to the inner body; and a locking mechanism carried by the inner body,
wherein the locking mechanism can be selectively engaged by moving the
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outer body with respect to the inner body to secure the lockdown tool to the
wellhead housing; wherein the inner body and the outer body each include a
central bore, the inner body includes at least one flow passage that is
independent of the central bore of the inner body, the outer body includes at
least one flow passage that is independent of the central bore of the outer
body, and the flow passages of the inner and outer bodies together enable
fluid
flow through the lockdown tool apart from the central bores of the inner and
outer bodies.
[000513] Some embodiments of the present disclosure relate to a method
comprising: running a casing hanger lockdown tool into a bore of a wellhead
housing, the casing hanger lockdown tool including: an inner body; an outer
body coupled to the inner body; and a locking mechanism carried by the inner
body, wherein the locking mechanism can be selectively engaged by moving
the outer body with respect to the inner body to secure the lockdown tool to
the wellhead housing; wherein the inner body and the outer body each include
a central bore, the inner body includes at least one flow passage that is
independent of the central bore of the inner body, the outer body includes at
least one flow passage that is independent of the central bore of the outer
body, and the flow passages of the inner and outer bodies together enable
fluid
flow through the casing hanger lockdown tool apart from the central bores of
the inner and outer bodies; and locking the casing hanger lockdown tool to the
wellhead housing to inhibit axial movement of a casing hanger inside the bore
of the wellhead housing below the casing hanger lockdown tool.
[0005d Some embodiments of the present disclosure relate to a system
comprising: a lockdown tool for inhibiting movement of a casing hanger within
a wellhead housing, the lockdown tool including: an inner body; an outer body
coupled to the inner body; a locking mechanism carried by the inner body,
wherein the locking mechanism can be selectively engaged by moving the
outer body with respect to the inner body to secure the lockdown tool to the
wellhead housing; a first pair of seals in sealing contact with the outer body
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and an inner surface of the inner body; and a second pair of seals in sealing
contact with the outer body and an outer surface of the inner body; wherein
the inner body includes a conduit that places a first region between the outer
body, the inner surface of the inner body, and the first pair of seals in
fluid
communication with a second region between the outer body, the outer surface
of the inner body, and the second pair of seals, and wherein the outer body
includes a test port in fluid communication with the conduit.
[0006] Various refinements of the features noted above may exist in
relation to various aspects of the present embodiments. Further features may
also be incorporated in these various aspects as well. These refinements and
additional features may exist individually or in any combination. For
instance,
various features discussed below in relation to one or more of the illustrated
embodiments may be incorporated into any of the above-described aspects of
the present disclosure alone or in any combination. Again, the brief summary
presented above is intended only to familiarize the reader with certain
aspects
and contexts of some embodiments without limitation to the claimed subject
matter.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features, aspects, and advantages of certain
embodiments
will become better understood when the following detailed description is read
with
reference to the accompanying drawings in which like characters represent like
parts
throughout the drawings, wherein:
[0008] FIG. I generally depicts various components, including one or more
tubular
strings and associated hangers, that can be installed at a well in accordance
with one
embodiment of the present disclosure;
[0009] FIG. 2 is an devotional view of a tool for installing a casing
hanger in a
wellhead housing and locking the casing hanger in place within the wellhead
housing in
accordance with one embodiment;
[0010] FIG. 3 is a section view of the tool of FIG. 2 positioned within a
wellhead
housing and depicts a retaining ring in an unlocked position in accordance
with one
embodiment;
[0011] FIG. 4 is a detail view depicting a hold pin and set screw disposed
in a hole
of the tool of FIG. 2 to engage a neck of the casing hanger in accordance with
one
embodiment;
[0012] FIG. 5 is a section view of the tool of FIG. 2 and depicts the
retaining ring
in a locked position after rotating an outer body of the tool to release the
retaining ring
in accordance with one embodiment;
[0013] FIG. 6 is a section view of the tool of FIG. 2 after rotating the
outer body
of the tool to return the retaining ring to the unlocked position in
accordance with one
embodiment;
[0014] FIG. 7 is a section view of the tool of FIG. 2 after continuing to
rotate the
outer body of the tool following the return of the retaining ring to the
unlocked
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position to disconnect an inner body of the tool from the casing hanger in
accordance
with one embodiment;
[0015] FIG. 8 is a section view of a tool for locking a casing hanger in
place within
the wellhead housing in accordance with one embodiment; and
[0016] FIGS. 9-12 are section views of another tool for locking a casing
hanger in
place within the wellhead housing in accordance with certain embodiments.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0017] Specific embodiments of the present disclosure are described below.
