U.S. patent application number 15/121774 was filed with the patent office on 2017-01-12 for compact compensating cylinder.
This patent application is currently assigned to MHWIRTH AS. The applicant listed for this patent is MHWIRTH AS. Invention is credited to LARS POEHNER.
Application Number | 20170009537 15/121774 |
Document ID | / |
Family ID | 50478535 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170009537 |
Kind Code |
A1 |
POEHNER; LARS |
January 12, 2017 |
COMPACT COMPENSATING CYLINDER
Abstract
A compensating cylinder unit for compensating relative movements
between a stationary frame and a compensated frame which includes
parts of a coiled tubing compensation system. The compensating
cylinder unit includes a fluid reservoir configured to connect to
the stationary frame, and a compensating cylinder configured to
connect to the compensated frame, to at least partly enclose the
fluid reservoir, and to be in a fluid communication with the fluid
reservoir to allow for an axial displacement of the compensating
cylinder relative to the fluid reservoir.
Inventors: |
POEHNER; LARS; (HORTEN,
NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MHWIRTH AS |
KRISTIANSAND |
|
NO |
|
|
Assignee: |
MHWIRTH AS
KRISTIANSAND
NO
|
Family ID: |
50478535 |
Appl. No.: |
15/121774 |
Filed: |
February 17, 2015 |
PCT Filed: |
February 17, 2015 |
PCT NO: |
PCT/EP2015/053248 |
371 Date: |
August 26, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 19/09 20130101;
E21B 19/006 20130101; E21B 19/22 20130101 |
International
Class: |
E21B 19/00 20060101
E21B019/00; E21B 19/22 20060101 E21B019/22 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2014 |
NO |
20140255 |
Claims
1-20 (canceled)
21. A compensating cylinder unit for compensating relative
movements between a stationary frame and a compensated frame
comprising parts of a coiled tubing compensation system, the
compensating cylinder unit comprising: a fluid reservoir configured
to connect to the stationary frame; and a compensating cylinder
configured to connect to the compensated frame, to at least partly
enclose the fluid reservoir, and to be in a fluid communication
with the fluid reservoir to allow for an axial displacement of the
compensating cylinder relative to the fluid reservoir.
22. The compensating cylinder unit as recited in claim 21, wherein,
the fluid reservoir comprises a first fluid reservoir end which
comprises an opening, and further comprising: a gas reservoir
comprising a second gas reservoir end; and a connection element
attached to the second gas reservoir end and arranged into the
opening of the first fluid reservoir end of the fluid reservoir so
as to provide an axial interconnection between the gas reservoir
and the fluid reservoir, wherein, the compensating cylinder is
further configured to slide around a circumference of the
connection element.
23. The compensating cylinder unit as recited in claim 22, wherein
the first fluid reservoir end of the fluid reservoir further
comprises a protruding fluid reservoir flange.
24. The compensating cylinder unit as recited in claim 22, wherein
the connection element comprises at least one pressure equalizing
channel configured to enable a fluid communication between the
fluid reservoir and the gas reservoir.
25. The compensating cylinder unit as recited in claim 22, wherein,
the first fluid reservoir end further comprises an inner radial
surface, the connection element comprises a protruding piston
flange which comprises an outer radial surface, and the connection
element is configured to releasably interconnect the second gas
reservoir end to the first fluid reservoir end through abutment of
the outer radial surface of the protruding piston flange against
the inner radial surface of the first fluid reservoir end.
26. The compensating cylinder unit as recited in claim 25, wherein,
the first fluid reservoir end further comprises an outer surface,
the compensating cylinder comprises a first axial cylinder end
which comprises an inner surface, the compensating cylinder, the
gas reservoir, and the fluid reservoir are each configured to be
axially displaceable, the axial displacements being confined
between, an operational configuration where the gas reservoir is
locked to the fluid reservoir, and a transport configuration where
the outer surface of the first fluid reservoir end abuts the inner
surface of the first axial cylinder end of the compensating
cylinder (1), and where the gas reservoir is axially released from
the fluid reservoir.
