Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Slip Assembly for Casing Running Tool
The present application is a divisional of Canadian Patent Application Serial
No.
2,871,095.
Field of the Invention
The present invention relates to a device and a system for lifting, lowering
and
rotating casing joints to make up and break out casing strings.
Background
In down-hole drilling and extraction processes, casing, also called tubulars
or
piping, is run down the wellbore for the purposes of drilling, performing
operations or
producing oil from the well. Casing is made up by connecting multiple threaded
casing
sections together and feeding them into the wellbore. Typically, casing
sections have a
tapered female thread at one end and a tapered male thread at the other end.
The
male end of a second casing section is threaded into the female end of a first
casing
section to makeup the casing string. Certain casings are equipped with what
are often
referred to as premium grade connections. Rotation of the first casing into
the second
casing is conducted until the tapered ends engage one another at the shoulder
point. A
metal-to-metal seal is thus formed by engagement of the two threaded casing
sections.
A typical procedure for making up casing strings involves first connecting a
single
joint elevator assembly, casing running tool (CRT) and other related devices
to a top
drive system. The entire assembly is then lowered to the rig floor and the
single joint
elevator assembly picks up a new joint of casing to be made up. The assembly
is raised
to raise the casing joint into position below the CRT and above a casing
string to be
made up, the casing string being gripped in place by a flush mount spider or
similar
device. The entire assembly is then lowered so that the male thread of the
casing joint
is engaged with the female thread of the uppermost casing of the casing string
and the
CRT rotatably grips the casing joint, either internally or externally.
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The top drive is rotated to make up the threads between the new casing joint
and
the uppermost casing of the casing string. The CRT's gripping mechanism grips
the new
casing joint and transfers the weight of the newly made up connection from the
flush
mount spider, so that the spider can be released. The CRT assembly then lowers
the
newly made up connection to the rig floor where the spider grips an upper end
of the
newly made up casing section of the casing string. The single joint elevator
assembly is
then released and is prepared to pick up the next casing joint to be made up.
The CRT
gripping mechanism is released from the casing joint and the top drive, CRT
and single
joint elevator assembly, now carrying a new joint to be installed in the
string, are lifted
into position for the 'next make up.
A reverse procedure is practiced for breaking out casing joints from a casing
string.
Casing running tools conduct a number of complex operations and are typically
made up of numerous moving and working parts. The casing running tool must be
able
to carry large loads while rotationally gripping the casing joint to be made
up. It also
provides a hydraulic seal between the casing and the top drive to enable the
circulation
of fluids. It must be easily operated and controlled and rapidly maintainable
during
wellbore operations.
A constant need and interest therefore exists in the art to develop improved
casing running tool devices and methods for making up casing strings.
Summary
A device is taught for gripping casing joints for making up or breaking out
casing
strings. The device comprises a gripping system, said gripping system
comprising one or
more slips cammed against one or more inclined recesses when the gripping
system is
rotated to maintain gripping engagement of the casing.
A further device is taught for gripping casing joints for making up or
breaking out
casing strings. The device comprises a gripping system, said gripping system
comprising
one or more slips received into one or more inclined recesses.
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Brief Description of the Drawings
The present invention will now be described in greater detail, with reference
to the
following drawings, in which:
Figure la is a first isometric view of one example of the casing running tool
and related
devices of the present invention;
Figure 1b is a second isometric view of one example of the casing running tool
and
related devices of the present invention;
Figure 2a is a first cross-sectional elevation view of one example of the
casing running
tool of the present invention;
Figure 2b is a second cross-sectional elevation view of one example of the
casing
running tool of the present invention;
Figure 2c is a detailed cross-sectional elevation view of one example of a
tubular guide
of the casing running tool of the present invention;
Figure 3a is a cross-sectional elevation view of the present invention,
showing short and
long stroke cylinders in an extended position;
Figure 3b is a cross-sectional elevation view of the present invention,
showing short
stroke cylinders in a retracted position and long stroke cylinders in an
extended
position;
Figure 3c is a cross-sectiohal elevation view of the present invention,
showing short and
long stroke cylinders in a retracted position;
Figure 4 is a schematic diagram of one example of the hydraulic system for the
gripping
members of the present invention;
Figure 5a is an isometric view of a part of the gripping members of the
present
invention;
Figure 5b is an isometric view of further parts of gripping members of the
present
invention;
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Figure 5c is an isometric view of further parts of gripping members of the
present
invention;
Figure 5d is an isometric view of yet further parts of gripping members of the
present
invention; and
Figure 5e is a top plan view of one embodiment of the present gripping members
Description of the Invention
The present invention relates to a device and system for making up casing
strings. The present invention more specifically relates to a casing running
tool (CRT)
that connects directly or indirectly to a top drive on a drilling rig.
