U.S. patent application number 14/396867 was filed with the patent office on 2015-03-26 for casing running tool.
The applicant listed for this patent is McCoy Corporation. Invention is credited to Jonathan Ancelet, Daniel S. Bangert, Vetsouvanh Malathong.
Application Number | 20150083391 14/396867 |
Document ID | / |
Family ID | 49482068 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150083391 |
Kind Code |
A1 |
Bangert; Daniel S. ; et
al. |
March 26, 2015 |
CASING RUNNING TOOL
Abstract
A device is taught for gripping casing joints comprising one or
more first cylinders and one or more second cylinders actuated by a
singular hydraulic system. A second device is taught comprising 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
third device is taught comprising a gripping system, said gripping
system comprising one or more slips received into one or more
inclined recesses. A fourth device is taught comprising one or more
dies supported on one or more said slips by means of mating load
transfer profiles. A fifth device is taught comprising a tubular
guide means. A sixth device is taught comprising an integral fluid
compensator chamber. A seventh device is taught comprising a
hydraulic swivel comprising one or more sealing means having
predictable seal fluid leak rates.
Inventors: |
Bangert; Daniel S.;
(Lafayette, LA) ; Malathong; Vetsouvanh;
(Broussard, LA) ; Ancelet; Jonathan; (Broussard,
LA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
McCoy Corporation |
Edmonton |
|
CA |
|
|
Family ID: |
49482068 |
Appl. No.: |
14/396867 |
Filed: |
April 25, 2013 |
PCT Filed: |
April 25, 2013 |
PCT NO: |
PCT/CA2013/000410 |
371 Date: |
October 24, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61638057 |
Apr 25, 2012 |
|
|
|
Current U.S.
Class: |
166/77.52 ;
166/77.51; 166/77.53 |
Current CPC
Class: |
E21B 17/042 20130101;
E21B 19/10 20130101; E21B 34/02 20130101; E21B 33/0422 20130101;
E21B 19/07 20130101; E21B 17/00 20130101; E21B 19/06 20130101; E21B
17/046 20130101 |
Class at
Publication: |
166/77.52 ;
166/77.53; 166/77.51 |
International
Class: |
E21B 19/06 20060101
E21B019/06; E21B 17/046 20060101 E21B017/046; E21B 17/042 20060101
E21B017/042; E21B 34/02 20060101 E21B034/02; E21B 19/10 20060101
E21B019/10 |
Claims
1. A device for gripping casing joints for making up or breaking
out casing strings comprising one or more hydraulic cylinders
comprising: a) one or more first cylinders to actuate gripping and
releasing of casing joints; and b) one or more second cylinders,
retractable for maintenance and replacement of gripping elements of
the device, wherein said one or more hydraulic cylinders are
actuated by a singular hydraulic system.
2. The device of claim 1, wherein the singular hydraulic system
comprises: a) one or more operation valves to control fluid flow to
extend and retract the one or more first cylinders and to maintain
the one or more second cylinders in an extended position during
casing makeup and break out; and b) one or more maintenance valves,
openable to supply fluid to retract the one or more second
cylinders.
3. The device of claim 1, wherein the one or more first cylinders
are long stroke cylinders and the one or more second cylinders are
short stroke cylinders.
4. The device of claim 3, wherein the one or more first cylinders
are arranged in series with the one or more second cylinders.
5. The device of claim 4, wherein the one or more first cylinders
are located axially below the one or more second cylinders.
6. The device of claim 5, wherein each of the one or more first
cylinders is arranged in a pair with each of the one or more second
cylinders.
7. The device of claim 6, comprising three pairs of a first
cylinder and a second cylinder in series.
8. A device for gripping casing joints for making up or breaking
out casing strings comprising 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 enhance
gripping engagement of the casing.
9. The device of claim 8, wherein the one or more inclined recesses
capture at least a portion of the one or more slips.
10. The device of claim 9, wherein at least an axial portion of
said one or more inclined recesses surrounds greater than 180
degrees of the one or more slips.
11. The device of claim 10, wherein the one or more slips have a
smaller cross section than said one or more inclined recesses.