27. The compensating cylinder unit as recited in claim 26, further
comprising: a connection element comprising a surface, the
connection element being fixed to the second gas reservoir end of
the gas reservoir and arranged into the opening of the first fluid
reservoir end of the fluid reservoir so as to provide an axial
interconnection between the gas reservoir and the fluid reservoir,
wherein, the fluid reservoir further comprises a second fluid
reservoir end which comprises an inner radial surface, and the
transport configuration includes an abutment of the surface of the
connection element towards the inner radial surface of the second
fluid reservoir end of the fluid reservoir.
28. The compensating cylinder unit) as recited in claim 27,
wherein, the compensating cylinder comprises a volume, and further
comprising: a fluid channel configured to provide a fluid
communication between the fluid reservoir and the volume within the
cylinder arranged outside of the fluid reservoir.
29. The compensating cylinder unit as recited in claim 28, wherein
the fluid channel is further configured to extend from the second
fluid reservoir end) of the fluid reservoir to the volume within
the cylinder situated outside the fluid reservoir.
30. The compensating cylinder unit as recited in claim 29, wherein
the fluid channel comprises a through-going accumulator passage
which is configured to penetrate the second fluid reservoir
end.
31. The compensating cylinder unit as recited in claim 28, wherein
the fluid channel further comprises a fluid guiding feeding tube
configured to extend from the second fluid reservoir end of the
fluid reservoir.
32. The compensating cylinder unit as recited in claim 31, wherein,
the connection element further comprises at least one radial
channel, the connection element being arranged into the opening of
the first fluid reservoir end of the fluid reservoir so as to
provide an axial interconnection between the gas reservoir and the
fluid reservoir, wherein, the fluid guiding feeding tube comprises
at least one radial bore which is alignable to the at least one
radial channel to provide a fluid communication between the fluid
guiding feeding tube and the volume within the cylinder situated
outside the fluid reservoir and the gas reservoir.
33. The compensating cylinder unit as recited in claim 26, wherein,
the gas reservoir further comprises outer walls, the first fluid
reservoir end further comprises an outer radial surface which is
arranged to face the first axial cylinder end of the compensating
cylinder, and the compensating cylinder further comprises inner
walls and axial walls which are configured to slidingly surround
the connection element, the second gas reservoir end and the first
fluid reservoir end so as to form a fluid tight first cylinder
chamber which is bounded by at least the inner walls of the
compensating cylinder, the outer walls of the gas reservoir, and
the outer radial surface of the first fluid reservoir end facing
the first axial cylinder end of the compensating cylinder.
34. The compensating cylinder unit as recited in claim 33, wherein,
the fluid reservoir further comprises outer walls, and the first
fluid reservoir end further comprises a protruding fluid reservoir
flange comprising an outer radial surface which is arranged to face
away from the first fluid reservoir end, the protruding fluid
reservoir flange being configured to provide a second cylinder
chamber which is bounded by at least, the inner walls of the
compensating cylinder, the outer walls of the fluid reservoir, and
the outer radial surface of the protruding fluid reservoir flange
of the first fluid reservoir end facing away from the first fluid
reservoir end.
35. The compensating cylinder unit as recited in claim 34, further
comprising: a pressure control device configured to provide
pressure adjustments within the second cylinder chamber, wherein,
the second cylinder chamber is connected to the pressure control
device.
36. The compensating cylinder unit as recited in claim 34, further
comprising: a fluid channel configured to provide a fluid
communication between the fluid reservoir and the fluid tight first
cylinder chamber, the fluid channel comprising, a through-going
accumulator passage configured to penetrate the second fluid
reservoir end of the fluid reservoir, a valve device arranged
outside the fluid reservoir to be in a fluid communication with the
through-going accumulator passage, and a fluid guiding feeding tube
comprising a first longitudinal end arranged to be in a fluid
communication with the fluid tight first cylinder chamber during
operation, and a second longitudinal end arranged to be in a fluid
communication with the valve device.
37. A method for altering a compensating cylinder unit from an
operational configuration to a transport configuration, the
compensating cylinder unit comprising: a compensating cylinder
comprising a first axial side and a second axial side, a fluid
reservoir, and a gas reservoir interconnected in a fluid
communication with the fluid reservoir, the compensating cylinder
being in fluid communication with the fluid reservoir to allow for
an axial displacement of the compensating cylinder relative to the
fluid reservoir, the method comprising: venting each of a first
volume within the compensating cylinder, a second volume in the
fluid reservoir, and a third volume in the compensating cylinder to
an ambient pressure; and applying an external contraction force on
at least one of the first axial side and the second axial side of
the compensating cylinder unit to axially displace the gas
reservoir relative to the fluid reservoir.
