U.S. patent application number 13/985272 was filed with the patent office on 2014-01-09 for well barrier.
This patent application is currently assigned to WTW SOLUTIONS AS. The applicant listed for this patent is Bard Martin Tinnen. Invention is credited to Bard Martin Tinnen.
Application Number | 20140008085 13/985272 |
Document ID | / |
Family ID | 46672803 |
Filed Date | 2014-01-09 |
United States Patent
Application |
20140008085 |
Kind Code |
A1 |
Tinnen; Bard Martin |
January 9, 2014 |
Well Barrier
Abstract
A well barrier is for sealing off a first portion of a wellbore
from a second portion of the wellbore, the first portion having a
higher fluid pressure than the second portion. The well barrier is
held in place in the wellbore by a holding means. The well barrier
is preshaped to disintegrate in at least three barrier elements
upon activation of a disintegration means, at least one of the
barrier elements having a surface area facing the first portion of
the wellbore that is larger than the surface area facing the second
portion of the wellbore. A method is for controlling a
disintegration of the well barrier.
Inventors: |
Tinnen; Bard Martin;
(STAVANGER, NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tinnen; Bard Martin |
STAVANGER |
|
NO |
|
|
Assignee: |
WTW SOLUTIONS AS
STAVANGER
NO
|
Family ID: |
46672803 |
Appl. No.: |
13/985272 |
Filed: |
February 9, 2012 |
PCT Filed: |
February 9, 2012 |
PCT NO: |
PCT/NO12/50020 |
371 Date: |
September 9, 2013 |
Current U.S.
Class: |
166/387 ;
166/134 |
Current CPC
Class: |
E21B 29/00 20130101;
E21B 33/12 20130101; E21B 34/063 20130101; E21B 33/1204 20130101;
E21B 33/134 20130101 |
Class at
Publication: |
166/387 ;
166/134 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 33/134 20060101 E21B033/134 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2011 |
NO |
20110246 |
Claims
1. A well barrier for sealing off a first portion of a wellbore
from a second portion of the wellbore, the first portion having a
higher fluid pressure than the second portion, wherein the well
barrier is held in place in the wellbore by a holding means
preventing movement of the well barrier in a direction from the
first portion to the second portion, the well barrier comprising:
multiple barrier elements initially held together by a connection
means to form the barrier, the barrier having a surface area facing
the first portion of the wellbore that is larger than the surface
area facing the second portion of the wellbore; a sealing means for
preventing fluid flow from the first portion to the second portion;
and a destabilizing mechanism arranged for disengaging the
connection means from at least one of the barrier elements upon
activation of the mechanism, so that support between adjoining
barrier elements is removed thereby disintegrating the well
barrier.
2. The well barrier of claim 1, wherein the multiple barrier
elements are formed in one piece provided with notches in at least
a portion of the surface of the well barrier, and the connection
means comprises the non-notched portion of the well barrier.
3. The well barrier of claim 1, wherein the barrier elements are
provided by means of separate, preshaped barrier elements being
connected to each other by the connection means, the connection
means being selected from one of or a combination of: an adhesive;
a wire; the sealing means, to form the well barrier.
4. The well barrier of claim 1, wherein the well barrier is further
provided with a support element for supporting the barrier
elements, the support element facing the second portion of the
wellbore.
5. The well barrier of claim 1, wherein the sealing means is a
sealing element facing the first portion of the wellbore.
6. The well barrier of claim 5, wherein the sealing element is
selected from the group consisting of an elastomeric membrane, a
coating, and an adhesive.
7. The well barrier of claim 1, wherein the sealing means is the
non-notched portion of the well barrier.
8. The well barrier of claim 1, wherein the well barrier is
provided with a pressure arch towards the first portion of the
wellbore.
9. The well barrier of claim 1, wherein the well barrier is
provided with a further well barrier, the further well barrier
being mirrored with respect to the well barrier about a plane being
perpendicular to a longitudinal axis of the wellbore.
10. The well barrier of claim 9, wherein the second portion of the
wellbore is defined between the well barrier and the further well
barrier.
11. The well barrier of claim 1, wherein the destabilizing
mechanism comprises a releasable holding means arranged such that
upon releasing the holding means the well barrier is moved by the
fluid in the first portion, the movement causing the well barrier
to disintegrate.
12. The well barrier of claim 1, wherein the destabilizing
mechanism is an arrangement for raising the pressure of the fluid
in the second portion to a level higher than the fluid pressure in
the first portion of the wellbore facing the further well
barrier.
13. The well barrier of claim 1, wherein at least one of the
multiple barrier elements has a form as a keystone supporting
adjoining barrier elements, the keystone element having a surface
area facing the first portion of the wellbore that is larger than
the surface area facing the second portion of the wellbore.
14. The well barrier of claim 13, wherein the at least one keystone
element is provided by means of multiple elements.
15. The well barrier of claim 1, wherein the barrier facing the
first portion of the wellbore has a concave lens shape, and wherein
a majority of the barrier elements are wedge shaped with a surface
area facing the first portion of the wellbore that is larger than
the surface area facing the second portion of the wellbore.
16. A method for controlling a disintegration of a well barrier for
sealing off a first portion of a wellbore from a second portion of
the wellbore, the first portion having a higher fluid pressure than
the second portion, wherein the well barrier is held in place in
the wellbore by a holding means prevention movement of the well
barrier in a direction from the first portion to the second
portion, the well barrier comprising: multiple barrier elements
initially held together by a connection means to form the barrier,
the barrier having a surface area facing the first portion of the
wellbore that is larger than the surface area facing the second
portion of the wellbore; a sealing means for preventing fluid flow
from the first portion to the second portion; and a destabilizing
mechanism arranged for disengaging the connection means from at
least one of the barrier elements upon activation of the mechanism,
so that support between adjoining barrier elements is removed,
thereby disintegrating the well barrier, the method comprising:
pre-shaping the barrier to disintegrate in multiple barrier
elements of desired size and shape; and activating a destabilizing
mechanism that will provide a force sufficient to break a
connection means initially holding the multiple barrier elements
together, thereby causing the barrier to disintegrate into said
multiple barrier elements of desired size and shape.
