U.S. patent application number 10/518209 was filed with the patent office on 2005-08-18 for subsea hydrocarbon production system.
Invention is credited to Appleford, David Eric, Lane, Brian William.
Application Number | 20050178556 10/518209 |
Document ID | / |
Family ID | 9939534 |
Filed Date | 2005-08-18 |
United States Patent
Application |
20050178556 |
Kind Code |
A1 |
Appleford, David Eric ; et
al. |
August 18, 2005 |
Subsea hydrocarbon production system
Abstract
A system (1) for extracting subsea hydrocarbon fluid has five
discrete subsea developments (10, 12, 14, 16, 18) for hydrocarbon
extraction linked to four hydrocarbon receiving facilities (2, 4,
6, 8) by a pipeline network (94). Each subsea development (10, 12,
14, 16, 18) has a manifold to which pipelines of the network (94)
are connected, and a pair of retrievable modules (22) docked on the
manifold. Each module has a control pod which is able to control
flows of fluids between the subsea developments and between the
subsea developments and the receiving facilities, and each control
pod is connected to monitoring devices for monitoring parameters
pertaining to the subsea developments. Parameters are monitored at
a first one of the subsea developments and a requirement for a
first fluid type is identified and parameters at another second one
of the subsea developments are monitored and a surplus of the first
fluid type is identified. The relevant control pods are then
operated to enable a quantity of the first fluid to be conveyed
from the second to the first subsea development via the pipeline
network (94).
Inventors: |
Appleford, David Eric;
(Theydon Bois, GB) ; Lane, Brian William; (Canvey
Islands, GB) |
Correspondence
Address: |
SUMMA & ALLAN, P.A.
11610 NORTH COMMUNITY HOUSE ROAD
SUITE 200
CHARLOTTE
NC
28277
US
|
Family ID: |
9939534 |
Appl. No.: |
10/518209 |
Filed: |
December 16, 2004 |
PCT Filed: |
June 27, 2003 |
PCT NO: |
PCT/GB03/02767 |
Current U.S.
Class: |
166/366 |
Current CPC
Class: |
E21B 43/017
20130101 |
Class at
Publication: |
166/366 |
International
Class: |
E21B 007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2002 |
GB |
0215064.7 |
Claims
1. A system for extracting subsea hydrocarbon fluid comprising at
least three discrete subsea developments for hydrocarbon extraction
and a hydrocarbon receiving facility linked by a pipeline network
configured to permit: (a) diversion of fluid from at least one of
said subsea developments selectively to one or more of said other
developments; and (b) conveyance of fluid from each of said subsea
developments to said receiving facility.
2. The system as claimed in claim 1, wherein said pipeline network
is also configured to permit conveyance of fluid from at least one
of said subsea developments to said receiving facility selectively
via at least two alternative routes.
3. The system as claimed in claim 1 comprising a plurality of
receiving facilities, wherein said pipeline network is configured
to permit conveyance of fluid from each of said subsea developments
to any said receiving facility.
4. The system as claimed in claim 1, wherein said pipeline network
further comprises plural pipelines between at least two of said
subsea developments, said pipelines being suitable for respectively
conveying different fluids such as hydrocarbon liquid, hydrocarbon
gas and water.
5. The system as claimed in claim 3, comprising a control means for
controlling flows of fluids between said subsea developments and
between said subsea developments and at least one said receiving
facility.
6. The system as claimed in claim 5, wherein said control means
comprises a monitoring means for monitoring parameters pertaining
to at least one of said subsea developments.
7. The system as claimed in claim 5, wherein said control means
comprises signal processing means located at said subsea
developments, wherein said subsea developments communicate thereby
and control, at least to a limited extent, the distribution of
fluids around said pipeline network.
8. The system as claimed in claim 5, wherein the said control means
is arranged to operate by automatically sensing what items of
hardware are in use at a particular subsea development.
9. The system as claimed in claim 8, wherein each said item of
hardware comprises an electronic chip containing identification
information.
10. The system as claimed in any claim 5, comprising a remote
input/receiving device for effecting control of the flow of said
fluids.