12. The device of claim 11, wherein rotation of the gripping system
serves to rotate a front face of the one or more slips and to cam a
rear face of the one or more slips against the one or more inclined
recesses.
13. The device of claim 9, wherein one or more recesses have a
cross sectional geometry selected from the group consisting of
partial circles, partial rectangles, partial squares, partial
ovals, partial rhomboids and partial triangles.
14. The device of claim 13, wherein at least a portion of the one
or more inclined recesses have a part cylindrical geometry and at
least a portion of the one or more slips have a corresponding
cylindrical geometry.
15. The device of claim 8, wherein the one or more inclined
recesses are housed in a seat.
16. The device of claim 15, wherein the seat has geometry selected
from conical and cylindrical.
17. The devices of claim 16, wherein the one or more inclined
recesses are uniformly spaced around the seat.
18. A device for gripping casing joints for making up or breaking
out casing strings comprising a gripping system, said gripping
system comprising one or more slips received into one or more
inclined recesses.
19. The device of claim 18, wherein at least a portion of the one
or more slips are captured by the one or more inclined
recesses.
20. The device of claim 19, wherein the one or more recesses
comprise a cross sectional geometry for at least a portion of the
axial length thereof that surrounds greater than 180 degrees of the
one or more slips.
21. The device of claim 18, wherein the one or more slips have a
smaller cross section than said one or more inclined recesses.
22. The device of claim 21, wherein rotation of the gripping system
serves to rotate a front face of the one or more slips and to force
a rear face of the one or more slips against the one or more
inclined recesses.
23. The device of claim 18, wherein one or more recesses have a
cross sectional geometry selected from the group consisting of
partial circles, partial rectangles, partial squares, partial
ovals, partial rhomboids and partial triangles.
24. The device of claim 23, wherein at least a portion of the one
or more inclined recesses have a part cylindrical geometry and at
least a portion of the one or more slips have a corresponding
cylindrical geometry.
25. The device of claim 24, wherein at least a portion of the axial
length of the inclined recess has a cross sectional geometry that
is more than a semi-circle.
26. The device of claim 18, wherein the one or more inclined
recesses are housed in a seat.
27. The device of claim 26, wherein the seat has geometry selected
from conical and cylindrical.
28. The devices of claim 27, wherein the one or more inclined
recesses are uniformly spaced around the seat.
29. A device for gripping casing joints for making up or breaking
out casing strings, said device comprising one or more dies
supported on one or more slips by means of mating axial load
transfer profiles formed on said slips and on each of said
dies.
30. The device of claim 29, wherein the mating axial load transfer
profile comprises a tongue and groove profile.
31. The device of claim 30, wherein the tongue and groove profile
comprises one or more tongues formed on said slip and one or more
grooves formed on each of said dies.
32. A device for gripping casing joints for making up or breaking
out casing strings, said device comprising a tubular guide
extending from a lower end of the device to receive and center the
casing joint into a central bore of the device.
33. A device for making up or breaking out casing strings
comprising an integral fluid compensator chamber.
34. The device of claim 33, wherein the integral fluid compensator
chamber is defined by one or more fixed walls and one or more
movable walls.
35. The device of claim 34, wherein the integral fluid compensator
chamber is expandable and contractible to compensate for axial
movement during casing make up or casing break out.
36. The device of claim 35, wherein the integral fluid compensator
chamber is a pneumatic compensator chamber.
37. The device of claim 36, wherein the integral fluid compensator
chamber is a hydraulic compensator chamber.
38. A device for making up or breaking out casing strings
comprising a hydraulic swivel to house fluids for hydraulic
actuation of the device, wherein said hydraulic swivel comprises
one or more sealing means having predictable and controllable seal
fluid leak rates.
Description
FIELD OF THE INVENTION
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] A reverse procedure is practiced for breaking out casing
joints from a casing string.
[0006] 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.
[0007] 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
[0008] A first device is taught for gripping casing joints for
making up or breaking out casing strings comprising one or more
hydraulic cylinders. The one or more hydraulic cylinders comprise
one or more first cylinders to actuate gripping and releasing of
casing joints and one or more second cylinders, retractable for
maintenance and replacement of gripping elements of the device,
wherein said one or more hydraulic cylinders are actuated by a
singular hydraulic system.