Description
[0001] This invention relates to a barrier. More particularly it
relates to a well barrier and/or zone isolation devices for sealing
off a first portion of a wellbore from a second portion of the
wellbore in wells related to the production of hydrocarbons.
[0002] In conjunction with the completion of wells, involving steps
such as the installation of production casing, production liner
(lower completion) and production tubing (upper completion),
barrier systems are commonly used.
[0003] In one scenario, a barrier is mounted in top of the lower
completion (production liner), to isolate the reservoir whilst
installing the production tubing (upper completion) in the upper
section of the well.
[0004] In another scenario, a barrier is installed in the bottom of
the production tubing during the installation of this. Once the
tubing is positioned correctly, pressure is applied on the inside
to set the production packer. To form a sealed enclosure during
such operation, to allow for pressurizing the internals of the
tubing, the bottom of the tubing has to be sealed off. Most
commonly, such seal is provided for by using a barrier device.
[0005] A common requirement to the above described barrier systems
is the ability to withhold the required pressure during the stages
where such barrier functionality is required. A second, equally
important requirement is that the barrier can be opened or removed
when barrier functionality is no longer required, to open the liner
and/or production tubular so that fluids can flow through it.
[0006] Traditionally, these temporary completion barriers were
installed and retrieved using well service techniques such as
wireline or coil tubing.
[0007] In many offshore fields, very costly drilling rigs are
utilized for the purpose of drilling and completing a well. In such
cases, any time spent on wireline or coil tubing operations will
contribute to making the completion of the well increasingly
expensive, as it increases the time the drilling rig has to be
rented for the completion of the well. To eliminate the need to
operate the above mentioned barrier systems on wireline or coil
tubing, barriers that can be operated to open without the need for
physical intervention into the well have been developed. Initial
systems of such kind were ball valves, flapper valves, sliding
sleeves or similar that was operated open by cycling well pressure
using a pump at the surface of the well.
[0008] Cycling pressure means repeated pressurizing and
depressurizing (bleeding down) the tubing (and/or liner top)
pressure in order to operate mechanical counter systems associated
with the downhole barrier. Typically, after a certain amount of
pressure cycles, the mechanical counter system will engage with a
barrier activation mechanism that causes the barrier/valve to open.
Typically, such engagement is achieved by the counter mechanism
ultimately operating a valve member of the activation system, that
allows well pressure to work against an atmospheric chamber via a
piston, and the resulting work is used to shift the valve member to
an open position. In other versions, such engagement is achieved by
the counter mechanism ultimately operating a mechanical lock of the
activation system that releases a pre-tensioned spring mechanism in
the activation mechanism, whereupon this causes the valve member to
shift to an open position. Other similar methods of activating and
shifting the valve member may be applied. Such methods would be
appreciated by a person skilled in the art, and are not described
further herein.
[0009] A drawback with barriers made of metal, such as the barrier
systems described in the previous section, is that if the cycle
open mechanism or activation mechanism fails to operate, or if the
valve element fails to shift open for any other reason,
alternatives for mechanical removal of the barrier are associated
with a relatively high cost and risk. An example of alternative
removal is to use coil tubing to shift open, or in the worst case
mill out a ball valve or a steel flapper valve.
[0010] Typical causes of failure may be debris in the well that
jams the cycle open mechanism, the activation mechanism or the
valve element itself.
[0011] Other related barrier systems are made of non-metallic
materials such as for example glass, ceramics, salt or other more
brittle materials. A common method for barrier removal in this
respect is a mechanical cycle open mechanism that triggers an
activation mechanism where an explosive charge is detonated inside
or in close proximity to the brittle barrier. An alternative method
entails the mechanical cycle open mechanism to operate a mechanical
lock that holds a pre-tensioned spring system. When releasing the
pre-tensioned spring, this will drive an impact device such as a
spear into the brittle barrier to crush it.
[0012] A great benefit with using brittle, non-metallic barrier
elements is that they are easier to remove mechanically than steel
barriers should the mechanical cycle open method of activation fail
for any reason. Rather than having to use coil tubing to mill out a
steel barrier, wireline could be used, together with a spear,
hammer device or other device or combination of devices to crush
the barrier. Thus, a quicker, more cost effective backup activation
is possible.
[0013] Publication US 2003000710 A1 discloses a downhole
non-metallic sealing element system related to downhole tools such
as bridge plugs, frac-plugs, and packers having a non-metallic
sealing element system for isolation of formation or leaks within a
wellbore casing or multiple production zones.
[0014] Publication US 2009283279 A1 discloses a zonal isolation
system for use in a well. The zonal isolation system includes a
zonal isolation tool, at least one anchor, and at least one
polished bore receptacle. The zonal isolation system includes a
setting string for activation of the zonal isolation tool and/or
the at least one anchor. It may also include an isolation string
for maintaining separation zones during production or injection of
the well.
[0015] Publication US 2002195739 A1 discloses to a method of
manufacturing a sealing or an anti-extrusion component for use in a
downhole tool. The component is formed from a composition that
contains a polyetherketoneketone or a derivative of a
polyetherketoneketone.
[0016] Publication US 2009151958 A1 discloses a method and device
for temporary well zone isolation. In particular, it discloses
temporary well zone isolation devices with frangible barrier
elements and methods for the disintegration of frangible barrier
elements.
[0017] Publication GB 2391566 A discloses a formation isolation
valve for use in a subterranean well. A mechanical apparatus may be
used to open and close the valve. The actuators may include a
rupture disc or other forms of remotely operable actuator.
[0018] U.S. Pat. No. 6,167,963 B1 discloses a drillable composite
packer or bridge plug including substantially all nonmetallic
components.
[0019] U.S. Pat. No. 6,796,376 B2 discloses a composite bridge plug
system for containing a well bore with reduced drill up time.
[0020] A generic problem with barriers made of brittle materials is
that impact or a large force is required to crush them. In the case
where explosives are used, this may entail a potential safety risk.
Requirements to create mechanical impact and/or a large force in an
activation system make it somewhat more complex and susceptible to
failure. The presence of debris/impurities in the well may impair
the performance to the extent where the opening/removal activation
fails.
