A FPSO-power generation and distribution system and a method for assisting renewable power sources adoption in a fpso

Abstract

The invention discloses a Floating Production Storage and Offloading, FPSO, power generation and distribution system, including a primary power grid and a secondary power grid, the secondary power grid electrically coupled to the primary power grid at a coupling point, the primary power grid including a plurality of primary power sources and one or more of first type FPSO consumers, each of the plurality of primary power sources configured to provide electrical power to one or more of the plurality of the first type FPSO consumers, the secondary power grid including a plurality of secondary power sources and one or more of second type FPSO consumers, each of the plurality of secondary power sources configured to provide electrical power to one or more of the second type FPSO consumers, each one of the one or more first type FPSO consumers at least partially located on a FPSO, wherein at least one secondary power source of the secondary power grid is configured to provide green electrical power converted from a renewable energy source to one or more of the second type FPSO consumers, wherein the system further includes a switch device configured to couple and decouple the primary power grid and the secondary power grid at the coupling point based on a consumer electrical power demand and an electrical power availability at the plurality of primary and secondary power sources.

Description

[0001] A FPSO-POWER GENERATION AND DISTRIBUTION SYSTEM AND A METHOD FOR ASSISTING RENEWABLE POWER SOURCES ADOPTION IN A FPSO

[0002] Field of the invention

[0003] The invention relates to a Floating Production Storage and Offloading (FPSO)-power generation and distribution system. The invention further relates to a method for assisting renewable power sources adoption in an FPSO.

[0004] Background

[0005] Offshore facilities utilizing renewable energy are for example disclosed in WO2021 / 158209 where a water production system suitable for water injection into an offshore hydrocarbon well is powered by the electrical energy obtained by conversion of wind energy into electricity by a wind turbine. Water injection helps to achieve Enhanced Oil Recovery (EOR) where crude oil is extracted from a reservoir or well, therefore increasing the amount of oil that can be recovered from a field. In WO2021 / 219739A1 a floating offshore production support facility comprising a wind turbine is disclosed which supports hydrocarbon production by a production vessel such as an FPSO. There is a drive to integrate more renewable power source, such as wind power, in offshore applications to target decarbonization and lower greenhouse gas emissions.

[0006] However, power generation on the FPSO consists of multiple gas or steam turbines in single or combined cycle mode. The profile of the FPSO consumers is very stable and the turbines generators operate mostly in fixed power setpoints. Due to the intermittent nature of renewable power sources, technical challenges arise at the integration of renewable energy in FPSO applications. Renewable power sources such as the wind or the sun can bring some instabilities on the island off-grid power generation system of an FPSO. These instabilities can be absorbed by constant counter fluctuations of the existing prime movers, but can affect their lifetime, maintenance and costs. In addition, operators tend to not feel comfortable with such dynamic operational modes and clients of oil and gas assets resist on production profile risks.

[0007] It is therefore an object of the present invention to provide a power generation and distribution system that allows to assist renewable power sources adoption in an FPSO without affecting the oil and gas production. It is further an object of the present invention to provide a method for assisting renewable power sources adoption in an FPSO. Summary of the invention

[0008] According to a first aspect of the invention, a Floating Production Storage and Offloading, FPSO, power generation and distribution system, comprises a primary power grid and a secondary power grid, the secondary power grid electrically coupled to the primary power grid at a coupling point, the primary power grid comprising a plurality of primary power sources and one or more of first type FPSO consumers, each of the plurality of primary power sources configured to provide electrical power to one or more of the plurality of the first type FPSO consumers, the secondary power grid comprising a plurality of secondary power sources and one or more of second type FPSO consumers, each of the plurality of secondary power sources configured to provide electrical power to one or more of the second type FPSO consumers, wherein a number of second type FPSO consumers consists in 10 to 50% of a total load of FPSO consumers corresponding to a combined load of the first type and the second type FPSO consumers, each one of the one or more first type FPSO consumers at least partially located on a FPSO, wherein at least one secondary power source of the secondary power grid is configured to provide green electrical power converted from a renewable energy source to one or more of the second type FPSO consumers, wherein the system further comprises a switch device configured to couple and decouple the primary power grid and the secondary power grid at the coupling point based on the first type FPSO consumer and the second type FPSO consumer electrical power demand and an electrical power availability at the plurality of primary and secondary power sources. By separating FPSO consumers into a main power generation and distribution system and a secondary system to be powered at least partly from renewable energy sources it is possible to integrate renewable energy into powering of FPSO. The renewable energy source is at least one of the wind, the sun, the sea waves, the sea tide. Fluctuations arising from renewable energy sources may be decoupled from the main power generation and distribution system. In fact a secondary power grid including a number of secondary consumers can be generated, to which all fluctuations from renewable energy sources can be imposed as it can accept some intermittency, without affecting the oil and gas production on short term. Disconnection of the secondary consumers from the main grid is facilitated during load shedding. All in all, the FPSO topsides for hydrocarbons storage and processing may be operated and designed as usual while all available renewable electrical power may be monetized. Process topsides can continue operations uninterrupted and unaffected from renewable sources absorption. This also accounts for the combined cycle mode in the primary grid, where steam turbines and their auxiliaries are not as quick to respond to fluctuations as gas turbines. Up to half of the FPSO consumers may be powered from renewable energy sources which allows for impactful integration of renewable energies while hydrocarbon processing may be sustained by the other half of the FPSO consumers.