38. The method as recited in claim 17, wherein that the
compensating cylinder unit comprises: a fluid reservoir configured
to connect to the stationary frame; and a compensating cylinder
configured to connect to the compensated frame, to at least partly
enclose the fluid reservoir, and to be in a fluid communication
with the fluid reservoir to allow for an axial displacement of the
compensating cylinder relative to the fluid reservoir.
39. A coiled tubing compensation system comprising: a stationary
frame; a compensated frame; and the compensating cylinder unit as
recited in claim 21, wherein, the stationary frame is configured to
connect to the fluid reservoir, and the compensated frame is
configured to connect to the compensating cylinder.
40. The coiled tubing compensation system as recited in claim 19
comprising at least two compensating cylinder units arranged so as
to have their respective longitudinal axes arranged in parallel.
Description
CROSS REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a U.S. National Phase application under
35 U.S.C. .sctn.371 of International Application No.
PCT/EP2015/053248, filed on Feb. 17, 2015 and which claims benefit
to Norwegian Patent Application No. 20140255, filed on Feb. 27,
2014. The International Application was published in English on
Sep. 3, 2015 as WO 2015/128217 A1 under PCT Article 21(2).
FIELD
[0002] The present invention relates generally to the field of
floating offshore platforms or vessels for the exploitation of
undersea deposits of petroleum and natural gas. The present
invention more specifically relates to compensating cylinders for
compensating relative movements within a coiled tubing compensation
system.
BACKGROUND
[0003] Coil tubing provides a rig crew with a quick and easy access
to live wells in order to perform various well intervention
operations. The coil tubing equipment generally consists of a
coiled tube, a drive unit, and a control cabinet. The equipment is
normally not fixed to one rig, but can be transported between
various locations. The coil tubing has a long track record for
onshore land drilling, where the implementation is fairly simple.
When used offshore on floating drilling units, it must also have
some sort of compensation. With a traditional derrick with a drill
string compensator or a ram rig system, the drive unit of the coil
tubing is supported in a fixed coil tubing unit. This is hung up in
either the elevator or the bails. Many of the latest rigs have
substituted the regular drill string compensator with an active
compensated drawwork. This is, however, not suitable for the more
fragile operations like coil tubing. Any abruption of the active
compensation when the coil tubing is fixed to seabed may easily
destroy the coil tubing. The coil tubing frame itself must have a
compensating feature in such cases.
[0004] There have been some recent proposals to address the
challenge of obtaining active compensation while providing a
satisfactory low risk of abruption. WO 2005/061803 describes an
inline compensator with two passive cylinders on a frame replacing
the vertical beams. US 2012/0227976 A1 describes a similar
solution.
[0005] Common for the previously-described compensation systems is
that the pressure vessels are not located on the compensating unit
itself. The supply of compressed air to drive the compensation
motion is furthermore performed by one or two relatively large size
hoses, which is highly unfavorable for safety reasons.
SUMMARY
[0006] An aspect of the present invention is to provide a less
space demanding yet secure compensating cylinder when installed in
a system such as in a coil tubing system. Another aspect of the
present invention is to provide a less space demanding compensating
cylinder also after decoupling from the operational system, for
example, during transport.
