U.S. patent application number 15/376893 was filed with the patent office on 2018-07-26 for methods for conducting a subsea well intervention, and related system, assembly and apparatus.
This patent application is currently assigned to CapWell AS. The applicant listed for this patent is CapWell AS. Invention is credited to Tore Aarsland, John Helvik, Morten Talgo.
Application Number | 20180209236 15/376893 |
Document ID | / |
Family ID | 53719895 |
Filed Date | 2018-07-26 |
United States Patent
Application |
20180209236 |
Kind Code |
A1 |
Talgo; Morten ; et
al. |
July 26, 2018 |
Methods for Conducting a Subsea Well Intervention, and Related
System, Assembly and Apparatus
Abstract
A method for conducting a subsea well intervention at a subsea
well, and a related system. In particular embodiments, an assembly
is provided comprising a wireline drum pressure container unit, a
lubricator package having a lock chamber tube enclosing a tool
string and having at least one valve in a vertical bore, and a
connector used to connect the assembly to a well control package on
a well head of the well. In such an embodiment, the method can
include displacing well fluid in a cavity between the valve of the
lubricator package and a valve of the well control package, using a
clean fluid, while the valve of the lubricator package is closed.
The assembly can then be disconnected from said well control
package at the connector and retrieved to the surface, whereby
contamination of seawater due to disconnection can be reduced or
minimized.
Inventors: |
Talgo; Morten; (Sandnes,
NO) ; Helvik; John; (Stavanger, NO) ;
Aarsland; Tore; (Naerbo, NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CapWell AS |
Stavanger |
|
NO |
|
|
Assignee: |
CapWell AS
Stavanger
NO
|
Family ID: |
53719895 |
Appl. No.: |
15/376893 |
Filed: |
June 19, 2015 |
PCT Filed: |
June 19, 2015 |
PCT NO: |
PCT/NO2015/050111 |
371 Date: |
December 13, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/076 20130101;
E21B 33/072 20130101; E21B 47/117 20200501; E21B 23/14
20130101 |
International
Class: |
E21B 33/076 20060101
E21B033/076; E21B 33/072 20060101 E21B033/072; E21B 23/14 20060101
E21B023/14; E21B 47/10 20060101 E21B047/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2014 |
NO |
20140782 |
Claims
1. A method for conducting a subsea well intervention at a subsea
well, the subsea well comprising a subsea tree with a well adapter
and a well control package comprising at least one valve in a bore,
the method comprising the steps of: (a) making up an assembly of a
wireline drum pressure container unit arranged on a lubricator
package with a lock chamber tube enclosing a tool string and having
at least one valve in the vertical bore and a connector; (b)
lowering said assembly to said well control package and connecting
the assembly using said connector to the well control package; (c)
pressure testing between said valve of the well control package and
said valve of the lubricator package; (d) opening the valve of the
lubricator package and the valve of the well control package; (e)
lowering said tool string into the well; (f) conducting a well
operation using said tool string in the well; (g) retrieving said
tool string from the well back into the lock chamber tube; (h)
closing the valve of the well control package; (i) closing the
valve of the lubricator package; (j) further pressure testing
between said valve of the well control package and said valve of
the lubricator package; (k) while the valve of the lubricator
package is closed, displacing well fluid in a cavity between the
valve of the lubricator package and the valve of the well control
package; (l) disconnecting said assembly comprising said lubricator
package and said wireline drum pressure container unit from said
well control package at said connector; and (m) retrieving the
disconnected assembly to the surface.
2. The method of claim 1, wherein the wireline drum pressure
container unit comprises an enclosed traction winch.
3. The method of claim 1, which further comprises using a clean
fluid bottle for local storage of the displacement fluid in the
proximity of the subsea tree and a fluid transfer system to drive
the fluid from the clean fluid bottle through the cavity to one of
a collector bottle, the well, or a production fluid outlet.
4. The method of claim 1, wherein the well control package is
connected to the lubricator package at surface, prior to performing
steps (a) to (m).
5. The method of claim 1, wherein either or both of the valve of
the well control package, and the valve of the lubricator package,
is arranged for being capable of shearing a line attached to the
tool string.
6. The method of claim 1, which further comprises, subsequently to
step (k), receiving flushed-out well fluid in a collector bottle
arranged on said lubricator package.
7. A subsea well intervention system comprising: an assembly of a
wireline drum pressure container package on a lubricator package on
said well control package, said lubricator package for holding on a
wireline a tool string in a lock chamber tube of the lubricator
package, wherein the system is arranged for running said assembly
to a well adapter; a connector for connecting and disconnecting
said well control package to and from said well adapter; a first
valve in said lubricator package; a second valve in said well
control package, a connector between said first and second valves;
and a fluid transfer system arranged for displacing well fluid in a
cavity between the first and second valves while the first valve is
closed.