In an
effort to provide a concise description of these embodiments, all features of
an actual
implementation may not be described in the specification. It should be
appreciated that
in the development of any such actual implementation, as in any engineering or
design
project, numerous implementation-specific decisions must be made to achieve
the
developers' specific goals, such as compliance with system-related and
business-related
constraints, which may vary from one implementation to another. Moreover, it
should
be appreciated that such a development effort might be complex and time
consuming,
but would nevertheless be a routine undertaking of design, fabrication, and
manufacture for those of ordinary skill having the benefit of this disclosure.
[0018] When introducing elements of various embodiments, the articles "a,"
"an,"
"the," and "said" arc intended to mean that there arc one or more of the
elements. The
terms "comprising," "including," and "having" arc intended to be inclusive and
mean
that there may be additional elements other than the listed elements.
Moreover, any use
of "top," "bottom," "above," "below," other directional terms, and variations
of these
terms is made for convenience, but does not require any particular orientation
of the
components.
[0019] Turning now to the present figures, a system 10 is illustrated in
HG. 1 in
accordance with one embodiment. Notably, the system 10 is a production system
that
facilitates extraction of a resource, such as oil, from a reservoir 12 through
a well 14.
Wellhead equipment 16 is installed on the well 14. As depicted, the wellhead
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equipment 16 includes at least one casing head 18 and tubing head 20, as well
as
wellhead bangers 22. But the components of the wellhead equipment 16 can
differ
between applications, and could include a variety of casing heads, tubing
heads, spools,
hangers, sealing assemblies, stuffing boxes, pumping tees, and pressure
gauges, to name
only a few possibilities.
[0020] The wellhead hangers 22 can be positioned on landing shoulders 24
within
hollow wellhead bodies (e.g., within the tubing and casing heads). These
landing
shoulders 24 can be integral parts of tubing and casing beads or can be
provided by
other components, such as sealing assemblies (e.g., packoffs) or landing rings
disposed
in the tubing and casing heads. Each of the hangers 22 can be connected to a
tubular
string, such as a tubing string 26 or a casing string 28, to suspend the
string within the
well 14. The well 14 can include a single casing string 28 or include multiple
casing
strings 28 of different diameters. Any suitable devices or machines may be
used to run
tubular strings into wells through wellheads and install hangers attached to
the tubular
strings in the wellheads. For example, a top drive can be used to run a casing
string into
a well and a casing hanger into a wellhead.
[0021] Casing strings 28 arc often cemented in place within the well. In
some
instances, cement is pumped down a casing string 28 and into an annular space
around
the casing string 28. A plug can then be pumped down the casing string 28 with
a
displacement fluid (e.g., drilling mud) to generally push additional cement in
the casing
string out the bottom and into the annular space. As the cement fills the
annular space,
it displaces drilling mud present in the annular space before cementing began.
This
causes the displaced drilling mud to flow up the well to the wellhead. Cement
hydration
during setting of the cement generates heat, which in some instances could
cause the
casing string to move upward in the well, lifting an attached hanger 22 off
its landing
shoulder 24 within the wellhead assembly. This displacement can complicate
completion of the well 14, such as by interfering with the installation of a
seal assembly
or other components above the raised casing hanger. And pushing the hanger and
the
casing string back down could damage cement that has begun to set.
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[0022] Various embodiments of the present disclosure relate to lockdown
tools for
locking casing hangers in place within wellheads to prevent unwanted lifting
of the
casing hangers off their landing shoulders, such as during cementing of casing
strings
connected to the hangers. Some lockdown tools can also serve as running tools
and
cementing tools, allowing a single tool to be used to run a casing hanger into
a wellhead
housing, to lock the casing hanger in place within the wellhead housing (e.g.,
by locking
the tool in place above the wellhead housing), and to allow fluids displaced
during
cementing to flow up the well through flow-by passages provided in the tool.
