U.S. patent application number 15/769507 was filed with the patent office on 2018-11-01 for well tool comprising a frangible well barrier, and a method for providing such a well tool.
This patent application is currently assigned to Interwell Technology AS. The applicant listed for this patent is Interwell Technology AS. Invention is credited to Espen Hiorth.
Application Number | 20180313183 15/769507 |
Document ID | / |
Family ID | 56824058 |
Filed Date | 2018-11-01 |
United States Patent
Application |
20180313183 |
Kind Code |
A1 |
Hiorth; Espen |
November 1, 2018 |
WELL TOOL COMPRISING A FRANGIBLE WELL BARRIER, AND A METHOD FOR
PROVIDING SUCH A WELL TOOL
Abstract
A well tool device includes a housing, a frangible disc and a
seat for supporting the frangible disc in relation to the housing.
The housing has an inner surface defining a through bore. The
frangible disc is provided in the through bore and includes a side
surface. The seat includes a side surface. A sealing device is
provided between the frangible disc and the seat. The sealing
device provided between the side surface of the frangible disc and
the side surface of the seat is made from a vulcanized rubber
material.
Inventors: |
Hiorth; Espen; (Trondheim,
NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Interwell Technology AS |
Ranheim |
|
NO |
|
|
Assignee: |
Interwell Technology AS
Ranheim
NO
|
Family ID: |
56824058 |
Appl. No.: |
15/769507 |
Filed: |
November 3, 2016 |
PCT Filed: |
November 3, 2016 |
PCT NO: |
PCT/EP2016/076480 |
371 Date: |
April 19, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/12 20130101;
E21B 33/1208 20130101; E21B 33/134 20130101; E21B 34/063
20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2015 |
NO |
20151496 |
Claims
1. A well tool device, comprising: a housing having an inner
surface defining a through bore; a frangible disc provided in the
through bore, where the frangible disc comprises a first side
surface; a seat for supporting the frangible disc in relation to
the housing, where the seat comprises a second side surface; and a
sealing device provided between the frangible disc and the seat,
wherein the sealing device provided between the first side surface
of the frangible disc and the second side surface of the seat is
made from a vulcanized rubber material.
2. The well tool device according to claim 1, wherein the seat has
been pre-treated before an assembly of the well tool device.
3. The well tool device according to claim 2, wherein the seat has
been pre-treated with a sand-blowing process and a priming process
before the assembly of the well tool device.
4. The well tool device according to claim 1, wherein the frangible
disc (20) has been pre-treated before an assembly of the well tool
device.
5. The well tool device according to claim 4, wherein the frangible
disc has been pre-treated with a priming process before the
assembly of the well tool device.
6. The well tool device according to claim 1, wherein a
reinforcement fiber is incorporated into the vulcanized rubber
material of the sealing device.
7. The well tool device according to claim 1, wherein the housing
comprises: a main housing section in which the seat is provided,
where a section of the main housing section comprises an inwardly
threaded area; and an auxiliary housing section comprising a
corresponding outwardly threaded area for connection to the
inwardly threaded area of the main housing section.
8. The well tool device according to claim 1, wherein the housing
comprises: a first housing section, wherein a first seat section is
provided in the inner surface of the first housing section; a
second housing section, wherein a second seat section is provided
in the inner surface of the second housing section; and a third
housing section provided circumferentially outside the first and
second housing sections, wherein the sealing device is provided
continuously in an annular compartment provided axially between the
first and second housing sections and radially between the first
side surface of the frangible disc and an inner surface of the
third housing section.
9. The well tool device according to claim 7, wherein each of the
first and second housing sections comprises a piston surface facing
away from the first and second seat sections, respectively.
10. The well tool device according to claim 1, further comprising
an adhesive between the sealing device and the frangible disc.
11. A method for manufacturing a well tool device, comprising: a)
providing a frangible disc; b) aligning the frangible disc in
relation to a seat provided in an inner surface of a housing; c)
providing a rubber material into a compartment provided between the
seat and the frangible disc; and d) vulcanizing the rubber material
provided in the compartment, thereby forming a sealing element
provided between the housing and the frangible disc.