8. The system of claim 7, further comprising a well adapter for
installing on a subsea tree, the well adapter being arranged for
receiving a well control package on top of the well adapter.
9. The system of claim 7, further comprising a clean fluid bottle
for local storage of non-polluting displacement fluid in proximity
of the subsea tree.
10. The system of claim 7, wherein either or both of the first and
second valves is a ball valve.
11. The system of claim 7, wherein said wireline drum pressure
container package comprises, within a pressure vessel connectable
on top of said lubricator package: a motor driven drum for said
wireline and arranged for maintaining a back tension on said
wireline; and a motor driven traction winch for lowering and
hoisting said line with said tool string in said lubricator and
said well.
12. The system of claim 7, wherein the well fluid is displaced
using a displacement fluid (F1C).
13. The system of claim 12, wherein the displacement fluid
comprises seawater from a seawater inlet (72).
14. The system of claim 7, wherein said well control package has a
vertical bore and comprises a lower shear/seal valve and an
isolation shear seal ball valve in the vertical bore.
15. An assembly for performing a subsea well intervention at a
subsea well, the assembly being configured to be releasably
connected to a well head via a connector, the assembly comprising a
lubricator package for containing a tool string in a chamber
thereof, and being configured for displacing well fluid from a
cavity between the chamber and the well head for preventing
pollution of the sea upon disconnection of the assembly, the cavity
being isolated from the chamber.
16. Apparatus for use in performing a subsea well intervention at a
subsea well, wherein an assembly is releasably connected to a well
head via a connector, the assembly comprising a lubricator package
for containing a tool string in a chamber thereof, the apparatus
being configured to displace well fluid from a cavity between the
chamber and the well head for preventing pollution of the sea upon
disconnection of the assembly, the cavity being isolated from the
chamber.
17. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to well intervention, and in
particular relates to methods for conducting a subsea well
intervention and a related system, assembly and apparatus.
BACKGROUND
[0002] Well interventions can be required from time to time. In the
oil and gas exploration and production industry, for example,
interventions may be performed to facilitate producing petroleum
fluids from a well. In this regard, a tool string comprising
various tools may be deployed on a line, such as a wireline cable
or a rope, fed into a wellbore and used to perform a well
intervention operation in the well. In order to deploy a tool
string into a subsea well, an assembly containing the tool string
in a chamber can be connected to a well head at the seabed,
allowing the tool string to access the wellbore. The tool string is
moved out of the chamber and into the wellbore for performing the
intervention. Afterwards, the assembly or parts thereof may
typically be disconnected from the well head. Upon disconnection,
residual well fluids including for example hydrocarbon fluids can
remain in the assembly from the intervention operation. If
appropriate measures are not taken, such well fluids may spill into
the sea and cause undesired contamination.
[0003] Published patent applications WO2008/015387 and
WO2001/025593 describe techniques which include displacing well
fluids of a vessel used for storing and deploying tools during
subsea well interventions.
[0004] In particular, WO2008/015387 describes purging fluid upward
through a tool storage package and winch arrangement. Such a
technique can involve substantial volumes of fluid to be displaced
and associated infrastructure which can be complex, and/or may be
substantial in size, capacity and/or cost.
[0005] Furthermore, there can be a need for avoiding contamination
by well fluids such as when disconnecting equipment from a subsea
well head, and for ensuring that components at the well and/or in
the assembly have appropriate pressure integrity.
[0006] An object is to address various needs, and/or obviate or at
least mitigate drawbacks or difficulties associated with the prior
art.
SUMMARY OF THE INVENTION
[0007] In light of the above, according to a first aspect of the
invention, there is provided a method for conducting a subsea well
intervention at a subsea well, the subsea well comprising a subsea
tree with a well adapter and a well control package comprising at
least one valve in a bore, the method comprising the steps of:
[0008] (a) making up an assembly of a wireline drum pressure
container unit arranged on a lubricator package with a lock chamber
tube enclosing a tool string and having at least one valve in the
bore and a connector;
[0009] (b) lowering said assembly to said well control package and
connecting the assembly using said connector to the well control
package;
[0010] (c) pressure testing between said valve of the well control
package and said valve of the lubricator package;
[0011] (d) opening the valve of the lubricator package and the
valve of the well control package;
[0012] (e) lowering said tool string into the well;
[0013] (f) conducting a well operation using said tool string in
the well;
[0014] (g) retrieving said tool string from the well back into the
lock chamber tube;
[0015] (h) closing the valve of the well control package;
[0016] (i) closing the valve of the lubricator package;
[0017] (j) further pressure testing between said valve of the well
control package and said valve of the lubricator package;
[0018] (k) while the valve of the lubricator package is closed,
displacing well fluid in a cavity between the valve of the
lubricator package and the valve of the well control package;
[0019] (l) disconnecting said assembly comprising said lubricator
package and said wireline drum pressure container unit from said
well control package at said connector; and
[0020] (m) retrieving the disconnected assembly to the surface.
