U.S. patent application number 11/060660 was filed with the patent office on 2006-08-17 for co-linear tensioner and methods of installing and removing same.
This patent application is currently assigned to Control Flow Inc.. Invention is credited to Richard D. Williams.
Application Number | 20060180314 11/060660 |
Document ID | / |
Family ID | 36814490 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060180314 |
Kind Code |
A1 |
Williams; Richard D. |
August 17, 2006 |
Co-linear tensioner and methods of installing and removing same
Abstract
The invention is directed to a tensioner for providing linear
and angular movement of a drilling or production facility relative
to a conduit or riser secured to the tensioner and to the wellhead
in offshore operations. The tensioner compensates for vessel motion
induced by wave action and heave and maintains a variable tension
to the riser string alleviating the potential for compression and
thus buckling or failure of the riser string. The tensioner of the
present invention preferably includes at least one top load plate
that facilitates easy and quick installation and removal of the
tensioner from the rig floor of the vessel or platform. The
tensioner also facilitates the placement of at least one piece of
equipment disposed within the area formed by the tensioning
cylinders. The tensioner may also include one or more pieces of
equipment, e.g., a rotary table, integrally formed with the
tensioner to further increase the ease and speed of installation
and removal of the tensioner from the rig floor. Methods for
installing and removing tensioners from the rig floor are also
disclosed.
Inventors: |
Williams; Richard D.; (Sugar
Land, TX) |
Correspondence
Address: |
ANTHONY F. MATHENY;BRACEWELL & GIULIANI LLP
711 LOUISIANA STREET
SUITE 2300
HOUSTON
TX
77002
US
|
Assignee: |
Control Flow Inc.
|
Family ID: |
36814490 |
Appl. No.: |
11/060660 |
Filed: |
February 17, 2005 |
Current U.S.
Class: |
166/355 |
Current CPC
Class: |
E21B 19/006
20130101 |
Class at
Publication: |
166/355 |
International
Class: |
E21B 33/038 20060101
E21B033/038 |
Claims
1-19. (canceled)
20. A tensioner comprising: at least one top load plate having at
least one blow-out preventer formed integral with the at least one
top load plate, at least one upper swivel assembly, at least one
tensioning cylinder plate, at least one tensioning cylinder, and a
base, the at least one tensioning cylinder being in communication
with the at least one tensioning cylinder plate and with the base;
wherein the at least one top load plate, the at least one upper
swivel assembly, the at least one tensioning cylinder plate, the at
least one tensioning cylinder, and the base are assembled to form a
unitary, co-linear tensioner.
21. The tensioner of claim 20, wherein the base is in communication
with at least one extension rod and at least one extension
platform.
22. The tensioner of claim 21, wherein at least one piece of
equipment is disposed on the extension platform.
23. The tensioner of claim 22, wherein the at least one piece of
equipment includes at least one blowout preventer.
24. The tensioner of claim 20, wherein each of the at least one
tensioning cylinders includes a tensioning cylinder casing having a
length and at least one fluid control port.
25. The tensioner of claim 24, wherein each of the at least one
fluid control ports is disposed along the length of each of the
tensioning cylinder.
26. The tensioner of claim 24, wherein at least one of the at least
one fluid control ports is disposed along the length of each of the
tensioning cylinders.
27. A tensioner comprising: at least one top load plate having at
least one rotary table formed integral with the at least one top
load plate, at least one upper swivel assembly, at least one
tensioning cylinder plate, at least one tensioning cylinder, and a
base, the at least one tensioning cylinder being in communication
with the at least one tensioning cylinder plate and with the base;
wherein the at least one top load plate, the at least one upper
swivel assembly, the at least one tensioning cylinder plate, the at
least one tensioning cylinder, and the base are assembled to form a
unitary, co-linear tensioner.
28. The tensioner of claim 27, wherein the base is in communication
with at least one extension rod and at least one extension
platform.
29. The tensioner of claim 28, wherein at least one piece of
equipment is disposed on the extension platform.
30. The tensioner of claim 29, wherein the at least one piece of
equipment includes at least one blowout preventer.
31. The tensioner of claim 27, wherein each of the at least one
tensioning cylinders includes a tensioning cylinder casing having a
length and at least one fluid control port.
32. The tensioner of claim 31, wherein each of the at least one
fluid control ports is disposed along the length of each of the
tensioning cylinder.
33. The tensioner of claim 31, wherein at least one of the at least
one fluid control ports is disposed along the length of each of the
tensioning cylinders.