11. The system as claimed in claim 5, wherein said control means
further comprises means to calculate the best place to store or
dispose of a particular fluid.
12. The system as claimed in claim 1, wherein at least one of said
subsea developments comprises separating means for at least
substantially separating constituent components of fluid received
by said subsea development from each other.
13. The system as claimed in claim 1, wherein at least one of said
subsea developments comprises a manifold connected to said pipeline
network; and at least one retrievable module having equipment for
acting on fluid received thereby; wherein said module is docked
with said manifold for fluid connection to said pipeline
network.
14. The system as claimed in claim 3, comprising a network of power
lines between said subsea developments and each receiving facility
for distributing power.
15. The system as claimed in claim 3, comprising a network of
control lines between said subsea developments and each said
receiving facility for transmitting control signals.
16. The system as claimed in claim 3, comprising a network of
chemical injection lines between said subsea developments and each
said 3receiving facility for conveying chemical injection
fluids.
17. A method of operating a system for extracting subsea
hydrocarbon fluid, the system comprising plural discrete subsea
developments for hydrocarbon extraction and a hydrocarbon receiving
facility linked by a pipeline network and control means for
controlling flows of fluids between the subsea developments and
between the subsea developments and the receiving facility, the
control means comprising monitoring means for monitoring parameters
pertaining to the subsea developments, the method comprising the
steps of: (i) monitoring parameters at a first subsea development
and identifying a requirement for a first fluid type; (ii)
monitoring parameters at a second subsea development and
identifying a surplus of the first fluid type; and (iii) operating
the control means to convey a quantity of the first fluid from the
second to the first subsea development via the pipeline
network.
18. The method as claimed in claim 17, wherein the system comprises
plural receiving facilities and at least one of the subsea
developments comprises separating means for at least substantially
separating constituent components of fluid received by the
development from each other, the method comprising the steps of:
(i) at least substantially separating fluid received by the subsea
developments into first and second fluid types; (ii) conveying the
first fluid type to one of the receiving facilities; and (iii)
conveying the second fluid type to another of the receiving
facilities.
Description
[0001] The present invention relates to a system and method for
extracting hydrocarbons from subsea reservoirs and more
particularly to a system including plural geographically separate
fields.
[0002] Where plural separate fields are to be exploited, a host
facility is normally provided with fluid pipelines, control/power
lines etc. radiating out therefrom to extraction facilities at
different locations. Each extraction facility may include a central
unit connected to receive fluid from a plurality of wells. This
fluid may include a mixture of fluids including hydrocarbon liquid,
hydrocarbon gas and water, the volumetric ratios of which to each
other will vary considerably from field to field and throughout the
life of a particular field. In certain situations the extraction
facilities are connected to each other in series in a so-called
daisy chain arrangement, the series connected extraction facilities
being connected to a host facility. In general, the majority of the
fluid produced by the fields is all conveyed to the host facility
and if any fluid needs to be provided at an extraction facility
(e.g. water for pressure boosting injection into a subsea
reservoir) it is pumped from the host facility to the particular
extraction facility. The capital cost associated with installing
the pipelines for conveying the fluids is very high and any cost
saving resulting from the pipelines being designed for a lower
volumetric throughput is extremely desirable. It is also desirable
to minimise the amount of water which is returned to the host
facility because water so returned needs extensive processing prior
to disposal overboard and can accordingly incur a tariff. A further
drawback with existing series connected or radially connected
extraction facilities is that if a pipeline needs to be taken out
of service for any reason, then the flow of fluid being conveyed by
the pipeline is interrupted which may effectively result in the
shutting in of one or more fields. In addition to reducing
production output, such shutting in may also make it difficult to
restart the wells from those fields.
[0003] Taking the above drawbacks of prior art systems into
consideration, the invention provides a system for extracting
subsea hydrocarbon fluid comprising at least three discrete subsea
developments for hydrocarbon extraction and a hydrocarbon receiving
facility linked by a pipeline network configured to permit:
[0004] (a) diversion of fluid from at least one of the subsea
developments selectively to one or more of the other developments;
and
[0005] (b) conveyance of fluid from each of the subsea developments
to the receiving facility.