[0021] The wireline drum pressure container unit may comprise an
enclosed traction winch.
[0022] The well fluid may be replaced by displacement fluid, e.g.
clean fluid. The method may further comprise using a clean fluid
bottle for local storage of the displacement fluid in the proximity
of the subsea tree and a fluid transfer system to drive the fluid
from the clean fluid bottle through the cavity to one of a
collector bottle, the well, or a production fluid outlet.
[0023] The well control package may be connected to the lubricator
package at surface, prior to performing steps (a) to (m).
[0024] Either or both of the valve of the well control package and
the valve of the lubricator package, may be arranged for being
capable of shearing a line attached to the tool string.
[0025] The method may further comprise, subsequently to step (k),
receiving flushed-out well fluid in a collector bottle arranged on
said lubricator package.
[0026] The bore may preferably be a vertical bore. The well may
typically be a petroleum well.
[0027] According to a second aspect of the invention, there is
provided a subsea well intervention system comprising: [0028] an
assembly of a wireline drum pressure container package on a
lubricator package on said well control package, said lubricator
package for holding on a wireline a tool string in a lock chamber
tube of the lubricator package, wherein the system is arranged for
running said assembly to a well adapter; [0029] a connector for
connecting and disconnecting said well control package to and from
said well adapter; [0030] a first valve in said lubricator package;
[0031] a second valve in said well control package, [0032] a
connector between said first and second valves; and [0033] a fluid
transfer system arranged for displacing well fluid in a cavity
between the first and second valves while the first valve is
closed.
[0034] The system may further comprise a well adapter for
installing on a subsea tree, where the well adapter may be arranged
for receiving a well control package on top of the well
adapter.
[0035] The system may further comprise a clean fluid bottle for
local storage of non-polluting displacement fluid in proximity of
the subsea tree.
[0036] Either or both of the first and second valves may be a ball
valve.
[0037] The wireline drum pressure container package may comprise,
within a pressure vessel connectable on top of said lubricator
package: [0038] a motor driven drum for said wireline and arranged
for maintaining a back tension on said wireline; and [0039] a motor
driven traction winch for lowering and hoisting said line with said
tool string in said lubricator and said well.
[0040] The well fluid may be displaced using a displacement
fluid.
[0041] The displacement fluid may comprise seawater from a seawater
inlet. The displacement fluid may comprise non-polluting fluid,
e.g. non-polluting to seawater.
[0042] The well control package may have a vertical bore. The well
control package may comprise a lower shear/seal valve and an
isolation shear seal ball valve in the bore.
[0043] According to a third aspect of the invention there is
provided an assembly for performing a subsea well intervention at a
subsea well, the assembly being configured to be releasably
connected to a well head via a connector, the assembly comprising a
lubricator package for containing a tool string in a chamber
thereof, and being configured for displacing well fluid from a
cavity between the chamber and the well head for preventing
pollution of the sea upon disconnection of the assembly, the cavity
being isolated from the chamber.
[0044] The chamber may be defined inside a lock chamber tube. The
assembly may further comprise a fluid transfer system for
displacing the well fluid from the cavity. The lubricator package
may comprise at least one valve. The valve may be arranged for
isolating the chamber from the wellbore. The valve may be further
arranged to isolate the cavity from the chamber. The well head may
comprise at least one valve, e.g. within a well control package
provided thereupon. The cavity may thus be isolated between the
valve of the lubricator package and the valve of the well head or
well control package. The connector may comprise first and second
parts, which may be connectable together to form the connection
between the assembly and the well head. The connector may thus be
provided between the valve of the lubricator package and the valve
of the well head or well control package.
[0045] According to a fourth aspect of the invention there is
provided apparatus for use in performing a subsea well intervention
at a subsea well, wherein an assembly is releasably connected to a
well head via a connector, the assembly comprising a lubricator
package for containing a tool string in a chamber thereof, the
apparatus being configured to displace well fluid from a cavity
between the chamber and the well head for preventing pollution of
the sea upon disconnection of the assembly, the cavity being
isolated from the chamber.