12. The method according to claim 11, where step b) comprises: c1)
heating of the rubber material; and c2) injecting the rubber
material into the compartment.
13. The method according to claim 12, wherein the step of injecting
the rubber material into the compartment is performed until the
rubber material is exiting through a channel provided in the
housing radially outside of the seat.
14. The method according to claim 11, further comprising the step
of incorporating a reinforcement fiber into the rubber material
before step d).
15. The method according to claim 11, wherein the method comprises
the following step before step b): treating the seat with a
sand-blowing process and a priming process.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a well tool comprising a
frangible well barrier, and a method for providing such a well
tool.
BACKGROUND OF THE INVENTION
[0002] Frangible well plugs are commonly used in tools for oil
and/or gas wells. These plugs provide a pressure barrier in the
tool, for example during periodic or permanent isolation of zones
in the well, during well integrity testing, etc.
[0003] These frangible well plugs have a frangible barrier element
in the form of a frangible disc made from glass, hardened glass,
ceramics etc. The barrier element is provided in a seat in a metal
housing. The barrier element may be removed by means of various
techniques, where the purpose is to disintegrate the element into
small pieces.
[0004] An example of a glass plug is known from NO 321 976 (TCO
AS). The plug comprises a number of layered or stratified ring
discs of a given thickness, which are placed in abutment on top of
one another. Between the different layers of the plug an
intermediate film of plastic, felt or paper is inserted; the
various glass layers may also be joined by means of lamination by
an adhesive such as a glue. During use the plug will be mounted in
a plug-receiving chamber in a tubing, where the underside of the
plug rests in a seat at the bottom of the chamber. An explosive
charge is furthermore incorporated in the top of the plug by one or
more recesses being drilled out from the top of the plug, in which
recesses the explosive charge(s) are placed.
[0005] Another example is known from NO 20130427 (Vosstech AS).
Here, the plug has one glass disc, which may be disintegrated by a
radial pin or loading device being pushed into the glass disc.
[0006] Glass disks made of float glass of soda lime type are
commonly used in such well plugs. Today, the highest available
thickness for float glass of soda lime type of acceptable quality
is produced at a maximum thickness of ca 25 mm. The maximum
pressure a glass disc may withstand will depend on the glass
quality and the diameter of the glass disc. Hence, this thickness
of ca 25 mm represents a pressure limit for the glass plug. If the
glass plug is to be used for higher pressures and higher diameters,
several such glass discs must be used together in order to
withstand higher pressures. The above NO 321 976 shows an example
where several glass discs are assembled into one larger glass disc
body.
[0007] With the above prior art well plugs, different types of
seals or sealing elements are used between the metal and the glass.
Often, one type of seal (typically o-ring) is used
circumferentially around the glass disc to as a pressure seal to
avoid fluid flow between the glass disc and the metal housing and a
second type of seal or sealing element is used as a seal in the
upper part and lower part of the seat to avoid contact between the
glass disc and the metal housing, as such contact will cause an
undesired breaking of the glass disc. A disadvantage with these
prior art seals is that they require a very fine precision during
machining of the metal housing and during polishing and hardening
of the glass disc. Hence, it is an object of the invention to avoid
or reduce the need of such fine precision machining operations.
[0008] Another disadvantage with these seals is that they are made
of expensive materials, typically one O-ring, and two seat seals
(upper and lower seat surface) needed for one glass disc will cost
about NOK 3-5000. One object of the invention is to be able use
alternative and cheaper seal materials.
[0009] Another disadvantage with the above seals is they are
vulnerable to physical impacts. Hence, if a prior art well tool are
falling to the ground during lifting the well tool for
transportation, there is a risk for undesired breaking of the glass
disk. One object of the invention is therefore to improve the
support of, and the protection of, the glass disc within the seat
of the well tool against physical impacts.
