U.S. patent application number 14/017891 was filed with the patent office on 2015-03-05 for capping stack for use with a subsea well.
This patent application is currently assigned to TRENDSETTER ENGINEERING, INC.. The applicant listed for this patent is Brent Cox. Invention is credited to Brent Cox.
Application Number | 20150060081 14/017891 |
Document ID | / |
Family ID | 52581535 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150060081 |
Kind Code |
A1 |
Cox; Brent |
March 5, 2015 |
CAPPING STACK FOR USE WITH A SUBSEA WELL
Abstract
A capping stack for use with a subsea well has a body with a
flow passageway extending therethrough, a first bore having one end
opening to an outlet end of the flow passageway, a second bore
opening to the outlet end of the flow passageway, a first flowline
affixed to the first bore and extending upwardly therefrom, a
second flowline affixed to the second bore and extending upwardly
therefrom, a first valve cooperative with the first flowline so as
to be movable between an open position and a closed position, and a
second valve cooperative the second flowline so as to be movable
between an open position and a closed position. The inlet end of
the flow passageway is suitable for connection to a blowout
preventer or to a wellhead of a subsea well. Each of the bores
extends upwardly at an acute angle to vertical from the flow
passageway.
Inventors: |
Cox; Brent; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cox; Brent |
Houston |
TX |
US |
|
|
Assignee: |
TRENDSETTER ENGINEERING,
INC.
Houston
TX
|
Family ID: |
52581535 |
Appl. No.: |
14/017891 |
Filed: |
September 4, 2013 |
Current U.S.
Class: |
166/363 ;
166/368 |
Current CPC
Class: |
E21B 33/064
20130101 |
Class at
Publication: |
166/363 ;
166/368 |
International
Class: |
E21B 33/038 20060101
E21B033/038; E21B 33/064 20060101 E21B033/064 |
Claims
1. A capping stack for use with a subsea well, the capping stack
comprising: a body having a flow passageway extending therethrough,
said flow passageway of said body having an inlet end and an outlet
end, said inlet end suitable for connection to a fluid passageway
of a blowout preventer or to a wellhead of the subsea well, said
body having a first bore having one end opening to said outlet of
said flow passageway, said first bore extending upwardly from said
flow passageway, said body having a second bore having one end
opening to said outlet end of said flow passageway, said second
bore extending upwardly from said flow passageway; a first flowline
affixed to said first bore and extending upwardly therefrom; a
second flowline affixed to said second bore and extending upwardly
therefrom; a first valve cooperative with said first flowline so as
to be movable between an open position and a closed position, said
open position allowing fluids from the subsea well to flow through
said first flowline, said closed position suitable for blocking
fluids from passing outwardly of said first flowline; and a second
valve cooperative said second flowline so as to be movable between
an open position and a closed position, said open position of said
second valve suitable allowing fluids from the subsea well to flow
through said second flowline, said closed position of said second
valve suitable for blocking fluids from passing outwardly of said
second flowline.
2. The capping stack of claim 1, further comprising: a connector
affixed to a lower end of said body, said connector suitable for
connecting said body to either the blowout preventer or the
wellhead.
3. The capping stack of claim 1, further comprising: a frame
connected to said body and extending upwardly therefrom, said frame
supporting said first and second flowlines thereon.
4. The capping stack of claim 1, said first bore diverging away
from said second bore in a direction away from said outlet end of
said flow passageway.
5. The capping stack of claim 4, said first bore extending an angle
of 60.degree. or less to vertical, said second bore extending at an
angle of 60.degree. or less to vertical.
6. The capping stack of claim 1, said one end of said first bore
being in spaced relation to said one end of said second bore at
said outlet end of said flow passageway.
7. The capping stack of claim 1, each of said first and second
bores having a cross-sectional area less than a cross-sectional
area of said flow passageway.
8. The capping stack of claim 1, further comprising: a third bore
having one end opening to said outlet end of said flow passageway,
said third bore extending upwardly from said flow passageway; a
third flowline affixed to said third bore and extending upwardly
therefrom; and a third valve cooperative with said third flowline
so as to be movable between an open position and a closed position,
said open position of said third valve allowing fluids from the
subsea well to flow through said third flowline, said closed
position of said third valve blocking fluids from passing outwardly
of said third flowline.
9. The capping stack of claim 8, said third bore diverging away
from said first and second bores in a direction away from said
outlet end of said flow passageway.
10. The capping stack of claim 1, said first valve comprising a
pair of valves cooperative with said first flowline, said pair of
valves being in spaced relationship to each other, said second
valve another pair of valves cooperative with said second flowline,
said another pair of valves being in spaced relationship to each
other.
11. The capping stack of claim 1, each of said first and second
flowlines comprising: a first portion having a first end and a
second end, said first end connected to the respective bore, said
first portion extending at an acute angle to vertical away from the
respective bores; and a second portion extending from said second
end of said first portion and extending vertically upwardly
therefrom.
12. The capping stack of claim 1, each of said first and second
flowlines having a connecting portion at an upper end thereof, said
connecting portion suitable for connection to a conduit so as to
allow fluids from the subsea well to flow therethrough.