Moreover, using a single tool for running, locking, and cementing (with one
trip into
the well) can save time and expense compared to inserting and pulling
multiple,
different tools into the well for performing these functions. While certain
embodiments
of lockdown tools are described below in connection with locking down a casing
hanger, it will be appreciated that lockdown tools could also be used to
secure other
components within a wellhead housing.
[0023] With this in mind, one example of a lockdown tool 32 for locking a
casing
banger 34 in place within a wellhead housing is depicted in FIG. 2. In the
depicted
embodiment, the lockdown tool 32 also serves as a running tool and cementing
tool, as
described in greater detail below. The lockdown tool 32 is coupled at its
lower end to
the casing hanger 34 and at its upper end to a landing string 36, such as a
pup joint. The
landing string 36 can be connected to a top drive or any other suitable
machine for
lowering and raising the lockdown tool 32, the casing hanger 34, and an
attached casing
string with respect to the well 14 and wellhead equipment 16.
[0024] The lockdown tool 32 includes an inner body 40 coupled to an outer
body 42. In the embodiment depicted in FIG. 2, a locking mechanism is provided
as an
outwardly biased, collapsible retaining ring 44 (e.g., a C-ring) carried by
the inner
body 40. Once the casing hanger 34 is landed on its landing shoulder 24 in a
wellhead
housing, the retaining ring 44 can be selectively engaged by moving (e.g.,
rotating) the
outer body 42 with respect to the inner body 40 to allow the retaining ring 44
to expand
and secure the lockdown tool to the wellhead housing. This serves to also lock
the
casing hanger 34 in place and inhibits axial movement of the casing hanger 34
off its
landing shoulder 24 within the wellhead housing. \Vhile certain embodiments
are
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described herein as haying locking mechanisms in the form of retaining rings,
any other
suitable locking mechanisms could be used to lock the tool 32 and the casing
banger 34
in place within a wellhead housing. For instance, in some embodiments the
locking
mechanisms could instead be provided as pins or lockscrews.
[0025] Additional features of the lockdown tool 32 are also visible in FIG.
2 on the
exterior of the tool. For example, the lockdown tool 32 includes various flow-
by or
flow-through passages to facilitate cementing of a casing string attached to
the casing
hanger 34 while the casing hanger 34 is locked in place by the tool 32. More
specifically,
the inner body 40 includes flow slots 48 in its exterior surface and the outer
body 42
includes flow ports 50. Cement can be pumped down through central bores of the
landing string 36, the outer body 42, the inner body 40, the casing hanger 34,
and an
attached casing string. The slots 48 and ports 50 are separate from the
central bores of
the inner and outer tool bodies 40 and 42, allowing drilling mud displaced by
the
cement to flow up the well and through the lockdown tool 32 via the slots 48
and
ports 50 even while cement or other fluids are pumped down through the central
bores.
The lockdown tool 32 also includes holes 54 and 56. In at least some
embodiments, and
as described in greater detail below, the holes 54 include screws for engaging
an internal
stop ring and the holes 56 include pins for engaging the casing hanger 34.
[0026] A section view of the lockdown tool 32 and the casing hanger 34
within a
wellhead housing 60 is provided in FIG. 3. The wellhead housing 60 can be a
casing
head 18 or some other component. As shown here, the inner body 40 and the
outer
body 42 are threaded to one another via mating threaded surfaces 62 and 64,
and the
outer body 42 is threaded down onto the inner body 40 to restrain the
retaining ring 44
within a circumferential groove 66 of the inner body 40. A stop ring 68 is
positioned
within an outer groove 70 of the inner body 40 and an inner groove 72 of the
outer
body 42. The stop ring 68 limits the extent to which the outer body 42 can
move along
the inner body 40 when rotating the outer body 42 along the threads of the
surfaces 62
and 64.
