U.S. patent application number 16/096292 was filed with the patent office on 2019-05-16 for blowout preventer bonnet assembly.
This patent application is currently assigned to ELECTRICAL SUBSEA & DRILLING AS. The applicant listed for this patent is ELECTRICAL SUBSEA & DRILLING AS. Invention is credited to JOHN L. ALSUP, MARION E. EAGLES, THOR ARNE HAVERSTAD, J. GILBERT NANCE, ERIK NORBOM, BOLIE C. WILLIAMS.
Application Number | 20190145217 16/096292 |
Document ID | / |
Family ID | 58739318 |
Filed Date | 2019-05-16 |
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United States Patent
Application |
20190145217 |
Kind Code |
A1 |
ALSUP; JOHN L. ; et
al. |
May 16, 2019 |
BLOWOUT PREVENTER BONNET ASSEMBLY
Abstract
A blow out preventer includes a main body with a main passage
arranged therethrough, a ram movable between a first ram position
in which the ram is spaced from the main passage and a second ram
position in which the ram at least partly interrupts the main
passage, and a bonnet releasably secured to the main body. The
bonnet includes a hydraulic ram actuator coupled to the ram. The
hydraulic ram actuator includes a primary piston arranged within a
primary cylinder and fixed to a piston rod, and a secondary piston
arranged within a secondary cylinder to be slidable on the piston
rod. The primary piston and the secondary piston are each arranged
to actuate the ram via the piston rod. The primary piston and the
secondary piston each comprise a stroke length, the stroke length
of the secondary piston being shorter than the stroke length of the
primary piston.
Inventors: |
ALSUP; JOHN L.; (HOUSTON,
TX) ; WILLIAMS; BOLIE C.; (HOUSTON, TX) ;
NANCE; J. GILBERT; (KATY, TX) ; NORBOM; ERIK;
(HOEVIK, NO) ; HAVERSTAD; THOR ARNE; (VENNESLA,
NO) ; EAGLES; MARION E.; (HOUSTON, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ELECTRICAL SUBSEA & DRILLING AS |
STRAUME |
|
NO |
|
|
Assignee: |
ELECTRICAL SUBSEA & DRILLING
AS
STRAUME
NO
|
Family ID: |
58739318 |
Appl. No.: |
16/096292 |
Filed: |
April 24, 2017 |
PCT Filed: |
April 24, 2017 |
PCT NO: |
PCT/NO2017/050100 |
371 Date: |
October 25, 2018 |
Current U.S.
Class: |
166/339 |
Current CPC
Class: |
E21B 33/076 20130101;
E21B 33/062 20130101 |
International
Class: |
E21B 33/076 20060101
E21B033/076 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2016 |
NO |
20160701 |
Apr 27, 2016 |
NO |
20160702 |
Apr 27, 2016 |
NO |
20160705 |
Apr 27, 2016 |
NO |
21160704 |
Claims
1-33. (canceled)
34: A blow out preventer comprising: a main body comprising a main
passage arranged therethrough; a ram movable between a first ram
position in which the ram is spaced from the main passage and a
second ram position in which the ram at least partly interrupts the
main passage; and a bonnet releasably secured to the main body, the
bonnet comprising a hydraulic ram actuator which is coupled to the
ram, the hydraulic ram actuator comprising: a primary piston
arranged within a primary cylinder and fixed to a piston rod; and a
secondary piston arranged within a secondary cylinder so as to be
slidable on the piston rod, wherein, the primary piston and the
secondary piston are each arranged to actuate the ram via the
piston rod, and the primary piston and the secondary piston each
comprise a stroke length, the stroke length of the secondary piston
being shorter than the stroke length of the primary piston.
35: The blow out preventer as recited in claim 34, wherein, the
piston rod comprises a mechanical stop, and the secondary piston is
configured to engage the mechanical stop so as to actuate the ram
via the piston rod.
36: The blow out preventer as recited in claim 35, wherein, the
secondary cylinder further comprises a recess which is configured
to receive the mechanical stop for at least a part of a stroke
length of the piston rod.
37: The blow out preventer as recited in claim 34, wherein the
primary cylinder is arranged within the bonnet.
38: The blow out preventer as recited in claim 34, wherein the
bonnet further comprises: an attachment device; and an actuator
unit, wherein, the secondary cylinder is arranged in the actuator
unit, and the actuator unit is releasably fixed to the bonnet via
the attachment device.