[0009] In an embodiment, the one or more of the second type FPSO consumers include at least one of a water production facility comprising seawater pumps for water injection in an hydrocarbon well, an hydrogen or ammonia production facility and a facility for energy storage. Such FPSO consumers which are not running fulltime on the FPSO may accept some intermittency and be powered at least partly from renewable electrical energy via the secondary power grid. For instance, water injection is essential to achieve sufficient extraction of crude oil from a field.

[0010] In an embodiment the at least one secondary power source is selected from a group comprising a wind turbine, a solar panel array, a wave power or tide power convertor to convert wind energy, solar energy, wave or tide energy into green electricity, respectively.

[0011] In an embodiment, the at least one secondary power source is located either on the FPSO or at an offshore location, OL, remote from the FPSO. Integration of renewable power sources may either occur on location or remotely from the FPSO, where electrical energy may be further transported onto the FPSO to the second type consumers if at least partly located on the FPSO.

[0012] In an embodiment the at least one secondary power source comprises one or more floating wind turbines at the offshore location, OL.

[0013] In an embodiment the secondary power grid further comprises at least one of an AC converter coupled to the at least one secondary power source between the secondary power source and the one or more second type FPSO consumers. An AC converter may transform AC current into DC current or step up a voltage into a voltage that the consumer may use. As a result, suitable current / voltage may be distributed to the consumers in the grid.

[0014] In an embodiment the plurality of primary electrical sources comprises one or more gas and / or steam turbines in a single or a combined cycle mode. The main power grid comprises conventional engines producing mechanical energy for FPSO topsides. The system of the invention is therefore integrable into conventional existing FPSO.

[0015] In an embodiment, the secondary power grid further comprises at least one battery configured to store electrical power. Storage of renewable electrical energy allows to damp power inside the microgrid during power peak production and to keep the energy for later usage during low production periods. The storage further allows to optimize the balance of production versus demand at a given time.

[0016] In an embodiment the plurality of secondary power sources additionally comprises at least one or more secondary gas or steam turbines, and the number of secondary power sources is larger than a number of the secondary gas or steam turbines. By including a number of back up conventional engines in the secondary power grid, failure of the renewable sources due to low peak production and / or availability may be overcome by use of the back-up energy sources to power secondary type consumers.

[0017] In an embodiment, a controller is configured to monitor the consumer electrical power demand and the electrical power availability at the plurality of primary and secondary power sources and to control the switch device based on a result of monitoring. By monitoring and control of the switch device to couple or decouple the main and secondary grids, available power can be used to power consumers in either the main and / or the secondary power grid. Powering of the FPSO topsides may therefore be at least in part provided from the secondary grid, in so far as the switch device couples both grids.

[0018] In an embodiment the controller is configured to control operation of the at least one secondary gas or steam turbine based on the consumer electrical power demand and the electrical power availability. In this arrangement one of the gas or steam turbines of the main grid may be removed from the FPSO main power generation grid and connected to the secondary microgrid. By controlling the gas or steam turbine of the secondary grid, back up of conventional energy to power consumers may be adjusted to the power demand and power availability of renewable sources.