[0010] Another problem with the above seals is that when the
frangible disc is disintegrated, the seals may follow the
production flow and get stuck, in which case they may cause
problems when later operations are to be performed in the well.
SUMMARY OF THE INVENTION
[0011] The present invention relates to a well tool device,
comprising:
[0012] a housing having an inner surface defining a through
bore;
[0013] a frangible disc provided in the through bore, where the
frangible disc comprises a side surface;
[0014] a seat for supporting the frangible disc in relation to the
housing, where the seat comprises a side surface;
[0015] a sealing device provided between the frangible disc and the
seat;
characterized in that:
[0016] the sealing device provided between the side surface of the
frangible disc and the side surface of the seat is made from a
vulcanized rubber material.
[0017] Accordingly, the sealing device made from the vulcanized
rubber material is replacing the o-ring(s) commonly used in prior
art. In this aspect of the invention, prior art contact-preventing
sealing elements may be used between the upper chamfered supporting
surface of the seat and the upper chamfered supporting surface of
the disc, and between the lower chamfered supporting surface of the
seat and the lower chamfered supporting surface of the disc.
[0018] In another aspect of the invention, the sealing device made
from the vulcanized rubber material may be used between the
respective chamfered surfaces as well. In this aspect of the
invention, the sealing device made from one body of vulcanized
rubber material is replacing the previously known three separate
sealing elements (at least one o-ring and two contact-preventing
sealing elements).
[0019] One or several channels may be provided between the outside
of the housing and the seat to allow excessive rubber material to
escape out through the channel during the injection of the rubber
material.
[0020] According to one aspect of the invention, the seat has been
pre-treated before the assembly of the well tool device. The
pre-treatment can be a sand-blowing process and a priming process
before the assembly of the well tool device. Also the frangible
disc may be pre-treated before the assembly of the well tool
device. The pre-treatment can be a priming process before the
assembly of the well tool device.
[0021] In one aspect of the invention, a reinforcement fiber is
incorporated into the vulcanized rubber material of the sealing
device.
[0022] In one aspect, the housing comprises:
[0023] a main housing section in which the seat is provided, where
a section of the main housing section comprises an inwardly
threaded area;
[0024] an auxiliary housing section comprising a corresponding
outwardly threaded area for connection to the inwardly threaded
area of the main housing section.
[0025] In one aspect of the invention, the housing comprises:
[0026] a first housing section, where a first seat section is
provided in the inner surface of the first housing section;
[0027] a second housing section, where a second seat section is
provided in the inner surface of the second housing section;
[0028] a third housing section provided circumferentially outside
the first and second housing sections;
where the sealing device is provided continuously in an annular
compartment provided axially between the first and second housing
sections and radially between a side surface of the frangible disc
and an inner surface of the third housing section.
[0029] The first and second housing sections may comprise a piston
surface facing away from their respective seat sections.
[0030] In one aspect of the invention, an adhesive is provided
between the sealing device and the frangible disc. The adhesive is
typically added to the frangible disc before the injection of the
rubber material.
[0031] The present invention also relates to a method for
manufacturing a well tool device, comprising the steps of: [0032]
a) providing a frangible disc; [0033] b) aligning a frangible disc
in relation to a seat provided in an inner surface of a housing;
[0034] c) providing a rubber material into a compartment provided
between the seat and the frangible disc; [0035] d) vulcanizing the
rubber material provided in the compartment, thereby forming a
sealing element provided between the housing and the frangible
disc.
[0036] The compartment may comprise a first compartment defined as
the compartments between the upper chamfered supporting surface of
the seat and the upper chamfered supporting surface of the disc and
between the lower chamfered supporting surface of the seat and the
lower chamfered supporting surface of the disc, and a second
compartment defined as the compartment between the side surface of
the frangible disc and the side surface of the seat.
[0037] In one aspect, step b) comprises: [0038] c1) heating of the
rubber material; [0039] c2) injecting the rubber material into the
compartment.