With reference to Figures la, lb, 2a and 2b the present CRT 2 can preferably
be
used in association with a single joint elevator assembly 4 to pick up casing
joints 10
from the rig floor. An upper end 6 of the CRT 2 may be connected or indirectly
to the
top drive (not shown). In one embodiment the CRT 2 may be connected to the top
drive
by means of a sub that rotates with the top drive and the CRT 2. A lower end 8
of the
CRT 2 is configured to include a gripping system 14 to grip a casing section
or joint 10, to
thereby transfer top drive torque to makeup or breakout a casing connection at
the rig
floor level.
As seen in Figure 2 c, the lower end 8 preferably comprises a tubular guide 96
that acts to center and align the casing section 10 as it is fed into the
gripping system 14.
This ensures that the casing section is fed into a central bore of the
gripping system 14,
and prevents the casing section 10 from striking potential sensitive elements
within the
griping system 14.
The single joint elevator assembly 4 of the present invention comprises a
single
joint assembly frame 60 that is supported on the sub or on an upper end of the
CRT 2 in
a rotatable fashion such that the CRT 2 is allowed to rotate while the single
joint
assembly frame 60 remains stationary. In a further preferred embodiment, the
single
joint assembly frame 60 is attached to the CRT 2 by means of a ball bearing
connection
between the CRT 2 and one or more plates of the single joint assembly frame
60.
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Further preferably, the single joint assembly frame 60 may additionally be
attached for
non-rotation to a non-rotational part of the top drive by attachments 82 to
relieve any
dynamic friction that may build up between the CRT 2 and the single joint
assembly
frame 60 and to prevent rotation of the single joint assembly frame 60 due to
such
dynamic friction. Although the single joint assembly frame 60 is preferably
shown as
having the form of a rectilinear frame in the figures, it would be well
understood by
those skilled in the art that other structures are also possible and
encompassed by the
scope of the present invention.
One or more link tilt arms 62 are pivotably connected to the single joint
assembly frame 60 at an upper end thereof. A lower end of the one or more link
tilt
arms 62 are connected to a single joint elevator 80 for grasping a casing
joint 10 to be
made up on a casing string. The link tilt arms 62 are actuated to move about
pivot pin
66 by means of a pair of link arm cylinders 68 that swing the elevator
assembly 4 out to
grasp a casing joint 10 and swing the casing joint 10 back into position below
the CRT 2
and above a casing string at the rig floor. It would be well understood by a
person of skill
in the art that a single link tilt arm 62 or more than one link tilt arm 62
can be possible
and such embodiments are included within the scope or the present invention.
Should
more than more than one link tilt arms 62 be used, the multiple link tilt arms
62 are
connected at their upper ends to one or more sides of the single joint
assembly frame
60.
Alternative to using a single joint elevator assembly 4, it is also possible
to use a
pair of parallel arms that are pivotably suspended at a first end from a non-
rotational
portion of the top drive. The second end of the parallel arms can be fixed
with a device
that allows the parallel arms to pick up casing joints and lower the casing
joints below
the CRT 2 and over a casing string to be made up.