[0046] The apparatus may comprise a fluid transfer system.
[0047] According to a fifth aspect of the invention there is
provided a method of performing a subsea well intervention, using
the assembly of the third aspect or the apparatus of the fourth
aspect.
[0048] The method may include any one or more of: connecting the
assembly to the well head; isolating the chamber from the wellbore
and/or from the cavity; displacing the well fluid from the
cavity.
[0049] Any of the aspects of the invention may include further
features as described in relation to any other aspect, wherever
described herein. Features described in one embodiment may be
combined in other embodiments. For example, a selected feature from
a first embodiment that is compatible with the arrangement in a
second embodiment may be employed, e.g. as an additional,
alternative or optional feature, e.g. inserted or exchanged for a
similar or like feature, in the second embodiment to perform (in
the second embodiment) in the same or corresponding manner as it
does in the first embodiment.
[0050] Embodiments of the invention can be advantageous in various
ways as will be apparent from throughout the specification. An
advantage associated with some embodiments is that displacement of
fluids can be limited to a cavity between two rams.
DESCRIPTION AND DRAWINGS
[0051] There will now be described, by way of example only,
embodiments of the invention with reference to the accompanying
drawings, in which:
[0052] FIG. 1 is a representation of a well intervention system on
a subsea wellhead according to an embodiment of the invention;
[0053] FIGS. 2 to 13 are representations showing in sequence steps
in a method for conducting a well intervention according to an
embodiment of the invention; and
[0054] FIG. 14 is a schematic representation showing the cavity
from which well fluids are flushed out in the method of FIGS. 2 to
13.
[0055] With reference firstly to FIG. 1, a well intervention system
400 is shown. The system 400 has a winch package or line drum
pressure container package 100, a lubricator package 80, and a well
control package 30.
[0056] The line drum pressure container package 100 has a line drum
pressure container unit 101 comprising a pressure vessel.
[0057] The lubricator package 80 includes the following: [0058] a
first valve in the form of an upper shear seal ball valve 83;
[0059] a lock chamber pipe 81; [0060] a fluid transfer system 70;
[0061] a clean bottle 72 for flushing fluid; [0062] a collector
bottle 71 for well fluids; [0063] a hydraulic power unit (HPU) 60;
and [0064] a second valve in the form of a lower shear seal ball
valve 82.
[0065] The well control package 30 includes a third valve in the
form of an isolation [shear seal] ball valve 34 and a fourth valve
in the form of a lower shear seal [ball] valve 32.
[0066] As can be seen, the well head is at the seabed S and has a
well adapter 10 arranged on a horizontal subsea "christmas" tree 1.
The well adapter 10 is provided with a kill/flush line 2, and a
crown plug 3 is installed.
[0067] The system 400 further includes an upper quick connector 102
comprising parts 102a, 102b connecting the line drum pressure
container package 100 and the lubricator package 80. The system 400
further includes an upper quick connector 36 comprising parts 36a,
36b connecting the lubricator package 80 and the well control
package 30. Furthermore, the system 400 further includes a lower
quick-connector 11 comprising parts 11a, 11b connecting the well
control package 30 to the well adapter 10. The system also has a
pressure sensor 84.
[0068] The system 400 includes a tool string S1, S2 which in FIG. 1
is contained in the lock chamber pipe 81.
[0069] An assembly A includes the line drum pressure container
package 100, the lubricator package 80, and the well control
package 30. The line drum pressure container package 100 comprises
the pressure vessel assembled and mounted on the lubricator package
80 which is connector-mounted on the well control package 30 with a
further connection, together configured to be prepared with a tool
string S1, S2 and lowered in the sea for connecting the assembly A
to the well adapter 10 on the subsea wellhead. It can be noted that
the first valve 83 between the pressure vessel and the lubricator
package 80 may be a shear seal ball valve and is an optional
feature.
[0070] FIG. 2 shows the assembly A, including the line drum
pressure container package 100, the lubricator package 80, and the
well control package 30 being lowered to the well adapter 10 on the
subsea tree 1. In FIG. 2, a cavity 35 between the second valve 82
and the third valve 34 is indicated. The assembly A is being
lowered using a handling wire 90. A first tool string S1 is housed
and protected in the liquid-filled lubricator.
[0071] FIG. 3 illustrates the assembly A after being lowered onto
the well adapter 10. The well control package 30 is connected to
the well head with the crown plug 3 present, and pressure testing
is performed. The well control package 30 is connected to the well
adapter 10. The third valve 34 and the fourth valve 32 are open.