[0006] With such a system, if a first subsea development is
providing a surplus of one type of fluid (e.g. water) and a second
subsea development requires more of that fluid to function
effectively (e.g. for pressure boosting water injection) then water
can be conveyed through the pipeline network from the first to the
second subsea development. Alternatively, gas could be routed to a
subsea development where gas compression is available so that the
gas could be conveyed more effectively. Avoiding the requirement
to: (a) convey surplus fluids to the receiving host facility; and
(b) convey required fluids from the host to the subsea development
will reduce the maximum throughput that the pipelines to and from
the host are designed to accommodate and may even mean that the
requirement for one or more pipelines is obviated. Furthermore,
when water is used for well pressure boosting, the tariff paid to
the host operator will be reduced or even eliminated.
[0007] Fluids can accordingly be distributed around the pipeline
network when needed depending on demand, thereby realising
production efficiency.
[0008] Preferably, the pipeline network is also configured to
permit conveyance of fluid from at least one of the subsea
developments to the receiving facility selectively via two
alternative routes so that any work which needs to be carried out
on the pipelines or other parts of the system can be performed with
minimum interruption to the production process. Also, the pipeline
network allows efficient use of pipeline capacities.
[0009] The system preferably includes a plurality of receiving
facilities, the pipeline network being configured to permit
conveyance of fluid from each of the developments to any of the
receiving facilities. Each receiving facility may be in the form of
an offshore oil rig which may be floating or seabed supported, an
on-shore host facility or a floating storage and production unit.
With such an arrangement, if one receiving facility only has the
capability of catering for one type of fluid (e.g. liquid) and
another receiving facility has the capability of catering for
several fluid types (e.g. liquid and gas) then the flow of fluids
through the pipeline network can be controlled to route the
produced fluids to appropriate receiving facilities. Furthermore,
if the maximum capacity of a particular receiving facility is
reached or if a receiving facility becomes unavailable for use,
possibly because of political factors or because of maintenance
requirements, then it will be easily possible to divert produced
fluids to an alternative receiving facility.
[0010] To increase the flexibility of the system, the pipeline
network preferably includes, between at least two of the
developments, plural pipelines suitable for respectively conveying
different fluids such as hydrocarbon liquid, hydrocarbon gas and
water.
[0011] The system preferably also includes a control means for
controlling flows of fluids between the subsea developments and
between the developments and the or each receiving facility.
[0012] The subsea developments and the one or more receiving
facilities may also be connected by a network of power and/or
control lines and/or chemical injection lines for conveying
electric and/or hydraulic power and/or control signals and/or
chemical injection fluids. These power and control lines and
chemical injection lines conveniently follow the same routes as
those followed by the pipes of the pipeline network but need not do
so. With such an arrangement, the network could be used to
distribute power and/or control signals to the subsea developments
and also possibly to an offshore host facility via a choice of
routes.
[0013] The control means may employ advanced computer protocols to
standardise control hardware used to control the operation of the
subsea developments and the flow of fluids therebetween through the
pipeline network. Such a control means would preferably operate by
automatically sensing what items of hardware were in use at a
particular subsea development. Each item of hardware may include an
electronic chip containing identification information.
[0014] The control system may enable control of production rates
and flow distribution in the pipeline network from a remote
location which, by the use of global satellite communications,
could be anywhere in the world. Control could be effected from any
suitable input/receiving device such as a personal computer, a
personal digital assistant, a mobile telephone etc.
[0015] The control system may also include means to calculate the
best place to store or dispose of a particular fluid thereby
ensuring efficient use of the produced fluids.
[0016] By providing a control system which controls the
distribution of fluids, power and control over a large seabed area
and between the plurality of subsea developments, the need for host
platforms serving groups of subsea developments will be at least
reduced.
[0017] The control means may include signal processing means
located at the subsea developments which communicate with each
other and can control, at least to a limited extent, the
distribution of fluids around the pipeline network, possibly
independently of the host or receiving facility.
[0018] The control means preferably includes, at at least one of
the subsea developments, a monitoring means for monitoring
parameters pertaining to that subsea development.
[0019] Preferably at least one of the subsea developments includes
separating means for at least substantially separating constituent
components of fluid received by the development from each
other.