34. A tensioner comprising: at least one top load plate having at
least one snubbing unit formed integral with the at least one top
load plate, at least one upper swivel assembly, at least one
tensioning cylinder plate, at least one tensioning cylinder, and a
base, the at least one tensioning cylinder being in communication
with the at least one tensioning cylinder plate and with the base;
wherein the at least one top load plate, the at least one upper
swivel assembly, the at least one tensioning cylinder plate, the at
least one tensioning cylinder, and the base are assembled to form a
unitary, co-linear tensioner.
35. The tensioner of claim 34, wherein the base is in communication
with at least one extension rod and at least one extension
platform.
36. The tensioner of claim 35, wherein at least one piece of
equipment is disposed on the extension platform.
37. The tensioner of claim 36, wherein the at least one piece of
equipment includes at least one blowout preventer.
38. The tensioner of claim 34, wherein each of the at least one
tensioning cylinders includes a tensioning cylinder casing having a
length and at least one fluid control port.
39. The tensioner of claim 38, wherein each of the at least one
fluid control ports is disposed along the length of each of the
tensioning cylinder.
40. The tensioner of claim 38, wherein at least one of the at least
one fluid control ports is disposed along the length of each of the
tensioning cylinders.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to offshore drilling and production
operations and is specifically directed to drilling and production
tensioners and methods for installing and removing drilling and
production tensioners.
[0003] 2. Description of Related Art
[0004] A marine riser system is employed to provide a conduit from
a floating vessel at the water surface to the blowout preventer
stack or, production tree, which is connected to the wellhead at
the sea floor. A tensioning system is utilized to maintain a
variable tension to the riser string alleviating the potential for
compression and in turn buckling or failure.
[0005] Historically, conventional riser tensioner systems have
consisted of both single and dual cylinder assemblies with a fixed
cable sheave at one end of the cylinder and a movable cable sheave
attached to the rod end of the cylinder. The assembly is then
mounted in a position on the vessel to allow convenient routing of
wire rope which is connected to a point at the fixed end and strung
over the movable sheaves. A hydro/pneumatic system consisting of
high pressure air over hydraulic fluid applied to the cylinder
forces the rod and in turn the rod end sheave to stroke out thereby
tensioning the wire rope and in turn the riser.
[0006] Other prior tensioners require superstructure that restricts
to the top or the bottom of the tensioner the location of workover
equipment and other devices that are placed in-line with the
drilling or production string. These conventional type tensioning
systems have required high maintenance during normal operations due
to the constant motion producing wear and degradation of the wire
rope members. Replacing the active working sections of the wire
rope by slipping and cutting raises safety concerns for personnel
and has not proven cost effective. In addition, available space for
installation and, the structure necessary to support the units
including weight and loads imposed, particularly in deep water
applications where the tension necessary requires additional
tensioners poses difficult problems for system configurations for
both new vessel designs and upgrading existing vessel designs.
[0007] Other problems unaddressed by these prior tensioners include
the location of workover and other equipment placed in-line with
the production or drill string and the high cost, labor, and
increased safety concerns posed with the installation and removal
of these tensioners.
[0008] The tensioner system of the present invention is an
improvement over existing conventional and direct acting tensioning
systems. Beyond the normal operational application to provide a
means to apply variable tension to the riser, the system provides a
number of enhancements and options including vessel configuration
and its operational criteria. The tensioners of the invention may
include additional equipment or components to facilitate quick and
efficient installation and removal of the additional equipment
along with the tensioner. For example, workover equipment such as
workover units and snubbing units, may be disposed within the area
formed by the tensioning cylinders. Additionally, a rotary table
may be formed as part of the tensioner such that instead of
removing the rotary table, inserting the tensioner, and replacing
the rotary table, the tensioner can be installed with the rotary
table already secured to the tensioner. Because of this novel
design, the rotary table beams which support the rotary table may
be moved to create a larger opening for larger tensioners. The
larger opening also provides flexibility in the location of the
tensioning cylinders to facilitate placement of other equipment,
e.g., workover equipment.
[0009] Therefore, the tensioner and the methods of the present
invention provide the advantages of: providing relatively quicker
and safer installation of tensioners and other equipment; providing
flexibility in location of equipment in fluid communication with
the tensioners; eliminating offset and the resulting unequal
loading in the event one or more of the tensioning cylinders fail;
providing a system that is modular in construction, transportation,
and assembly; providing interchangeability with other drilling or
production facilities; reducing the amount of time that the
wellhead is "idle," i.e., that either a drilling riser or
production riser is out of use by facilitating quick and easy
installation of the tensioner, rotary table, and workover
equipment; providing sufficient tension to the long string of the
riser in deepwater over extended periods of time; providing a means
to maintain the riser in constant tension, with, if necessary,
overpull, while the riser is in service; providing the capability
to accommodate angular offset between the riser and the vessel
induced by vessel motion; and providing the capability to
accommodate axial torque induced in the riser string in the event
the drilling or production vessel rotates around the wellhead due
to weather and sea conditions.