[0027] In at least some embodiments, including that shown in FIG. 3, the
stop
ring 68 (e.g., a C-ring) is outwardly biased and pushed into the outer groove
70 of the
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inner body 40 by screws 74 threaded into the holes 54. During assembly of the
lockdown tool 32 before running the casing hanger 34 into the wellhead housing
60,
the outwardly biased stop ring 68 is positioned entirely within the inner
groove 72 of
the outer body 42, allowing the outer body 42 to be threaded onto the inner
body 40
and to collapse the retaining ring 44 into the groove 66. The screws 74 can
then be used
to push the stop ring 68 partially into the outer groove 70. In this position,
the stop
ring 68 can travel back and forth within the outer groove 70 when the outer
body 42 is
rotated to translate along the inner body 40. A shear screw 78 can also be
installed
through the outer body 42 and into the inner body 40 at a location that does
not have a
flow slot 48 (and is consequently depicted in the present figures within a
cutaway area).
The shear screw 78 facilitates running of the lockdown tool 32 and the casing
hanger 34 into the wellhead housing 60 by preventing inadvertent rotation of
the outer
body 42 with respect to the inner body 40 and premature release of the
retaining
ring 44 from the groove 66.
[0028] The inner body 40 and the casing hanger 34 are also threaded to one
another
with mating threaded surfaces 82 and 84 in FIG. 3. These two components can be
threaded together before running the tool 32 and the casing hanger 34 into the
wellhead housing 60. Seals 86 engage seal neck 88 of the casing hanger 34 to
inhibit
leakage. In at least some embodiments, holding pins are used to prevent
inadvertent
rotation of the inner body 40 with respect to the casing hanger 34. For
example, as
shown in FIG. 4, the seal neck 88 includes a recessed portion 90 that is
engaged by a
holding pin 92 positioned within a hole 56. A screw 94 is inserted into the
hole 56 and
shares a threaded interface 96 with the inner body 40. The screw 94 can be
threaded
into the hole 56 to push the bolding pin 92 into engagement with the recessed
portion 90 of the seal neck 88. While only one arrangement of a pin 92 and a
screw 94
in a hole 56 is depicted in FIG. 4, it is noted that such pins 92 and screws
94 could be
provided in multiple holes 56 about the inner body 40 for resisting rotation
of the inner
body 40 with respect to the casing hanger 34. The screws 94 could be tightened
to a
specified torque to force the pins 92 against the seal neck 88.
[0029] The lockdown tool 32 and the casing hanger 34 can be coupled to the
landing string 36 with a threaded surface 102 of the outer body 42 and then
run into
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the wellhead housing 60 to land the casing hanger 34 on its landing shoulder
24 (not
shown in FIG. 3). When the casing hanger 34 is landed on its shoulder, the
retaining
ring 44 is aligned with a groove 108 in the wellhead housing 60. The retaining
ring 44
can then be released by rotating the outer body 42 along the inner body 40 and
allowing
the retaining ring 44 to expand into and engage the groove 108, as shown in
FIG. 5. In
this position straddling both the groove 66 and the groove 108, the retaining
ring 44
secures the lockdown tool 32 to the wellhead housing 60 and inhibits axial
movement
of the lockdown tool 32 and the casing hanger 34 within the wellhead housing
60. In at
least some embodiments, the groove 108 is also used for installation of a seal
assembly
over the casing hanger 34 once cementing is complete and the tool 32 has been
removed.
[0030] In addition to locking the casing hanger 34 in place, the tool 32
also helps
ensure that the casing hanger 34 has been correctly landed. Particularly, the
tool 32, the
casing hanger 34, and the wellhead housing 60 are arranged such that the
retaining
ring 44 is aligned with the groove 108 only when the casing hanger is fully
landed
within the wellhead housing 60. If the casing hanger 34 is positioned off its
landing
shoulder, the retaining ring /I would not align with the groove 108 and would
not lock
the tool 32 and the casing hanger 34 in place.
[0031] Cement can be pumped down through the lockdown tool 32, the casing
hanger 34, and an attached casing string 28 to cement the casing string while
the tool 32
locks the casing hanger 34 in place within the wellhead housing 60 and limits
axial
movement of the casing hanger 34 off its landing shoulder. Drilling mud
returns (i.e.,
drilling mud displaced by the flowing cement) flow through the lockdown tool
32 via
the slots 48 and ports 50, as generally represented by the arrows drawn in
these
passages in FIG. 5.