13. The capping stack of claim 3, further comprising: a lifting
mechanism affixed to an upper portion of said frame in a location
generally centrally of said frame.
14. A flow diverting system for use with a subsea well, the flow
diverting system comprising: a blowout preventer; a body connected
to an upper end of said blowout preventer, said body having a flow
passageway extending therethrough, said flow passageway of said
body having an inlet end and an outlet end, said inlet end suitable
for connection to a fluid passageway of said blowout preventer,
said body having a first bore having one end opening to said outlet
end of said flow passageway, said first bore extending upwardly
from said flow passageway, said body having a second bore having
one end opening to said outlet end of said flow passageway, said
second bore extending upwardly from said flow passageway; a first
flowline affixed to said first bore and extending upwardly
therefrom; a second flowline affixed to said second bore and
extending upwardly therefrom; a first valve cooperative with said
first flowline so as to be movable between an open position and a
closed position, said open position allowing fluids from the subsea
well to flow through said first flowline, said closed position
blocking fluids from passing outwardly of said first flowline; and
a second valve cooperative said second flowline so as to be movable
between an open position and a closed position, said open position
of said second valve allowing fluids from the subsea well to flow
through said second flowline, said closed position of said second
valve blocking fluids from passing outwardly of said second
flowline.
15. The flow diverting system of claim 14, said first bore
diverging away from said second bore in a direction away from said
outlet end of said flow passageway.
16. The flow diverting system of claim 15, said first bore
extending an angle of 60.degree. or less to vertical, said second
bore extending at an angle of 60.degree. or less to vertical.
17. The flow diverting system of claim 14, further comprising: a
third bore having one end opening to said outlet end of said flow
passageway, said third bore extending upwardly from said flow
passageway; a third flowline affixed to said third bore and
extending upwardly therefrom; and a third valve cooperative with
said third flowline so as to be movable between an open position
and a closed position, said open position of said third valve
allowing fluids from the subsea well to flow through said third
flowline, said closed position of said third valve blocking fluids
from passing outwardly of said third flowline.
18. The flow diverting system of claim 14, each of said first and
second flowlines comprising: a first portion having a first end
second end, said first end connected to the respective bore, said
first portion extending at an acute angle to vertical away from the
respective bore; and a second portion extending from said second
end of said first portion and extending vertically upwardly
therefrom.
19. The flow diverting system of claim 14, further comprising: a
frame connected to said body and extending upwardly therefrom, said
frame supporting said first and second flowlines thereon.
20. The flow diverting system of claim 19, further comprising: a
lifting mechanism affixed to an upper portion of said frame in a
location generally centrally of said frame.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not applicable.
INCORPORATION-BY-REFERENCE OF MATERIALS SUBMITTED ON A COMPACT
DISC
[0004] Not applicable.
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] The present invention relates to blowout preventer systems
for use with subsea wells. More particularly, the present invention
relates to capping stacks as used in association with the wellhead
or the blowout preventer. More particularly, the present invention
relates to capping stacks having a plurality of flow passageways
formed therein so as to allow the fluid from the subsea well to
pass upwardly therethrough and therefrom.
[0007] 2. Description of Related Art Including Information
Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
[0008] As the worldwide demand for hydrocarbon fuel has increased,
and known onshore reserves have not kept up with the demand, there
has been increasing activity in offshore oil exploration and
production. Reserves of oil known to exist in the offshore areas
have steadily increased and an increasing percentage of world
production is from these offshore areas. The offshore environment
has presented numerous new challenges to the oil drilling industry
which have been steadily overcome to allow efficient drilling and
production in these areas, although the costs have been
considerably higher than those of onshore operations.
[0009] Not only has the offshore environment made production more
difficult to accomplish, it has also generally increased the risk
of environmental damage in the event of a well blowout or other
uncontrolled loss of hydrocarbons into the sea. As a result, known
safety equipment, such as blowout preventers which have been used
successfully in onshore operations, have been used in offshore
operations also. In spite of safety precautions, blowouts of
offshore oil wells are known to occur and will occur in the
future.
[0010] Subsea drilling operations may experience a blowout, which
is an uncontrolled flow of formation fluids into the drilling well.
These blowouts are dangerous and costly, and can cause loss of
life, pollution, damage to drilling equipment, and loss of well
production. To prevent blowouts, blowout prevention equipment is
required. This blowout prevention equipment typically includes a
series of equipment capable of safely isolating and controlling the
formation pressures and fluids at the drilling site. BOP functions
include opening and closing hydraulically-operated pipe rams,
annular seals, shear rams designed to cut the pipe, a series of
remote-operated valves to allow control the flow of drilling
fluids, and well re-entry equipment. In addition, process and
condition monitoring devices complete the BOP system. The drilling
industry refers to the BOP system as the BOP stack.
[0011] The well and the BOP connect the surface drilling vessel to
a marine riser pipe, which carries formation fluids (e.g., oil,
etc.) to the surface and circulates drilling fluids. The marine
riser pipe connects to the BOP through the Lower Main Riser Package
(LMRP) which contains a device to connect to the BOP, an annular
seal for well control, and flow control devices to supply hydraulic
fluids for the operation of the BOP. The LMRP and the BOP are
commonly referred to, collectively, as simply the BOP. Many BOP
functions are hydraulically controlled, with piping attached to the
riser supplying hydraulic fluids and other well control fluids.