The second, shear seal, valve 82 of the lubricator package 80 is
closed. Pressure testing above the crown plug 3 is performed.
[0072] FIG. 4 shows the crown plug 3 being pulled, subsequent to
the step shown in FIG. 3. The second valve 82 on the lubricator is
open, and the tool string S1 is lowered to pull the crown plug
3.
[0073] FIG. 5 shows the crown plug 3 being retrieved to the
lubricator, back into the lock chamber pipe 81, in a further step.
The fourth valve 32 [i.e. the lower shear/seal valve] is closed,
and the second valve 82 [i.e. the lubricator valve], is closed. The
third valve 34 is open. The region between the fourth valve 32 and
the second valve 82 [i.e. between the lower shear/seal valve and
the lubricator valve] is bled off, and the fourth valve 32 [i.e.
lower shear/seal valve] is pressure tested. A pressure sensor 84 in
the second valve 82 is provided for sensing pressure in a region
between the second valve 82 and the third valve 34 in the cavity
35. The crown plug 3 is retrieved from its position in FIG. 4 by a
distance D.
[0074] FIG. 6 shows a next step in which the cavity 35 is being
flushed by a clean fluid F1C from the clean bottle 72. Flushed
fluid in the form of well fluid F1P is collected in the collector
bottle 71. This will allow disconnection of the second valve 82
from the third valve 34 because the cavity fluid becomes clean and
thus environmentally friendly. The third valve 34 is closed. A
pressure test between the second valve 82 and the third valve 34 is
performed. The cavity 35 is then flushed with an environmentally
friendly fluid, between the second and third valves 82, 34.
[0075] In other embodiments, the clean fluid F1C may be provided
from the surface or from seawater from the surrounding sea.
[0076] In FIG. 7 a part of the assembly A is disconnected from the
well control package 30. The disconnected part of the assembly,
assembly A', includes the lubricator package 80 and the line drum
pressure container package 100. The assembly A' is shown with the
crown plug 3 on its way for being retrieved to the surface. The
well control package 30 is shown with two valves closed forming a
pressure tested barrier on the well adapter 10. The lubricator
package 80 is disconnected from the well control package 30. The
second, third and fourth valves 82, 34 and 32 are closed. The
lubricator package 80 and line drum pressure container package 100
are retrieved upward to the surface, as indicated by arrow U.
[0077] In FIG. 8, a subsequent step is shown in which the assembly
A', which was retrieved to the surface, has been prepared with a
new tool string S2 for operating in the well. In FIG. 8, the
assembly A' is lowered as indicated by arrow L. The new tool string
S2 is installed in the lock chamber pipe 81 in the lubricator and a
pressure test performed at the surface. The line drum pressure
container package 100 and the lubricator package 80, including the
new tool string S2 are run, toward the seabed S. The second, third
and fourth valves 82, 34, 32 are closed. The well control package
30 is arranged on the well adapter 10 as in the preceding step of
FIG. 7. The clean fluid bottle 72 contains clean fluid F1C for
flushing the cavity 35.
[0078] In one variant, the step illustrated in FIG. 8 can be
performed using a new assembly which is configured in the same way
as the assembly A'. Thus, other variants of the method are possible
where this step makes use of a new assembly which may not have
previously been used in the method.
[0079] In other embodiments, FIG. 8 may also be illustrative of a
first step of a method for conducting subsea well intervention when
a well control package 30 is already installed on the well adapter
10 on the subsea tree 1 prior to commencement.
[0080] In FIG. 9, a yet further step is shown in which the
lubricator package 80 containing the new tool string S2 is being
connected to the well control package 30. The third valve,
isolation valve 34 and the second valve, lubricator valve 82 are
pressure tested. Accordingly, pressure testing between the second
and third valves 82, 34 may be performed. The second, third and
fourth valves 82, 34, 32 are closed.
[0081] FIG. 10 shows a further step in which the third valve,
isolation valve 34 is opened and in-flow testing of the fourth
valve, shear-seal valve 32 is conducted. In doing so, the second
valve 82 is closed, the third valve 34 is open, and the fourth
valve 32 is closed.
[0082] FIG. 11 shows a further step in which the fourth valve,
shear-seal valve 32 is opened, the second valve, lubricator valve
82 is opened, and the tool string S2 is lowered into the well as
indicated by arrow R and used for conducting a mechanical, chemical
or logging operation in the well. The wireline W from the drum to
the logging string S2 may be a rope-like wireline with a very small
allowable bending radius, as described in patent publication
WO2013/036145. In FIG. 11, the second, third and fourth valves 82,
34, 32 are all open.