[0007] In an embodiment, the present invention provides a
compensating cylinder unit for compensating relative movements
between a stationary frame and a compensated frame which includes
parts of a coiled tubing compensation system. The compensating
cylinder unit includes a fluid reservoir configured to connect to
the stationary frame, and a compensating cylinder configured to
connect to the compensated frame, to at least partly enclose the
fluid reservoir, and to be in a fluid communication with the fluid
reservoir to allow for an axial displacement of the compensating
cylinder relative to the fluid reservoir.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention is described in greater detail below
on the basis of embodiments and of the drawings in which:
[0009] FIG. 1 shows a cross sectional side view of a compensated
coil tubing frame in accordance with the present invention,
including a support structure and a coiled tubing rigup;
[0010] FIG. 2A shows a cross sectional side view of a compact
compensating cylinder unit in accordance with the present invention
in an operational mode, where the accumulator assembly is stroked
in an intermediate position relative to the surrounding
compensating cylinder;
[0011] FIG. 2B shows a cross sectional side view of a compact
compensating cylinder unit in accordance with the present invention
in an operational mode, where the accumulator assembly is stroked
in an intermediate position relative to the surrounding
compensating cylinder;
[0012] FIG. 2C shows a cross sectional side view of a compact
compensating cylinder unit in accordance with the present invention
in an operational mode, where the accumulator assembly is stroked
in an intermediate position relative to the surrounding
compensating cylinder;
[0013] FIG. 2D shows a cross sectional side view of a compact
compensating cylinder unit in accordance with the present invention
in an operational mode, where the accumulator assembly is stroked
in an intermediate position relative to the surrounding
compensating cylinder;
[0014] FIG. 3A shows a side view of a compact compensating cylinder
unit in accordance with the present invention in an operational
mode, the accumulator assembly being stroked in an upper position
relative to the surrounding compensating cylinder;
[0015] FIG. 3B shows a side view of a compact compensating cylinder
unit in accordance with the present invention in an operational
mode, the accumulator assembly being stroked in an upper position
relative to the surrounding compensating cylinder;
[0016] FIG. 4A shows a side view of a compact compensating cylinder
unit in accordance with the present invention in an operational
mode, the accumulator assembly being stroked in a lower position
relative to the surrounding compensating cylinder;
[0017] FIG. 4B shows a side view of a compact compensating cylinder
unit in accordance with the present invention in an operational
mode, the accumulator assembly being stroked in a lower position
relative to the surrounding compensating cylinder;
[0018] FIG. 5A shows a side view of a compact compensating cylinder
unit in accordance with the present invention in a retracted
transport mode;
[0019] FIG. 5B shows a side view of a compact compensating cylinder
unit in accordance with the present invention in a retracted
transport mode; and
[0020] FIG. 5C shows a side view of a compact compensating cylinder
unit in accordance with the present invention in a retracted
transport mode.
DETAILED DESCRIPTION
[0021] The present invention in particular relates to a
compensating cylinder unit suitable for compensating relative
movements between a stationary frame and a compensated frame
constituting parts of a coiled tubing compensation system, where
the compensated frame is connected to the compensating cylinder.
All the necessary tools for the coiled tubing system may be
arranged on the compensated platform in order to provide
compensation of vertical movements during operation. The cylinder
unit comprises a compensating cylinder suitable for connection to
the compensated frame and a fluid reservoir suitable for connection
to the stationary frame, wherein the compensating cylinder is in
fluid communication with the fluid reservoir to allow for an axial
displacement of the compensating cylinder relative to the fluid
reservoir. The compensating cylinder is furthermore characterized
in that it at least partly encloses the fluid reservoir.
[0022] In an embodiment of the present invention, the cylinder unit
can, for example, further comprise a gas reservoir having a second
gas reservoir end and a connection element fixed to the second gas
reservoir end and arranged into an opening within a first fluid
reservoir end of the fluid reservoir, creating an axial
interconnection between the gas reservoir and the fluid reservoir,
wherein the cylinder is slidingly arranged around the circumference
of the connection element. The connection element may display at
least one pressure equalizing channel enabling fluid communication
between the reservoirs. The connection element may furthermore
comprise an outward protruding piston flange, wherein the
connection element releasably interconnects the second gas
reservoir end to the first fluid reservoir end through abutment of
an outer radial surface of the protruding piston flange against an
inner radial surface of the first fluid reservoir end.
[0023] In an embodiment of the present invention, a first fluid
reservoir end of the fluid reservoir can, for example, comprise an
outward protruding fluid reservoir flange.