[0021] Still another method for removing a barrier made of a
brittle material is to disintegrate the barrier by means of fluid
pressure. WO 2009126049 discloses a plug element for conducting
tests of a well, a pipe or the like, comprising one or more plug
bodies of disintegratable/crushable material set up to be ruptured
by internally applied effects. The plug comprises an internal
hollow space set up to fluid communicate with an external pressure
providing body, and the plug is designed to be blown apart by the
supply of a fluid to the internal hollow space so that the pressure
in the hollow space exceeds an external pressure to a level at
which the plug is blown apart.
[0022] However, brittle material barriers that are crushed by the
means mentioned above, may give rise to another problem. In some
cases, despite crackling the brittle barrier, the specific well
situation (local pressure, fluids, compacted debris surrounding the
barrier) may prevent the particles from physically being removed to
any significant distance from their original position. As a result,
the crackled (but not physically disintegrated) barrier may still
represent a relatively solid body in the well, preventing flow,
hence obstructing for subsequent operational steps. Ultimately,
such crackled barriers may have to be physically removed by
wireline or coil tubing interventions as described above.
[0023] The object of the invention is to remedy or reduce at least
one of the drawbacks of prior art.
[0024] The object is achieved in accordance with the invention, by
the characteristics stated in the description below and in the
following claims.
[0025] According to a first aspect of the present invention there
is provided a well barrier for sealing off a first portion of a
wellbore from a second portion of the wellbore, the first portion
having a higher fluid pressure than the second portion, wherein the
well barrier is held in place in the wellbore by a holding means
preventing movement of the well barrier in a direction from the
first portion to the second portion, the well barrier comprising:
[0026] multiple barrier elements initially held together by a
connection means to form the barrier, the barrier having a surface
area facing the first portion of the wellbore that is larger than
the surface area facing the second portion of the wellbore; [0027]
a sealing means for preventing fluid flow from the first portion to
the second portion; [0028] a destabilizing mechanism arranged for
disengaging the connection means from at least one of the barrier
elements upon activation of the mechanism, so that support between
adjoining barrier elements is removed, thereby disintegrating the
well barrier.
[0029] This has the effect that the shape and form of the
individual barrier elements after disintegration of the barrier can
be controlled so that the likelihood for the barrier elements
creating problems after disintegration is minimized. Further,
providing a preshape wherein at least one of the barrier elements
having a surface area facing the first portion of the wellbore that
is larger than the surface area facing the second portion of the
wellbore may provide a well barrier that is capable of carrying a
high fluid pressure in the first portion, but very vulnerable to
fluid pressure in the second portion of the wellbore.
[0030] In one embodiment of the present invention the multiple
barrier elements are formed in one piece provided with notches in
at least a portion of the surface of the well barrier, and the
connection means comprises the non-notched portion of the well
barrier.
[0031] In one embodiment of the present invention the barrier
elements are provided by means of separate, preshaped barrier
elements being connected to each other by the connection means, the
connection means being selected from one of or a combination of: an
adhesive; a wire; the sealing means, to form the well barrier.
[0032] In one embodiment of the present invention the preshape may
be provided by means of a combination of one or more portions of
the barrier being provided by notches and one or more portions of
the barrier being provided by separate, preshaped barrier
elements.
[0033] The well barrier may further be provided with a support
element for supporting the barrier elements. Preferably, the
support element faces the second portion of the wellbore.
[0034] The sealing means may be a sealing element. Preferably, the
sealing element faces the first portion of the wellbore. The
sealing element is selected from a material suitable for providing
an impermeable barrier between the fluid in the wellbore and the
barrier elements. In one embodiment the sealing element is selected
from the group comprising an elastomeric membrane, a coating, an
adhesive.
[0035] In one embodiment the sealing means is the non-notched
portion of the well barrier.
[0036] Preferably, the well barrier has the form of a pressure arch
towards the first portion of the wellbore.
[0037] In one embodiment the well barrier is provided with a
further well barrier, the further well barrier being mirrored with
respect to the well barrier about a plane being perpendicular to a
longitudinal axis of the well bore. The second portion of the
wellbore is in this embodiment defined between said well barrier
and said further well barrier.
[0038] In one embodiment of the present invention the destabilizing
mechanism comprises a releasable holding means arranged such that
upon releasing the holding means the well barrier is moved by the
fluid in the first portion, the movement causing the well barrier
to disintegrate.
[0039] In one embodiment of the present invention when the second
portion is defined between the well barrier and the further well
barrier, the destabilizing mechanism is an arrangement for raising
the pressure of the fluid in the second portion to a level higher
than the fluid pressure in the first portion of the wellbore facing
the further well barrier
[0040] At least one of the multiple barrier elements may have a
form as a keystone supporting adjoining barrier elements, the
keystone element having a surface area facing the first portion of
the wellbore that is larger than the surface area facing the second
portion of the wellbore. The at least one keystone element may be
provided by means of multiple elements.
[0041] The barrier facing the first portion of the wellbore may
have a concave lens shape, wherein a majority of the barrier
elements are wedge shaped with a surface area facing the first
portion of the wellbore that is larger than the surface area facing
the second portion of the wellbore.
[0042] In a second aspect of the present invention there is
provided a method for controlling a disintegration of a well
barrier according to the first aspect of the invention, the method
comprising: [0043] pre-shaping the barrier to disintegrate in
multiple barrier elements of desired size and shape; and [0044]
activating a destabilizing mechanism that will provide a force
sufficient to break a connection means initially holding the
multiple barrier elements together, thereby causing the barrier to
disintegrate into said multiple barrier elements of desired size
and shape.