SUMMARY OF INVENTION
[0010] The foregoing advantages have been obtained through the
present tensioner comprising: at least one top load plate; at least
one upper swivel member in communication with the at least one top
load plate; at least one cylinder plate in communication with the
at least one upper swivel member; at least one tensioning cylinder
having a blind end and a rod end, the blind end being in
communication with the at least one cylinder plate and the rod end
being in communication with at least one rod end swivel member; and
a base in communication with the at least one rod end swivel
member, thereby forming a unitary, co-linear tensioner.
[0011] A further feature of the tensioner is that the tensioner may
further comprise at least one piece of equipment being in
communication with the top load plate. Another feature of the
tensioner is that the at least one piece of equipment may be a
rotary table. An additional feature of the tensioner is that the
rotary table may be formed integral with the top load plate. Still
another feature of the tensioner is that the tensioner may include
at least two tensioning cylinders disposed along a tensioning
cylinder plate thereby forming an area in between the at least two
tensioning cylinders and may further comprise at least one piece of
equipment being disposed within the area formed in between the at
least two tensioning cylinders. A further feature of the tensioner
is that the tensioner may further comprise at least one equipment
guide rail and wherein the at least one piece of equipment includes
at least one guide slidably engaged with the at least one equipment
guide rail. Another feature of the tensioner is that the piece of
equipment may be at least one snubbing unit. An additional feature
of the tensioner is that the piece of equipment may be at least one
blowout preventer. Still another feature of the tensioner is that
the at least one piece of equipment may include at least one
equipment guide rail and the tensioner further comprising at least
one guide slidably engaged with the at least one equipment guide
rail. A further feature of the tensioner is that the piece of
equipment may be at least one snubbing unit. Another feature of the
tensioner is that the piece of equipment may be at least one
blowout preventer. An additional feature of the tensioner is that
the tensioner may further comprise at least one extension rod and
at least one extension platform in communication with the base.
Still another feature of the tensioner is that at least one piece
of equipment may be disposed on the extension platform. A further
feature of the tensioner is that the at least one piece of
equipment may include at least one blowout preventer. Another
feature of the tensioner is that each of the at least one
tensioning cylinders may include a tensioning cylinder casing
having a length and at least one fluid control port. An additional
feature of the tensioner is that each of the at least one fluid
control ports may be disposed along the length of each of the
tensioning cylinders. Still another feature of the tensioner is
that the tensioner may further comprise at least one lower swivel
member in communication with the base.
[0012] The foregoing advantages also have been obtained through the
present tensioner comprising: at least one top load plate, at least
one upper swivel assembly, at least one tensioning cylinder plate,
at least one tensioning cylinder, and a base, the at least one
tensioning cylinder being in communication with the at least one
tensioning cylinder plate and with the base, wherein the at least
one top load plate, the at least one upper swivel assembly, the at
least one tensioning cylinder plate, the at least one tensioning
cylinder, and the base are assembled to form a unitary, co-linear
tensioner.
[0013] A further feature of the tensioner is that the tensioner may
further comprise at least one lower swivel assembly. Another
feature of the tensioner is that the tensioner may include at least
four tensioning cylinders disposed along a tensioning cylinder
plate. An additional feature of the tensioner is that the at least
four tensioning cylinders may form an area in between the at least
four tensioning cylinders and may further comprise at least one
piece of equipment being disposed within the area formed in between
the at least four tensioning cylinders. Still another feature of
the tensioner is that a rotary table may be formed integral with
top load plate.
[0014] The foregoing advantages also have been obtained through the
present method of installing at least one tensioner through a
wellhead opening defining an open area size disposed along a rig
floor of a drilling or production vessel or platform, the method
comprising the steps of: providing a drilling or production vessel
or platform having a rig floor, the rig floor having a wellhead
opening, the wellhead opening defining an open area through which
the at least one tensioner is passed; providing at least one
tensioner having at least one top load plate, at least one upper
swivel assembly, at least one tensioning cylinder plate, at least
one tensioning cylinder, and a base, the at least one tensioning
cylinder being in communication with the at least one tensioning
cylinder plate and with the base, wherein the at least one top load
plate, the at least one upper swivel assembly, the at least one
tensioning cylinder plate, the at least one tensioning cylinder,
and the base are assembled to form a unitary, co-linear tensioner;
lowering the at least one tensioner through the open area of the
wellhead opening of the rig floor; installing the at least one
tensioner by contacting the top load plate with the rig floor
whereby the rig floor supports the at least one tensioner.