[0024] In an embodiment of the present invention, the cylinder unit
can, for example, further comprise a gas reservoir, wherein the
cylinder, the gas reservoir and the fluid reservoir are mutually
displaceable in the axial direction, the displacements being
confined between an operational configuration where the gas
reservoir is locked to the fluid reservoir and a transport
configuration where the outer surface of a first fluid reservoir
end of the fluid reservoir abuts the inner surface of a first
cylinder end of the cylinder, and where the gas reservoir is
axially released from the fluid reservoir. The term "locked" is
defined as the situation where the gas reservoir is immovable or
almost immovable relative to the fluid reservoir. The cylinder unit
may further comprise a connection element fixed to a second gas
reservoir end of the gas reservoir and arranged into an opening
within a first fluid reservoir end of the fluid reservoir so as to
create an axial interconnection between the gas reservoir and the
fluid reservoir, and where the transport configuration includes
abutment of the surface of the connection element towards the inner
surface of a second fluid reservoir end of the fluid reservoir.
[0025] In an embodiment of the present invention, the cylinder unit
can, for example, further comprise a fluid channel enabling fluid
communication between the fluid reservoir and a volume within the
cylinder situated outside the fluid reservoir. The fluid channel
may extend from a second fluid reservoir end of the fluid reservoir
to the volume within the cylinder situated outside the fluid
reservoir. The fluid channel may further comprise a through-going
accumulator passage penetrating the second fluid reservoir end. The
fluid channel may further comprise a fluid guiding feeding tube
extending from a second fluid reservoir end of the fluid reservoir
within the fluid reservoir.
[0026] In an embodiment of the present invention, the cylinder unit
can, for example, further comprise a gas reservoir comprising a
second gas reservoir end and a connection element fixed to the
second gas reservoir end comprising a radial channel, where the
connection element is arranged into an opening within a first fluid
reservoir end of the fluid reservoir so as to create an axial
interconnection between the gas reservoir and the fluid reservoir.
The fluid guiding feeding tube may further comprise at least one
radial bore being alignable to the at least one radial channel to
enable fluid communication between the feeding tube and a volume
within the cylinder situated outside the fluid reservoir and the
gas reservoir. Note that there is no fluid communication between
the pressure equalizing channel(s) and the radial channel(s).
[0027] In an embodiment of the present invention, the axial walls
of the compensating cylinder can, for example, slidingly surround
the connection element, the second gas reservoir end, and the first
fluid reservoir end, so as to form a fluid tight first cylinder
chamber bounded by at least inner walls of the cylinder, the outer
walls of the gas reservoir, and an outer radial surface of the
first fluid reservoir end facing a first axial cylinder end of the
cylinder. Note that "fluid tight" must be interpreted in accordance
with the prevailing requirements of the technical field in
question. The first fluid reservoir end may comprise an outwardly
protruding fluid reservoir flange creating a second cylinder
chamber bounded by at least the inner walls of the cylinder, the
outer walls of the fluid reservoir, and an outer radial surface of
the protruding fluid reservoir flange of the first fluid reservoir
end facing away from the first fluid reservoir end. The volume of
the second cylinder chamber can be less than the volume of the
first cylinder chamber. The second cylinder chamber can furthermore
be connected to a pressure control device which enables pressure
adjustments within the second cylinder chamber, for example, an
external accumulator and/or an active control system.
[0028] In an embodiment of the present invention, the cylinder unit
can, for example, further comprise a fluid channel enabling fluid
communication between the fluid reservoir and the first cylinder
chamber, where the fluid channel comprises a through-going
accumulator passage penetrating a second fluid reservoir end of the
fluid reservoir, a valve device arranged outside the fluid
reservoir in fluid communication with the through-going accumulator
passage, and a fluid guiding feeding tube comprising a first
longitudinal end arranged in fluid communication with the first
cylinder chamber during operation and a second longitudinal end
arranged in fluid communication with the valve device.
[0029] The present invention also provides a method for altering a
compensating cylinder unit from an operational configuration to a
transport configuration, which compensating cylinder unit comprises
a compensating cylinder, a fluid reservoir, and a gas reservoir
interconnected in fluid communication with the fluid reservoir. The
compensating cylinder is in fluid communication with the fluid
reservoir in order to allow for an axial displacement of the
compensating cylinder relative to the fluid reservoir. The method
comprises the steps of:
[0030] venting the volumes within the compensating cylinder and
both reservoirs to an ambient pressure;
[0031] optionally releasing the interconnection between the gas
reservoir and the fluid reservoir; and
[0032] applying an external contraction force on one or both axial
sides of the cylinder unit to axially displace the gas reservoir
relative to the fluid reservoir.
