U.S. patent application number 14/759857 was filed with the patent office on 2015-12-10 for telescopic riser joint.
This patent application is currently assigned to FMC KONGSBERG SUBSEA AS. The applicant listed for this patent is FMC KONGSBERG SUBSEA AS. Invention is credited to Tor-Oystein Carlsen, Bernt-Olav Tommermo.
Application Number | 20150354296 14/759857 |
Document ID | / |
Family ID | 49943378 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150354296 |
Kind Code |
A1 |
Tommermo; Bernt-Olav ; et
al. |
December 10, 2015 |
TELESCOPIC RISER JOINT
Abstract
The invention relates to a telescopic riser joint for connecting
a first riser part and a second riser part, the riser joint
comprising: a first pipe part (8) and a second pipe part (9)
comprising means for connection to the first riser part and the
second riser part respectively, which first and second pipe parts
in use are arranged to form part of a riser with an internal flow
passage, a cylinder arrangement comprising a first set of cylinders
(32), each cylinder having a piston rod with a piston head (51) and
a cylinder housing, the piston rod and cylinder housing being
respectively connectable to one of the first pipe part or second
pipe part, wherein one side of the piston head in use is in
communication with external pressure providing an axial force
acting in the longitudinal direction of the riser, and the other
side of the piston head is facing a sealed chamber (52), where the
cylinder arrangement is configured such that a fluid in the sealed
chamber and a fluid on the other side of the piston head give a
resultant force tensioning the first riser part and the second
riser part.
Inventors: |
Tommermo; Bernt-Olav;
(Notodden, NO) ; Carlsen; Tor-Oystein; (Kongsberg,
NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FMC KONGSBERG SUBSEA AS |
Kongsberg |
|
NO |
|
|
Assignee: |
FMC KONGSBERG SUBSEA AS
Kongsberg
NO
|
Family ID: |
49943378 |
Appl. No.: |
14/759857 |
Filed: |
January 7, 2014 |
PCT Filed: |
January 7, 2014 |
PCT NO: |
PCT/EP2014/050153 |
371 Date: |
July 8, 2015 |
Current U.S.
Class: |
166/355 |
Current CPC
Class: |
E21B 17/07 20130101;
E21B 19/006 20130101 |
International
Class: |
E21B 19/00 20060101
E21B019/00; E21B 17/07 20060101 E21B017/07 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 8, 2013 |
NO |
20130039 |
Claims
1. A telescopic riser joint comprising: a first pipe part and a
second pipe part which each comprise means for connection to
respective first and second riser parts, the first and second pipe
parts being overlapping and in use arranged to form part of a riser
with an internal flow passage; a cylinder arrangement comprising a
first set of cylinders, each cylinder having a piston rod with a
piston head positioned within a cylinder housing, the piston rod
and cylinder housing being respectively connected to one of the
first pipe part or the second pipe part; wherein one side of the
piston head in use is in communication with external pressure which
provides an axial force acting in a longitudinal direction of the
riser and the other side of the piston head faces a sealed chamber;
and wherein the first set of cylinders is configured such that a
fluid in the sealed chamber and the external pressure produce a
resultant force which tensions the first riser part and the second
riser part.
2. The telescopic riser joint according to claim 1, further
comprising a second set of cylinders, which each comprise a piston
rod with a piston head positioned within a cylinder housing, the
piston rod and the cylinder housing being respectively connected to
the first pipe part and the second pipe part, and wherein one side
of the piston head is in fluid communication with internal fluid in
the riser and compensates the telescopic riser joint for internal
pressures in the riser.
3. The telescopic riser joint according to claim 1, wherein the
riser joint comprises an override system adapted for increasing the
connection force between the first riser part and the second riser
part.
4. The telescopic riser joint according to claim 2, wherein the
first set of cylinders and the second set of cylinders are arranged
next to each other around the periphery of the riser.