[0015] A further feature of the method is that the rig floor may
include at least one moveable rotary table beam and the method may
include the further step of moving the at least one moveable rotary
table beam to increase the open area of the wellhead opening prior
to lowering the at least one tensioner through the open area of the
wellhead opening of the rig floor.
[0016] The tensioners and the methods of the present invention,
when compared with previous tensioners and methods, have the
advantages of: providing relatively quicker and safer installation
of tensioners and other equipment; providing flexibility in
location of equipment in fluid communication with the tensioners;
eliminating offset and the resulting unequal loading in the event
one or more of the tensioning cylinders fail; providing a system
that is modular in construction, transportation, and assembly;
providing interchangeability with other drilling or production
facilities; reducing the amount of time that the wellhead is
"idle," i.e., that either a drilling riser or production riser is
in use by facilitating quick and easy installation of the
tensioner, rotary table, and workover equipment; providing
sufficient tension to the long string of the riser in deepwater
over extended periods of time; providing a means to maintain the
riser in constant tension, with, if necessary, overpull, while the
riser is in service; providing the capability to accommodate
angular offset between the riser and the vessel induced by vessel
motion; and providing the capability to accommodate axial torque
induced in the riser string in the event the drilling or production
vessel rotates around the wellhead due to weather and sea
conditions.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a perspective view of one specific embodiment of
the tensioner of the present invention.
[0018] FIG. 2 is a cross-sectional top view of the tensioner
assembly plate of the tensioner shown in FIG. 1 taken along line
2-2.
[0019] FIG. 3 is a perspective view of another specific embodiment
of the tensioner of the present invention.
[0020] FIG. 4 is a cross-sectional top view of the tensioner
assembly plate of the tensioner shown in FIG. 1 taken along line
4-4.
[0021] FIG. 5 is a side view of another specific embodiment of the
tensioner of the present invention.
[0022] FIG. 6 is a top view of a production platform centered on a
wellhead.
[0023] FIG. 7 is a side view of one specific tensioner of the
present invention installed on the rotary beams of a production
platform.
[0024] FIG. 8 is a perspective close-up view of the guide and
equipment guide rail of the embodiment shown in FIG. 3.
[0025] While the invention will be described in connection with the
preferred embodiment, it will be understood that it is not intended
to limit the invention to that embodiment. On the contrary, it is
intended to cover all alternatives, modifications, and equivalents,
as may be included within the spirit and scope of the invention as
defined by the appended claims.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0026] In one aspect, the invention comprises elements that when
assembled form a unitary co-linear tensioner. The tensioner may be
used to replace both conventional and direct acting tensioning
systems. Further, variations of the tensioner may be utilized in
both drilling and production riser applications.
[0027] Referring now to FIGS. 1-4, broadly, the present invention
is directed to tensioner 30 having first tensioner end 31, second
tensioner end 32, a retracted position (as illustrated in FIG. 5),
and at least one extended position (e.g., as illustrated in FIG.
3). Preferably, tensioner 30 includes the following sub-assemblies:
at least one mandrel, or spool, 40 having at least one top load
plate 45; at least one upper swivel assembly 50 (which may be a
ball-joint, a flex-joint, or a bearing assembly, all of which are
known in the art); at least one tensioning cylinder, or cylinder,
70; and at least one base 85. Base 85 facilitates connecting second
end 32 of tensioner 30 to other subsea appliances or equipment,
e.g, blowout preventer stacks, production trees, manifolds, and
riser components, e.g., tubulars of the riser string. In a
preferred embodiment (shown in FIG. 3), base 85 is secured to
extension platform 90 by rigid extension rods 91 to facilitate
placement of additional equipment 200 such as blowout preventers
220 and spacer 206. Extension platform 90 also includes opening 94
which is adapted to facilitate connection to the riser or
additional components or equipment of the riser string, e.g.,
flange/connectors such as latch dog profile as discussed in greater
detail below regarding mandrel 40, locking rings, load rings, or
casing slips.
[0028] Either base 85 of tensioner 30 or extension platform 90 is
releasably secured to the riser or other riser component or
equipment through any method or device known to persons skilled in
the art, e.g., latch dogs, a locking ring, a load ring, or casing
slips disposed around the tubular. Preferably, riser connector
member 87 (FIG. 1) is included on base 85 and is powered, either
pneumatically or hydraulically to facilitate remotely securing and
releasing the tubular or other riser component.
[0029] Upper swivel assembly 50 and, in some specific embodiments,
at least one lower swivel assembly 80 is included to compensate for
vessel offset i.e., vessel position in relationship to the well
bore center and riser angle. As with upper swivel assembly 50,
lower swivel assembly 80 may be a ball-joint, a flex-joint, or a
bearing assembly, all of which are known in the art.