[0045] The following describes a non-limiting example of a
preferred embodiment illustrated in the accompanying drawings, in
which:
[0046] FIG. 1a-1c illustrate one example of generic use of the
invention;
[0047] FIG. 2-5c illustrate design, functionality and operation of
one barrier according to a preferred embodiment of the
invention;
[0048] FIG. 6 illustrates combination of barrier elements to
provide for two way pressure integrity;
[0049] FIG. 7 illustrates an embodiment where multiple barrier
elements are used to hold pressure from the same direction, to
provide for additional operational safety and redundancy;
[0050] FIG. 8a-8c illustrate additional system features used to
ensure a reliable barrier removal/disintegration process;
[0051] FIG. 9-14 illustrate use of pressure compensation systems in
conjunction with a double barrier design further to a preferred
embodiment. Such pressure compensation systems are used to provide
for a lower pressure between the barrier elements than on the
outside of the barrier elements, respectively;
[0052] FIG. 15 illustrates a preferred design principle for barrier
elements constituting the barrier;
[0053] FIG. 16a illustrates an exploded view of a barrier according
to the present invention;
[0054] FIG. 16b illustrates the barrier in FIG. 16a arranged in a
portion of a pipe; and
[0055] FIG. 16c illustrates the barrier in FIG. 16b seen from the
first portion of a wellbore.
[0056] FIG. 1a-1c illustrate a borehole 101. Casing 102 is used to
prevent the borehole 101 from collapsing during drilling and
subsequent production, and to seal off the borehole wall to prevent
unwanted leakage to or from strata/zones in the underground and
ultimately to provide a barrier between the pressurized hydrocarbon
reservoir and the open environment. In most cases, the casing is
cemented to the rock wall as will be appreciated by any person
skilled in the art and thus not illustrated herein. A generic well
completion is illustrated. In this illustrated case, the lower
completion comprises a cemented production liner 103 which is open
towards the hydrocarbon reservoir via perforations 104. A person
skilled in the art will know that the design and configuration of
the production liner 103 may vary significantly from what is
illustrated herein. The production liner 103 is anchored to and
forms a seal towards the casing 102 by means of a liner hanger
system 105.
[0057] The upper completion comprises the production tubing 106,
which is stung into the lower completion by means of a seal stinger
assembly 107. A sealing arrangement 108 comprising a barrier 114
according to the present invention is installed below a production
packer 109. In the top of the well, the tubing 106 is terminated in
the wellhead 110. The completion design may vary significantly from
what is shown in FIG. 1, and there are common completion components
that are not illustrated herein, such as a downhole safety valve.
These facts will be appreciated by a person skilled in the art.
Similarly, the device according to the present invention can be
used for other completion designs than what is shown herein, and
FIG. 1 provides for an example only.
[0058] When running the completion in the hole, the production
packer 109 is not activated, as illustrated in FIG. 1a.
[0059] The centerline 115 of the tubular is illustrated for
reference.
[0060] Now considering FIG. 1b, a pump 111 is put in fluid
communication with the wellhead 110. In order to set the production
packer 109, meaning to expand the mechanical anchors and seal
elements to engage with the casing 102, the pump 111 is used to
apply high pressure to the fluid inside the tubing 106. This is
possible due to the sealed enclosure formed by the tubing 106, the
sealing arrangement 108, the wellhead 110 and the pump 111. After
setting the packer 109, the barrier 114 is no longer required in
the well. The next step is to remove the barrier 114 so that the
well can be put on production or injection.
[0061] To remove the barrier 114, the fluid inside the tubing 106
is pressure-cycled as described earlier in this document, using the
pump 111. For each complete pressure cycle, a mechanical counter
mechanism 112 is operated one step. After a certain amounts of
steps, the mechanical counter mechanism 112 will interact with an
activation module 113 that triggers the opening and/or removal of
the barrier 114. In summary, after a certain amount of cycles, i.e.
pressurizing and de-pressurizing the tubing fluid, the barrier 114
opens. FIG. 1c illustrates the well completion after the barrier
114 has been removed.
[0062] The mechanical counter system 112 and activation system 113
could be replaced or supplemented by alternative activation
systems, such as battery operated, sensor based or timer based
activation systems, controlled by internal micro controllers or
similar available in the marked. Details of such associated
activation mechanisms would be appreciated by a person skilled in
the art and no further details of such are provided for herein.
[0063] FIG. 2 shows in a larger scale one embodiment of the barrier
114 with an associated activation system 113 according to present
invention. A counter system 112 as indicated in the FIGS. 1a-1c or
alternative systems for wireless activation of the barrier system
not shown herein. However such a system is assumed included in the
well completion, and in fluid communication with the activation
system 113 through a flow channel 201.
[0064] In a preferred embodiment, upon activation, a mechanical
counter system 112 as indicated in FIGS. 1a-1c, or alternative
system for wireless activation, operates a valve manifold so that a
pressurized fluid is lead into the activation system 113 through
the flow channel 201. Details of operation of any mechanical
counter system 112, or alternative wireless activation system,
valve manifolds etc. is known to a person skilled in the art and
not further described herein. In the embodiment shown in FIG. 2,
the activation system 113 has a tubular form and is incorporated or
connected the production tubing 106. Only one side of the cut
activation system 113 is illustrated. The center of the cut
activation system 113 is illustrated by the dotted line 115.
[0065] The barrier 114 shown in FIG. 2 is made up of smaller
barrier elements some of which are indicated by reference numerals
114a, 114b, 114k. A relatively thin-walled base dome 114s made of a
brittle material such as concrete is applied to simplify the
construction of the barrier 114 and to prevent unwanted premature
migration/movement of the barrier elements 114a, 114b, 114k with
respect to each other. In one embodiment of the present invention,
the barrier elements 114a, 114b, 114k are attached to the base dome
114s and/or each other by means of an adhesive agent, or using
metal wire or other suitable attachment methods. In another
embodiment, a relatively thin walled ring (not illustrated herein)
made of a similar brittle material is forming the circumference of
the barrier 114 to facilitate mounting and provide inter-component
stability of the barrier 114.
[0066] In an alternative embodiment, the barrier 114 is constituted
by one element provided with notches providing nicking of the
barrier 114 into barrier elements 114a, 114b, 114k of a desired,
predetermined size.
[0067] The barrier 114 is locked in place inside the tubular of the
activation system 113 by means of a finger coupling 207 and a
lock/cover sleeve 208.