[0040] The step of injecting the rubber material into the
compartment is performed until the rubber material is exiting
through a channel provided in the housing radially outside of the
seat.
[0041] In one aspect, the method comprises a step of incorporating
a reinforcement fiber into the rubber material before step d).
[0042] In one aspect the method comprises a step of treating the
seat with a sand-blowing process and a priming process step before
step b).
DETAILED DESCRIPTION
[0043] In the following, embodiments of the invention will be
described in detail with reference to the enclosed drawings,
where:
[0044] FIG. 1 illustrates a cross sectional side view of the first
embodiment;
[0045] FIG. 2a illustrates an enlarged view of the reinforcing
fibers in an alternative embodiment;
[0046] FIG. 2b illustrates an alternative embodiment of FIG.
2a;
[0047] FIG. 2c illustrates details of the seat;
[0048] FIG. 2d illustrates details of the frangible disc;
[0049] FIG. 3 illustrates a cross sectional side view of first step
in the manufacturing of the first embodiment;
[0050] FIG. 4 illustrates an injecting molding tool used during the
manufacturing;
[0051] FIG. 5 illustrates a side view of the first embodiment where
two such molding tools of FIG. 4 are used;
[0052] FIG. 6 illustrates a cross sectional side view of a second
embodiment;
[0053] FIG. 7 illustrates a detailed view of the third housing
section in FIG. 6;
[0054] FIG. 8 illustrates a detailed view of the first and second
housing sections of FIG. 6;
[0055] FIG. 9 illustrates a cross sectional side view of a further
embodiment
[0056] It is now referred to FIG. 1, where a well tool device is
indicated by reference number 1. The well tool device 1 comprises a
housing 10 having an inner surface 11 defining a through bore 12 in
the longitudinal or axial direction I through the housing 10. A
frangible disc 20 is provided in the through bore 12, for
preventing fluid flow through the bore until the frangible disc is
disintegrated. The housing 10 is typically cylindrical, and is made
of a metal suitable for the environment in the respective well.
[0057] A seat 13 is provided for supporting the frangible disc 20
in relation to the housing 10. In FIG. 1 the seat 13 is provided in
the inner surface 11 of the housing 10. The seat 13 is typically
provided as a widened section of the bore 12.
[0058] The frangible disc 20 is preferably a disc made of hardened
glass.
[0059] The well tool device 1 further comprises a frangible disc 20
provided in the seat 13, as shown in FIG. 1.
[0060] It is now referred to FIGS. 2c and 2d. In FIG. 2c, it is
shown that the seat 13 of the housing 10 comprises upper and lower
chamfered surfaces C13 and a side surface A13 between the upper and
lower chamfered surfaces C13. The side surface A13 is typically
provided in an axial direction, i.e. parallel to the longitudinal
axis I of the well tool device 1.
[0061] In FIG. 2d, it is shown that the disc 20 comprises upper and
lower chamfered surfaces C20 and a side surface A20 provided
between the upper and lower chamfered surfaces C20.
[0062] The purpose of the respective upper and lower chamfered
supporting surfaces C20, C13 is to transfer axial fluid pressure
applied by the fluid in the well bore 12 on the frangible disc 20
to the housing 10.
[0063] In FIG. 1, it is provided a first compartment 15a and a
second compartment 15b between the frangible disc 20 and the seat
13 for the sealing device 30.
[0064] The first compartment 15a is defined as the compartment
between the chamfered supporting surfaces C20, C13. Hence, there is
both an upper and a lower first compartment 15a.
[0065] The second compartment 15b is defined as the compartment
between the side surface A20 of the frangible disc 20 and the side
surface A13 of the seat 13.
[0066] In the present invention, the sealing device 30 is made from
a vulcanized rubber material. The rubber material is injected or
pressed into the first and second compartments 15a, 15b and
thereafter, a vulcanizing process is performed to harden the rubber
material. This injection and vulcanizing method will be described
further below. As the first and second compartments 15a, 15b are
filled with the rubber material, the rubber material will fill the
available space of the first and second compartments 15a, 15b, and
hence, the tolerances during the machining process during the
manufacturing of the housing device 10 and the frangible disc 20 is
no longer an important factor, as the entire space or void between
the housing and disc will be filled with rubber material.