[0030] As illustrated in FIG. 1, mandrel 40 includes first mandrel
end 41, second mandrel end 42, mandrel body 43, and at least one
top load plate 45. Top load plate 45 facilitates connection of
tensioner 30 to the superstructure of the drilling or production
vessel or platform by providing a portion of top load plate 45 to
be disposed on the superstructure so that tensioner 30 is supported
by top load plate resting on the superstructure. Top load plate 45
may be any shape or size desired or necessary to support tensioner
30 on the superstructure of the drilling or production vessel or
platform. As shown in FIGS. 1, 3, 5 and 7, top load plate 45 is
rectangularly shaped.
[0031] Mandrel 40 may be connected to a diverter assembly or other
piece of equipment (not shown), through an interface mandrel 46
having a mandrel lower connection flange 47 which may be connected
to hang-off joint 44 through any method known to persons of
ordinary skill in the art. As shown in FIG. 1, mandrel lower
connection flange 47 is connected to hang-off joint 44 through the
use of bolts 100.
[0032] In one specific embodiment of the invention, top load plate
45 may be formed as part of a rotary table 110 (FIG. 3) or other
equipment and secured directly to upper swivel assembly 50. Top
load plate 45 contacts the superstructure of the production or
drilling platform of a tension leg platform, drilling vessel,
production vessel or any other superstructure from which drilling
and production operations are staged so that tensioner 30 is
generally supported under the superstructure of the vessel or
platform. As shown in FIGS. 6-7, tensioner 30 is disposed on top of
rotary table beams 120. This allows for the complete tensioner 30,
including the riser, blow-out preventer stack, workover equipment,
or any other riser string component or equipment to be installed by
dropping the tensioner assembly 30 through wellhead opening 130 of
vessel or platform 150 and removing the entire tensioner assembly
30 by lifting tensioner assembly out of wellhead opening 130.
Vessel or platform 150 includes support beams 152 (FIG. 6).
[0033] Top load plate 45 may be integral to upper swivel assembly
50. Alternatively, top load plate 45 may be disposed along the
tensioning cylinders 70, thereby capturing tensioning cylinders 70
so that top load plate 45 is disposed more centrally to the overall
length of tensioner 30 (see FIG. 5). In this position, top load
plate permits transference of axial tension load from cylinder
casing 73 of tensioning cylinder 70 to mandrel 40 and then directly
to the platform or vessel superstructure shown in FIG. 6.
[0034] Second mandrel end 42 is in communication with upper swivel
assembly 50. Upper swivel assembly 50 includes first upper swivel
end 51, second upper swivel end 52, and housing 53 having at least
one swivel member, e.g., ball-joint, flexjoint, bearings, shackles,
which may be disposed within housing 53. Swivel members of upper
swivel assembly 50 permit rotational movement of tensioning
cylinders 70, and lower swivel assembly 80 in the direction of
arrows 58, 59 and arrows 10, 12. This arrangement allows for
mandrel 40 to be locked into a connector (not shown) or vessel or
platform 150 (FIG. 6) supported under the vessel or platform 150
which maintains the upper swivel assembly 50 and riser tubulars 190
(FIG. 7) in a locked, static position, while allowing tensioning
cylinder 70 and lower swivel assembly 80 to swivel in the direction
of arrows 58, 59 and arrows 10, 12. Upper swivel assembly 50
provides angular movement of approximately 15 degrees over 360
degrees compensating for riser angle and vessel offset. Upper
swivel assembly 50 may be any shape or size desired or necessary to
permit movement of tensioning cylinder 70 and lower swivel assembly
80 to a maximum of 15 degrees angular movement in any direction
over 360 degrees. As shown in FIG. 1, upper swivel assembly 50 is
cylindrically shaped.
[0035] Still with reference to FIG. 1, second upper swivel assembly
end 52 is in communication with tensioning cylinder plate 60
through any method or device known to persons of ordinary skill in
the art, e.g., mechanical connector, or bolts 100. In one
embodiment, upper swivel assembly 50 is integral with tensioner 30.
Upper swivel assembly 50 permits tensioning cylinder plate 60, and
thus, the mounted tensioning cylinders 70, to move in the direction
of arrows 58, 59 and arrows 10, 12 when in tension thereby
minimizing the potential to induce axial torque and imposing
bending forces on the mounted tensioning cylinders 70.