Typically, a central control unit allows an operator to monitor and
control the BOP functions from the surface. The central control
unit includes a hydraulic control system for controlling the
various BOP functions, each of which has various flow control
components upstream of it.
[0012] While many of the techniques used in onshore operations can
be applied in the offshore environment, they often prove to be less
effective and require a much longer time period for implementation.
For example, while relief wells can drilled to intercept the
blowout well, a great amount of time may be required in the
drilling operation. In drilling the relief wells, platforms or
other drilling support decks must be located and transported to the
blowout site before drilling operations can begin. Due to the
rugged offshore environment, more time is required to drill the
relief wells than would be required in onshore operations. As a
result of all of these difficulties, many months can pass between
the occurrence of an offshore oil well blowout and the successful
final capping of the blown-out well. In the intervening time, large
quantities of oil and gas can escape into the ocean with serious
environmental impact.
[0013] While a portion of the hydrocarbons lost from a subsea well
blowout may be trapped and skimmed by various containment booms and
oil skimmer ships, substantial quantities of hydrocarbons can still
escape such containment equipment. It can be seen that once the
hydrocarbons are allowed to reach the ocean, surface wave action
tends to disburse the lighter hydrocarbons which may mix with water
or evaporate into the air. The gaseous hydrocarbons, of course,
tend to escape into the atmosphere. The heavier ends of the crude
oil often form into globules or tar balls which may flow at, or
just below, the water's surface so as to make it difficult to
contain or to skim up.
[0014] In the past, various patents and patent publications have
issued relating to systems for the containment of oil spills and
blowouts. For example, U.S. Pat. No. 4,324,505, issued on Apr. 13,
1982 to D. S. Hammett, discloses a subsea blowout containment
method and apparatus. This blowout containment apparatus comprises
an inverted funnel adapted for positioning over a wellhead to
receive fluids from the well and direct them into a conduit
extending from the funnel to surface support and processing
equipment. The funnel and conduit are supported from the sea's
surface, preferably by a vessel such as a barge. The barge carries
the equipment to receive the full flow of fluids from the well, to
process the fluids, and to conduct the liquids to a nearby tanker
where the recovered liquid hydrocarbons may be stored.
[0015] U.S. Pat. No. 4,405,258, issued on Sep. 20, 1983 to O'Rourke
et al., describes a method for containing oil and/or gas within a
blow-out cover dome. This method includes the steps of deploying a
containment dome in shallow water near the location of the seabed
where the containment dome is to be located. The containment dome
has an upper expanded dome-like fluid impervious membrane, a fluid
impervious hollow peripheral ring attached to the periphery of the
membrane to provide a depending bag-like container, and discrete
water drainage means within the bag-like container for connection
to pump conduit means therefrom. Wet sand from the seabed is then
pumped into the bag-like container. Water is then drained from the
wet sand through the water drainage means so as to provide a body
of drained sand disposed within the bag-like container and
providing a hollow peripheral ring as a hollow peripheral torus
acting as a self-supporting structure and as an anchor for the
dome-like structural unit. The dome is then charged with a buoyant
amount of air and the buoyed dome is floated out to the site where
the dome is to be deployed. It is then submerged by controllably
releasing the air while substantially simultaneously filling the
dome with water, thereby sinking the dome until the
lighter-than-water fluid is captured within the dome.
[0016] U.S. Pat. No. 4,828,024, issued on May 9, 1989 to J. R.
Roche, describes a diverter system and blowout preventer. The
system comprises a blowout preventer attached above a spool having
a hydraulically-driven sleeve/piston. An outlet flow passage exists
in the spool. This outlet flow passage can be connected to a vent
line. The outlet flow passage is closed off by the sleeve wall when
the spool piston is at rest. Hydraulic ports are connected above
and below the blowout preventer annular piston and above and below
the spool annular piston. The ports below the blowout preventer
piston and above the spool piston are in fluid communication with
each other. A hydraulic circuit is provided having two valves
between a source of pressurized hydraulic fluid and a drain.
[0017] U.S. Pat. No. 5,984,012, issued on Nov. 16, 1999 to Wactor
et al., provides an emergency recovery system for use in a subsea
environment. This emergency recovery system has a casing that is
open at each end with a shackle connected to one end of the casing
with the opposite end of the shackle designed for connection to
appropriate points on the main stack and lower marine riser package
in any orientation. A flexible sling with a closed loop formed at
each end is used with one of the closed loops releasably connected
to the shackle and the end of the casing. The other end of the
sling has a flotation member attached to the sling adjacent the
closed loop. The sling is fan folded as it is lowered into the
casing. The flotation member is shaped to fit inside the other end
of the casing with the closed end loop of the sling protruding from
the casing. The flotation member is constructed of synthetic foam
and is sized to provide sufficient buoyancy to fully extend the
sling when the release ring is released by a remotely operated
vehicle in a subsea environment.