5. The telescopic riser joint according to claim 1, further
comprising a manifold which is adapted to distribute the internal
pressure within the riser to the different cylinders in the
cylinder arrangement, the manifold having at least one bore leading
to one cylinder comprising a floating piston and a stop surface for
the floating piston.
6. The telescopic riser joint according to claim 1, wherein the
riser joint is arranged in a lower half of the riser.
7. The telescopic riser joint according to claim 2, wherein the
number of cylinders in the first set of cylinders and in the second
set of cylinders are adjustable.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a telescopic joint to be used as
part of a riser configuration offshore. More particularly, the
invention relates to a heave compensating telescopic riser
joint.
BACKGROUND OF THE INVENTION
[0002] In offshore oil and gas exploration, well intervention and
hydrocarbon production from subsurface formations, it is normal to
equip floating surface equipment with a heave compensation system
that compensates for the relative movements between a floating
vessel and a riser. The riser is normally connected to the seabed
through a subsea structure, e.g. a wellhead. The heave compensation
system compensates for movements in the floating vessel caused by
e.g. wind and waves. A drawback of such topside heave compensation
systems is that they require large space on the vessel deck.
Additionally, these known systems comprise large, heavy equipment
that is difficult to move and/or maintain. It is also known prior
art solutions which relate to drilling apparatuses where the
tensioning equipment is arranged below the platform deck. Examples
of such solutions are disclosed in U.S. Pat. No. 3,211,224 and U.S.
Pat. No. 3,643,751.
[0003] Document U.S. Pat. No. 3,643,751 relates to a hydrostatic
riser pipe tensioner for use in underwater drilling operations, and
discloses a drilling assembly comprising a wellhead-connector,
ram-type blow-out preventers, sleeve-type blow out preventer, and a
telescoping joint in a marine conductor pipe which extends upwardly
to the vessel. The upper end of the conductor pipe is secured to
the vessel against relative vertical motion therewith by means of
tie rods or cables. The telescopic joint comprises an upper section
which is connected to the lower end of a major portion of the
conductor pipe and forms a continuation thereof, and a lower
section which is fixedly secured to the top of the blow-out
preventer, or the top of any other wellhead component arranged in a
series-connected arrangement forming a drilling passage for a drill
string.
[0004] It is an objective of the present invention to provide a
heave compensation system that addresses at least one of the
drawbacks of the prior art solutions.
[0005] Another objective of the invention is to provide a heave
compensation system that heave-compensates the entire length of the
riser, such as to minimize the loads exerted on the wellhead.
SUMMARY OF THE INVENTION
[0006] The invention is defined in the main claim, while the
dependent claims describe other characteristics of the
invention.
[0007] The invention relates to a telescopic riser joint for
connecting a first riser part and a second riser part giving the
possibility of telescopic movement between the riser parts while at
the same time forming a continuous riser.
[0008] The telescopic riser joint according to the invention
comprises a first pipe part and a second pipe part with means for
connection to, and forming part of, a riser with an internal flow
passage. The telescopic joint will connect a first riser part and a
second riser part to form a riser.
[0009] The telescopic joint comprises a cylinder arrangement
comprising a first set of cylinders, each cylinder having a piston
rod with a piston head and a cylinder housing and the piston rod
and cylinder housing being respectively connectable to one of the
first pipe part or second pipe part. One side of the piston head in
the first set of cylinders is, during use, in communication with
external pressure providing an axial force acting in the
longitudinal direction of the riser and the other side of the
piston head is facing a sealed chamber. The first set of cylinders
is configured such that a fluid in the sealed chamber and a fluid
on the other side of the piston head give a resultant force
tensioning the first riser part and the second riser part.
[0010] The sealed chamber will have a fluid with a relatively low
pressure compared with the pressure on the other side of the piston
head, creating a "vacuum effect" of the sealed chamber.
[0011] In the system according to the invention the riser is
typically connected to a subsea structure in its lower end and to a
floating vessel or platform in its upper end. Due to the
configuration of the arrangement, problems may occur when the
floating vessel heaves due to wind, waves and currents. To address
this problem it is provided a telescopic riser joint in the riser
as defined above.