[0036] As illustrated in detail in FIGS. 2 and 4 tensioning
cylinder plate 60 includes top surface 61, bottom surface 62, body
63, and opening 65. Top surface 61 of tensioning cylinder plate 60
preferably includes at least one cylinder attachment plate 15 for
securing each of the tensioning cylinders 70 to the tensioning
cylinder plate 60. In specific embodiments shown in FIGS. 1 and 3,
cylinder attachment plate 15 include control interface 64 which are
in communication with one or more of the at least one tensioner
cylinder 70 and at least one control source (not shown), e.g.,
through the use of gooseneck hose assemblies known to persons of
ordinary skill in the art. Examples of suitable control sources
include, but are not limited to, atmospheric pressure,
accumulators, air pressure vessels (A.P.V.), and hoses for
connecting the gooseneck hose assembly to the accumulator and air
pressure vessel. Alternatively, control interfaces 64 are disposed
along the length of each tensioning cylinders 70 as shown in FIG.
5.
[0037] Control interface 64 permits pressure, e.g., pneumatic
and/or hydraulic pressure, to be exerted from the control source,
through control interface 64 into tensioning cylinder 70 to provide
tension to tensioner 30 as discussed in greater detail below and to
move tensioner 30 from the retracted position to the extended
position and vice versa. It is to be understood that only one
control interface 64 may be used in connection with a manifold (not
shown) wherein the manifold places each tensioning cylinder 70 in
fluid communication with each other. Alternatively, a separate
control interface 64 may be included with each tensioning cylinder
70.
[0038] While tensioning cylinder plate 60 may be fabricated or
machined in any shape, out of any material, and through any method
known to persons of ordinary skill in the art, preferably top load
plate is machined in a rectangular or square configuration, out of
stainless steel.
[0039] As illustrated in FIG. 1, each tensioner cylinder 70
preferably includes blind end 71, rod end 72, cylinder casing 73
having length 75, rod 74, cylinder head 77, and cylinder cavity 78.
While cylinder casing 73 may be formed out of any material known to
persons of ordinary skill in the art, cylinder casing 73 is
preferably formed out of carbon steel, stainless steel, titanium,
or aluminum. Further, cylinder casing 73 may include a liner (not
shown) inside cylinder casing 73 that contacts rod 74.
[0040] Control interface 64 (FIGS. 1, 2, 4, 5, and 7) is in fluid
communication with cylinder cavity 78 thereby permitting fluid to
be injected into or withdrawn out of cylinder cavity 78 to
facilitate movement of rod 74 into and out of cylinder casing
73.
[0041] Each tensioning cylinder 70 may be disposed along tensioning
cylinder plate 60 in any configuration desired or necessary to
provide sufficient space within area 150 formed by the tensioning
cylinders such that equipment or tubulars can be disposed within
area 150.
[0042] Each tensioner cylinder 70 permits vertical movement of
tensioner 30 from, and to, the retracted position, i.e., each rod
74 is moved into the respective cylinder casing 73. Each tensioner
cylinder 70 also permits vertical movement of tensioner 30 from,
and to, the extended position, i.e., each rod 74 is moved from
within the respective cylinder casing 73. It is noted that
tensioner 30 includes numerous retracted positions and extended
positions and these terms are used merely to describe the direction
of movement. For example, movement from the retracted position to
the extended positions means that rod 74 is being moved from within
the respective cylinder casing 73 and movement from the extended
position to the retracted position means that rod 74 is being moved
into the respective cylinder casing 73. The use of the term "fully"
preceding extended and retracted is to be understood as the point
in which rod 74 can no longer be moved from within cylinder casing
73 ("fully extended"), and the point in which rod 74 can no longer
be moved into cylinder casing 73 ("fully retracted").
[0043] Tensioner 30 may be moved from the retracted position to the
extended position, and vice versa, using any method or device known
to persons skilled in the art. For example, tensioner 30 may be
moved from the retracted position to the extended position by
gravity. Alternatively, at least one control source in
communication with tensioner 30 as discussed above to facilitate
movement of tensioner 30 from the extended position to the
retracted position and vice versa.
[0044] In the specific embodiment shown in FIGS. 1 and 3, each
cylinder rod end 72 includes at least one swivel member 76, such as
shackles 176 (FIG. 3) or ball-joints or flex-joints 276 (FIGS. 1
and 3). Each swivel member 76 permits rotational movement of each
tensioning cylinder 70 in the direction of arrows 58, 59 and arrows
10, 12 in the same manner as discussed above with respect to upper
swivel assembly 50 and lower swivel assembly 80. As shown in FIG.
1, each swivel member 76 is in communication with base 85, and each
blind end 71 is in communication with bottom surface 62 of
tensioning cylinder plate 60. Alternatively, each swivel member 76
may be in communication with lower swivel assembly 80. Swivel
member 76 preferably has a range of angular motion of +/-15 degrees
for alleviating the potential to induce torque and/or bending
forces on cylinder rod 74.