39: The blow out preventer as recited in claim 37, wherein the
bonnet further comprises: a first segmented latch ring comprising
at least two latch ring parts, each of the at least two latch ring
parts comprising a serrated outer profile which is configured to
engage a first serrated surface on the bonnet; a first segmented
locking ring comprising at least two locking ring parts, each of
the at least two locking ring parts being configured to engage with
at least one of the at least two latch ring parts; and at least one
first fastener, wherein, the attachment device is fixed to the
bonnet via the first segmented latch ring and the first segmented
locking ring, and the at least one first fastener fixes each of the
at least two locking ring parts to either the bonnet or to the
actuator unit.
40: The blow out preventer as recited in claim 39, further
comprising: a second segmented latch ring comprising at least two
latch ring parts, each of the at least two latch ring parts
comprising a serrated outer profile which is configured to engage a
second serrated surface on the actuator unit; a second segmented
locking ring comprising at least two locking ring parts, each of
the at least two locking ring parts being configured to engage with
at least one of the at least two latch ring parts; a locking device
configured to selectively lock the ram in the second ram position;
and at least one second fastener, wherein, the locking device is
fixed to the actuator unit via the second segmented latch ring and
the second segmented locking ring, and the at least one second
fastener fixes each of the at least two locking ring parts to
either the actuator unit or to the locking device.
41: A blow out preventer comprising: a main body comprising a main
passage arranged therethrough; a ram movable between a first ram
position in which the ram is spaced from the main passage and a
second ram position in which the ram at least partly interrupts the
main passage; a bonnet releasably secured to the main body, the
bonnet comprising a hydraulic ram actuator which is coupled to the
ram; and at least one hydraulic bonnet actuator which is operable
independently of the hydraulic ram actuator and which is configured
to move the bonnet relative to the main body from at least one of:
a bonnet closed position in which the bonnet engages the main body
to a bonnet open position in which the bonnet is spaced from the
main body, and from the bonnet open position to the bonnet closed
position.
42: The blow out preventer as recited in claim 41, wherein, the
hydraulic bonnet actuator comprises a first piston extending from
the main body to a first cylinder formed within the bonnet and a
second piston extending from the main body to a second cylinder
formed within the bonnet, the first piston divides the first
cylinder into a first operating chamber and a second operating
chamber, and the second piston divides the second cylinder into a
third operating chamber and a fourth operating chamber.
43: The blow out preventer as recited in claim 42, wherein the
hydraulic bonnet actuator further comprises, a first connection
channel which fluidly connects the first operating chamber and the
third operating chamber, and a second connection channel which
fluidly connects the second operating chamber and the fourth
operating chamber.
44: The blow out preventer as recited in claim 42, wherein the
hydraulic bonnet actuator further comprises, a first hydraulic
supply channel which connects a first supply line to the first
operating chamber, and a second hydraulic supply channel which
connects a second supply line to the fourth operating chamber.
45: The blow out preventer as recited in claim 44, further
comprising: a first extendable hydraulic supply line which is
arranged to provide hydraulic fluid from the main body to the
hydraulic ram actuator in the bonnet open position and in the
bonnet closed position.
46: The blow out preventer as recited in claim 45, wherein, the
first extendable hydraulic supply line comprises a first tube which
extends from the main body into a second passage in the bonnet, the
first tube is movable in relation to the second passage and is
sealed against the second passage, and the second passage is
fluidly connected to the hydraulic ram actuator.
47: The blow out preventer as recited in claim 45, further
comprising: a second extendable hydraulic supply line which is
arranged to provide hydraulic fluid to the hydraulic ram actuator
in the bonnet open position and in the bonnet closed position.
48: The blow out preventer as recited in claim 47, wherein, the
second extendable hydraulic supply line comprises a second tube
which extends from the main body into a third passage in the
bonnet, the second tube is movable in relation to the third passage
and is sealed against the third passage, and the third passage is
fluidly connected to the hydraulic ram actuator.
49: The blow out preventer as recited in claim 47, further
comprising: a bonnet support rail arrangement which is configured
to guide the bonnet between the bonnet closed position the bonnet
open position, wherein, the first extendable hydraulic supply line
is adapted to actuate a ram open movement of the hydraulic ram
actuator, and the second extendable hydraulic supply line is
adapted to actuate a ram close movement of the hydraulic ram
actuator.
50: The blow out preventer as recited in claim 49, wherein the
bonnet support rail arrangement comprises: a first support rail
comprising a longitudinal axis, the first support rail being fixed
to the main body; a first pair of rail support bearings fixed to
the bonnet and being spaced apart in the longitudinal axis of the
first support rail; a second support rail comprising a longitudinal
axis, the second support rail being fixed to the main body; and a
second pair of rail support bearings fixed to the bonnet and being
spaced apart in the longitudinal axis of the second support rail,
wherein, the first pair of rail support bearings are arranged so
that an imaginary plane which is generally perpendicular to the
longitudinal axis of the first support rail in which a center of
gravity of the bonnet lies is located between the first pair of
rail support bearings, and the second pair of rail support bearings
are arranged so that the imaginary plane is located between the
first second of rail support bearings.