[0019] According to an aspect of the invention a method for assisting renewable power sources adoption in a FPSO is disclosed, the method comprising arranging a primary power grid comprising a plurality of primary power sources connected to one or more first type FPSO consumers arranged at least partially on the FPSO, arranging a secondary power grid to couple to the primary power grid at a coupling point, the secondary power grid comprising a plurality of secondary power sources connected to one or more second type FPSO consumers arranged optionally on the FPSO, at least one of the second number of secondary power sources configured to supply green electrical power converted from a renewable energy, wherein a number of second type FPSO consumers consists in 10 to 50% of a total load of FPSO consumers corresponding to a combined load of the first type and the second type FPSO consumers, the method further comprising, coupling or decoupling the secondary power grid and the primary power grid at the coupling point for electrical power to transfer from the secondary power grid into the primary power grid or vice-versa based on the the first type FPSO consumer and the second type FPSO consumer electrical power demand and the electrical power availability at the plurality of primary and secondary power sources. When an electrical power demand in one of the grids exceeds an electricity availability, coupling the primary and secondary power grids into a connected state at the coupling point allows the grids to function dependently of each other. When an electrical power demand in one of the grids is inferior or equal to an electricity availability decouple the primary and secondary power grids into an isolated state at the coupling point for the grids to function independently of each other.

[0020] Brief description of the drawings

[0021] An embodiment of a Floating Production Storage and Offloading (FPSO)-power generation and distribution system, and methods for assisting renewable power sources adoption in a FPSO will by way of non-limiting example be described in detail with reference to the accompanying drawings. In the drawings:

[0022] Figure 1 schematically illustrates an offshore site above a subsea hydrocarbon reservoir according to the prior art. Figure 2 schematically illustrates a FPSO power generation and distribution system according to the invention.

[0023] Figure 3 shows a FPSO power generation and distribution system for integration of wind power to an FPSO, according to an embodiment of the invention.

[0024] Figure 4 schematically illustrates a method for assisting renewable power sources adoption in an FPSO.

[0025] The FPSO and features thereof are shown schematically and not drawn to scale. The figures are for illustrative purposes only, and do not serve as restriction of the scope as laid down by the claims. In the drawings, identical or similar elements are indicated by the same reference sign or number.

[0026] Detailed description of the invention

[0027] Fig. 1 schematically illustrates an offshore site above a subsea hydrocarbon reservoir 1000 according to the prior art WO2021 / 219739A1 , including a floating offshore hydrocarbon production support facility 1010 and a floating production storage and offloading facility (FPSO) 1050, located at sea above the subsea hydrocarbon reservoir 1000. Any type of mooring system (not shown) such as spread mooring, turret mooring or taut mooring can be used to moor the FPSO 1050. The floating offshore hydrocarbon production support facility 1010 is moored to the FPSO via mooring line system 1070. The floating offshore hydrocarbon production support facility 1010 comprises a platform 1020 supporting a wind turbine 1030 and process equipment 1040 to perform offshore related functions required in and / or around the platform. Examples of such functions include water injection, CO2 injection, pipeline booster, amine facility, hydrogen generation, etc. The FPSO 1050 is coupled by risers (not shown) to one or more production wells on the seabed from which amongst others, hydrocarbon gases and crude oil are collected. The FPSO 1050 supports process equipment 1060 powered by gas turbines and / or steam turbines (not shown) on the FPSO to process and store hydrocarbons from the matter collected from the wells. Some or all of the power produced by the wind turbine 1030 on the floating offshore hydrocarbon production support facility 1010 is used to drive process equipment 1040. Although this construction is an improvement to conventional offshore system solely employing gas turbine or engine electrical power it may be that insufficient electrical power is available to perform the required offshore related functions based on the support facility 1010 due to the intermittent nature of wind power. Furthermore, the above construction isolates part of the process equipment 1040 from the FPSO 1050 and offers no insight as to the integration of wind power or more generally renewable power on the FPSO 1050 itself.