[0045] As shown in FIGS. 1, 2 and 4, blind ends 71 are drilled with
a bolt pattern to allow bolting in a compact arrangement on bottom
surface 62 of tensioning cylinder plate 60. Preferably, a plurality
of appropriately sized tensioning cylinders 70 equally, and
symmetrically, spaced around tensioning cylinder plate 60 are
employed to produce the tension required for the specific
application. Tensioning cylinders 70 are preferably disposed with
rod end 72 down, i.e., rod end 72 is closer to base 85, or lower
swivel member 80, than to tensioning cylinder plate 60. It is to be
understood, however, that one, or all, tensioning cylinders 70 may
be disposed with rod end 72 up, i.e., rod end 72 is closer to
tensioning cylinder 60.
[0046] Each tensioning cylinder 70 is designed to interface with at
least one control source, e.g., air pressure vessels and
accumulators via control interface 64 of cylinder attachment plate
15 (FIGS. 1-4) or through control interface 64 having transfer
piping 66 with hose attachment members 68 (FIGS. 5 and 7).
[0047] While it is to be understood that tensioning cylinder 70 may
be formed out of any material known to persons of ordinary skill in
the art, preferably, tensioning cylinder 70 is manufactured from a
light weight material that helps to reduce the overall weight of
the tensioner 30, helps to eliminate friction and metal contact
within the tensioning cylinder 70, and helps reduce the potential
for electrolysis and galvanic action causing corrosion. Examples
include, but are not limited to, carbon steel, stainless steel,
aluminum and titanium.
[0048] As discussed above, and shown in FIG. 1, in one specific
embodiment, lower swivel assembly 80 is in communication with base
85. Lower swivel assembly 80 consists of inner mandrel 83 and outer
radial member, or housing, 82 which contains at least one swivel
member (not shown), e.g., bearings, flex-joint, ball joint, etc.
Inner mandrel 83 may include flange 84 which is in communication
with riser tubular 190.
[0049] Swivel members of lower swivel assembly 80 permit movement
of upper swivel assembly 50, tensioning cylinder plate 60,
tensioning cylinder 70, and lower swivel assembly 80 in the
direction of arrows 58, 59 and arrows 10, 12. As with upper swivel
assembly 50, lower swivel assembly 80 is employed to further
alleviate the potential for induced axial torque while tensioner 30
is in tension. Preferably, lower swivel assembly 80 has a range of
angular motion of +/-15 degrees for alleviating the potential to
induce torque and/or bending forces on tensioner 30.
[0050] Lower swivel assembly 80 may be any shape or size desired or
necessary to permit radial movement of upper swivel assembly 50,
tensioning cylinder plate 60, tensioning cylinder 70, and lower
swivel assembly 80 in the direction of arrows 58, 59 and arrows 10,
12. As shown in FIG. 1, lower swivel assembly 80 is preferably
cylindrically shaped.
[0051] As mentioned above, base 85 may also be in communication
with a plurality of swivel members 76 for connecting tensioning
cylinder 70 to base. Swivel members 76 alleviate the potential for
tensioning cylinder 70 and rod 74 bending movement which would
cause increased wear in the packing elements (not shown) in the
gland seal (not shown) disposed at the interface between rod 74 and
cylinder casing 73. Each swivel member 76 provides an angular
motion of range of 15 degrees over 360 degrees in the direction of
arrows 58, 59 and arrows 10, 12.
[0052] Referring now to FIG. 3, in one specific embodiment,
tensioner 30 includes various pieces of equipment 200 disposed
within area 205 (see FIGS. 1, 3 and 7) formed by tensioning
cylinders 70. In the embodiment shown in FIG. 3, equipment 200 may
include snubbing unit 202, spacer 206, or multiple blow-out
preventers 220. Tensioner 30 shown in FIG. 3 also includes
additional blow-out preventers 224 and spacer 207 disposed on
extension platform 91. Therefore, as shown in FIG. 3, in this
arrangement, numerous pieces of equipment 300 can be disposed
placed in the riser string without increasing the length of the
riser string. Moreover, tensioner 30 may be customized with desired
or necessary equipment to engage in drilling, workover, or other
production operations prior to be transported to the vessel or
platform 150. Accordingly, the riser string, with tensioner 30 and
all equipment desired or necessary may be more quickly and easily
installed, thereby reducing well "downtime" and increasing
productivity of the well.
[0053] To facilitate movement of tensioner 30 in the direction of
arrows 94, 95, tensioner 30 (shown in FIG. 3 and shown in greater
detail in FIG. 8) includes at least one equipment guide rail 201
and the piece of equipment 200 includes at least one guide 208.