[0009] A second 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.
[0010] A third 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.
[0011] A fourth device is taught for gripping casing joints for
making up or breaking out casing strings. The device comprises one
or more dies supported on one or more slips by means of mating
axial load transfer profiles formed on said slips and on each of
said dies.
[0012] A fifth device is taught for gripping casing joints for
making up or breaking out casing strings, said device comprising a
tubular guide extending from a lower end of the device to receive
and center the casing joint into a central bore of the device.
[0013] A sixth device is taught for making up or breaking out
casing strings comprising an integral fluid compensator
chamber.
[0014] A seventh device for making up or breaking out casing
strings comprising a hydraulic swivel to house fluids for hydraulic
actuation of the device, wherein said hydraulic swivel comprises
one or more sealing means having predictable and controllable seal
fluid leak rates.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will now be described in greater
detail, with reference to the following drawings, in which:
[0016] FIG. 1a is a first isometric view of one example of the
casing running tool and related devices of the present
invention;
[0017] FIG. 1b is a second isometric view of one example of the
casing running tool and related devices of the present
invention;
[0018] FIG. 2a is a first cross-sectional elevation view of one
example of the casing running tool of the present invention;
[0019] FIG. 2b is a second cross-sectional elevation view of one
example of the casing running tool of the present invention;
[0020] FIG. 2c is a detailed cross-sectional elevation view of one
example of a tubular guide of the casing running tool of the
present invention;
[0021] FIG. 3a is a cross-sectional elevation view of the present
invention, showing short and long stroke cylinders in an extended
position;
[0022] FIG. 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;
[0023] FIG. 3c is a cross-sectional elevation view of the present
invention, showing short and long stroke cylinders in a retracted
position;
[0024] FIG. 4 is a schematic diagram of one example of the
hydraulic system for the gripping members of the present
invention;
[0025] FIG. 5a is an isometric view of a part of the gripping
members of the present invention;
[0026] FIG. 5b is an isometric view of further parts of gripping
members of the present invention;
[0027] FIG. 5c is an isometric view of further parts of gripping
members of the present invention;
[0028] FIG. 5d is an isometric view of yet further parts of
gripping members of the present invention; and
[0029] FIG. 5e is a top plan view of one embodiment of the present
gripping members
DESCRIPTION OF THE INVENTION
[0030] 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.
[0031] With reference to FIGS. 1a, 1b, 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.
[0032] As seen in FIG. 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.
[0033] 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. 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.
[0034] 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.
[0035] 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.
[0036] 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 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.
[0037] 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.
[0038] 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.
[0039] The CRT 2 of the present invention is shown in more detail
in cross sectional FIGS. 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.
[0040] 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
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.
[0041] 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.
FIG. 3a illustrates the lower long stroke cylinders 24 in an
extended position to set the casing gripping members. FIG. 3b shows
the lower long stroke cylinders 24 in a retracted position to
release casing gripping members and FIG. 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.
[0042] The one or more first and second cylinders are most
preferably actuated by a singular hydraulic system, represented in
the schematic diagram of FIG. 4, which allows control of both first
and second cylinders using only a single pair of hydraulic lines.
Referencing FIG. 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 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.
[0043] 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.
[0044] 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.
[0045] As seen in FIGS. 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.
[0046] 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.
[0047] 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 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.
[0048] 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.
[0049] Radial inward movement of the slips 18 and dies 20 to grip
the casing can be seen in FIGS. 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.
[0050] 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.
[0051] 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 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.
[0052] 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.
[0053] Preferably, the inclined recesses 90 are uniformly spaced
around the seat 16. Most preferably, the inclined recesses 90 are
arranged in diametrically opposing pairs.
[0054] The dies 20 of the present invention are illustrated in a
preferred embodiment in FIGS. 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
FIGS. 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.
[0055] 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.
[0056] 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 11/4'' (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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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 spirit and scope of the
invention.
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