51: A blow out preventer comprising: a main body comprising a main
passage arranged therethrough; a ram movable between a first ram
position in which the ram is spaced from the main passage and a
second ram position in which the ram at least partly interrupts the
main passage; a bonnet releasably secured to the main body, the
bonnet comprising a hydraulic ram actuator which is coupled to the
ram; and a first extendable hydraulic supply line, the first
extendable hydraulic supply line being arranged to provide
hydraulic fluid from the main body to the hydraulic ram actuator in
a bonnet open position and in a bonnet closed position.
52: The blow out preventer as recited in claim 51, wherein, the
first extendable hydraulic supply line comprises a first tube which
extends from the main body into a second passage in the bonnet, the
first tube is movable in relation to the second passage and is
sealed against the second passage, and the second passage is
fluidly connected to the hydraulic ram actuator.
53: The blow out preventer as recited in claim 52, further
comprising: a second extendable hydraulic supply line which is
arranged to provide hydraulic fluid to the hydraulic ram actuator
in the bonnet open position and in the bonnet closed position.
54: The blow out preventer as recited in claim 53, wherein, the
second extendable hydraulic supply line comprises a second tube
which extends from the main body into a third passage in the
bonnet, the second tube is movable in relation to the third passage
and is sealed against the third passage, and the third passage is
fluidly connected to the hydraulic ram actuator.
55: The blow out preventer as recited in claim 53, wherein, the
first extendable hydraulic supply line is adapted to actuate a ram
open movement of the hydraulic ram actuator, and the second
extendable hydraulic supply line is adapted to actuate a ram close
movement of the hydraulic ram actuator.
56: The blow out preventer as recited in claim 51, further
comprising: a bonnet support rail arrangement which is configured
to guide the bonnet between the bonnet closed position and the
bonnet open position.
57: The blow out preventer as recited in claim 54, wherein the
bonnet support rail arrangement comprises: a first support rail
comprising a longitudinal axis, the first support rail being fixed
to the main body; a first pair of rail support bearings fixed to
the bonnet and being spaced apart in the longitudinal axis of the
first support rail; a second support rail comprising a longitudinal
axis, the second support rail being fixed to the main body; and a
second pair of rail support bearings fixed to the bonnet and being
spaced apart in the longitudinal axis of the second support rail,
wherein, the first pair of rail support bearings are arranged so
that an imaginary plane which is generally perpendicular to the
longitudinal axis of the first support rail in which a center of
gravity of the bonnet lies is located between the first pair of
rail support bearings, and the second pair of rail support bearings
are arranged so that the imaginary plane is located between the
first second of rail support bearings.
Description
CROSS REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a U.S. National Phase application under
35 U.S.C. .sctn. 371 of International Application No.
PCT/NO2017/050100, filed on Apr. 24, 2017 and which claims benefit
to Norwegian Patent Application No. 20160701, filed on Apr. 27,
2016, Norwegian Patent Application No. 20160702, filed on Apr. 27,
2016, Norwegian Patent Application No. 20160704, filed on Apr. 27,
2016, and to Norwegian Patent Application No. 20160705, filed on
Apr. 27, 2016. The International Application was published in
English on Nov. 2, 2017 as WO 2017/188822 A1 under PCT Article
21(2).
FIELD
[0002] The present invention relates to a bonnet assembly for a
blow out preventer and a blow out preventer.
BACKGROUND
[0003] Blowout preventers (BOPs) were developed to cope with
extreme erratic pressures and uncontrolled flow emanating from a
well reservoir during drilling. Known as a "kick", this flow of
pressure can lead to a potentially catastrophic event called a
blowout. In addition to controlling the downhole well pressure and
the flow of oil and gas, blowout preventers are intended to prevent
tubular goods used in well drilling, such as, drill pipe, casing,
collars, tools and drilling fluid, from being blown out of the
wellbore when a kick or blowout threatens. Blowout preventers are
critical to the safety of the crew, the drilling rig, the
environment, and to the monitoring and maintenance of well
integrity; blowout preventers are thus intended to provide an
additional and fail-safe barrier to the systems in which they are
included.
[0004] Ram-type blowout preventers are part of an overall pressure
control system used in oil and gas operations commonly used as
pressure containment and unexpected wellbore pressure spikes and
well pressure control events. A ram-type BOP is similar in
operation to a gate valve, but uses a pair of opposing steel
plungers or, rams. The rams extend toward the center of the
wellbore to restrict flow or to retract open to permit flow. The
inner and top faces of the rams are fitted with composite steel and
elastomeric packers that press against each other, against the
wellbore, and around well tubular members running through the
wellbore. Outlets at the sides of the BOP housing (body) are used
to connect to choke and kill lines or valves. The rams are
typically actuated by hydraulic actuators arranged within, or
connected to, the BOP housing. The ram type blowout preventer is
further integrated with additional well containment and control
devices that inclusively make up a subsea blowout preventer
stack.