Each of the at least one equipment guide rails 201 slidably engages
a corresponding guide 208 to facilitate movement of equipment 200
in the direction of arrows 94, 95. Preferably, two or more
equipment guide rails 201 and two or more guides 208 are provided
on tensioner 30 and equipment 200. Notwithstanding the foregoing
description of equipment guide rail 201 and guide 208, it is to be
understood, however, that tensioner 30 may include guide 208 and
the piece of equipment 200 may include equipment guide rail
201.
[0054] In drilling applications, tensioner 30 is connected to the
diverter (not shown), which is generally supported under the
drilling rig floor sub-structure through any method or manner known
by persons skilled in the art. In one specific embodiment, the
connection between tensioner 30 and the diverter may be
accomplished by means of a bolted flange, e.g., via a studded
connection. In another specific embodiment, tensioner 30 is
connected to the diverter by inserting mandrel interface 47 into a
connector (not shown) attached to the diverter. In this embodiment,
interface mandrel 46 includes latch dog profile 49 that connects to
the connector via matching latch dogs which may be hydraulically,
pneumatically, or manually energized. In addition, a metal to metal
sealing gasket profile is preferably machined in the top of mandrel
40 to effect a pressure containing seal within the connector.
[0055] A production or a drilling riser, collectively "riser," can
be run to depth with tensioner 30 using a lifting device, e.g., a
crane, jack knife hoisting rig, rack and pinion elevator assembly,
or other suitable lifting device. Therefore, in one embodiment, the
production riser for drill step tests and other uses, or, in
another embodiment, the drilling riser, can be assembled without
the need for large amounts of heavy equipment, e.g., a full size
derrick.
[0056] Due to the novel features of the tensioners of the present
invention, tensioners may be easily installed and removed from the
vessel or platform superstructure. Broadly, the method of
installing tensioner 30 of the invention includes the steps of
providing tensioner 30 described in greater detail above, and
drilling or production facility, e.g., drilling/production vessel
or platform 150, having rig floor 154 and wellhead opening 130
defining an open area 133, e.g., rotary table opening 132, through
rig floor 154 providing access from rig floor 154 to the surface of
the water. Tensioner 30 includes weight and size dimensions such
that existing lifting devices can handle and maintain tensioner 30.
During workover operations, rig floor 154 has installed a rotary
table (not shown) disposed above wellhead 160 which is preferably
centered within wellhead opening 130. Prior to installation of
tensioner 30, the rotary table is removed from the superstructure
so that tensioner 30 may be dropped through rig floor 154 until top
load plate 45 is in contact with the rotary beams 120 (see FIGS.
6-7). In one specific embodiment, after removal of the rotary
table, rotary beams 120 may be moved in the directions of arrows
121, 122 to increase the size of rotary table opening 132, thereby
permitting larger sized tensioners 30 to be installed on the same
vessel or platform 150.
[0057] Removal of tensioner 30 is easily accomplished by lifting
tensioner 30 out of wellhead opening 130 in the similar manner as
which tensioner 30 was installed.
[0058] In the embodiments of the tensioners 30 of the invention in
which mandrel 40 is in communication with rotary table 110 (FIG.
3), the rotary table removed from the vessel or platform 150 is not
required to be re-installed, thereby reducing the down-time of the
well. While the foregoing method has been described with respect to
inclusion of a rotary table as part of tensioner 30, it is to be
understood that tensioner 30 may include one or more pieces of
equipment in addition to, or in place of, rotary table 110.
Moreover, while the methods of the invention may have been
described, in greater detail referring to rig floor 154 of a
vessel, it is to be understood that rig floor 154 may be disposed
on a platform.
[0059] It is to be understood that the invention is not limited to
the exact details of construction, operation, exact materials, or
embodiments shown and described, as obvious modifications and
equivalents will be apparent to one skilled in the art. For
example, the rod end of the tensioning cylinder may be in
communication with the tensioning cylinder plate. Also, the
individual sub-assemblies may be manufactured separately and
assembled using bolts, welding, or any other device or method known
to persons of ordinary skill in the art. Moreover, the individual
assemblies may be manufactured out of any material and through any
method known to persons of ordinary skill in the art. Additionally,
one or more manifolds may be included as part of the tensioner to
facilitate controlling the pressure contained in each of the
cylinder cavities. Further, the equipment disposed within the area
formed by the tensioning cylinders may be any piece of equipment
desired or necessary to provide the required function of production
or drilling. Accordingly, while the invention has been described
with respect to certain workover equipment, it is understood that
any other type of equipment may be disposed within the area formed
by the tensioning cylinders. Moreover, the swivel members may be a
flex-joint, ball-joint, clevis and pin, shackle, or other
mechanical joining or lifting device that provides angular
movement. Accordingly, the invention is therefore to be limited
only by the scope of the claims.
* * * * *