[0067] The rubber material may for example be a synthetic rubber
material, selected among those materials suitable for the
environment in the hydrocarbon well (i.e. dependent on temperature,
pressure and amount of H2S content etc in the well). The rubber
material may for example be NBR (Nitrile Butadiene rubber), HNBR
(Hydrogenated Nitrile Butadiene Rubber), FKM (fluoroelastomers),
FFKM (perfluoro-elastomers) or other suitable materials.
[0068] According to the embodiment in FIG. 1, the vulcanized rubber
material is provided between the side surface A20 of the frangible
disc 20 and the side surface A13 of the seat 13, and between the
respective upper and lower chamfered surfaces C13 and C20.
[0069] In FIG. 1, a channel 15c is shown between the outside of the
housing 10 and the seat 13. The purpose of the channel 15c is to
avoid air/gas pockets in the rubber material of the sealing device
30, as air and excessive rubber material is allowed to escape out
through the channel 15c during the injection process. There might
be several such channels 15c circumferentially through the housing
10.
[0070] In FIG. 2a, an alternative embodiment is disclosed. Here,
reinforcement fibers 32 are incorporated into the vulcanized rubber
material. The fibers 32 are provided as three upper rings and three
lower rings provided between the respective upper and lower
chamfered supporting surfaces C20, C13. These rings of fibers 32
are provided in planes being perpendicular to the longitudinal axis
I.
[0071] In FIG. 2b, yet an alternative embodiment is disclosed.
Here, the reinforcement fibers 32 are also provided into the
vulcanized rubber material, but in a more axial direction, i.e.
from the upper side of the frangible disc 20, down between the
upper chamfered supporting surfaces C20, C13, then down along the
side of the disc 20 and then further down between the lower
chamfered supporting surfaces C20, C13 to the lower side of the
disc 20, as shown in FIG. 2b. Several such fibers will then be
distributed around the disc 20.
[0072] In yet an alternative, the fibers 32 could be provided as
short fibers mixed into the rubber material and then being injected
together with the rubber material. The fibers 32 will then be
distributed randomly in the rubber material.
[0073] The fibers can be made of any suitable material, for example
aramid.
[0074] It is now referred to FIG. 3. Here, it is shown that the
housing 10 comprises a main housing section 10a and an auxiliary
housing section 10b. An area of the main housing section 10a
comprises an inwardly threaded area 14, and the auxiliary housing
section 10b comprises a corresponding outwardly threaded area 14
for connection to the inwardly threaded area 14 of the main housing
section 10a. The seat 13 is formed in the main housing section 10a
axially above the auxiliary housing section 10b, where the lower
chamfered supporting surface C10 of the seat 13 is provided in the
upper part of the auxiliary housing section 10b.
[0075] It is now referred to FIG. 6. Here it is shown that the
housing 10 comprises a first, a second and a third housing section
with reference numbers 10c, 10d and 10e respectively.
[0076] The first housing section 10c comprises a first seat section
13a comprising the upper chamfered surface C13 of the seat 13. The
first seat section 13a is provided in the inner surface 11 of the
first housing section 10c. The second housing section 10d comprises
a second seat section 13b comprising the lowered chamfered surface
C13 of the seat 13. The second housing section 13b is provided in
the inner surface 11 of the second housing section 10d. As shown in
FIGS. 6 and 8, the upper part of the seat 13 is provided in the
lower part of the first housing section 10c and the lower part of
the seat 13 is provided in the upper part of the second housing
section 10d. Here, there is no channel 15c for excessive rubber
material, instead there is an annular compartment 16 formed axially
between the first and second housing sections 10c, 10d.