[0005] Previously reported solutions and techniques useful for
understanding and practicing the present invention are described in
U.S. Pat. Nos. 7,051,990 B2, 2,912,214, 4,969,390 and 8,596,484
B1.
[0006] The operational requirements for blow out preventers can be
very demanding and, due to the tendency of the industry to move
into harsher and more challenging environments, such as deepwater
or arctic areas, these very demanding operational requirements are
likely to continue.
SUMMARY
[0007] An aspect of the present invention is to provide improved
techniques and solutions in order to provide BOPs having an
increased operational reliability, as well as a design which is
compact and permits uncomplicated manufacturing and maintenance.
Another aspect of the present invention is to provide an improved
hydraulically actuated subsea ram type blowout preventer having a
ram bonnet with a hydraulically actuated ram actuator.
[0008] In an embodiment, the present invention provides a blow out
preventer which includes a main body comprising a main passage
arranged therethrough, a ram movable between a first ram position
in which the ram is spaced from the main passage and a second ram
position in which the ram at least partly interrupts the main
passage, and a bonnet releasably secured to the main body. The
bonnet comprises a hydraulic ram actuator which is coupled to the
ram. The hydraulic ram actuator comprises a primary piston arranged
within a primary cylinder and fixed to a piston rod, and a
secondary piston arranged within a secondary cylinder so as to be
slidable on the piston rod. The primary piston and the secondary
piston are each arranged to actuate the ram via the piston rod. The
primary piston and the secondary piston each comprise a stroke
length, the stroke length of the secondary piston being shorter
than the stroke length of the primary piston.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will now be described in greater
detail below on the basis of embodiments and of the drawings in
which:
[0010] FIG. 1 shows various views of blow out preventers;
[0011] FIG. 2 shows the blow out preventer of FIG. 1 with
additional auxiliary tandem actuators arranged between the
respective bonnet and the locking devices, and with the hydraulic
supply pipes with the bonnet detached and spaced from the main
body;
[0012] FIG. 3 shows a view of the blow out preventer of FIG. 2 in
an open operational configuration;
[0013] FIG. 4 shows a top view of the blow out preventer of FIG. 2
in a closed operational configuration, cut centrally between the
upper and the lower ram actuator.
[0014] FIG. 5 shows a top view of the blow out preventer of FIG. 2
in a closed operational configuration, cut centrally between the
upper and the lower ram actuator;
[0015] FIG. 6 shows an attachment device for a blow out preventer
in a perspective view;
[0016] FIG. 7 shows an attachment device for a blow out preventer
in a cross-sectional view;
[0017] FIG. 8 shows a detailed view of a bonnet assembly and
associated components in a perspective view;
[0018] FIG. 9 shows an aspect of a bonnet assembly for a blow out
preventer;
[0019] FIG. 10 shows details of the ram actuators and the tandem
actuators in the configuration shown in FIGS. 3-5;
[0020] FIG. 11 shows details of the ram actuators and the tandem
actuators in the configuration shown in FIGS. 3-5;
[0021] FIG. 12 shows the bonnet with extendible hydraulic supply
pipes for the bonnet in a fully dismantled position where the
bonnet has two protrusions;
[0022] FIG. 13 shows the hydraulic supply pipes extending into a
respective passage in the bonnet;
[0023] FIG. 14 shows a top view of the blow out preventer of FIG.
2, cut centrally between the upper and the lower ram actuator;
[0024] FIG. 15 shows a top view of the blow out preventer of FIG.
2, cut centrally between the upper and the lower ram actuator;
[0025] FIG. 16 shows various aspects of a hydraulic bonnet actuator
for a blow out preventer;
[0026] FIG. 17 shows various aspects of a hydraulic bonnet actuator
for a blow out preventer;
[0027] FIG. 18 shows an aspect of a bonnet assembly for a blow out
preventer where the bonnet has two protrusions; and
[0028] FIG. 19 shows an aspect of a bonnet assembly for a blow out
preventer where the bonnet has two protrusions.
DETAILED DESCRIPTION
[0029] FIG. 1 shows a blow out preventer having a base 100, a main
body 101 with a main passage 102 which will, in use, form part of a
wellbore and receive tubulars or other equipment used in the
wellbore. Bonnets 103 and 104 are releasably attached to the main
body 101, for example, via a set of bolts. The bonnets 103 and 104
comprise ram actuators as will be described in further detail
below. Locking devices 105a-d are provided, the locking devices
105a-d being fixed to the bonnets being arranged to lock the ram
actuators in an advanced position, as will also be described
further below. Support rails 106a and 106b support the weight of
the respective bonnet when detached from the main body.