[0068] Upon activation, pressurized fluid is routed from a valve
manifold operated as described elsewhere in the document and into
the activation system 113 via channel 201. Here, the pressurized
fluid acts on piston 202. The piston 202 is mechanically in contact
with holding profile 204 via piston mandrel 203. Longitudinal slots
205 are provided in the piston mandrel 203. A set of engagement
bolts 209 are screwed into the lock/cover sleeve 208, the
engagement bolts 209 protruding through the slots 205 of the piston
mandrel 203.
[0069] In one embodiment, the smaller elements 14a, 14b, 114k are
free to move with respect to each other, but form a mechanically
stable geometry when mounted as shown in FIG. 2. In alternative
embodiments, a thin walled dome 14s assists in holding the geometry
of the barrier 114 stable. In the described embodiment, the barrier
114 is designed to hold forces from a direction illustrated by
arrow 210.
[0070] Thus, there is provided a well sealing arrangement 108 where
the force integrity is provided by at least one barrier 114
associated with at least one activation system 113 that includes at
least one operable support element 207, wherein said barrier 114 is
construed by smaller barrier elements 114a, 114b, 114k that form a
stable mechanical structure against forces from at least one side
of the sealing arrangement 108; and said stable mechanical
structure becomes unstable by means of operating at least one
support element 207.
[0071] Thus there is provided well sealing arrangement 108 where
the force integrity is provided by at least one barrier 114
associated with at least one activation system 113, wherein said
barrier 114 is construed by smaller barrier elements 114a, 114b,
114k that form a stable mechanical structure against forces from at
least one side of the sealing element 108, said stable mechanical
structure becomes unstable by means of operating the activation
system 113.
[0072] To ensure pressure integrity and not only force integrity,
the barrier 114 is in the embodiment shown provided with an
elastomeric membrane 212. In other embodiments, the elastomeric
membrane 212 could be replaced with other coating agents suitable
for forming a seal. Such a coating agent may be adhesives, resin
coating or similar.
[0073] Now consider FIG. 3. When the high pressurized fluid pushes
the piston 202 downwards, the holding profile 204 is shifted
simultaneously. After a certain travel, the holding profile 204
will no longer radially support the finger coupling 207. When the
radial support is removed from the finger coupling 207, the fingers
will be pushed radially outward and away from the centerline 115 of
the tubing 106. In the embodiment shown in FIG. 4, the finger
coupling 207 is formed so that the fingers bias towards a position
that is radially outward into a recess 503 from the resting
position when the barrier 114 is assembled. In another embodiment,
the push created by the pressure force indicated by arrow 210
acting on barrier 114 forces the fingers of the finger coupling 207
radially outward into the recess 503.
[0074] Now consider FIG. 5a. As a consequence of the finger
coupling 207 no longer supporting the barrier 114, the barrier 114
is free to move downwards. As piston 202, piston mandrel 203 and
support element 204 is shifted downwards; some distance after the
radial support is removed from the finger coupling 207, the piston
mandrel 203 engages with the engagement bolt 209 when the bolt 209
abuts an end portion of the slot 205. As a consequence, the
hold/cover sleeve 208 is shifted downwards. At the time when the
engagement bolt 209 and associated profile in the hold/cover sleeve
208 lands on a shoulder 501 provided in a tubing recess 502, the
downward movement of piston 202, piston mandrel 203 and support
element 204 stops. At this point in time the lock/cover mandrel 208
covers the opening between the bore and the recess 503. Preferably,
a mechanical lock system will ensure that the lock/cover mandrel is
locked in place with respect to recess 503. Such a lock system is
not shown, but may for example be a snap lock or other suitable
locking device that will be appreciated by a person skilled in the
art.
[0075] Still considering FIG. 5a, the barrier 114 is now free to
move further downwards in the tubing 106. In a preferred embodiment
of the invention, the barrier 114 will now disintegrate due to
forces caused by pressure according to arrow 210, associated flow
forces, collisions with the wall of the tubing 106, or collision
with other objects in the well. In a preferred embodiment, the
smaller barrier elements 114a, 114b, 114k are free to move with
respect to each other, or engaged to each other by means of
relatively weak adhesive, thin metal wires, or other means that
will disengage when relatively modest forces are acting on the
barrier 114. In the case a relatively thin walled dome 114s is
used, alternatively in combination with a thin walled rim in the
circumference of the barrier 114, a preferred embodiment of this is
that the thin walled dome 114s and/or rim is made in a brittle
material that will crush in the process subsequent to the radial
disengagement of finger coupling 207. FIG. 5b illustrates the
situation where the barrier 114 is in the process of
disintegrating.
[0076] As would be appreciated by a person skilled in the art, a
barrier element of the kind illustrated herein as barrier 114 is
designed to withstand a larger forces from the direction
illustrated by arrow 210 than in the opposite direction (from below
in the embodiment illustrated.
[0077] FIG. 5c illustrates another preferred feature. Here, the
elastomeric membrane 212 is physically bonded to the cover mandrel
208 along its circumference 504. By means, when activating the
barrier 114, the barrier elements 114a, 114b, 114k etc will be
physically separated from the elastomeric membrane 212. Moreover,
the elastomeric membrane 212 will ultimately be inverted and
torn/permanently destructed from the fluid forces acting on it.
This way, one avoids a potential problem of the mechanical parts
such as barrier elements 114a, 114b, 114c and sealing parts such as
the elastomeric membrane 212 of the barrier 114 being able to
re-form a barrier seal elsewhere in the well. The bonding between
elastomeric membrane 212 and cover mandrel 208 could be achieved by
means of mechanical fixture means, adhesives, or by vulcanizing the
elastomeric membrane 212 to cover mandrel 208.
[0078] FIG. 6 illustrates a barrier system comprising two barriers
114, 601. Barrier 601 is added to enable the system to withstand
forces and pressure according to arrow 604. As illustrated in FIG.
6, barrier 601 is held in place by holding sleeve 603 and wedge
602. Further to this embodiment, barrier 601 is removed as a
consequence of removing or disintegrating barrier 114. When barrier
114 is disintegrated as shown in FIG. 5c, barrier 601 will be
exposed to the disintegrated barrier 114 and to fluid forces acting
on barrier 601 from a direction indicated by arrow 210, where
barrier 601 has a very limited pressure integrity.