[0077] The third housing section 10e is provided circumferentially
around the first and second housing sections 10c, 10d. The third
housing section 10e is also provided axially above and below the
first and second housing sections 10c, 10d. The third housing
section 10e also has a through bore 12, where the diameter of the
bore 12 preferably is the same axially through the well tool device
1, as indicated in FIG. 6, where diameter D10e=diameter
D10c=diameter D10d. The only area of the bore 12 having a larger
diameter than the diameter D10e is the area of the seat 13
itself.
[0078] As shown in FIG. 6, the sealing device 30 is provided
continuously in the annular compartment 16 axially between the
first and second housing sections 10c, 10d and radially between the
side surface A20 of the frangible disc 20 and an inner surface of
the third housing section 10e (the above second compartment 15b).
It should be noted that the sealing device 30 may also be provided
in the first compartment 15a as described with reference to FIG. 1,
i.e. in between the chamfered supporting surfaces (reference
numbers C13 and C20 of FIG. 1). As in the embodiment in FIG. 1, the
vulcanized sealing material has the function of preventing fluid
flow between the upper side and lower sides of the frangible disc
20 and at the same time has the function of preventing contact
between the frangible disc 20 and the seat 13 of the housing 10
when a high fluid pressure is applied to one side of the frangible
disc 20 (i.e. to avoid undesired shattering of the frangible
disc).
[0079] As shown in FIGS. 6 and 7, the third housing section 10e
comprises a recess 19 where the inner surface 11a has a larger
diameter (diameter D11a of FIG. 6). The recess 19 is forming a
compartment for the first and second housing sections 10c, 10d.
[0080] Each of the first and second housing sections 10c, 10d
comprises a piston surface 17 facing away from their respective
seat sections 13a, 13b, as shown in FIG. 8. Hence, when fluid
pressure is increasing above the frangible disc 20 in relation to
the fluid pressure below the frangible disc 20, then a positive
force A will be applied to the piston surface 17 of the first
housing section 10c. This force A will apply a pressure to the
vulcanized rubber material of the sealing device 30 as the first
housing section 10c may move downwardly. It should be noted that
the second housing section 10d can not move downwardly, hence, the
vulcanized rubber material will be compressed. Consequently, some
of the vulcanized rubber material will be pressed radially out from
the annular compartment 16 and apply a pressure towards the surface
11a of the third housing section 10e. Hence, no fluid will be able
to pass from the upper side of the frangible disc 20 to the lower
side of the frangible disc 20 along the surface 11a. Even better,
if the pressure and hence the force A increases, this force will
increase the axial pressure on the vulcanized rubber material which
in turn will increase the sealing effect between the frangible disc
20, the first and second housing sections 10c, 10d and the surface
11a of the third housing section 10e.
[0081] In FIG. 8, it is shown that the first seat section 13a
comprises the upper chamfered surface C13 and an upper subsurface
of the side surface A13, while the second seat section 13b
comprises the lower chamfered surface C13 and a lower subsurface of
the side surface A13.
[0082] The well tool device 1 may further comprise a primer
material or an adhesive material between the sealing device 30 and
the frangible disc 20 and/or between the sealing device 30 and the
housing 10, in order to improve the sealing effect of the sealing
device 30.
[0083] Preferably, also the seat 13 of the housing device 10 has
been pre-treated before applying primer and/or adhesive and then
the rubber material to improve the sealing effect. Such a
pre-treatment may for example be a sand-blowing process.
[0084] The method for manufacturing the well tool device 1 will now
be described with reference to FIGS. 3, 4 and 5.
[0085] Initially, the different parts are provided, i.e. the
frangible disc 20 and the housing 10, together with the rubber
material for the sealing device 30. They may be pre-treated, for
example by the above described sand-blowing process, priming
applying process and/or adhesive applying process.