The CRT further comprises a swivel 72 that houses fluids for hydraulic
actuation
of the CRT 2. An outer shell 74 of the swivel 72 is prevented against rotation
by being
attached to the single joint assembly frame 60 and optionally also by being
attached to
non-rotational parts of the top drive. This allows the outer shell 74 of the
swivel 72 to
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connect to hosing and tubing supplying hydraulic fluids to the swivel 72. The
swivel 72
acts to transfer fluid pressure from the hydraulic hoses to the CRT 2. In a
further
preferred embodiment, the present swivel 72 incorporates the use of either
seals with a
predictable leak rate or controlled gap seals with a defined leak rate to
provide
lubrication to the seals of the swivel 72. These seals leak at a controlled
rate, without
failing.
The CRT's gripping system 14 allows the top drive to hold the weight of the
newly added casing joint 10 as well as the weight of the casing string
suspended below it
and then reposition the casing string for subsequent casing sections to be
made up.
When the casing joint 10 is initially picked up, an extended stinger, also
called a
circulating and fill-up tool (CFT) 76 is positioned inside of the casing
section 10 to seal
off the inside diameter of the casing section 10 and allow circulation of
fluids to occur
while controlling back flow of fluids from the wellbore. CFT's are
commercially available
and well known in the art and any number of varieties of such devices can be
used with
the present invention without departing from the scope thereof.
The CRT 2 can optionally provide push down weight in combination with
simultaneous rotation and circulation, in the case of "drilling with casing"
operations or
to assist in lowering the casing string to a desired depth in a deviated
wellbore.
The CRT 2 of the present invention is shown in more detail in cross sectional
Figures 3a, 3b and 3c. The CRT 2 comprises a casing gripping system 14
preferably
comprising a machined seat 16, one or more slips 18 slidingly received in said
seat 16,
and one or more dies 20 supported on the slips 18. Although the figures
illustrate three
dies 20 per slip 18, it would be well known to a person skilled in the art
that one or any
number of dies 20 may be supported on each slip 18 and that there may be any
number
of slips 18 received in the seat 16, without departing from the scope of the
present
invention.
One or more cylinders preferably actuate setting and releasing of the casing
gripping system on the casing sections 10. One or more first cylinders 24
extend to set
one or more casing gripping members and retract to release said casing
gripping
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members during casing make up or break out. One or more second cylinders 22
are
maintained in an extended position during casing make up or break out and are
retracted for maintenance or replacement of said gripping members.
Preferably, the one or more first cylinders 24 are long stroke cylinders and
the
one or more second cylinders 22 are short stroke cylinders. Further
preferably, the one
or more first cylinders 24 and one or more second cylinders 22 are mounted in
series.
More preferably, the second short stroke cylinders 22 are located axially
above the first
long stroke cylinders 24. First long stroke cylinders 24 extend to set casing
gripping
members and retract to release casing gripping members during casing make up
or
break out, thereby providing fast set and release response without the need
for
mechanical stops or detents. The second short stroke cylinders 22 are
maintained in an
extended position during casing make up or break out operations and can be
retracted
to allow access to the slips 18 and dies 20 for maintenance or replacement.
Figure 3a
illustrates the lower long stroke cylinders 24 in an extended position to set
the casing
gripping members. Figure 3b shows the lower long stroke cylinders 24 in a
retracted
position to release casing gripping members and Figure 3c illustrates both the
short
stroke cylinder 22 and the long stroke cylinder 24 in a retracted position, to
allow access
to the casing gripping members for maintenance and repair. More preferably,
each of
the one or more first cylinders is arranged in a pair with each of the one or
more second
cylinders. Most preferably three pairs comprising a first cylinder and a
second cylinder in
series are used.
The one or more first and second cylinders are most preferably actuated by a
singular hydraulic system, represented in the schematic diagram of Figure 4,
which
allows control of both first and second cylinders using only a single pair of
hydraulic
lines. Referencing Figure 4, the circuitry of the short stroke cylinders 22 is
tied into the
circuitry of the long stroke cylinders 24 by means of one or more operation
valves 26
that supply fluid to keep the short stroke cylinders 22 in an extended
position. The one
or more operation valves 26 are preferably in the form of pilot operated
control valves
(POCV) 26. When required, one or more maintenance valves 28 are opened to
supply
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fluid to the short stroke cylinders 22 to thereby close them. The one or more
maintenance valves may be either a manual valve or a control valve.