[0030] FIG. 2 shows a blow out preventer having a similar design as
that in FIG. 1, with the exception that the blow out preventer in
FIG. 2 has additional auxiliary tandem actuators 107a and 107b
arranged between the respective bonnet 103, 104 and the locking
devices 105b and 105c. The auxiliary tandem actuators 107a and 107b
will be described in further detail below.
[0031] In the blow out preventer in FIG. 2, the bonnets 103 and 104
are detached from the main body 101 and supported by the support
rails 106a and 106b. This permits the bonnets 103 and 104 to be
separated from the main body 101 to allow access to components of
the blow out preventer, such as the rams.
[0032] FIGS. 3-5 show various views of the blow out preventer shown
in FIG. 2 in an operational configuration. In addition to those
components described above, the blow out preventer comprises two
sets of rams with associated ram actuators. The ram actuators
comprise hydraulically driven piston-cylinder arrangements. An
upper pair of rams 110a and 110b are actuated by pistons 108a and
108b, operable in cylinders 109a and 109b, respectively. A lower
pair of rams 111a and 111b are actuated by pistons 112a and 112b
operable in cylinders 113a and 113b, respectively, and by floating
pistons 114a and 114b operating within cylinders 115a and 115b,
respectively.
[0033] Each ram 110a, 110b, 111a and 111b is movable in a
respective guideway 116 and 117 (see FIG. 3) transverse to the main
passage 102. Each ram can thus be moved between a first, open
position and a second, closed position. In the embodiment shown,
the upper pair of rams 110a and 110b are pipe rams whereas the
lower pair of rams 111a and 111b are blind shear rams. Any type or
combination of rams may, however, be used in the blow out
preventer, including pipe, variable bore pipe, blind, shear, or
blind shear rams.
[0034] FIGS. 3 and 5 show the blow out preventer in an open
position, whereas FIG. 4 shows the blow out preventer with both set
of rams in a closed position. In use, either set of rams will be
independently operable, so that the upper pair of rams 110a and
110b can, for example, be operated to close and seal around a pipe
or tubular present in the main passage 102. In the case of an
emergency, the lower pair of rams 111a and 111b may be operated to
shear any object present in the main passage 102 and seal the main
passage. This may be done independent of the position of the upper
pair of rams 110a and 110b.
[0035] The locking devices 105a-d may be fixed to the bonnets 103
and 104 via an attachment device. The attachment device may also be
used to fix the locking devices 105c and 105d to the respective
tandem actuators 107a and 107b, and/or to fix the tandem actuators
107a and 107b to the bonnets 103 and 104.
[0036] FIGS. 6 and 7 show an attachment device having a segmented
latch ring 210 and a segmented locking ring 220. The latch ring 210
is made up of two latch ring segments 200 and 201, and the locking
ring 220 is made up of two lock ring segments 202 and 203. The
latch ring 210 and locking ring 220 may be made up of a larger
number of segments, for example, 3, 4, 5, or 6 or more segments.
The latch ring 210 and locking ring 220 may be made up of a
different number of segments, for example, the latch ring 210 may
be made up of three or more segments while the locking ring 220 may
be made up of two segments.
[0037] The locking device 105a has an annular flange which is
inserted into a correspondingly sized circular aperture in the
bonnet 103, followed by the latch ring 210 and locking ring 220, so
that the annular flange is clamped, and thus held captive, between
the bonnet and the latch ring, The segmented latch ring 210 has a
series of ridges 204 that engage corresponding ridges 205 on the
bonnet or tandem actuator inner diameter to provide an interlocking
engagement between male and female profiles. The locking ring 220
engages the latch ring 210 and holds the latch ring 210 in
interlocking engagement with the ridges 205. The segmented latch
ring 210 contacts a load shoulder 206 on the locking device 105a,
or an equivalent load shoulder on the tandem actuator 107a and
107b, to restrain axial movement. Fasteners, which are provided as
bolts 207 in the example shown in FIGS. 6 and 7, hold the locking
ring 220 in place by securing it to either the bonnet 103, the
respective locking device 105a-d, the respective tandem actuator
107a and 107b, or to the latch ring 210.
[0038] Attachment of the tandem actuators 107a and 107b to the
bonnet 103, and the locking device 105b to the tandem actuator
107b, can be arranged equivalently. This attachment device thus
provides a secure connection between the locking devices 105a-d,
the tandem actuators 107a and 107b, and the bonnet 103 and 104,
while allowing for a simple and fast removal of the attachment
device, for example, for repair or maintenance.