[0028] Figure 2 shows a FPSO power generation and distribution system 1 according to the invention. The system comprises a primary power grid 2 and a secondary power grid 3. The primary power grid 2 and the secondary power grid 3 are connected at a coupling point 4. The coupling point 4 comprises a switch device 40 allowing to electrically couple or decouple the primary and secondary power grids 2, 3. The primary power grid 2 comprises four primary electrical power sources 5, 6, 7, 8 and a plurality of first type FPSO consumers 20 including eight consumers 21 , 22, 23, 24, 25, 26, 27, 28. The primary power sources 5, 6, 7, 8 are configured to power the first type FPSO consumers 20. A primary power source 5, 6, 7, 8 may serve to power one or more of the first type FPSO consumers 20 located at least partially on a FPSO, such as on the FPSO deck, or within the hull, (not illustrated) which may also be known to the skilled person as FPSO topside processing equipment. FPSO topside processing equipment will be known to the skilled person as comprising consumers necessary for hydrocarbon processing and storing on the FPSO and may comprise at least one of a group including seawater lift pumps, compressors, control panels and / or hydraulic power units. At least one of the first type FPSO consumers 20 may be in electrical connection with an external emergency generator (not shown) for backup in case of failure of the primary electrical power sources 5, 6, 7, 8. The secondary power grid 3 comprises three secondary type electrical power sources 9, 10, 11 , of which in the illustrated arrangements two are wind turbines 9, 10 and one is a conventional gas or steam turbine 11 , 12. Green electrical power produced by the wind turbines 9, 10 runs through at least one AC converter 13, 14 configured to make the electrical power suitable for distribution to the grid. A majority of the secondary type electrical power sources 9, 10, 11 consists therefore of power sources providing green electrical power obtained from renewable sources, in this case a wind turbine. It is noted that in other embodiments falling within the scope of the invention, secondary power sources may obtain their electrical power by conversion from renewable energy obtained from at least one of a solar panel, a wave power or tide power convertor to convert wind energy, solar energy, wave or tide energy into green electricity. The conventional gas or steam turbine is optional, and may serve as back-up in periods of intermittency of the green electrical power. The secondary electrical power sources are configured to power a plurality of second type FPSO consumers 30, including seven consumers 31 , 32, 33, 34, 35, 36, 37. The second type FPSO consumers may include any of a seawater pump for water injection in an hydrocarbon well, a water injection auxiliary, an hydrogen or ammonia production facility and a facility for energy storage or any other consumers which will be known to the skilled person as allowing some intermittency and / or set to function only at defined setpoints. In an islanding mode where the switch device does not couple the primary and secondary grids 2, 3 the secondary power grid 3 is stand-alone and both grids 2, 3 function independently. In a grid-connected mode (not shown), the switch device 40 interconnects the primary 2 and secondary 3 power grids so that electrical power may be exchanged between the grids. The coupling point 4 may further include an AC / DC converter (not shown). In other embodiments falling within the scope of the invention the primary and secondary power grids may comprise a different number of electrical sources, of consumers and / or a different electrical arrangement within each grid. Furthermore either one of the primary and secondary power grids may further comprise a battery (not shown) to store electrical energy.

[0029] Figure 3 shows an offshore site comprising a FPSO power generation and distribution system 1 for integration of renewable electrical power to an FPSO 50 to achieve enhanced oil recovery (EOR) from a subsea hydrocarbon reservoir or well 200, according to an embodiment of the invention. The offshore site above the subsea hydrocarbon reservoir or well 200 comprises a floating FPSO 50 and two floating wind turbines 18, 19 moored (not shown) at an offshore location OLi , OL2 around the FPSO 50. A water production system 38 installed on a deck of the FPSO is configured to pump sea water (SW) and to process it before injecting it (ISW) into the reservoir or well 200. The water production system 38 is therefore configured to perform water injection to increase oil extraction and therefore achieve EOR. In other embodiments falling within the scope of the invention the water production system may be located at a different location aboard the FPSO and / or at least in part remote to the FPSO. A plurality of first type consumers 20 is further located aboard the FPSO. The water production system 38 is electrically connected via subsea cables 16, 17 to an electrical output of the wind turbines 18, 19 comprising AC converters 13, 14. The water production system 38, the wind turbines 18, 19 and intermediaries (converters, cables 13, 14, 16, 17) are part of a secondary power grid of the FPSO system 1 of the type illustrated in Fig. 2. The system further comprises a switch device (not shown) which allows to connect the secondary grid to a primary power grid comprising conventional power equipment (not shown) such as gas or steam turbines and the first type FPSO consumers 20. The primary power grid may further include a battery 60 for energy storage. Monitoring of the energy available in each power grid is performed by a controller 70 located on the FPSO configured to receive power data from each grid. In other embodiments the controller 70 may be located at a remote location offshore or onshore.