[0032] The lockdown tool 32 can then be disconnected from the casing hanger
34
(e.g., after the cement in the annular space outside the casing string is
confirmed to be
hard). To facilitate disconnection of the lockdown tool 32 from the casing
hanger 34, in
at least some instances the threaded surfaces 62 and 64 have threads provided
in one
direction and the threaded surfaces 82 and 84 have threads provided in an
opposite
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direction. By way of example, the threaded surfaces 62 and 64 have right-
handed
threads and the threaded surfaces 82 and 84 have left-banded threads in at
least one
embodiment. In such an embodiment, once the casing hanger 34 is run into and
landed
within the wellhead housing 60 with the lockdown tool 32 (as shown in FIG. 3),
the
landing string 36 is rotated counter-clockwise to turn the outer body 42
counter-
clockwise about the inner body 40. As the outer body 42 turns in this manner,
it
translates up the inner body 40 and allows the collapsed retaining ring 44 to
expand
into the groove 108 and lock the tool 32 and the casing hanger 34 within the
wellhead
housing 60 (as shown in FIG. 5). Further counter-clockwise rotation of the
outer
body 42 is limited by engagement of the stop ring 68 with the upper shoulder
of the
groove 70 of the inner body 40.
[0033] To unlock the tool 32 from the wellhead housing 60 (such as after
cementing
is completed and the cement has hardened), the landing string 36 can be
rotated
clockwise to thread the outer body 42 back down the inner body 40 and collapse
the
retaining ring 44 out of the groove 108. Axial movement of the outer body 42
down
along the inner body 40 is again limited by engagement of the stop ring 68,
this time
with the lower shoulder of the groove 70. Continued clockwise rotation of the
landing
string 36 then causes both the outer body 42 and the inner body 40 to rotate
together
(after overcoming friction of the pins 92 on the seal neck 88) and backs the
inner
body 40 off of the casing hanger 34 until the tool 32 disconnects, as shown in
FIG. 7.
The tool 32 can then be removed from the wellhead housing 60 and a seal
assembly
(e.g., a packoff) can be installed over the casing hanger 34. In some
embodiments, the
groove 108 can also be used during installation of the seal assembly.
[0034] An additional lockdown tool 112 is depicted in FIG. 8 in accordance
with
another embodiment. The lockdown tool 112 includes an inner body 114 coupled
to an
outer body 116 via mating threaded surfaces 122 and 124. The lockdown tool 112
also
includes a collapsible retaining ring 118 that functions similarly to the
retaining ring 44
described above. That is, the outer body 116 can be rotated (e.g., by a
landing string 36
coupled to the outer body 116) to translate along the inner body 114 and
selectively
release the retaining ring 118. The lockdown tool 112 and the casing hanger 34
can be
locked in place by releasing the retaining ring 118 to extend out of groove
126 of the
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inner body 114 and into the groove 108, and then unlocked by collapsing the
retaining
ring 118, using the outer body 116. The inner body 114 and the outer body 116
include
flow slots 128 and flow ports 130, which at least function similarly to slots
48 and
ports 50 described above in that thcy allow drilling mud returns to flow
through the
tool 112. One or more stop pins 134 in the outer body 116 extend into a groove
136
and function similarly to the stop ring 68 to limit axial movement of the
outer
body 116 with respect to the inner body 114. Indeed, the stop pins 134 could
be
replaced by the stop ring 68 in other embodiments.
[0035] While the tool 112 depicted in FIG. 8 is configured as a lockdown
and
cementing tool, it is not configured as a running tool. Rather, the casing
hanger 34 is
installed in the wellhead housing 60 on a landing shoulder with a separate
running tool.