[0033] The compensating cylinder unit used in the method may be in
accordance with the compensation cylinder described above.
[0034] The present invention also provides a coiled tubing
compensation system comprising a stationary frame, a compensated
frame, and a compensating cylinder unit in accordance with the
cylinder unit described above, wherein the stationary frame
connects to the fluid reservoir and the compensated frame connects
to the compensating cylinder. The system may comprise at least two
compensating cylinder unit having their longitudinal axes arranged
in parallel. The term "stationary" means stationary relative to an
underlying platform or vessel.
[0035] Numerous specific details are introduced in the following
description to provide a thorough understanding of, and an enabling
description for, embodiments of the claimed apparatus and method.
One skilled in the relevant art will recognize, however, that these
embodiments can be practiced without one or more of the specific
details, or with other components, systems, etc. In other
instances, well-known structures or operations are not shown, or
are not described in detail, to avoid obscuring aspects of the
disclosed embodiments.
[0036] FIG. 1 shows the main components of a coiled tubing system
30 in accordance with the present invention. The coiled tubing
system 30 comprises a coiled tubing machine (injector head) 31
containing the mechanism to push and pull a coiled tubing pipe or
string 34 in and out of a well (not shown). The coiled tubing
machine 31 has a curved guide beam 32 on top, often called a guide
arch or gooseneck, which threads the coiled tubing pipe 34 into the
body of the coiled tubing machine 31. A blowout preventer (BOP) 33
may be arranged to form an intermediate component between the
coiled tubing machine 31 and the coiled tubing pipe 34. The BOP 33
may cut the coiled tubing pipe 34 with subsequent sealing.
Components 31-34 are supported on a compensated frame 50 where each
longitudinal end is connected to a compensating cylinder 1 of an
inventive compensating cylinder unit 100 having the ability to
compensate for environmentally induced forces such as sea current
or sea waves. The compensating cylinder unit 100 thus forms an
integral part of the coiled tubing system 30. The two longitudinal
ends 10a, 5b of each compensating cylinder unit 100 are connected
to a common top frame 60 and a common lower support frame 40,
respectively. As will be apparent from the description below, the
accumulator and pressure vessels 5,10 are included into the
compensating cylinder 1. There is thus no need for large hydraulic
or pneumatic hoses to external sources. The top frame 60 interfaces
the lifting equipment in the derrick, and the lower support frame
40 may rest on deck. The structure that bonds the two cylinder
tubes together will now function as a compensated platform for
where to place all the necessary tools for the coil tubing system.
This particular configuration separates this arrangement to a large
degree from similar prior art systems which must be lifted well
clear of the drill floor (not shown).
[0037] FIG. 2A shows a principal side view sketch of the
compensating cylinder unit 100 in accordance with the present
invention. A pressure vessel 10 and a fluid accumulator 5 are
interconnected via a central piston 2, forming an accumulator
assembly. The central piston 2 is fixed to a lower axial vessel end
10b of the pressure vessel 10 and is releasably fixed to a
protruding upper axial accumulator end 5a of the fluid accumulator
5. The latter connection may be obtained by maintaining a
protruding piston flange 14 pushed towards the inner surface of
protruding upper axial accumulator end 5a by pressure or other
suitable means. The fluid accumulator 5 and the pressure vessel 10
are further slidingly journaled into a common compensating cylinder
or barrel 1, forming a closed annulus cylinder chamber between the
inner wall of the compensating cylinder 1 and the outer wall of the
journaled accumulator assembly 5,10. The cylinder chamber is
divided into an upper cylinder chamber 1' and a lower cylinder
chamber 1'' by the protruding upper axial accumulator end 5a. The
other longitudinal ends of the upper and lower cylinder chambers
1',1'' are bounded by an upper axial cylinder end la and a lower
axial cylinder end lb, respectively. One or more through-going
axial drillings 6 are provided into the central piston 2 in order
to provide fluid communication between the interior of the pressure
vessel 10 and the interior of the fluid accumulator 5. A fluid
channel 8 (FIG. 2B) is further provided to run from the interior of
the fluid accumulator 5 to the upper cylinder chamber 1'. This
fluid channel 8 comprises: [0038] a lower end accumulator drilling
12 penetrating a lower axial accumulator end 5b; [0039] a suitable
feeding tube 11 comprising upper and lower longitudinal ends
11a,11b arranged from the lower axial accumulator end 5b to at
least near the lower axial vessel end 10b; [0040] a valve device 13
providing a controllable fluid communication between the lower
accumulator drilling 12 and the feeding tube 11; and [0041] one or
more radial oriented bores 20 arranged at an upper longitudinal end
11a of the feeding tube 11 providing fluid communication between
the interior of the feeding tube 11 and the upper cylinder chamber
1'.