[0039] Reference is now made to FIG. 8, which shows in more detail
the bonnet 103 and associated components, and to FIG. 9. The bonnet
103 has a support system comprising support rails 106b and 106c
arranged on either side of the bonnet 103 for supporting the weight
of the bonnet 103 in the detached position (as shown in FIG. 2).
The support rails 106b and 106c each have a longitudinal axis, and
an end connector 304 which is fixed to the main body 101. The
support system further comprises a support rail bracket 301 and
first and second support rail bearings 302 and 303. The first
support rail bearing 302 is arranged on the support rail bracket
301, which is fixed to the bonnet 103, while the second support
rail bearing 303 is fixed directly to the bonnet 103. The support
rail 106b engages with the support rail bearings 302 and 303 to
support the support rail 106b whilst allowing the support rail 106b
to slide along the support rail bearings 302, 303 parallel to its
longitudinal axis. The support rails 106b, 106 may thus be used to
control the motion of the bonnet 103.
[0040] The support system comprises a rail stop 305 which
cooperates with a slot 306 in the support rail 106b to define an
end position of the bonnet, i.e., a bonnet open position. The
location of the support rail bearings 302 and 303 (and the
equivalent support rail bearings on the opposite side of the bonnet
103) are spaced apart in the longitudinal direction of the support
rails 106b and 106c. Their location is arranged to provide that the
center of gravity of the bonnet 103 lies on an imaginary plane
generally perpendicular to the longitudinal axis of the support
rail 106b which falls between the two bearings regardless of the
bonnet configuration (with or without tandem actuators), bonnet
position (open or closed), ram position (open or closed) or state
of assembly (locking devices and actuator piston assemblies
installed or uninstalled).
[0041] The blow out preventer may comprise tandem actuators 107a
and 107b. The tandem actuators 107a and 107b may be releasably
attached to the bonnet 103 via an attachment device, for example,
according to that above in relation to FIGS. 6 and 7 or a different
type of connection arrangement. Alternatively, the tandem actuators
107a and 107b may be permanently fixed to the bonnet 103.
[0042] By providing the tandem actuators 107a and 107b with a
releasable attachment device, the blow out preventer may be adapted
for any particular use by the operator. For example, during regular
drilling operations, the blow out preventer may be configured as
shown in FIG. 3, whereby the tandem actuators 107a and 107b provide
additional shearing force for the blind shear rams 111a and 111b to
provide that the drill string can be severed effectively. For other
types of operations, for example, wireline well intervention, less
shearing force may be required and the blow out preventer may be
configured as shown in FIG. 1, i.e., without the tandem actuators
107a and 107b. The same flexibility will be achieved if using
different types of rams in the blow out preventer, for example, in
certain configurations, the blind shear rams 111a and 111b in FIG.
3 may be replaced by an additional set of pipe rams in which case
the tandem actuators 107a and 107b may not be necessary.
[0043] FIGS. 10 and 11 show further details of the ram actuators
and the tandem actuators in the configuration shown in FIGS. 3-5.
The bonnet 103 houses two ram actuators. The ram actuators have
cylinders 109b and 113b arranged in the bonnet 103, with respective
pistons 108b and 112b. A tandem actuator 107b is provided in
conjunction with the lower ram actuator. The tandem actuator 107b
also has a cylinder 115b and respective piston 114b. The tandem
actuator 107b is secured to the bonnet 103 by an attachment device
having a latch ring 210 and a locking ring 220, as described above.
Locking devices 105a and 105b are attached in an equivalent manner
to the bonnet 103 and the tandem actuator 107b, respectively.
[0044] An upper main rod 411 is fixed to the upper piston 108b and
extends out of the bonnet 103. A connector 413 is provided for
fixing the upper main rod 411 to a ram, for example pipe ram 110b
(see FIG. 5). An upper tail rod 412 is fixed to the upper main rod
411 and/or the upper piston 108b and extends into the locking
device 105a. When the upper actuator is in the advanced position,
the locking device 105a may be operated to engage the upper tail
rod 412 and prevent movement of the upper tail rod 412 away from
the main passage 102. The locking device 105a may thus be used to
lock the upper actuator in the advanced position.
[0045] A lower main rod 414 is fixed to the lower piston 112b and
extends out of the bonnet 103 to a connector 417 for connecting the
lower main rod 414 to a ram, for example blind shear ram 111b (see
FIG. 5). A connecting rod 415 is fixed to the lower main rod 414
and/or the piston 112b and extends into the tandem actuator 107b.