The seat 16 of the casing gripping system 14 of the present casing running
tool 2
preferably comprises an array of one or more separate inclined elements 30 for
receiving slips 18.
In a further preferred embodiment, the inclined elements 30 comprise one or
more integral or non-integral means of laterally retaining the slips 18 in the
inclined
elements 30, in such a way that the slips 18 are prevented from falling or
tipping
towards a central bore of the casing gripping system 14. Examples of non-
integral
retaining means include but are not limited to strips, plates, clips, cages,
bars, tabs and
rings that can be removably attached to at least a portion of the slip 18 and
at least a
portion of the seat 16 to laterally retain the slip 18 to the inclined element
30. Integral
retaining means can include but are not limited to mating profiles on at least
a portion
of the slip 18 and on at least a portion of the inclined elements 30 that
connect to hold
the slip 18 to the inclined element 30; such mating profiles can include
shiplap profiles,
tongue-and-groove profiles, dovetail profiles or other profiles well known in
the art.
As seen in Figures 5a and 5b, the inclined elements 30 can more preferably be
in
the form of an array of one or more inclined recesses 90 that correspond to a
rear face
32 of the slips 18, thereby generating radially inward movement of the slips
18 to grip
the casing joint 10 as the slips 18 slide into inclined recesses 90, without
the need for
separate tracks, cam followers, springs or other means.
Preferably, the inclined recesses 90 have a cylindrical geometry and part-
circular
cross section to match a cylindrical geometry and part circular cross section
of the slips
18. It is also possible for the inclined recesses 90 and slips 18 to have
cross sections that
are partial rectangles, partial squares, partial ovals, partial rhomboids and
partial
triangles or other cross-sectional geometries.
In a preferred embodiment, the inclined recesses 90 can comprise an integral
retaining means along at least a portion of the axial length of the inclined
recess 90. In
one example, at least a portion of longitudinal edges 92 of the inclined
recesses 90
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comprise an integral throat, tab or strip that act to restrict the size of the
mouth 94 of
the inclined recess 90,to thereby capture slips 18 and laterally retain slips
18 from falling
or tipping into the central bore of the seat 16.
In a further preferred embodiment, the inclined recesses 90 are machined to a
cross sectional geometry that restricts the mouth 94 of the inclined recesses
90 to be
smaller than the widest cross section of the slip 18. In this embodiment the
recesses 90
function to partially circumferentially capture the slips 18. To effect this
embodiment,
at least a portion of the axial length of the inclined recesses 90 is machined
such that
the desired cross sectional geometry converges to restrict mouth 94. In the
preferred
case of a partial circle cross-section, at least a portion of the axial length
of the inclined
recess 90 is formed as more than half of a circle, otherwise put, more than a
semi-circle,
to provide a restriction to mouth 94 such that the slip 18 cannot fall into
the central
bore of the seat 16.
Radial inward movement of the slips 18 and dies 20 to grip the casing can be
seen in Figures 3a and 3b; as the slips 18 move axially downwardly in the
inclined
recesses 30 of the seat 16. Most preferably, the inclined elements 30 are
uniformly
spaced around the seat 16.
In a preferred embodiment of the present invention, the slips 18 and the
recesses 90 interact in such a way as to enhance gripping forces on the casing
section 10
during rotation. In a preferred embodiment, the slips 18 are caused to cam or
wedge
into the recesses 90 to thereby maintain a firm penetration of the dies 20 in
the slips 18
and a firm grip of the outer surface of the casing section 10 by the dies 20
during casing
make up or break out operations.
Most preferably slips 18 are nominally smaller in cross section than inclined
recesses 90. When the slips 18 and dies 20 of the present gripping system 14
are set on
the casing section 10 to be made up, the top drive is rotated to rotate
gripping system
14. During rotation, gripping torque causes the slightly smaller slip 18 to
advantageously rotate slightly. This results in a line of force in which the
dies 20 are
forced into a front face 36 of the slips 18, in turn forcing a rear face 32 of
the slip to cam
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into and against the inclined recesses 90. This serves to further frictionally
arrest the
dies 20 into the slips 18, and the slips 18 into the inclined recesses 90, and
thereby
enhances frictional engagement of the dies to the casing section 10 during
make up and
break out operations.