[0018] U.S. Pat. No. 7,165,619, issued on Jan. 23, 2007 to Fox et
al., teaches a subsea intervention system that includes a BOP
module and CT module. A tool positioning system is used for
positioning a selected subsea tool stored within a rack with a tool
axis in line with the BOP axis, while a marinized coiled string
injector is moved by positioning system to an inactive position.
Power to the subsea electric motors is supplied by an electrical
line umbilical extending from the surface for powering the pumps.
An injector is provided that includes a pressure compensator roller
bearing and a pressure-compensated drive system case.
[0019] U.S. Pat. No. 7,597,811, issued on Oct. 6, 2009 to D. Usher,
provides a method and apparatus for subsurface oil recovery using a
submersible unit. The submersible vehicle is positioned above the
bed of a diver supported on a platform above the pollutant. A wand
at one end of a pipe evacuated by a centrifugal pump is manipulated
to draw the pollutant to the surface for treatment or disposal.
[0020] U.S. Pat. No. 7,921,917, issued on Apr. 12, 2011 to Kotrla
et al., shows a multi-deployable subsea stack system. This subsea
stack system includes a lower marine riser package, a blowout
preventer stack with a first ram blowout preventer, and an
additional blowout preventer package releasably coupled to the
blowout preventer stack and comprising a second ram blowout
preventer. The subsea blowout preventer stack assembly can be
deployed by coupling a drilling riser to the lower marine riser
package that is releasably connected to the blowout preventer
stack. The lower marine riser package and blowout preventer stack
are then attached to a subsea wellhead and then landed on the
additional blowout preventer package that is coupled to the subsea
wellhead.
[0021] U.S. Patent Publication No. 2009/0095464, published on Apr.
16, 2009 to McGrath et al., provides a system and method for
providing additional blowout preventer control redundancy. This
system has backup or alternate fluid flow routes around
malfunctioning BOP control components using a remotely-installed
removable hydraulic hose connection. The backup fluid flow route
sends pressure-regulated hydraulic fluid to a BOP operation via an
isolation valve rigidly attached to the BOP, then to a hose
connected to an intervention panel on the BOP, and finally through
a valve that isolates the primary flow route and establishes a
secondary flow route to allow continued operation.
[0022] U.S. Patent Publication No. 2009/0260829, published on Oct.
22, 2009 to D. J. Mathis, provides a subsea tree safety control
system that limits the probability of failure on demand of a subsea
test tree. A safety shut-in system is provided for actuating a
safety valve of the subsea test tree. The safety shut-in system
includes a surface control station positioned above a water surface
connected via an umbilical to a subsea control system positioned
below the water surface so as to actuate the safety valve.
[0023] U.S. patent application Ser. No. 13/160,032, filed on Jun.
14, 2011 to the present assignee, discloses a diverter system for a
subsea well. This diverter system is commonly known as a "capping
stack". This diverter system includes a body having a flow
passageway extending therethrough, a ram affixed to the body and
extending in transverse relationship to the flow passageway, at
least one channel in fluid communication with the flow passageway
so as to allow fluid in the flow passageway to pass outwardly of
the body, and at least one flowline in valved communication with
the flow passageway of the body so as to selectively allow a fluid
to be introduced into the flow passageway. The body has an inlet
end and an outlet end. The inlet end is suitable for application to
an outlet of a blowout preventer. The ram is actuatable so as to
change a flow rate of fluid passing through the flow passageway.
The channel includes a first channel in valved communication with
the flow passageway and a second channel in valved communication
with the flow passageway. Each of these channels extend in
transverse relationship to the flow passageway so as to pass fluid
from the flow passageway to a location away from the body.
[0024] The product that is sold by Trendsetter Engineering, Inc.
that is the subject of U.S. application Ser. No. 13/160,032 has
been a highly successful product for the company. This product is
relatively heavy and has a weight in the order of between 100 to
150 tons. Since the flow diverter sends the fluid flow in
perpendicular relationship to the flow from the blowout preventer,
there is a possibility of erosion to the internal components of the
capping stack when the fluid flows at very high rates. The single
centralized bore is limited by the available valve/ram sizes. In
this product, the central bore extends entirely through the body of
the capping stack. As such, in order to install the capping stack,
the central bore remains open during installation. As such, the
fluid flowing from the blowout preventer will pass freely through
the central bore of the capping stack during installation. Once the
product is installed on the blowout preventer, the central bore is
closed by rams (in the nature of a blowout preventer) so as to stop
the flow through the central bore of the capping stack. At that
time, the channels can be either closed so as to retain the flow of
fluids in the well or open so as to allow the fluids to be removed
from the capping stack.
[0025] After extended use of the present invention, it was found
that it would be desirable to significantly reduce the weight of
the capping stack. The weight of the capping stack requires that
the capping stack be assembled on location. Very few airplanes have
the capacity to carry the entire assembled capping stack to the
desired location. The relatively large size of the this capping
stack can be somewhat difficult to maneuver between the risers of
tension leg platforms or spar platforms. Additionally, although the
capping stack is within the limits of cranes associated with
offshore platforms, it does require the maximum capacity of such
equipment. Since the capping stack is required to be assembled at
the location, additional testing is required once the capping stack
is reassembled. Although the capping stack is very heavy, the
actual weight of the capping stack is of no particular value for
the closing or control of the well.