[0083] FIG. 12 illustrates the tool string S2 in a further step
retrieved back to the lock chamber pipe 81 in the lubricator and
with the lower valve 82 of the lubricator package 80 closed.
Similar preparations as above may be taken to test valves and clean
the cavity 35 before disconnecting the lubricator package 80 from
the well control package 30. The well control package 30 may be
left residing on the wellhead adapter 10 for subsequent
installation of a crown plug 3 or a subsequent well intervention.
The second valve 82 is closed, the third valve 34 is closed and the
fourth valve 32 is closed. A bleed off is performed, between the
second valve 82 and the fourth valve 32. The fourth valve 32 is
inflow tested. The cavity 35 between the second and third valves
82, 34 is flushed clean by non-polluting clean fluid F1C below the
second valve, and flushed well fluids F1P are retained in the
collector bottle 71. The lubricator package 80 is then disconnected
non-pollutingly from the well control package 30.
[0084] FIG. 13 illustrates the disconnected assembly A' including
the line drum pressure container package 100 [including unit 101]
and the lubricator package 80 being retrieved to the surface as
indicated by arrow U'. The tool string S2 is retrieved in the lock
chamber tube 81 of the lubricator package 80, the lower shear-seal
valve 32 and lubricator valve 82 have been closed and bled off. The
fourth valve, shear seal valve 32 has been in-flow tested, third
valve, isolation valve 34 is closed, cavity 35 has been flushed
with non-polluting fluid F1C, and flushed well fluid F1P has been
collected in collector bottle 71. Lubricator package 80 has been
disconnected from well control package 30 to obtain non-polluting
disconnection. No well fluid is spilt into the seawater.
[0085] With reference to FIG. 14, the cavity 35 is shown between
the second and third valves 82, 34 when first and second parts of
connector 36a, 36b are connected. Clean fluid F1C is supplied from
the bottle 72 through inlet 73 into the cavity 35, and flushed well
fluid F1P in the cavity 35 is flushed out of the cavity 35 through
an outlet 74 to the collector bottle 71. In other variants, a
seawater inlet may provide a supply of seawater from the sea
through the inlet 73 to flush out the cavity 35, instead of from
the bottle 72.
[0086] It is important in subsea well intervention operations to
ensure that there are always two pressure barriers between the well
and the sea. In addition, it is important to test these barriers
when established, before conducting a subsequent operation.
Furthermore, it is important to avoid polluting the sea when
disconnecting valve packages for retrieving them to the surface.
Such precautions can prevent leakage and pollution in case one
barrier should fail by accident.
[0087] In an embodiment of the invention, with reference again to
the FIGS. 1 to 14, a method for conducting an intervention of
subsea petroleum wells comprises utilizing a well adapter 10, a
well control package 30, a lubricator package 80 and a winch
package 100 comprising the line drum pressure container unit 101.
These are installed on the subsea tree 1. The well adapter 10 is an
interface between the subsea tree 1 and the well control package 30
and may include hydraulic and electrical features in addition to
the mechanical features. The well control package 30 is equipped
with at least one valve 32, 34 in a vertical bore. Additional
valves can preferably be added for increased versatility and
reliability. The lubricator package 80 is likewise equipped with at
least one valve 82 in the vertical bore, a lock chamber pipe 81 and
a fluid transfer system 70. The lock chamber pipe 81 acts as a
deployment chamber for the tool string S1, S2 during the start and
end of the operation. The fluid transfer system 70 may be used for
two purposes, a first purpose being to displace the fluids in the
cavity 35 between the closed valves 82, 34 of the lubricator
package and the well control package respectively, and a second
purpose being used to verify the integrity of the system. The
lubricator package 80 can also have a valve 83 in the vertical bore
above the lock chamber pipe 81 which will be redundant to the
valves further below and constitute a backup in case these are
blocked by the tool string S1, S2.
[0088] The subsea well intervention method starts by assembling the
winch package 100 and the lubricator package 80 that enclose the
first tool string S1. The tool string S1 is attached to the lower
end of the line spooled on the winch drum. Said assembly 100, 80 is
lowered to the well control package 30 installed on the subsea tree
1 by means of the well adapter 10, and is then connected 36a, 36b
(see e.g. FIG. 8).
[0089] In an embodiment of the invention the pressure integrity of
the aforementioned connection (36a, 36b) is validated by using the
fluid transfer system 70 to generate a monitored over-pressure in
the cavity 35 between the lowermost valve 82 of the lubricator
package 80 and the uppermost valve 34 of the well control package
(see e.g. FIG. 9 and related description above).