[0079] In another embodiment of the invention, barrier 601 may be
activated by a similar activation system and method as described in
relation to FIGS. 2-5. Such an activation mechanism could be
independent to or form integral part of activation system 113.
[0080] In one embodiment of the present invention, the lower of the
two barriers, i.e. barrier 601 is the one that is operated by the
activation system 113 as discussed above. This means that the
barrier system disclosed in FIG. 6 is turned upside down. In many
cases it is desirable to open the well in an underbalanced state,
meaning that the volume above the upper barrier 114 has been filled
with a relatively light fluid, such as brine, on that the reservoir
is able to produce fluids into the well immediately upon barrier
removal. By means, "shock-injecting" potentially polluted fluid
into the formation is avoided, and a potential cleaning effect by
"shock producing" from the reservoir into the well when removing
the barrier is achieved. Thus, to enable barrier removal at
underbalance, the lower barrier 601 must be removed prior to
removing the upper barrier 114.
[0081] In even another embodiment of the invention, barriers 114
and 601 are operated simultaneously when activating the activation
system 113.
[0082] In one embodiment of the present invention barriers 114 and
601 are fully or partially merged into one structural element with
a cavity inside of it.
[0083] In all embodiments exemplified in FIGS. 2-6, the barriers
such as barrier 114 are prevented from disintegrating in the
reverse direction from what is illustrated in FIG. 5 by mechanical
forces applied by such as finger coupling 207, holding sleeve 208
and elastomeric membrane 212. Also, in a preferred embodiment of
the invention, barriers such as barrier 114 are further held in
place by the aid of pressure forces acting on them via the
elastomeric membranes such as elastomeric membrane 212. Further to
FIG. 6, this is achieved by always ensuring that there is a lower
pressure between the barriers 114, 601 than there is on the top of
barrier 114 and bottom of barrier 601, respectively. In one
embodiment, this is achieved by having atmospheric pressure
conditions in the area between the barriers 104, 601. By means,
well pressure from above barrier 114 and below barrier 601 will
keep the barriers in place until the activation system 113 is
activated.
[0084] In one embodiment, vacuum is applied to the cavity between
barrier 114 and 601, to ensure that pressure forces keep the
barriers in place and intact while handling them on the surface,
with atmospheric pressure in the surroundings.
[0085] In one embodiment, the activation system 113 does not
comprise the finger coupling 207 and associated mechanisms.
Instead, the barriers 114 and 601 are removed by leading high
pressure into the cavity there between, either sourced from a
location above barrier 114 or below barrier 601, or on the radial
outside of thereof or from a pressurized fluid reservoir that forms
part of the installed downhole assembly. One such activation system
is known from the publication WO 2009126049.
[0086] In one embodiment, disintegration of the barrier according
to the present invention is achieved by leading high pressure fluid
into the cavity between the barriers 114, 601 as shown, in
combination with removal of mechanical support of one or more
barrier.
[0087] In one embodiment, the elastomeric membrane 212 will hold
the barrier 114 mechanically stable by means of mechanical
forces/mechanical rigidity associated with membrane 212 (similar
considerations applying for barrier 601).
[0088] In one embodiment, the cycle open system 112 and/or
activation system 113 are incorporated in one or all of the
barriers 114, 601, and/or smaller barrier elements 114a, 114b,
114k.
[0089] In the following figures, for simplicity, the inner parts of
the cut activation system are not shown.
[0090] Now consider FIG. 7. Further to the illustrations herein, in
one embodiment of the invention, the barriers 114, 601 described in
FIG. 6 are supplemented with additional barriers 114', 601'. This
may be required in cases where added safety and/or redundancy are
needed.
[0091] FIG. 8a illustrates an embodiment where the barriers 114,
601 are provided with rod elements 801, 802 that will apply push to
the keystones 114k, 804 when one or both of the barriers 114, 601
are activated. In other embodiments of the invention, the rods 801,
802 are replaced by cutting elements that will be forced up
between, inside or through the barriers 114, 601 and through the
elastomeric membranes such as elastomeric membrane 212. The
intention with the design shown in FIG. 8 is to prevent accidental
occurrences where the barriers 114, 601 re-form stable barrier
constructions after activation rather than to disintegrate.
[0092] In a preferred embodiment, should the main (cycle open)
barrier removal/disintegration method fail to operate, a cutting
device will be deployed on wireline or coil tubing and applied to
cut through the membrane 212. By means, this will entail that the
upper barrier 114 will leak, and this will cause pressure to act on
top of barrier 601 so that this disintegrates (as it is not
designed to hold pressure from that direction). By subsequently
bleeding off pressure above barrier 114, this will disintegrate,
too, for similar reasons, as the higher reservoir pressure will act
on it in the reverse direction. In some embodiments, the membrane
212 is mechanically protected or double barriers are applied (as
described in relation to FIG. 7). This could be the case if the
operational sequence of completing the well involves risks of
objects accidentally falling down on the membrane 212 and causing
this to leak when it was supposed to provide pressure integrity. In
such cases, further to another embodiment of the invention, a spear
device will be deployed on wireline or coil tubing and applied to
crush the barrier 114. In one embodiment the wireline tool will be
a combined cutting and spear device.
[0093] Now consider FIG. 5b. For simplicity, only one barrier 114
is shown. In this embodiment, the finger coupling 207 is different
in form and function from what has been described above. In FIG. 8b
two different profiles are supporting the barrier 114. The
supporting profiles are lower support shoulder 805 and upper
support shoulder 806. In the embodiment shown, the lower support
shoulder 805 is part of the finger coupling 207, and can be
operated in a radial or longitudinal direction as illustrated by
arrows 807 and 808. In the same embodiment, the upper support
shoulder 806 forms part of or is fixed to the tubing 106. Thus,
when the lower support shoulder 805 is released, pressure forces
further to arrow 210 will attempt to force the barrier 114
downwards. The upper support shoulder 806 will oppose this, but
further to a preferred embodiment, this shoulder is made so thin
that the local compression forces on the barrier 114 where this is
in contact with upper support shoulder 806 will cause the barrier
114 to deform or partly disintegrate along this surface. Upon this,
the barrier 114 will be forced through upper support shoulder 806.