[0020] In order to increase the flexibility of the system and
permit each subsea development to be adapted as the requirement on
it changes, at least one and preferably each of the subsea
developments comprises a manifold to which pipelines of the network
are connected and at least one retrievable module including
equipment for acting on fluid received thereby and docked with the
manifold for fluid connection to the pipeline network. Such
equipment is designed by Alpha Thames Ltd of Essex, United Kingdom,
and marketed under the name AlphaPRIME. With such an arrangement,
as the requirement of a particular subsea development changes, a
module in the development can be replaced by an alternative one
with different processing capabilities.
[0021] According to a second aspect of the invention, there is
provided a method of operating a system for extracting subsea
hydrocarbon fluid, the system comprising plural discrete subsea
developments for hydrocarbon extraction and a hydrocarbon receiving
facility linked by a pipeline network and control means for
controlling flows of fluids between the subsea developments and
between the subsea developments and the receiving facility, the
control means including monitoring means for monitoring parameters
pertaining to the subsea developments, the method comprising the
steps of:
[0022] (i) monitoring parameters at a first subsea development and
identifying a requirement for a first fluid type;
[0023] (ii) monitoring parameters at a second subsea development
and identifying a surplus of the first fluid type; and
[0024] (iii) operating the control means to convey a quantity of
the first fluid from the second to the first subsea development via
the pipeline network.
[0025] Preferably the system includes plural receiving facilities
and at least one of the subsea developments includes separating
means for at least substantially separating constituent components
of fluid received by the development from each other, the method
including the steps of:
[0026] (i) at least substantially separating fluid received by the
subsea developments into first and second fluid types;
[0027] (ii) conveying the first fluid type to one of the receiving
facilities; and
[0028] (iii) conveying the second fluid type to another of the
receiving facilities.
[0029] The invention will now be described by way of example only
with reference to the accompanying schematic drawings in which:
[0030] FIG. 1 shows a system according to the invention for
extracting hydrocarbons from plural subsea developments; and
[0031] FIG. 2 shows a typical module for use in one of the subsea
developments shown in FIG. 1.
[0032] The system 1 shown in FIG. 1 includes four receiving
facilities, two of which 2, 4 are shore-based, one of which
comprises an offshore fixed platform 6 and one of which comprises a
floating production and storage unit 8. The system also includes
five subsea developments 10, 12, 14, 16 and 18. Each of the subsea
developments comprises a base structure 20 containing one or more
piping manifolds to which one or more retrievable modules 22 are
connected. The system shown in FIG. 1 includes base structures 20
all configured to accept two modules. Each base structure could
alternatively be configured to accept any other number of modules.
Plural wellheads 32 supply production fluid to the manifolds in the
associated base 20 by means of production fluid conduits 34.
[0033] A typical retrievable module 22 is shown in FIG. 2 which is
designed to effect separation of two fluids (e.g. liquid such as
oil and gas) from each other. Each module could however be
configured in an alternative manner depending on requirements. The
modules could for example be configured to separate three fluids
from each other by means of three phase separators or simply route
fluid round a loop and into an output pipe of the manifold in the
base structure.
[0034] The module 22 includes a module part 24 of a multi-ported
fluid connector 27 which is adapted to mate with a complementary
base part 26 thereof forming part of the base 20. Each connector
part 24, 26 includes isolation valves 28, 30 for isolating flow to
and from the module 22 when it is to be replaced. Production fluid
from the production fluid conduits 34 is routed to the module by
fluid inlet pipes 36 in the base 20 via the multi-ported fluid
connector 27 and into inlet conduits 38. The flow through the inlet
conduits 38 is regulated by pressure control valves 40 which are
adjusted by actuators 42 under the control of a control module 44.
Electrical signal lines are shown with dashed lines and fluid
conduits and pipes are shown with solid lines in FIG. 2.