The connecting rod 415 is fixed to a tail rod 416 in the tandem
actuator 107b. The tail rod 416 extends into the locking device
105b, and the locking device 105b may be operated to engage the
tail rod 416 and to prevent movement of the tail rod 416 away from
the main passage 102. The locking device 105b may thus be used to
lock the lower actuator in the advanced position.
[0046] The piston 114b of the tandem actuator 107b is a floating
piston 114b which is slidably arranged on the tail rod 416. The
tail rod 416 comprises a mechanical stop 422. The mechanical stop
422 may be a shoulder on the tail rod 416. When the back side of
the floating piston 114b is pressurized in cylinder 115b, the
floating piston 114b will be urged towards the mechanical stop 422
and thus contribute to actuating the ram via the tail rod 416,
connecting rod 415, and lower main rod 414.
[0047] The floating piston 114b may have a shorter stroke length
than the lower piston 112b. This may be beneficial, for example, in
the arrangement shown in FIG. 5. When cutting an object in the main
passage 102, for example, a drill string, with the blind shear rams
111a and 111b, the highest force requirements will be during the
cutting process. After the cut has been done, the final movement of
the rams will be to fully close the main passage and actuate the
seals. This final movement requires much less actuation force.
[0048] By providing the floating piston 114b with a shorter stroke
length than the lower piston 112b, the floating piston 114b may
contribute actuation force for part of the ram stroke, while not
consuming hydraulic fluid during the rest of the actuation stroke
(for example, during the final movement as noted above). This can
be achieved by designing the cylinder 115b so that the floating
piston 114b is stopped against an end stop within the cylinder
after a pre-determined stroke length.
[0049] The cylinder 115b may be provided with a recess 424 being
adapted for receiving the mechanical stop 422 during part of the
stroke length of the actuator. This allows the end stop for the
floating piston 114b to be the end 423 of the cylinder 115b, while
the tail rod 416 with the mechanical stop 422 may continue its
motion over the final part of the actuation stroke as the floating
piston 114b stays in place at the end 423 of the cylinder 115b, the
tail rod 416 thus sliding along within the floating piston 114b.
This allows the cylinder 115b to be designed with a length
substantially equal to the stroke length of the floating piston
114b, thus allowing for a shorter and more compact tandem actuator
107b.
[0050] Hydraulic fluid may be provided to the cylinder 115b of the
tandem actuator 107 by means of hydraulic supply pipes 420 and 421
(see FIG. 8) or, alternatively, by hydraulic channels within the
body of the tandem actuator 107.
[0051] Various elastomeric seals and bushings, for example, seals
418 and 419, may be provided to seal around the rods 411, 412, 414,
415 and 416, as appropriate. Similarly, the pistons 108b, 112b, and
114b are sealed against their respective cylinders in the
conventional manner. The floating piston 114b may, similarly, be
sealed against the tail rod 416 as necessary.
[0052] The rods in the shown embodiment are made up of individual
segments, i.e., main rod, tail rod and connecting rod, however,
they may also be formed in one piece as a single rod.
[0053] The blow out preventer may further comprise extendible
hydraulic supply pipes arranged between the main body 101 and the
bonnet 103. FIG. 12 shows the bonnet 103 with extendible hydraulic
supply pipes 701, 702, 703 and 704 for the bonnet 103 in a fully
dismantled position (main body 101 not shown). FIG. 2 shows the
hydraulic supply pipes 701 and 702 with the bonnet 103 detached and
spaced from the main body 101.
[0054] The ends of hydraulic supply pipe 701 and hydraulic supply
pipe 702 are fixed to a hydraulic supply system (not shown) within
the main body 101 and extend from the main body 101 into the bonnet
103. FIG. 13 shows the hydraulic supply pipes 701 and 702 extending
into a respective passage 705 and 706 in the bonnet 103. The supply
pipes 701 and 702 are arranged to be slidable within the respective
passage 705 and 706. Seals 707 and 708 are provided in an interface
between the passage 705 and 706 and the respective supply pipes 701
and 702.
[0055] The passages 705 and 706 are fluidly connected to the upper
ram actuator, specifically the passages 705 and 706 are each
connected to the cylinder 109b but on opposite sides of the piston
108b. Providing hydraulic fluid to pipe 701 thereby produces an
opening motion of the upper ram actuator, while providing hydraulic
fluid to pipe 702 produces a closing motion of the upper ram
actuator.
[0056] The supply pipes 703 and 704 are arranged equivalently, and
connected to the lower ram actuator, i.e., fluidly connected to
cylinder 113b. Bonnet 104 is arranged with extendible hydraulic
supply pipes equivalently.