In a preferred embodiment, this sequence of events will cause the
barrier 114 to open in a fashion where the lower, now unsupported
outskirts of the barrier 114 will be forced towards the tubing
wall, and barrier 114 opens similarly to "a flower that is
blooming". The intention with the features described above and
indicated in FIG. 8b is to provide for as controlled a
disintegration of barrier 114 as possible, and to avoid an
accidental situation where the barrier 114 looses support, but does
not disintegrate, and where it lands on a lower-lying shoulder (not
shown) in the well and re-establishes as a stable structure.
[0094] FIG. 8c illustrates the process of opening the barrier like
a blooming flower in more detail. Here, the lower support shoulder
805 shown in FIG. 8b has been removed, and the barrier 114 now only
rests on the upper support shoulder 806. The loss of radial support
combined with the force (indicated by arrow 210) acting on the
barrier, causes the barrier elements 114a, 114b, 114c to be forced
outwards towards the tubing wall, as illustrated by arrows 809a and
809b. The outward movement can be a result of physical displacement
of the barrier elements 114a, 114b, 114c, 114k as well as
deformation and physical destruction from exposure to the fluid
force 210. In the embodiment shown, the barrier elements 114a,
114b, 114c will be forced outwards to such a degree that the "key
stone" element 114k of the barrier elements can pass through the
center of the barrier 114, as illustrated by arrow 810, whereupon
the entire barrier structure will collapse.
[0095] In one embodiment, both the upper support shoulder 806 and
lower support shoulder 805 are operable. For example, both
shoulders 806, 805 could be operable in a longitudinal direction of
the well as indicated by arrow 808. For this embodiment, it is
preferred that the upper support shoulder 806 has a longer
permitted distance of movement than the lower support shoulder 806,
so that the support shoulders does not re-establish in a fully
supporting modus with respect to barrier 114. For this embodiment,
as the lower support shoulder 805 is permitted to travel a certain
longitudinal distance before landing on a dedicated stop profile, a
shock force will be applied on the barrier 114 in addition to the
static fluid pressure forces. In one embodiment, such shock force
will help deforming and/or partly disintegrating the barrier 114 in
the area where this is in contact with lower support shoulder
805.
[0096] In the embodiment shown in FIG. 9, an associated system
component is introduced in the form of a pressure compensation
system 901. To facilitate the illustration of the pressure
compensation system 901, the right side of the cut tubing is shown
in a larger scale with respect to the barrier and pipe dimension. A
main intention with a pressure compensation system is to balance
pressure in the cavity 902 between barriers 114, 601 (the second
portion of the wellbore) with respect to the pressure on the
outside of the barriers 114, 601 (the first portion of the
wellbore). That way, the barriers 114, 601 may not be required to
withstand as large forces as would be the case if there was
atmospheric pressure inside cavity 902. This may entail the
barriers 114, 601 to be built more slender. In some cases, the
inclusion of pressure compensation 901 will enable use of the
barrier in cases where it would not be physically possible to apply
a similar barrier system with atmospheric pressure inside cavity
902. The illustrated pressure compensation system 901 balances the
cavity 902 pressure with respect to tubing pressure above the
barrier 114. In an alternative embodiment (not shown), the pressure
compensation system 901 balances the pressure with respect to
tubing pressure below barrier 601, or from the annulus between the
tubing and the casing of the well. The pressure compensation system
901 is in fluid communication with the inside of the tubing via
channel 903 and in fluid communication with the cavity 902 via
channel 904. Channel 903 is in fluid contact with piston 905 which
is supported by spring 906. By means, as the completion is run in
the hole, the increased tubing pressure will act on piston 905 via
channel 903, whereupon the piston 905 will travel downwards and
pressurize the fluid of cavity 902 via channel 904. However, due to
the spring 906 exerting force on the low side of the piston 905,
the pressure inside cavity 902 will always be lower than the
pressure inside the tubing, acting on channel 903.
[0097] In one embodiment of the invention, the cavity 902 is filled
with a vacuumed fluid, which may for example be inserted in
combination with a small gas pocket. The gas pocket is intended to
compensate for temperature derived fluid expansion inside cavity
902 as the system is lowered into the hot well climate. Such
temperature expansion could, if not compensated for, cause barriers
114, 601 to leak and malfunction. In another embodiment, said
temperature expansion is compensated for by allowing for a
compensating travel of piston 905.
[0098] In one embodiment of the invention, the system is prepared
for installation in the well by pushing the piston 905 to a
position where the spring 906 is compressed whilst filling cavity
902 with said fluid and/or fluid/gas mixture. After filling the
cavity 902 and closing the fill port (not shown in the drawing),
piston 905 is released so that the spring 906 pushes it upwards. By
means, a pressure that is lower than the surrounding (atmospheric)
pressure is created inside the cavity 902. This may assist keeping
the barrier elements 114,601 more stable during assembly and
intervention into the well, as the elastomeric membrane will be
subject to suction forces from the inside of the barrier.
[0099] Now consider FIG. 10. In many cases, during the installation
sequence of the well completion, the pressure on top of barrier 114
and barrier 601, respectively, may vary with respect to each other.
For example, the completion equipment may be run in drilling mud,
hence barrier 114 as well as barrier 601 may be exposed to
pressures equal to the hydrostatic column of drilling mud when
installed at depth. In the tubing above barrier 114, the mud may be
displaced with so-called completion fluids, normally salt water,
prior to setting the production packer and opening the barrier. As
the completion fluid normally is less dense than the drilling mud,
the pressure on top of barrier 114 may now become significantly
lower than the pressure below barrier 601. In other circumstances,
other parameters may change this relation. In all cases, it is
important that the pressure inside cavity 902, which is the second
portion of the wellbore as stated in the first aspect of the
invention, always is lower than the pressure in the first portion
of the wellbore, i.e. the pressure above barrier 114 and below
barrier 601 as shown in the figures, during all relevant stages of
the well completion process. Should the cavity 902 pressure exceed
any of those pressures at any stage, this may entail leaks, and in
worst case a premature disintegration of the barriers 114, 601. To
prevent the cavity 902 pressure from exceeding a defined maximum
pressure, the piston 905 is provided with a stop rod 1001. After a
certain travel of piston 905, the stop rod 1001 will abut against
the bottom of the drilled bore 1002 and prevent the piston 905 from
travelling further. Hence, the pressure inside cavity 905 will not
increase as a function of deploying the barrier further into the
well. This is illustrated in FIG. 11.