[0026] It is an object of the present invention to provide a
capping stack of relatively small size and of minimal weight.
[0027] It is another object of the present invention to provide a
capping stack having bores and flowlines which minimize the effects
of erosion when fluids flow through such bores and flowlines at
high flow rates.
[0028] It is another object of the present invention to provide a
capping stack that has a minimal number of components.
[0029] It is another object of the present invention to provide a
capping stack that does not require reassembly and retesting.
[0030] It is another object of the present invention to provide a
capping stack which avoids the use of rams for the closing of the
flow passageway.
[0031] It is another object of the present invention to provide a
capping stack that provides the ability to capture fluids from the
subsea well.
[0032] It is a further object of the present invention to provide a
capping stack which allows the weight of the capping stack to be
actively used to create pressure against the flow of fluid from the
well.
[0033] It is still another object of the present invention to
provide a capping stack that can be easily maneuvered between the
risers of tension leg platforms or spar platforms.
[0034] It is still a further object of the present invention to
provide a capping stack that is relative easy to handle on boats
and offshore platforms and easily within the limits of existing
equipment.
[0035] It is still a further object of the present invention to
provide an assembled capping stack that can be shipped as air
freight, on demand, to a desired location.
[0036] It is still a further object of the present invention to
provide a capping stack that minimizes the risk of damage to a
wellhead.
[0037] These and other objects and advantages of the present
invention will become apparent from a reading of the attached
specification and appended claims.
BRIEF SUMMARY OF THE INVENTION
[0038] The present invention is a capping stack for use with a
subsea well. The capping stack includes a body with a flow
passageway extending therethrough. The flow passageway has an inlet
suitable for connection to a fluid passageway of a blowout
preventer or to a wellhead of subsea well. The body has a first
bore having one end opening to an outlet end of the flow
passageway. The first bore extends upwardly from the flow
passageway. The body of the second bore has one end opening to the
outlet end of the flow passageway. The second bore also extends
upwardly from the flow passageway. A first flowline is affixed to
the first bore and extends upwardly therefrom. A second flowline is
affixed to the second bore and extends upwardly therefrom. A first
valve is cooperative with the first flowline so as to be movable
between an open position and a closed position. The open position
is suitable allowing fluids from the subsea well to flow through
the first flowline. The closed position is suitable for blocking
fluids from passing outwardly of the first flowline. A second valve
is cooperative the second flowline so as to be movable between an
open position and a closed position. The open position of the
second valve allows fluid from the subsea well to flow through the
second flowline. The closed position of the second valve blocks
fluid from passing outwardly of the second flowline.
[0039] In the present invention, a connector is affixed to a lower
end of the body. The connector is suitable for connecting the body
to either the blowout preventer or the wellhead. A frame is
connected to the body and extends upwardly therefrom.
[0040] The first bore diverges away from the second bore in a
direction away from the outlet end of the flow passageway. The
first bore extends an angle of 60.degree. or less to vertical. The
second bore extends at an angle of 60.degree. or less to vertical.
One end of the first bore is in spaced relation to the end of the
second bore at the outlet end of the flow passageway. Each of the
first and second bores has a cross-sectional area less than a
cross-sectional area of the flow passageway.
[0041] In the present invention, there can be a third bore having
one end opening to the outlet end of the flow passageway. The third
bore extends upwardly from the flow passageway. A third flowline is
affixed to the third bore and extends upwardly therefrom. A third
valve is cooperative with the third flowline so as to be movable
between an open position and a closed position. The open position
of the third valve allows fluids from the subsea well to flow
through the third flowline. The closed position of the third valve
blocks fluids from passing outwardly of the third flowline. The
third bore diverges away from the first and second bores in a
direction away from the outlet end of the flow passageway.
[0042] In the present invention, the first valve can include a pair
of valves that are cooperative with the first flowline. The pair of
valves are in spaced relationship to each other. The second valve
can also be a pair of valves that are cooperative with the second
flowline. The pair of valves of the second valve are in spaced
relationship to each other.
[0043] Each of the first and second flowlines includes a first
portion having a first end and a second end. The first end
connected to the respective bore. The first portion extends at an
acute angle to vertical away from the respective bore. Each of the
first and second flowlines also includes a second portion extending
from the second end of the first portion and extending vertically
upwardly therefrom. Each of the first and second flowlines has
connecting portion at an upper end thereof. This connecting portion
is suitable for connection to a conduit so as to allow fluids from
the subsea well to flow therefrom.
[0044] A lifting mechanism can be affixed to an upper portion of
the frame in a location generally centrally of the frame. This
lifting mechanism is suitable for allowing a hoist or a crane to
lift the capping stack and to lower the capping stack, as
desired.
[0045] The foregoing Section is intended to describe, with
particularity, the preferred embodiment of the present invention.