[0035] The control module 44 receives power from a power line 46
via a disengageable power connector 48 and a transformer 49, and
signals from a signal line 50 via a disengageable signal connector
52. Pressure transducers 54 monitor pressure in the inlet conduit
38 and if over-pressurisation is detected, actuators 56 of two
series connected fail-safe closed valves 58 are de-powered to allow
the valves 58 to close. Fluid from the inlet conduit 38 is routed
into a separation vessel 60 where hydrocarbon gas 62 is separated
from produced liquid 64. The separator may be a gravity separator
as shown or a dynamic separator such as a hydro-cyclone separator.
Gas is routed out of the vessel 60 and through a gas outlet conduit
66, a gas compressor 68 and a venturi meter 70. Produced liquid 64
is routed via a liquid outlet conduit 72, a liquid pump 74 and a
flow control valve 76 controlled by an actuator 78 to the
multi-ported fluid connector 27. The interface between the gas 62
and produced liquid 64 is detected by a level sensor 80, the output
from which is used to control the flow control valve 76. Partial
closing of the flow control valve 76 forces produced liquid to be
returned to the separator vessel 60 via a flow restrictor 82 and a
liquid recirculation pipe 84. This would be effected if the
interface between the gas and the produced liquid in the vessel 60
became too low. Injection chemicals are routed to the module via
chemical injection connectors 86 and chemical injection lines 88
from which chemicals can be injected into the gas and liquid outlet
conduits 66, 72. Gas and liquid are respectively led away from the
module 22 by a gas outlet pipe 90 and a liquid outlet pipe 92
constituting part of the manifold system in the base structure
20.
[0036] The pipework manifold in each base structure 20 is connected
by a pipeline network to the pipework manifold of at least two
other subsea developments and in certain cases one of the receiving
facilities 2, 4, 6 or 8. The pipeline network is shown
schematically in FIG. 1 by solid lines extending between the subsea
developments and the receiving facilities. Although only one line
is shown extending between the subsea developments/receiving
facilities or nodes of the network, each internodal pipeline
connection 94 may include plural pipelines. Separate pipelines may
be provided for oil, gas, water, injection chemicals and/or test
flows for example. A network of internodal signal or power and
control lines 96 also extends between the subsea developments and
the receiving facilities which signal lines are shown by broken
lines. The signal line network is shown to have the same internodal
connections as the pipeline network. These two networks may not
necessarily be coincident however and some of the signal lines may
for example be replaced by communication links via some remote
receiving and transmitting means, eg a satellite communication
system.
[0037] When the system 1 shown in FIG. 1 is operating, continuous
or periodic communication between individual subsea developments
and between the subsea developments and one or more of the
receiving facilities will take place by means of a data bus
constituted by the signal line network. The control module 44 of
each retrievable module 22 will be configured to transmit
information via the data bus concerning the operation of each
retrievable module 22 including information such as the quantity of
one or more fluids being received and/or separated by the module,
the pressure sensed by some or all of the pressure sensors 54 etc.
The control module 44 will also be adapted to receive such
information from other subsea developments via the data bus. Some
or all of this information will also be transmitted to the
receiving facilities 2, 4, 6 and 8. The data bus is also configured
to transmit control signals from the receiving or host facilities
to the subsea developments.
[0038] Valves (not shown) arranged to control the flows of fluids
between the subsea developments and between the subsea developments
and the receiving facilities will be controlled to route fluids in
an appropriate manner through the network of internodal pipelines
94. The control of the valves may be effected directly as a result
of communication between two or more subsea developments or may
involve communication with one of the host facilities or even some
remote control means possibly via satellite or other like
communication systems. The subsea developments or nodes can
accordingly act as separation, diverter or boosting stations
depending on demand. Furthermore, power and control signals and
subsea development supporting fluids such as injection water and
chemicals have alternative routes from a selected host to a
particular subsea development.
[0039] An ideal medium for incorporation into the network system
described above would be one using advanced computer protocols
enabling computer control hardware to be standardised. By using
multi-layered hardware and software architecture, changes to the
system (e.g. changing one type of removable module for another
having a different function) could be readily catered for. Control
software and hardware could be arranged to automatically recognise
that the change had occurred and communicate with the control
module of the new removable module appropriately. To avoid the
requirement of changing control system hardware, it is capable of
being remotely upgraded by software methods to take account of the
installation of the new module or other apparatus.
* * * * *