[0086] First, the frangible disc 20 is aligned in relation to the
seat 13. In the aligning step, it should be ensured that there is a
compartment 15a, i.e. a first compartment, and a compartment 15b,
i.e. a second compartment, between the frangible disc 20 and the
seat 13 for the embodiment in FIGS. 1 and 3. In FIG. 3, the
frangible disc 20 is inserted into the bore 12 of the main housing
10a and located in the seat 13 before the auxiliary housing 10b is
connected to the main housing 10 by means of the threaded
connection 14.
[0087] In the embodiment in FIG. 6, it should also be ensured that
there is an annular compartment 16 between the first and second
housing sections 10c, 10d, in addition to the first and second
compartments 15a and 15b. As shown in FIG. 7, there is a threaded
connection 14 for the third housing section 10e, in order to be
able to insert the first and second housings sections 10c, 10d and
the frangible disc 20 into the recess 19 of the third housing
section 10e. Accordingly, also the third housing section 10e
comprises a main housing and an auxiliary housing connectable to
each other via the threaded connection 14.
[0088] In order to align the parts together, spacers or similar
other means may be used to keep a distance between the parts before
the injection of the rubber material.
[0089] If reinforcement fibers 32 are to be used, they are first
located in the first compartment 15a for the embodiment in FIG. 2a,
and in first and second compartments 15a, 15b for the embodiment in
FIG. 2b.
[0090] In FIG. 4, an injection mold IM is shown, comprising a body
B and injection channels IC. One such injection mold IM is provided
above the frangible disc 20 and one such injection mold IM is
provided below the frangible disc 20, as shown in FIG. 5. The
injection channels IC are provided to guide rubber material into
the first compartment 15a.
[0091] In the next step, the rubber material is injected via the
injection mold IM into the first and second compartments 15a, 15b
provided between the seat 13 and the frangible disc 20. The rubber
material is injected until the rubber material is exiting out
through the channels 15c in the embodiment of FIGS. 1 and 2. In the
embodiment of FIG. 6, air and gas will exit along surface 11a.
However, it is not possible to visually observe when the rubber
material is reaching the surface 11a. Hence, the injection process
may be stopped when the injection pressure reaches a predetermined
pressure threshold etc.
[0092] During the injection, the rubber material and possibly also
the housing 10 may be preheated for increasing the viscosity of the
rubber material.
[0093] In the next step, a vulcanizing process is performed. The
vulcanizing process results in an increased strength in the rubber
material.
[0094] The well tool device 1 shown in FIG. 1, i.e. with a sealing
device 30 made from a vulcanized rubber material, has been
pressurized to 6500 psi (.about.448 bar) at a temperature of
120.degree. C.
[0095] For the above embodiments, it has been described that the
vulcanized rubber material is used as a sealing device 30 both in
the first compartment 15a and also in the second compartment 15b
and hence, the sealing device 30 are serving two purposes, i.e. as
a fluid seal and to prevent contact between seat of housing and
disc.
[0096] It should be noted that in an alternative embodiment to
those described above, the sealing device 30 made of vulcanized
rubber material may be used for the function of preventing fluid
flow between the upper side and lower sides of the frangible disc
20 only. This is illustrated in FIG. 9, where the vulcanized rubber
material is provided in the second compartment 15b only, i.e. the
vulcanized rubber material is provided between the side surface A20
of the frangible disc 20 and the side surface A13 of the seat
13.
[0097] In such an embodiment, another material, such as prior art
sealing materials may be used in the first compartment 15a between
the chamfered supporting surfaces C13 and C20 for the function of
transferring axial forces from the frangible disc 20 to the seat 13
of the housing 10 and hence to avoid contact between the frangible
disc 20 and the seat of the housing 10.
[0098] The well tool device 1 described herein may be a part of a
plugging device, such as a bridge plug. The housing 10 will then
typically be a part of the mandrel of the plugging device. The well
tool device 1 may also be a part of a completion string, where the
purpose of the frangible glass disc is used to pressure test the
completion string, and when the frangible disc is removed, in order
to start the production from the well. The housing 10 will here
typically be a part of the completion string. The well tool device
1 may also be a part of other well tools where a temporary barrier
is needed.
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