[0042] FIG. 2B provides further operational details of the
compensating cylinder unit 100 indicating by arrows the pathway of
the fluid channel 8. The fluid accumulator 5 in FIG. 2B is
illustrated as partly filled with pressurized fluid 22, while the
pressure vessel 10 is illustrated as filled with pressurized gas 21
(for example, air). Due to the through-going axial drillings 6, the
pressures in the pressure vessel 10 and the fluid accumulator 5 are
equalized. If the valve device 13 is opened, the pressurized fluid
22 is forced through the fluid channel 8 into the upper cylinder
chamber 1' via the axial feeding tube 11 and the radial bores 20.
As a result, the pressure in the pressurized fluid 22 is converted
to a force within the upper cylinder chamber 1' of the cylinder 1
that equals the effective chamber or annulus area times the fluid
pressure. The axial force components (F.sub.a) acting on the inner
surface of an upper axial cylinder end la of the cylinder 1 and the
outer surface of the protruding upper axial accumulator end 5a
cause a vertical motion of the cylinder 1 when the fluid
accumulator 5 is fixed to a rigid support such as a compensated
frame 50 (FIG. 1). For example, if the axial (or vertical) force
components (F.sub.a) within the upper cylinder chamber 1' increases
due to increased pressure within the fluid channel 8, the
accumulator assembly 5,10 moves along the axial direction of the
cylinder 1 away from the upper cylinder end 1a. Likewise, if the
axial (or vertical) force components (F.sub.a) within the upper
cylinder chamber 1' decreases due to decreased pressure within the
fluid channel 8 and the fluid accumulator 5, the accumulator
assembly moves along the axial direction of the cylinder 1 towards
the upper cylinder end 1a. A compensating effect similarly to the
effect of the prior art compensating cylinders is consequently
achieved, but with a more compact compensating cylinder unit
100.
[0043] Due to the different outer diameters of the pressure vessel
10 and the fluid accumulator 5, the forces acting in the upper
cylinder chamber 1' is in general larger than the forces acting in
the lower cylinder chamber 1''. The lower cylinder chamber 1'' may
be connected to a low pressure accumulator to keep the chamber
volume oil-filled and lubricated. It may, however, also (or
alternatively) be used to actively control the compensation in a
similar way as, for example, in low pressure accumulator of prior
art dual acting type cylinders. By adding an active control loop
such as a hydraulic control loop to the lower cylinder chamber 1'',
the force of the overall cylinder tensioning may be controlled by
use of active means. The nature of a regular passive cylinder is
that the pressure in the pressure vessel often varies with the
position of the compensator stroke, which in general is undesired.
The effect can be neutralized, or nearly neutralized, via the
mentioned control loop, resulting in a cylinder providing a more
stable compensating force throughout the stroke length compared
with cylinders without active control loops.
[0044] An about 1:22 scale side view drawing of an operational
compact compensating cylinder unit 100 in an intermediate stroke
position and a corresponding sectional drawing along line B-B is
shown in FIGS. 2C and 2D, respectively. The valve device 13
providing controlled fluid communication between the lower
accumulator drilling 12 and the feeding tube 11 is partly
illustrated in FIG. 3D.
[0045] FIGS. 3A and 3B show side view drawings of the same
operational compensating cylinder unit 100 as in FIGS. 2C and 2D
(the latter along D-D) but where the accumulator assembly 5,10 is
stroked in an upper position relative to the surrounding
compensating cylinder 1, i.e., a position where the outer radial
surface of the protruding upper axial accumulator end 5a abuts the
inner radial surface of the upper cylinder end la due to increased
pressure force (F.sub.a) within the first cylinder chamber 1'.