It is understood that modifications to this preferred embodiment
can be made within the scope of the present invention. As such,
this Section is not intended, in any way, to be limiting of the
broad scope of the present invention. The present invention should
only be limited by the following claims and their legal
equivalents.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0046] FIG. 1 is a perspective view of the capping stack of the
present invention.
[0047] FIG. 2 is a cross-sectional view showing the capping stack
of the present invention.
[0048] FIG. 3 is an exploded view showing the relationship of the
capping stack of the present invention to a blowout preventer.
[0049] FIG. 4 is a perspective view showing an alternative
embodiment of the capping stack of the present invention.
[0050] FIG. 5 is an upper perspective view of a further alternative
embodiment of the capping stack of the present invention.
[0051] FIG. 6 is an internal perspective view showing the
arrangement of bores formed within the body of the capping stack of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0052] Referring to FIG. 1, there is shown the capping stack 10 in
accordance with the teachings of the present invention. The capping
stack 10 includes a body 12 having a connector 14 located at a
bottom end thereof. The body 12 has a generally cylindrical
configuration. The connector 14 is suitable for connection to
either a subsea wellhead or an upper end of a blowout preventer. A
frame 16 is affixed to the body 12 at an upper end of the body 12.
The frame 16 supports a first flowline 18 and a second flowline 20
thereon. Each of the first flowline 18 and the second flowline 20
extends vertically upwardly. A third flowline 22 can also be
supported by the frame 16. As will be described hereinafter, there
is a first valve associated with the flowline 18, a second valve
associated with the second flowline 20 and a third valve associated
with the third flowline 22. As can be seen in FIG. 1, the frame 16
supports a panel 24. The panel 24 supports a first actuator 26 for
control of the valve associated with the first flowline 18, a
second actuator 28 that controls the operation of the valve
associated with the second flowline 20 and a third actuator 30 that
controls the operation of the valve associated with the third
flowline 22. A suitable lifting mechanism, such as padeye 32, is
positioned on an upper portion of the frame 16 so as to allow
suitable cranes or hoists to lift and lower the capping stack 10,
as desired.
[0053] FIG. 2 shows a cross-sectional view of the capping stack 10
of the present invention. The capping stack 10 includes the body 12
having the connector 14 at a lower end thereof. The body 12 has a
flow passageway 34 extending vertically therethrough. Flow
passageway 34 has a relatively large diameter. The flow passageway
34 has an inlet end 36 and an outlet end 38. As can be seen in FIG.
2, the body 12 includes a lower body portion 40 that is bolted to
an upper body portion 42.
[0054] The upper body portion 42 has a first bore 44 and a second
bore 46 extends therethrough. Although the term "bore" is used, it
is understood that, within the concept of the present invention,
similar items, such as pipe, conduits, hoses, or other devices,
could also be considered as "bores".
[0055] In FIG. 3, it can be seen that the first bore 44 has one end
opening to the outlet end 38 of the flow passageway 34. The second
bore 46 also has an end opening to the outlet end 38 of the flow
passageway 34. Each of the bores 44 and 46 diverge away from each
other in a direction away from the outlet end 38 of the flow
passageway 34. The ends of the bores 44 and 46 are in spaced
relationship to each other at the outlet end 38 of the flow
passageway 34. Within the concept of the present invention, each of
the bores 44 and 46 extends upwardly at an acute angle of less than
60.degree. to vertical. In the preferred embodiment of the present
invention, the bores 44 and 46 should extend at 45.degree. to
vertical.
[0056] Through the arrangement of the bores 44 and 46, as shown in
FIG. 2, the fluid passing through the flow passageway 34 is
diverted into the bores 44 and 46. Since the bores 44 and 46 extend
at an acute angle to vertical, rather than transverse to vertical,
there is less possibility of erosion caused by particles entrained
within a fluid passing at a high flow rate through the flow
passageway 34 and into the bores 44 and 46. Each of the bores 44
and 46 has a cross-sectional area that is less than the
cross-sectional area of the flow passageway 34. As such, the flow
passageway 34 is diverted into smaller bores.
[0057] The first bore 44 is connected to the first flowline 18. A
first valve 48 is cooperative with the first flowline 18 so as to
control the flow of fluid into and through the first flowline 18.
The first valve 48 is a gate valve. A suitable ROV can be utilized
so as to open and close the valve 48. In the closed position, the
valve 48 blocks the flow of fluid from the bore 44 into the
flowline 18. In the open position, the valve 48 allows for the flow
of fluid from the bore 44 through the flowline 18.
[0058] The second bore 46 is connected to the second flowline 20. A
second valve 50 is cooperative with the second flowline 20 so as to
control the flow of fluid from the bore 46 into and through the
second flowline 20. In the open position, the valve 50 allows for
the flow of fluid from the bore 46 through the second flowline 20.
In the closed position, the valve 50 will block the flow of fluid
from the bore 46 into the second flowline 20.