Although present seat 16 is preferably shown as having a conical form, it
would
be well understood by a person of skill in the art that numerous alternative
forms of
seats 16 are possible that would cause the slips 18 to bias radially inwardly
as they move
axially down the seat 16. For example, the seat 16 may alternatively have a
cylindrical
form comprised of one or more inclined elements 30.
Preferably, the inclined recesses 90 are uniformly spaced around the seat 16.
Most preferably, the inclined recesses 90 are arranged in diametrically
opposing pairs.
The dies 20 of the present invention are illustrated in a preferred embodiment
in
Figures 5b and 5c. Most preferably each slip 18 comprises three dies 20
arranged
axially along the slip 18. Support means are provided to support the dies 20
on the slips
18. A most preferred embodiment of dies 20 and slips 18 is depicted in Figures
5c and
5d, in which independent axial load transfer keys or tongues 34 are formed on
a front
face 36 of the slip 18 that are received in corresponding load transfer
grooves 38
formed on a rear face 40 of the dies 20. A front face 42 of the dies 20 can
have any
number of profiles and gripping surfaces well known in the art to engage and
grip a
range of casing joint diameters. The profile may be concave or may be any
suitable
profile to capture a tubular member when the die 20 comes in contact with such
member. Examples of such profiles are well known in the art and would be
understood
by a skilled practitioner to be included in the scope of the present
invention. If concave,
the profile of the front face 42 of the dies 20 may preferably have a singular
radius of
curvature, or a compound radial profile comprising one or more profile
sections each
having the same or different radii of curvature with either the same or
different centers.
The surface of the front face 42 of the die 20 may be smooth or may be
textured,
scored, etched or ridged to provide further gripping of the casing joint 10.
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During casing make up operations and also in the cases of 'drilling with
casing'
and horizontal wellbore operations, significant downwards forces are required
to
counteract any upwards pressure experience by the casing string from wellbore
fluids or
from friction as the casing string is drilled into the wellbore. The operator
may use a
variety of methods, including circulation of drilling fluids in combination
with rotation
and/or reciprocation to reduce the friction and counteract these forces. The
operator
may also augment the weight of the casing string with a portion of the top
drive weight
to push down through the CRT 2. The present CRT 2 is preferably rated for
circulation
and fill-up pressures to approximately 5000 psi (34,474 kPa) and rotation at
speeds of
100 rpm. Up to 30,000 lbs of compressive force (133 kN) or top drive weight
can also be
transferred through the present CRT 2 into the casings being run into the
wellbore.
The top drive rotates to makeup the threads between the new casing joint 10
and
last casing joint of the casing string. In some cases as many as 10 turns are
needed to
fully makeup the connection. For a common thread density of 8 threads per inch
(3.15
threads per cm), 10 turns will consume 1 1/4" (3.2 cm) of thread, also known
as thread
loss. Thus, make up operations tend to shorten the distance between the casing
string
that is held in place typically by a flush mount spider or similar device, and
the casing
joint 10 that is gripped by and the CRT 2.
To avoid very high tensile loads on the string from thread loss, it is
possible for the
operator to attempt to compensate for thread loss by lowering the top drive.
However,
it is extremely difficult to lower the top drive in such small increments
without risking
too much top drive weight being set down and damaging the partially made-up
threads.
The present CRT 2 preferably incorporates a fluid compensator in the form of a
chamber 48 integral to the CRT 2, comprising one or more movable walls and one
or
more fixed walls. The fluid compensator provides a controlled spring-like
action that
allows a portion of the present CRT 2 to travel downward at a distance
proportional to
the thread loss to prevent high axial tension forces during casing make up.
The fluid
chamber 48 eliminates the need to move the top drive to compensate for thread
loss.