[0090] Proceeding further, all of the valves of the lubricator
package 80 and of the well control package 30 are opened. This may
be done in a manner with consecutive integrity checks of each step
(see e.g. FIG. 10 and related description above).
[0091] When the pressure integrity has been confirmed throughout
and the valves 82, 32, 34 are open, the tool string S1 is then
lowered into the well (see e.g. FIGS. 10 and 11 and related
description above) by lowering using the winch in the line drum
pressure container unit 101. The tool string S1 is then used to
conduct a well intervention inside the well before at least a part
of it is retrieved back up into the lock chamber tube 81 and the
valves 82 of the lubricator package 80 and the valves 32, 34 of the
well control package 30 are closed.
[0092] The tool string comprises elements which are mechanical,
electrical, radiating, explosive, or optical or any combination of
these. The tool string can be used to activate actions or passively
monitor the conditions of the well. It may also include driven
machinery such as well tractors and/or milling tools.
[0093] The fluid transfer system 70 is used to validate the
pressure integrity of the said closed valves 82 of the lubricator
package 80 and the valves 32, 34 of the well control package 30,
and to displace the fluids in the cavity 35 between the two said
valves 82, 34. The displacement of fluids replaces the potentially
polluting well fluid trapped in the cavity 35 by a non-polluting
fluid (see e.g. FIG. 12 and related description above).
[0094] The assembly 100, 80 of the lubricator package 80 and winch
package 100 can then be disconnected from the well control package
30 at the said connection 36a, 36b and retrieved to surface without
spilling any potentially polluting or harmful fluids to the sea
(see e.g. FIG. 13). The aforementioned method can be repeated with
the same or other tool strings for various well intervention tools
for intervention operations according to the operator's desire.
[0095] In an embodiment of the invention, the winch package 100
comprises a traction winch 102 and a drum, enclosed inside a
pressure container unit 101. Such a line drum pressure container
arrangement is exemplified by patent publication WO2013/036145.
[0096] In an embodiment of the invention, the fluid transfer system
70 comprises a clean fluid bottle 72 for local storage of the
non-polluting displacement fluid in the proximity of the subsea
tree 1. Said vessel is preferably used to bring the non-polluting
displacement fluid from the surface to the seabed and thus
eliminates the need for a dedicated fluid line from the surface.
The displacement of fluids from the cavity 35 between the two
valves 82, 32 is performed by driving non-polluting displacement
fluid held from the clean fluid bottle 71 through the cavity 35 to
either a collector bottle 71, into the well or to a production
fluid outlet. The driving mechanism for displacing the displacement
fluid can be a piston, a pump, utilizing differential pressure, or
a combination of these. The driving mechanism intended for driving
the displacement fluid can secondarily be used for integrity
testing by generating a controlled over-pressure.
[0097] In an embodiment of the invention, the well control package
30 is installed on the well adapter 10 on the subsea tree 1 prior
to commencing the method as seen in FIG. 8.
[0098] In an embodiment of the invention, the well control package
30 is installed to the lubricator package 80 at surface, prior to
the commencement of the method, as seen in FIG. 2. The subsequent
steps of the method are then adapted accordingly. The well adapter
may be an integral part of either the well control package 30 or
the subsea tree 1.
[0099] In an embodiment of the invention at least one of the valves
32, 34 of the well control package 30 and/or the valve 82 of the
lubricator package is arranged for being capable of shearing the
line W attached to the tool string S1 and/or the tool string S1
itself.
[0100] In an embodiment of the invention at least one of valve 32
and valve 82 of the lubricator package 80 is a ball valve.
[0101] Various modifications and improvements may be made without
departing from the scope of the invention herein described.