[0059] The first flowline 18 has a first portion 52 that has an end
connected to the first bore 44. The first portion 52 extends at the
same acute angle that the first bore 44 extends and is axially
aligned with the first bore 44. The opposite end of the first
portion 52 is connected to a second portion 54. The second portion
54 extends vertically upwardly. The first flowline 18 includes an
outlet 56 at an upper end thereof. Outlet 56 is located at a
convenient location for the attachment of a conduit, or other
piping, such that fluids passing through the first flowline 18 can
be diverted to another location, such as surface location. Through
this angled relationship, the flow of fluid through the first
portion 52 and the second portion 54 is gradually transitioned
rather than having any sharp angles (which could cause erosion). It
can be seen that there is connection portion 58 located adjacent to
the end 56. Connection portion 58 allows the first flowline 18 to
be connected to the corresponding conduit.
[0060] The second flowline 20 also includes a first portion 60 and
second portion 62 that extend in similar manner as portions 52 and
54 of the first flowline 18. The valves 48 and 50 are respectively
connected to the first portion 52 and 60 of the respective
flowlines 18 and 20. The second flowline 20 also includes a
connection portion 64 located adjacent to the end 66.
[0061] FIG. 2 further shows the frame 16 as supporting the
flowlines 18 and 20 thereon. The frame 16 provides a strong
structure for the support of the various components of the present
invention. Additionally, another type of lifting mechanism 68 is
secured to the frame 16 so as to facilitate the ability to lift and
lower capping stack 10, as desired.
[0062] With reference to FIG. 2, it can be seen that valves 48 and
50 are utilized in the capping stack 10. As such, the capping stack
10 avoids the use of complicated ram mechanisms associated with
other capping stacks. The valves 48 and 50 are readily available
for use. As such, the constructural complexity associated with
installing the ram mechanisms on the capping stack 10 is avoided.
Since each of the bores 44 and 46 and the flowlines 18 and 20 are
of a relatively minimal diameter, the requisite flow of fluid
through the interior of the capping stack 10 can be achieved. As
such, when it is desired to place the capping stack 10 upon a
blowout preventer or on a wellhead, the valves 48 and 50 can be
opened so as to allow for the free flow of fluid therethrough. As
such, if fluids are being released by the blowout preventer, the
fluid will enter the flow passageway 34, pass through the bores 44
and 46, and outwardly through the flowlines 18 and 20. Since there
is small area of contact between the ends of the bores 44 and 46 at
the outlet end 38 of the flow passageway 34, a certain amount of
resistance will occur when attempting to the lower the capping
stack 10 onto the wellhead or the blowout preventer. However, the
present invention actually uses the weight of the capping stack 10
so as to overcome any resistance that may be created by this small
surface. As such, the present invention effectively utilizes the
weight of the capping stack in the capping of the blowout
preventer.
[0063] Once the capping stack 10 is installed, the valves 48 and 50
can be closed so as to close off the blowout preventer or the
wellhead. When proper pressures are realized, and when suitable
conduits are connected to the connection portions 58 and 64 of the
capping stack 10, the valves 48 and 50 can be respectively opened
so as to allow for the release of fluids therethrough. As such,
these fluids can be effectively recovered at another location, such
as a surface location.
[0064] FIG. 3 shows the installation of the capping stack 10 onto a
blowout preventer 70. It can be seen that the blowout preventer 70
is secured to a wellhead 72 located at a subsea floor 74. In normal
fashion, the blowout preventer 70 is properly secured to the
wellhead 72 and extends upwardly therefrom. There is a mandrel 76
located at the upper end of the blowout preventer 70.
[0065] The capping stack 10 is secured by placing the connector 14
over the mandrel 76. Suitable conventional locking mechanisms can
be provided whereby the body 12 of the capping stack 10 is secured
to the mandrel 76 in fluid-tight relationship. As such, the body 12
can be suitably locked to the mandrel 76 so as to establish a fluid
flow relationship between the fluid passing through the mandrel 76
of the blowout preventer 70 and the flow passageway 34 of the body
12.
[0066] FIG. 3 shows the capping stack 10 as having three bores, and
showing in particular, a third bore 78. Third bore 78 can have a
third valve 80 positioned thereon. Additionally, the third flowline
22 will extend from the third bore 78. As such, FIG. 3 shows a
total of three bores that are utilized so as to divert the fluid
flow from the blowout preventer 70.
[0067] With reference to FIG. 3, there are certain circumstances
where the blowout preventer 70 may be slightly tilted at an angle
to vertical. This could occur during a subsea event or if the
blowout preventer 70 is improperly installed. In past
circumstances, if the capping stack 10 were too heavy, then it
could exert forces which would tend to further deflect the blowout
preventer 70. The lower weight of the capping stack 10 is less
likely to create such forces and will operate so as to maintain the
blowout preventer 70 in its existing orientation.
[0068] In certain circumstances, the capping stack 10 could be
applied to the wellhead 72 rather than the blowout preventer. Under
this circumstance, the connector 14 of the body 12 is simply placed
over the wellhead 72 such that the capping stack 10 is joined
directly to the wellhead 72 so as to control for the release of
fluids from the well.
[0069] FIG. 4 shows another embodiment of the capping stack 100 of
the present invention. Capping stack 100 includes a body 102 and
flowlines 104, 106 and 108 extending upwardly therefrom.