The tool 112 can then be run into the wellhead housing 60 to lock the
installed casing
hanger 34 in place during cementing. The inner body 114 includes one or more
spring-
loaded, anti-rotation pins 140 that prevent rotation of the inner body 114
with respect
to the casing hanger 34. The springs allow the pins 140 to retract into the
inner
body 114 when the tool 112 is landed onto the casing hanger 34 with the pins
140 out
of alignment with mating recesses in the casing hanger 34. The tool 112 can
then be
turned on the casing hanger 34. When the pins 140 are aligned with the mating
recesses
in the casing hanger 34, the biasing force of the springs pushes the pins 140
into the
recesses. The mating engagement of the pins 140 with the recesses allows the
inner
body 114 to remain stationary while the outer body 116 is rotated to release
and
collapse the retaining ring 118.
[0036] Another lockdown tool 146 is depicted in FIG. 9 in accordance with
one
embodiment. The lockdown tool 146 includes an inner body 148, an outer body
150,
and a collapsible retaining ring 152. The inner body 148 is coupled to a
casing
hanger 34 via mating threaded surfaces 84 and 154, and to the outer body 150
via
mating threaded surfaces 156 and 158. The retaining ring 152 is similar or
identical to
the retaining rings 44 and 118, and can be selectively collapsed or released
by rotating
the outer body 150 about the inner body 148.
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[0037] The wellhead housing 60 can have multiple grooves 108 capable of
receiving
a retaining ring 44, 118, or 152. In FIG. 5, the depicted portion of the
wellhead
housing 60 has two grooves and the retaining ring 44 of the lockdown tool 32
is
received in the lower groove 108. In contrast, the retaining ring 152 is shown
in FIG. 9
as extending from a groove 160 of the tool 146 and into an upper groove 108
(e.g., a
tubing hanger locking groove) of the wellhead housing 60; this locks the tool
146 and
the casing hanger 34 in place within the housing 60.
[0038] The lockdown tool 146 includes flow ports 162 through the inner body
148
and flow ports 164 through the outer body 150. Similar to the flow slots 48
and flow
ports 50 described above, these flow ports 162 and 164 can be spaced
circumferentially
about the lockdown tool 146 and allow fluid (e.g., drilling mud returns) to
flow through
the tool 146, as generally represented by the arrows in FIG. 9. The flow ports
162 are
positioned through the inner body 148 apart from the retaining ring 152, and
this
separation can reduce contamination of the groove 160 during cementing in some
instances (e.g., in the event of over-cementing the casing).
[0039] The lockdown tool 146 also includes a stop ring 168 (e.g., a C-ring)
that
limits axial travel of the inner body 148 with respect to the outer body 150.
In at least
some embodiments, the stop ring 168 is inwardly biased and extends between a
groove 170 of the inner body 148 and a groove 172 of the outer body 150.
During
assembly of the lockdown tool 146, screws can be inserted through holes 174 in
the
outer body 150 and threaded into tapped holes of the stop ring 168 to expand
and hold
the stop ring 168 in the groove 172 so that the stop ring 168 does not
interfere with
receipt of the inner body 148 in the outer body 150. Alignment of the screw
holes 174
through the outer body 150 and the tapped holes in the stop ring 168 can be
maintained with a locating peg. Once the grooves 170 and 172 are aligned, the
assembly screws can be removed to allow the inward bias of the stop ring 168
to cause
the stop ring 168 to contract and extend into the groove 170 of the inner body
148
from the groove 172.
[0040] The lockdown tool 146 can include various features to inhibit
rotation of
components relative to one another during assembly and running into a
wellhead. For
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instance, like the shear screw 78 of the lockclown tool 32, a shear screw 178
can be
installed through the outer body 150 and into the inner body 148 to prevent
inadvertent
rotation of the outer body 150 with respect to the inner body 148 during
running of
the casing hanger 34 and the lockdown tool 146 into the wellhead housing 60
(e.g., via a
landing string 36 threaded to the upper end of the tool 146). Although not
shown in
FIG. 9, the lockdown tool 146 could also use holding pins, such as pins 92
described
above with respect to FIG. 4, inserted through the inner body 148 into contact
with the
seal neck 88 of the casing hanger 34 to avoid unintentional rotation of the
inner
body 148 with respect to the casing hanger 34.