[0102] Various other aspects or embodiments of the invention are
set out in the following numbered paragraphs: [0103] 1. A method
for conducting a subsea well intervention, said subsea well
comprising a subsea tree (1) with a well adapter (10) and a well
control package (30) comprising at least one valve (32) in the
vertical bore); (FIG. 8) comprising the steps of: [0104] making up
an assembly (100, 80) of a wireline drum pressure container unit
(100, 101) arranged on a lubricator package (80) with a lock
chamber tube (81) enclosing a tool string (s2) and having at least
one valve (82) in the bore and a connector (36a, b); [0105]
lowering said assembly (100, 80) to said well control package (30)
and connecting it using said connector (36a, b) to said well
control package (30); (FIG. 9) [0106] pressure testing between said
well control package's (30) valve (32) and said lubricator's valve
(82), (FIG. 9); [0107] opening said lubricator package's (80) valve
(82) and the well control package's (30) one or more valves (32,
34); (FIG. 10) [0108] lowering said tool string (S2) into the well;
(FIG. 11) [0109] conducting a well operation using said tool string
(s2) in the well, (FIG. 11) [0110] retrieving said tool string (S2)
from the well back into the lock chamber tube (81), (FIG. 12);
[0111] closing said well control package's (30) one or more valves
(32, 34); [0112] closing said lubricator package's (80) valve (82);
[0113] pressure testing between said well control package's (30)
valve (32) and said lubricator package's (80) valve (82); [0114]
displacing the well fluids in the cavity (35) between the two said
valves (82 and 32) with a non-polluting fluid (F1C) [non-polluting
to seawater] [0115] disconnecting said assembly (100, 80)
comprising said lubricator package (80) and said wireline drum
pressure container unit (100, 101) from said well control package
(30) at said connector (36a, b), and retrieving them to the
surface. [0116] 2. A method according to paragraph 1, wherein said
wireline drum pressure container unit (100, 101) comprises an
enclosed traction [capstan] winch. [0117] 3. A method according to
paragraph 1 or 2, using a clean fluid bottle (72) for local storage
of the non-polluting displacement fluid (F1C) in the proximity of
the subsea tree (1) and a fluid transfer system (70) to drive the
non-polluting fluid from the clean fluid bottle (72) through the
cavity (35) to either a collector bottle (71), into the well or to
a production fluid outlet. [0118] 4. The method according to any of
paragraphs 1 to 3 wherein the well control package (30) is
installed to the lubricator package (80) at surface, prior to the
commencement of the method. [0119] 5. The method according to any
of paragraphs 1 to 4 wherein at least one of the said well control
package's valve (32) or lubricator package's valve (82) is arranged
for being capable of shearing the line attached to the tool string.
[0120] 6. The method according to any of paragraphs 1 to 5,
subsequent to displacing the well fluids in the cavity (35) between
the two said valves (82 and 32) with a non-polluting fluid (F1C)
[non-polluting to seawater], retaining flushed-out well fluid (F1P)
to a collector bottle (71) arranged on said lubricator package
(80). [0121] 7. A subsea well intervention system comprising:
[0122] an assembly (100, 80, 30) of a wireline drum pressure
container package (100, 101) on a lubricator package (80) on said
well control package (30), said lubricator package (80) for holding
on a wireline a tool string (S1, S2) in its lock chamber tube (81),
and arranged for running said assembly (100, 80, 30) to a well
adapter (10) (FIG. 2) and comprising a connector (11) for
connecting and disconnecting said well control package (30) to and
from said well adapter (10) (FIG. 3), [0123] a first valve [e.g.
lower shear seal ball valve (82)] in said lubricator package (80),
[0124] a second valve [e.g. isolation shear seal ball valve (32)]
in said well control package (30), [0125] a connector (36) between
said first valve and said second valve, [0126] a fluid transfer
system (70) arranged for displacing the well fluids in the cavity
(35) between the said first valve and said second valve [0127] 8.
The device according to paragraph 7, comprising a well adapter (10)
for installing on a subsea tree (1), said well adapter (10)
arranged for receiving a well control package (30) on top of it,
(FIG. 2), [0128] 9. The device according to paragraph 7 or 8
wherein said fluid transfer system (70) comprising a clean fluid
bottle (72) for local storage of the non-polluting displacement
fluid (F1C) in the proximity of the subsea tree (1) [0129] 10. The
device according to paragraph 7, 8 or 9 wherein at least one of the
said well control package's (30) valve or lubricator package's (80)
valve is a ball valve. [0130] 11. The device according to any of
paragraphs 7 to 10, wherein said wireline drum pressure container
package (100, 101) comprises [0131] a motor driven drum for said
wireline and arranged for maintaining a back tension on said
wireline, [0132] a motor driven traction [capstan] winch for
lowering and hoisting said line with said tool string (S1, S2) in
said lubricator and said well, [0133] all within a pressure vessel
connectable on top of said lubricator package (80). [0134] 12. The
device according to any of paragraphs 7 to 11, wherein said
non-polluting displacement fluid (F1C) is constituted by seawater
(F1C) from a seawater inlet (72). [0135] 13. The device according
to any of paragraphs 7 to 12, said well control package (30)
comprising in addition to said at least one valve (32) in the
vertical bore, a lower shear/seal valve (32) and optionally an
isolation shear seal ball valve (34).
* * * * *