[0012] The cylinder arrangement may be arranged on the radial
outside of the pipe parts, the cylinder arrangement may be arranged
at least partly outside the pipe parts.
[0013] Parts of the cylinder arrangement may be provided in between
the pipe parts. It is also possible to envisage parts of the
cylinder arrangement provided inside the pipe parts.
[0014] The telescopic joint according to the invention may be
provided in different kinds of risers. The riser may stand in
seawater or within another riser, and it may or may not be
configured to tolerate higher internal pressures. It may be
provided in different riser, such as a marine riser, a workover
riser or possibly a drill string riser, an open sea workover riser
or in a production riser.
[0015] By having a telescopic joint according to the invention
which provide heave compensation of the riser, will give a
possibility to clear space on the vessel deck. The telescopic joint
according to the invention may on the piston side be exposed to
external pressure. The external pressure may be the ambient
seawater, or another external pressure source such as a column with
a heavy fluid inside a marine riser, or possibly also a separate
pipe or hose with a fluid arranged inside or outside the riser and/
or marine riser. It would be the static height of the fluid that
provides the external pressure in the telescopic joint. It would
also be possible to provide the connection to the external fluid
pressure with a pressure intensifier, e.g a pump. This could be
interesting when applying the invention in situations with less
water depths. Another possibility is to provide the telescopic
joint with means providing additional external forces assisting the
pressure from the external fluid, normally seawater. This
additional means may be accumulators, springs, booster pump,
weights etc. The alternative pressure sources for the external
pressure may be used alone or in combinations. The external
pressure, independent on which source, must always give a pressure
on the system larger than the pressure from the sealed chamber.
[0016] The force acting on the telescopic joint is dependent on the
working area of the cylinder piston heads and the sea depth, i.e.
the weight of the column working on the cylinder piston heads. At
larger depths the hydrostatic pressure exerted from the fluid above
the cylinder pistons increases, resulting in a greater withstanding
force preventing separation of the first riser part and the second
riser part. Similarly, at shallower depths the hydrostatic pressure
exerted from the fluid above the cylinder pistons decreases,
resulting in a smaller withstanding force preventing separation of
the first riser part and the second riser part.
[0017] The telescopic riser joint is typically constructed in a
collapsed state while, in use, it is set in "an operational
position", i.e. a position pre-tensioning both the first and second
riser parts (both above and below the telescopic riser joint) while
at the same time allowing the riser to move both upwards and
downwards, extending and collapsing the riser joint. The telescopic
joint will, in use, provide tension in both the first and second
riser parts due to that the cylinder arrangement is connectable to
the first or second pipe parts and the forces will try to collapse
the telescopic joint and therefore make a pull or tension in both
of the riser parts. The hydrostatic column works on one side of the
piston head, while the sealed chamber provides a "vacuum effect" on
the other side of the piston head, resulting in that the fluid in
the sealed chamber and the fluid on the other side of the piston
head give a resultant force tensioning the first and second riser
parts. The "vacuum effect" in the sealed chamber increases as the
first and second pipe parts move relatively away from each other,
and decreases a bit as the first and second pipe parts are moved
towards each other again. However the change in tension may be
quite limited.
[0018] In an aspect of the invention it is possible to provide a
pressure compensated telescopic joint for risers wherein there is a
fluid under pressure. According to the invention the telescopic
joint may then be provided with a second set of cylinders in the
cylinder arrangement. The second set of cylinders is arranged for
pressure compensating the riser for the end cap effect of the
internal pressure in the riser. The second set of cylinders are
configured such that the pressure within the riser act on a piston
head in the cylinders and counteract the end cap effect of the
pressure within the riser. The second set of cylinders have a
piston rod with a piston head and a cylinder housing respectively
connectable to the first pipe part and the second pipe part, where
one side of the piston head is in fluid communication with the
internal fluid in the riser and compensates the riser joint for the
internal pressures inside the riser.
[0019] The first set of cylinders and the second set of cylinders
may in one embodiment have similar length.