Importantly, in FIG. 4, it can be seen that the first flowline 104
includes a first valve actuator 106 provided on the frame 108. A
second valve actuator 110 is also supported by the frame 108.
[0070] The first flowline 104 will include a first valve associated
with the actuator 106 and a second valve 112 located at an upper
end thereof. As such, these valves will be in spaced relationship
to each other. It is found that, under certain circumstances,
customers desire to have redundancy in the control of fluids from
the subsea well. As such, applying two valves to each of the
flowlines 104 and 106 can accomplish this purpose. Flowline 104
will also include a transition section 116 so as to allow for a
suitable connector to be applied to flange 118 so as to allow for
the release of fluids from the first flowline 104. The second
flowline 106 also includes a valve associated with the actuator 104
located on the first portion of the transition member 106 adjacent
to the bores and the body 102 and a second valve 120 positioned in
spaced relationship to the first valve. Another diverter member 122
is located at the upper end of the second flowline 106 so as to
allow for the diverter member 122 to transmit fluids outwardly of
the flange portion 124.
[0071] The capping stack 100 includes various lifting bars 126, 128
and 130 extending upwardly therefrom. Additionally, a padeye 132
can be directly affixed to the frame 108. As such, these lifting
mechanisms facilitate the ability to lift and lower the capping
stack 100.
[0072] FIG. 5 shows a further embodiment of the capping stack 200
of the present invention. Capping stack 200 includes a body 202
having a connector 204 located at a lower end thereof. The capping
stack 200 includes four flowlines 206, 208, 210 and 212. The frame
214 supports each of the flowlines 206, 208, 210 and 212 such that
they extend upwardly vertically. FIG. 5 shows a bucket 216 for the
control of the valve associated with the flowline 210 and a bucket
218 for the control of the valve associated with the flowline 220.
Suitable additional buckets (not shown) can be utilized so that an
ROV can effectively control the operation of the flowlines 206 and
208. The body 202 will include a total of four bores which extend
so as to be connected to each of the flowlines 206, 208, 210 and
212 in the manner described in the previous embodiments. As such,
the capping stack 200 allows for the diversion of flow along four
separate pathways. The capping stack 200 is adaptable to enhance
the capacity to remove greater amounts of fluid from the well or
for the ability to reduce the diameter of each of the flowlines
206, 208, 210 and 212, along with the valves associated
therewith.
[0073] FIG. 6 shows a detailed view of the upper body which
includes the bore spool 222 of the capping stack 200. As can be
seen, the bore spool 222 includes a first bore 224, a second bore
226, a third bore 228 and a fourth bore 230 extending so as to
diverge from one another within the bore spool 222. The bore spool
222 has a flange 232 that is suitable for attachment to the lower
body portion of body 222. Each of the bores 224, 226, 228 and 230
has a flange thereon whereby the respective bores can be secured to
the respective flowlines 206, 208, 210 and 212. Each of the bores
224, 226, 228 and 230 has a lower end that will open to the outlet
end 234 of the flow passageway (such as flow passageway 34 in FIG.
2). In this manner the flow of fluids through the flow passageway
34 is diverted at acute angles to vertical through the respective
bores 224, 226, 228 and 230.
[0074] The present invention significantly reduces the size and
weight of the capping stack. Since the size is reduced, it is
easier to maneuver between the risers of tension leg platforms or
spar platforms. Additionally, the relatively small size of the
capping stack of the present invention allows the entire capping
stack to be positioned within the storage bay of a transport
airplane. Since the weight of the capping stack of the present
invention is estimated to be between thirty and forty tons, it can
be easily transported by conventional air transport planes. As
such, the capping stack of the present invention can be stored in
one location and delivered to a remote location in a relatively
minimal amount of time. As such, the present invention avoids the
need to deploy separate capping stacks in the various areas of
hydrocarbon production. The relatively small weight of the capping
stack allows it to be easily handled on boats or with existing
equipment on an offshore platform.
[0075] The gradual transitions between the flow passageway and the
bores and the flowlines reduces the possibility of erosion. If
sharp turns of a fluid will occur in a capping stack, then there is
the possibility, over time, of the erosion of the internal
structures of the capping stack. As such, the gradual transitions
provided by the capping stack of the present invention will
minimize the risk of erosion caused by the high rates of fluid.
[0076] The present invention has a smaller number of components
than existing capping stacks. As such, the amount of testing is
reduced. There is less reassembly and retesting of the capping
stack. The capping stack, in view of its small size and weight, can
be delivered entirely intact to the desired location. As such, it
is not necessary to deliver the capping stack in pieces and then
assemble the capping stack at the location.
[0077] The present invention utilizes valves instead of rams. As
such, it is not limited, in any way, by ram availability or ram
sizes. It also avoids the complex mechanisms associated with the
installation of such rams.
[0078] The foregoing disclosure and description of the invention is
illustrative and explanatory thereof. Various changes in the
details of the illustrated construction can be made within the
scope of the appended claims without departing from the true spirit
of the invention. The present invention should only be limited by
the following claims and their legal equivalents.
* * * * *