[0057] The extendible hydraulic supply pipes thus maintain fluid
communication between the hydraulic supply system in the main body
101 and the ram actuators at any time, also when the bonnets 103
and 104 are in the detached position and spaced from the main body
101. This allows operation of the ram actuators by the BOP's main
hydraulic system regardless of the position of the bonnet 103 or
104, for example, for moving the rams during maintenance, testing
or replacement when the bonnet is in the position shown in FIG.
2.
[0058] Referring now to FIGS. 14-17, the blow out preventer may
further comprise a hydraulic bonnet actuator which is operable to
move the bonnet 103 or 104 relative to the main body 101. FIGS. 14
and 15 show a top view of the blow out preventer shown in FIG. 2,
cut centrally between the upper and the lower ram actuator (see
also FIG. 5).
[0059] A first piston rod 601 and a second piston rod 602 are
provided, the first and second piston rods being fixed to the main
body 101. The first and second piston rods 601 and 602 extend into
a respective first cylinder 603 and a second cylinder 604 in the
bonnet 104. Piston heads 605 and 606 are provided on the ends of
piston rods 601 and 602 and are operable within cylinders 603 and
604 so as to create a piston front side 605a and 606a (see FIG. 17)
and a piston back side 605b and 606b for each of the piston heads
605 and 606. By pressurizing the respective chamber or chambers
within cylinders 603 and/or 604, the hydraulic bonnet actuator may
move the bonnet 104 relative to the main body 101.
[0060] Piston rods 601 and 602 may comprise respective fluid
channels 607 and 608 (see FIG. 17) therethrough, whereby hydraulic
fluid may be transmitted from a hydraulic fluid supply 609 and 610
in the main body 101 to the cylinders 603 and 604. Fluid channel
607 in piston rod 601 ends in the fluid chamber delimited by piston
front side 605a, i.e. the fluid chamber in front of the piston head
605 within cylinder 603. An opening 614 extending through piston
head 605 is provided for this purpose. Fluid channel 608 ends in
the fluid chamber delimited by piston back side 606b, i.e., the
fluid chamber behind piston head 606 within cylinder 604. A fluid
channel 613 is provided in the piston head 606 for this
purpose.
[0061] Communication channel 612 (see FIG. 16) provides fluid
communication between cylinders 603 and 604 substantially at their
outermost ends. Communication channel 611 provides fluid
communication between cylinders 603 and 604 substantially at their
innermost ends. Since the cylinders 603 and 604 are each divided
into two fluid chambers by the pistons 605 and 606, it can be seen
that the communication channels 611 and 612 will equalize the
pressures acting on the front side of the pistons 605 and 606, and
equalize the pressures acting on the back side of pistons 605 and
606. Providing fluid pressure through channel 607 will therefore
provide an actuation force from both cylinder/piston arrangements,
and produce a force driving the bonnet 104 away from the main body
101. Conversely, providing a fluid pressure through channel 608
will produce a force driving the bonnet 104 towards the main body
101.
[0062] Bonnet 103 may be arranged equivalently thereto.
[0063] It is therefore possible to displace the bonnets 103 and 104
from the main body 101 via the hydraulic bonnet actuator without
the need for external force or support, as well as bring the
bonnets 103 and 104 back towards the main body 101 for
re-attachment. The bonnets 103 and 104 can be moved relative to the
main body 101 independently of the ram actuators or their
positions. This can be advantageous, for example, for testing of
the ram actuator functionality, whereby the bonnet actuator will
maintain the bonnet in a given position while the ram actuator(s)
is/are being operated for testing or other purposes.
[0064] The blow out preventer may further comprise an end capture
providing an interlocking engagement between male and female
profiles to reduce stresses and deflections in the main body 101
and/or the bonnets 103 and 104.
[0065] FIGS. 12, 18 and 19 show the bonnet 103 having a protrusion
501 and a protrusion 502. The protrusion 501 is adapted for
interlocking arrangement with a corresponding recess 503 in the
main body 101 and the protrusion 502 similarly cooperates with a
recess 504 (see FIGS. 18 and 2.)
[0066] The main rod 411 may extend out of the bonnet 103 through
the protrusion 502 (see FIG. 12). This may provide the advantage
that the interlocking engagement of the protrusion 502 and the
recess 504 is provided in a region of the bonnet 103 and main body
101 where tension stresses are high during operation. A support
element 505 (see FIG. 18) may, optionally, be provided to further
improve stress distribution in this region.
[0067] Hydraulic supply pipes 701 and 702 may extend through the
protrusion 501.
[0068] According to various embodiments of the present invention,
there is thus provided a new and improved subsea ram type blow out
preventer. The blow out preventer according to the present
invention may provide advantages of design simplicity, ease of
manufacturing and maintenance, improved reliability of hydraulic
functions and system reliability.
[0069] The present invention is not limited to embodiments
described herein; reference should be had to the appended
claims.
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