[0020] The first set of cylinders and the second set of cylinders
may be arranged next to each other, around the periphery of the
riser. They may also be arranged with several cylinders in each
set, alternating around or alternating in groups around the
circumference of the pipe parts. In one embodiment at least one of
the sets of cylinders may also be an annular cylinder. The first
and second set of cylinders may be arranged such that they are
positioned with the first set radially within the second set of
cylinders. This giving the possibility of removing the second set
of cylinders in cases where the riser is not experiencing internal
pressure and adding them in case there are going to be internal
pressure.
[0021] According to an aspect of the invention the cylinder
arrangement may be configured such that some of the cylinders in
one set of cylinders, or the whole set of cylinders, may be removed
or added to the telescopic joint. This will give flexibility in
adapting the system to different water depths or with or without
internal pressure within the telescopic joint.
[0022] The telescopic joint may also be provided with an override
system to be used in situations where it is expected large external
forces on the system, i.e. to provide a system that increases the
connection force between the first and second riser parts, i.e. the
first pipe part and the second pipe part. One such situation is for
instance when the riser joint is lifted through the splash zone.
The telescopic joint may be configured such that it can be extended
or collapsed to an end position. The telescopic joint may be
configured to be mechanically or hydraulically be locked in such a
position. This may be unlocked remotely or by for instance an ROV,
when in position or when there is no longer a need for locking the
joint. This override system might be done with separate cylinders
or with the cylinders used for reading the external pressure or
cylinders pressure compensating the telescopic joint. These
cylinders may also be provided with a remotely operated valve in
the connection, giving the possibility of locking the telescopic
joint in a position by locking a fluid, preferably liquid, within
the cylinders.
[0023] Another alternative is to provide a separate cylinder/piston
arrangement connected between the first and the second pipe parts,
or alternatively by using all or some of the second set of
cylinders for this function, or position these specific cylinders
in between the cylinders in the first set of cylinders. The
cylinder arrangement providing the override system is then fluid
filled and locked in a set position. The fluid may be locked in the
cylinders by means of a valve which may be remotely operated. The
fluid locked inside the cylinders may be released to an active
receiver with for instance 1 bar pressure, or to the sea.
Alternatively, one may add an additional pressure to the fluid in
the cylinder by a connection to a pressure cylinder with for
instance .about.700 bar pressure. This override system may comprise
a set of cylinders, including one cylinder, but preferably two or
more separate cylinders such as to provide redundancy in the
system.
[0024] In an aspect the riser joint may comprise a manifold adapted
for distributing a fluid in order to compensate for the internal
pressure within the riser to the different cylinders in the second
set of cylinders. Further, the manifold may comprise at least one
flow regulating means, which flow regulating means may be adapted
for regulating to which of the cylinders the fluid is distributed.
The flow regulating means may then also be used when removing or
adding cylinders from the telescopic joint.
[0025] Additionally or alternatively the manifold may be adapted
for distributing the internal pressure within the riser to the
different cylinders in the cylinder arrangement, having at least
one bore in the manifold, leading to one cylinder comprising a
floating piston and a stop surface for the floating piston.
[0026] In an aspect the telescopic riser joint may be arranged in
the lower half of the riser. According to one embodiment it may be
arranged in close proximity of the wellhead, possibly as a joint
above the wellhead. It may be positioned as a joint close to the
wellhead.
[0027] The number of cylinders in the first set of cylinders and in
the second set of cylinders may be adjustable. The number of
cylinders in a set may be one, two, three, four, five or another
number higher than this. There may be different numbers in the
different sets. The number of cylinders in the first set of
cylinders and in the second set of cylinders may be adjustable. The
riser joint may for this be equipped with means for connecting and
disconnecting cylinders in both the first set and second set of
cylinders. The connection means for the second set of cylinders
comprises quick couplings, which when connected also opens a fluid
connection between the cylinder and the fluid within the riser
joint. The quick coupling closes the fluid connection automatically
when a cylinder is removed from the riser joint. There may be
different connection means for the cylinders of the first set of
cylinders and the second set of cylinders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 shows an overview of a riser system
configuration.