FIGS. 4A and 4B also show side view drawings as in FIGS. 2C, 3A,2D,
and 3B, respectively (FIG. 4B seen along C-C of FIG. 4A), but where
the accumulator assembly 5,10 is stroked in a lower position
relative to the surrounding compensating cylinder 1, i.e., a
position where the outer radial surface of the protruding upper
axial accumulator end 5a facing towards the lower axial accumulator
end 5b abuts the inner radial surface of the lower cylinder end lb
due to decreased pressure force (F.sub.a) within the first cylinder
chamber 1'.
[0046] FIG. 5A shows a principal side view sketch of the
compensating cylinder unit 100 in accordance with the present
invention and arranged in a retracted transport mode, i.e., a
position where the outer radial surface of the protruding upper
axial accumulator end 5a abuts the inner radial surface of a first
cylinder end la, while the radial surface of the central piston 2
abuts the inner radial surface of the lower axial accumulator end
5b. This transport configuration or mode may be obtained by axially
releasing the pressure vessel 10 from the fluid accumulator 5, for
example, by venting the volumes within the compensating cylinder 1,
the fluid accumulator 5 and the pressure vessel 10 to an ambient
pressure and/or imparting an axial force on the cylinder unit 100,
thereby enforcing an axial movement of the fluid accumulator 5 into
the pressure vessel 10. Note that the central piston 2 on the
pressure vessel 10 may be releasably connected to the fluid
accumulator 5 by means other than, or in addition to, pressure
induced connection, for example, via various
mechanically-releasable coupling devices. An about 1:22 scale side
view drawing of a compact compensating cylinder unit 100 as in FIG.
5A, i.e., retracted transport mode, and a corresponding sectional
drawing along line A-A is shown in FIGS. 5B and 5C,
respectively.
[0047] In the preceding description, various aspects of the system
and method according to the present invention have been described
with reference to the illustrative embodiment. For purposes of
explanation, specific numbers, systems and configurations are set
forth in order to provide a thorough understanding of the apparatus
and its workings. However, this description is not intended to be
construed in a limiting sense. Various modifications and variations
of the illustrative embodiment, as well as other embodiments of the
apparatus, which are apparent to persons skilled in the art to
which the disclosed subject matter pertains, are deemed to lie
within the scope of the present invention. Reference should also be
had to the appended claims.
LIST OF REFERENCE NUMERALS
[0048] F.sub.a Axial/vertical force component/pressure force [0049]
1 Compensating cylinder/barrel [0050] 1' First cylinder
chamber/upper cylinder chamber [0051] 1'' Second cylinder
chamber/lower cylinder chamber [0052] 1a Upper cylinder end/upper
axial cylinder end/first cylinder end [0053] 1b Lower cylinder
end/lower axial cylinder end [0054] 2 Central piston/connection
element [0055] 5 Fluid accumulator/fluid reservoir [0056] 5a
Protruding upper axial accumulator end/first fluid reservoir end
[0057] 5b Lower axial accumulator end/second fluid reservoir end
[0058] 6 Axial drilling/pressure equalizing channel [0059] 8 Fluid
channel [0060] 10 Pressure vessel/gas reservoir [0061] 10a Upper
axial vessel end/first gas reservoir end [0062] 10b Lower axial
vessel end/second gas reservoir end [0063] 11 Fluid guiding feeding
tube/feeding tube [0064] 11a Upper longitudinal end/first
longitudinal end [0065] 11b Lower longitudinal end/second
longitudinal end [0066] 12 Lower end accumulator
drilling/Through-going accumulator passage [0067] 13 Valve device
[0068] 14 Protruding piston flange [0069] 16 Protruding accumulator
flange/protruding fluid reservoir flange [0070] 20 Radial bore
[0071] 21 Pressurized gas [0072] 22 Pressurized fluid [0073] 23
Radial channel [0074] 30 Coiled tubing system/Coiled tubing
compensation system [0075] 31 Coiled tubing machine/injector head
[0076] 32 Curved Guide beam/Guide Arch/Gooseneck [0077] 33 Blowout
Preventer (BOP) [0078] 34 Coiled tubing pipe/Coiled tubing string
[0079] 40 Lower support frame/stationary frame [0080] 50
Compensated frame [0081] 60 Upper support structure/Top frame
[0082] 100 Compensating cylinder unit
* * * * *