[0100] FIG. 12 illustrates a different approach to avoid
over-pressurizing cavity 902. Here, channel 903 is in fluid
communication with the top of piston 905 via channel 1202 in plug
1201. Plug 1201 is provided with elastomeric seals in both ends. In
the initial position, plug 1201 is attached to the tubing wall by
means of shear pins 1203. The cavity 1204 formed by the right end
of plug 1201 and the associated bore in the tubing, and sealed off
by the right end seal of plug 1201, is initially housing a gas at
near atmospheric pressure. As the barrier is lowered into the well
and the surrounding pressure increases, the shear pins 1203 will
shear at a certain depth, hence pressure due to forces generated by
the pressure differential between cavity 1204 and the surrounding
pressure. This is illustrated in FIG. 13 and will cause the plug
1201 to move to the right. When fully shifted, the left side seal
of plug 1201 will be in contact with the wall of channel 903 and
form a seal. Hence, further pressure increases inside cavity 902 as
a function of lowering the barrier into the well will not take
place.
[0101] FIG. 14 illustrates an embodiment where the piston and plug
mechanism is mirrored above and below barriers 114 and 601, to
compensate from both top and bottom of the barrier. The capacity of
the shear pins 1203 in the upper piston and plug mechanism as shown
in FIG. 13 may be equal to or different from the capacity of the
shear pins for the mirrored piston and plug mechanism arranged
below the barrier 601. The capacity may be selected depending on
the given case specifications.
[0102] FIG. 15 illustrates one method for defining the barrier
elements of the barrier 114, some of which are indicated by
reference numerals 114a, 114b, 114c, 114k. In the embodiment shown
in FIG. 15 cuts are made in the concave lens shape of the barrier
114 from an imaginary point 1501 located somewhere on the center
line axis 115 pointing straight out of the center of the barrier
114, i.e. the center axis 115 of the wellbore or tubular element
(not shown) wherein the barrier 114 is mounted.
[0103] In the embodiment shown, the lens-shaped barrier 114 is
provided with cuts running from the point 1501, the cuts being
symmetrical with respect to the center line axis 115 of the
wellbore/tubular. In one embodiment, two sets of cuts such as the
illustrated cuts are made perpendicular (or in any desired angle)
to each other with respect to the xy plane. As a result, the
smaller elements 114a, 114b will assume a wedge shaped form with a
cubic base along the outskirts of barrier 114, whereas the form
will be a concave cubic/rectangular shape in the center of the
lens.
[0104] In a preferred embodiment, the smaller elements 114a, 114b,
114c, 114k are made by providing circular cuts that are concentric
with the circumference of the barrier 114, the cuts being made
along lines that resemble the lines running out of point 1501.
Subsequently, radial cuts are made from the outskirts of the
barrier 114 towards the centre. In one embodiment, the entire
barrier is cut by the said radial cuts all the way from the
outskirts to centre. In another embodiment, the centre barrier
element 114k, the "key stone", is not cut. Hence, the barrier
elements 114a, 114b, 114c will be formed from concentric and radial
cut intersections, with the exception of the key stone barrier
element 114k that will have a substantially frustoconical shape
wherein the surface area facing the first portion of the wellbore
is larger than the surface area facing the second portion of the
wellbore. This is clearly shown in FIGS. 16a-16c that will be
discussed below.
[0105] The barrier elements 114a, 114b, 114c, 114k will in the
embodiment shown resemble building blocks of an igloo; however the
blocks along the circumference of the "lens" will be supported by
an angled base rather than a horizontal base.
[0106] In one embodiment, the barrier 114 will be constituted by
barrier elements 114a, 114b, 114c, 114k defined by cuts that run
all the way from the top/outer end to the bottom/inner end of the
barrier. In another embodiment, layered sub elements (not shown)
that are constituted by smaller barrier elements 114a, 114b, 114c,
possibly with thin walled dome elements (similar to the dome
element 114s shown for example in FIG. 2) in between and/or on the
outskirts of the layer barrier elements, form the complete
assembled barrier 114.
[0107] In a preferred embodiment the smaller elements 114a, 114b
are molded elements, made of fibre armed concrete or other rugged
materials suitable for molding, able to withstand the required
forces. In another embodiment, the smaller elements 114a, 114b,
114c, 114k are machined or manufactured in alternative known
fashions. Preferably, the barrier elements are made of a material
having a higher density than that of the fluid in the wellbore.
This to ensure that the disintegrated barrier elements sink down in
the well and do not represent any risk for malfunction of e.g. any
valves arranged downstream of the sealing arrangement 108 arranged
in a producing well. However, the barrier elements may also be made
of a material having a lower density than that of the fluid in the
wellbore, if it is desired to prevent the disintegrated barrier
elements to sinking in the well.
[0108] FIG. 16 a-c illustrates further details of a design of the
force bearing part of barrier 114 according to one embodiment of
the present invention. FIG. 16a shows an exploded isometric view,
FIG. 16b shows and isometric view of an assembled barrier 114 shown
in FIG. 16a and FIG. 16c shows a top view of the assembled barrier
114. Further to this embodiment, the barrier 114 is made up of
rings 1601-1604 cut in a concentric fashion, with an angle on the
outskirts further to the logic as explained with respect to FIG.
15. The rings 1601-1604 are radially cut in barrier elements 114a,
114b, 114c, 114k. In the embodiment shown, the barrier elements in
one ring are mounted with an angular displacement with respect to
the barrier elements in adjoining ring(s). This way, for the
embodiment shown, the splice between two barrier elements of ring
1601 meets the center of a barrier element in ring 1602 etc. This
way, the barrier 114 becomes more physically stable.
* * * * *