[0029] FIG. 2 shows a simplified perspective view of a first set of
cylinders according to the invention.
[0030] FIG. 3 shows a perspective view of an override system
according to the invention.
[0031] FIG. 4 shows an alternative embodiment of the invention.
[0032] FIG. 1 shows an overview of a riser system configuration
including subsea equipment connected to a riser, which riser
extends through a body of water up to a floating vessel, where the
riser is tensioned by a tensioning system connected to the platform
in one end and to the riser in the other end. The maximum
operational trim condition for the riser is disclosed in the
Figure.
[0033] FIG. 2 shows a simplified perspective view of a first set of
cylinders according to the invention. The first set of cylinders 32
may comprise one, two or several cylinders. In the disclosed
embodiment, the cylinders of the first set of cylinders 32 are
provided with at least one opening 56 to the sea in the volume 50
on the upper side of the cylinder piston 51, and has a fluid on the
lower side 52 of the piston 51, i.e. in the sealed chamber.
Alternatively, the cylinder piston 51 and cylinder may be rotated
180 degrees such that the opening 56 is arranged on the lower side
of the piston 51 (as disclosed in FIG. 4). The figure shows that
the piston rod 57 is mechanically linked to the first pipe part 8
and the cylinder is mechanically linked to the second pipe part 9.
The first and second pipe parts 8 are connectable to first and
second riser parts (not shown). When the telescopic riser joint 4
is extending, the external pressure, e.g. from the seawater, acting
on the upper side of the cylinder piston 51 and the "vacuum effect"
(low pressure) from the sealed chamber 52 on the lower side of the
piston 51 both assist in forcing the two pipe parts 8, 9 to a
collapsed state, i.e. they provide a force that acts against the
separation forces in the telescopic riser joint 4 heave
compensating the riser.
[0034] FIG. 3 shows a perspective view of an override system
according to the invention. The override system may be used in
situations where it is expected large external forces on the
system, i.e. to provide a system that increases the connection
force between the first and second pipe parts 8, 9. This might be
done by providing a separate cylinder/piston arrangement 40 between
the first and the second pipe parts 8, 9, or alternatively by using
the second set of cylinders, or a combination of the second set of
cylinders and the separate cylinder/piston arrangement 40 for this
function. The volume 41 above the pistons 42 in the override
cylinders 47 constituting the separate cylinder/piston arrangement
40 is then fluid filled and locked in a set position. The fluid may
be locked in the override cylinders 47 by means of a valve (not
shown) which may be remotely operated. The locked fluid within the
override cylinders 47 may be released to an active receiver 43 with
for instance 1 bar pressure or to the sea 44. Valves 45, 46 may be
provided between the sea 44 and the override cylinders 47 and
between the active receiver 43 and the override cylinders 47.
Alternatively, one may add an additional pressure to the fluid in
the override cylinders 47 by a connection to a pressure cylinder 48
with for instance 700 bar pressure. This override system may
comprise a set of cylinders 47, including one cylinder, but
preferably two or more separate cylinders such as to provide
redundancy in the system.
[0035] FIG. 4 shows an alternative embodiment of the invention,
where the cylinder arrangement in the telescopic riser joint has
been turned 180 degrees. The piston rod 57 is in this embodiment
mechanically linked to the second pipe part 9 and the cylinder is
mechanically linked to the first pipe part 8. As the telescopic
riser joint 4 is extending, the pressure from the seawater acting
on the lower side of the cylinder piston 51 and the "vacuum effect"
from the sealed chamber 52 on the upper side of the piston 51 both
assist in forcing the two pipe parts 8, 9 to a collapsed state.
[0036] The invention is herein explained with reference to the
accompanied drawings. A person skilled in the art will understand
that there may be made alterations and modifications to this
embodiment that are within the scope of the invention as defined in
the attached claims.
* * * * *