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More preferably, the fluid compensator is a hydraulic or pneumatic compensator
in
the form of an integral chamber 48 formed in the CRT 2, and most preferably it
is a
pneumatic chamber 48. More preferably, the pneumatic chamber 48 is defined by
an
upper fixed plate 50 and a lower movable piston 52. Most preferably the lower
movable piston 52 is a lower end of a central CRT mandrel. If necessary to
breakout a
connection, the fluid compensator 48 offsets the weight of the joint being
broken out
plus the weight of the lower end of the CRT 2. The integral pneumatic
compensator 48
opens during breakout to avoid developing the high axial compression forces
that would
occur if all components were fixed vertically.
In a typical make up operation, the present CRT 2, together with a CFT, an
elevator
assembly 4 and other optional devices are raised to the rig floor where they
are
attached to a threaded lower end of the top drive. The top drive is then
lowered to a
position near the rig floor while the link tilt arm 62 is pivoted outward in
preparation for
picking up a new section of casing that has been raised from a pipe rack
adjacent to the
rig. The casing section 10 is presented on the rig floor at a location and
angle that
allows the single joint elevator 80 to grip the new casing section.
The top drive is raised to thereby pull the casing joint 10 up and along the
rig's v-
door ramp until it swings into a vertical position directly below the CRT 2,
the motion
being regulated by a pressure relief valve. The top drive then is raised until
the new
casing joint 10 is positioned above the existing casing string, set in a flush
mount spider
or similar device at the rig floor.
The top drive is lowered to allow the male thread of the casing joint 10 to
engage
the female thread of the uppermost casing of the casing string. The top drive
continues
to be lowered to engage the CFT with an upper end of the new casing joint 10.
The CRT
2 gripping system 14 engages an outer diameter of the new casing joint 10.
Once
engaged by the CFT and CRT 2 and positioned over the existing casing string,
the
gripping system 14 of the CRT 2 is set on the new casing joint 10.
The top drive is slowly rotated to makeup the threads between the new casing
joint 10 and the uppermost casing of the casing string, set in a flush mount
spider or
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similar device. After one or two turns, the speed may be increased to a
typical 10 to 20
rpm to spin-in the remaining threads. As the connection makes-up, the torque
rises
and the operator may slow down the rotation to 2 to 5 rpm for the final turns
required
to reach full makeup torque. The present CRT 2 preferably can transmit right-
hand or
left-hand torque of up to 35,000 ft lbs (47.5 kN m). As described above in a
most
preferred embodiment, configuration of the slips 18 and inclined recesses 90
of the
present gripping system 14 serve to laterally retain and lock the slips 18
into the inclined
recesses during torqueing. This serves to add mechanical strength to retain
the gripping
elements 14 in a set position during torqueing. This in turn alleviates at
least some of
the pressure on cylinders 24 as they extend to set the slips and lessens wear
of the
hydraulic swivel.
At this point, a rig pump can be engaged to fill the casing string with
drilling fluid.
Overflow is prevented by engagement of the CFT inside of the new casing joint
10.
Once made up, the top drive is raised. The CRT's gripping system 14 continues
to
grip the casing joint 10 and transfers the lifting force into the newly made
up connection
at the rig floor. As the top drive continues to be raised, the weight of the
entire casing
string, previously supported by a flush mount spider or similar device, is now
transferred
to the top drive and CRT 2. The weight can be very significant for deep wells
requiring
large diameter, thick walled casing goods. Additionally, in wells that are
deviated, the
frictional drag in the wellbore adds to this lifting load. The present CRT 2
is preferably
rated to lift loads to about 315 tonnes or 700,000 lbs.
Once the flush mount spider or similar device has been relieved of the casing
string
load, it can be released and opened to lower the newly connected casing into
the well
bore until the uppermost casing of the casing string reaches the rig floor.
The elevator
assembly 4 can either be remotely or locally released, allowing the elevator
assembly's
tilt arm 68 to pivot outward and upward to prepare to pick-up a new joint of
casing.
In the foregoing specification, the invention has been described with a
specific
embodiment thereof; however, it will be evident that various modifications and
changes
may be made thereto without departing from the broader scope of the invention.
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