[0041] Seals 182 of the tool 146 inhibit leaking between the inner body 148
and the
outer body 150. In one embodiment, the tool 146 includes a single seal 182
provided
between an inner surface of the inner body 148 and an adjacent surface of the
outer
body 150, such as shown in FIG. 9. In another embodiment, such as that
depicted in
FIG. 10, the lockdown tool 146 includes a pressure-testable seal arrangement
with a
first pair of seals 182 in contact with the inner surface of the inner body
148 and an
adjacent surface of the outer body 150, and a second pair of seals 182 at the
exterior of
the inner body 148 (i.e., in contact with the outer surface of the inner body
148 and an
adjacent surface of the outer body 150). The lockdown tool 146 is shown in
FIG. 10 as
having a test port 184 in the outer body 150 and a fluid conduit 186 through
the inner
body 148. The fluid conduit 186 is provided between two flow ports 162 of the
inner
body 148 and connects the sealed regions between the inboard seals 182 and the
outboard seals 182 so that both of these sealed regions and the conduit 186
are in fluid
communication with the test port 184. This enables pressure testing of the
seals 182 via
the port 184 to verify proper sealing. The casing hanger 34 and thelockdown
tool 146
can be assembled and pressure-tested at a remote facility before being shipped
to a
wellsite for installation in a wellhead housing 60.
[0042] When running the casing hanger 34 and the lockdown tool 146 into the
wellhead housing 60, the stop ring 168 can be positioned in an intermediate
position
between the upper and lower ends of the groove 170, as shown in FIG. 10. After
the
casing hanger 34 is landed within the wellhead housing 60, the outer body 150
can be
rotated with respect to the inner body 148 (e.g., via the landing string 36)
to break the
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shear screw 178 and then release the retaining ring 152 and lock the tool 146
in place, as
shown in FIG. 9. In at least some embodiments, the surfaces 156 and 158 (along
with
the surfaces 84 and 154) are threaded with left-handed threads and the outer
body 150
is rotated clockwise to cause the outer body 150 to travel upward along the
inner
body 148. When rotating the outer body 150 to release the retaining ring 152,
the stop
ring 168 travels with the outer body 150 toward the upper end of the groove
170. With
the lockdown tool 146 secured in the bore of the wellhead housing 60, the well
can be
cemented as described above.
[0043] To remove the lockdown tool 146 from the wellhead housing 60 (e.g.,
once
cement in the well has sufficiently hardened), the outer body 150 is rotated
(counter-
clockwise in the case of left-handed threaded surfaces 156 and 158) to move
the outer
body 150 down along the inner body 148 and retract the retaining ring 152 from
the
groove 108. The outer body 150 can then continue to be rotated down the inner
body 148 until the stop ring 168 retracts inwardly into a recessed portion 190
at the
lower end of the groove 170, as shown in FIG. 11. With the stop ring 168
received in
the recessed portion 190, which can also be referred to as an additional
groove 190, the
outer body 150 can then be rotated in the opposite direction (e.g., clockwise
in the case
of left-handed threaded surfaces 156 and 158). The stop ring 168 in the
recessed
portion 190 causes the inner body 148 to rotate synchronously with the outer
body 150,
allowing the rotation to unthread the inner body 148 from the casing hanger
34. The
disconnected lockdown tool 146 can then be pulled out of the wellhead housing
60.
[0044] Finally, although the various lockdown tools described above can
include
one-piece outer bodies, in at least some embodiments a lockdown tool can
include an
outer body assembled from multiple components. For example, as shown in FIG.
12,
the outer body 150 of the lockdown tool 146 is formed from two components
coupled
together via a threaded interface 192. Set screws 194 can be used to prevent
inadvertent
unthreading of the two components. In some instances, a multi-piece outer body
can
be used for ease of manufacturing.
[0045] While the aspects of the present disclosure may be susceptible to
various
modifications and alternative forms, specific embodiments have been shown by
way of
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example in the drawings and have been described in detail herein. But it
should be
understood that the invention is not intended to be limited to the particular
forms
disclosed. Rather, the invention is to cover all modifications, equivalents,
and
alternatives falling within the spirit and scope of the invention as defined
by the
following appended claims.