[0030] Figure 4 shows a flowchart 100 of a method of assisting renewable power sources adoption in a FPSO according to the invention. In a first step 110 of the method, a primary power grid comprising at least a plurality of gas or steam turbines located on the FPSO configured to power one or more first type FPSO consumers located at least partially on the FPSO is arranged. In step 120 a secondary power grid is arranged to be electrically connectable at a coupling point to the first power grid, the secondary power grid comprising at least one secondary power source configured to provide renewable energy to one or more secondary type FPSO consumers that are different from the first type FPSO consumers. The secondary type FPSO consumers may be located at a location on or remote of the FPSO. The remote location includes both offshore location and onshore location. In step 130 it is determined whether the electrical power demand of at least one of the first type and second type consumers exceeds the electrical power available in their respective primary and secondary power grids, i.e. the electrical power availability from the primary power grid and the secondary power grid. If it is determined in step 130 that the electrical power demand exceeds the electrical power availability in at least one of the grids, the primary and secondary grids are electrically coupled in step 140 so that power may be exchanged between the primary and secondary grids. If it is determined in step 130 that the electrical power demand does not exceed the electrical power availability in any of the power grids the grids may remain uncoupled and further monitoring done according to 130 until coupling is deemed necessary. If following the coupling it is determined in step 150 that the electrical power demand stops exceeding the electrical power availability in both grids, the primary and secondary grids may be electrically decoupled in step 160 to function independently from each other.

[0031] The invention has been described with reference to the preferred embodiment. Obvious modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims.

Claims

Claims1 . A Floating Production Storage and Offloading, FPSO, power generation and distribution system (1), comprising a primary power grid (2) and a secondary power grid (3), the secondary power grid (3) electrically coupled to the primary power grid (2) at a coupling point (4), the primary power grid (2) comprising a plurality of primary power sources (5, 6, 7, 8) and one or more of first type FPSO consumers (20), each of the plurality of primary power sources (5, 6, 7, 8) configured to provide electrical power to one or more of the plurality of the first type FPSO consumers (20), the secondary power grid (3) comprising a plurality of secondary power sources (9, 10, 11) and one or more of second type FPSO consumers (30), each of the plurality of secondary power sources (9, 10, 11) configured to provide electrical power to one or more of the second type FPSO consumers (30), wherein a number of second type FPSO consumers (20) consists in 10 to 50% of a total load of FPSO consumers corresponding to a combined load of the first type and the second type FPSO consumers (20, 30), each one of the one or more first type FPSO consumers (20) at least partially located on a FPSO (50), wherein at least one secondary power source (9, 10) of the secondary power grid (3) is configured to provide green electrical power converted from a renewable energy source to one or more of the second type FPSO consumers (30), wherein the system further comprises a switch device (40) configured to couple and decouple the primary power grid (2) and the secondary power grid (3) at the coupling point (4) based on the first type FPSO consumer and the second type FPSO consumer electrical power demand and an electrical power availability at the plurality of primary and secondary power sources (5, 6, 7, 8, 9, 10, 11).

2. The system according to claim 1 , wherein the one or more of the second type FPSO consumers (30) include at least one of a water production facility (38) comprising seawater pumps for water injection in an hydrocarbon well (HW), an hydrogen or ammonia production facility and a facility for energy storage.

3. The system according to any one of the preceding claims, wherein the at least one secondary power source (9, 10) is selected from a group comprising a wind turbine (18, 19), a solar panel array, a wave power or tide power convertor to convert wind energy, solar energy, wave or tide energy into green electricity, respectively.

4. The system according to any one of the preceding claims, wherein the at least one secondary power source (9, 10) is located either on the FPSO (50) or at an offshore location, OL, remote from the FPSO (50).

5. The system according to claim 4, wherein the at least one secondary power source comprises one or more floating wind turbines (18, 19) at the offshore location, OL.

6. The system according to any one of the preceding claims, wherein the secondary power grid (3) further comprises at least one of an AC converter (13, 14, 15) coupled to the at least one secondary power source (9, 10) between the secondary power source and the one or more second type FPSO consumers (20).

7. The system according to any one of the preceding claims, wherein the plurality of primary electrical sources (5, 6, 7, 8) comprises one or more gas and / or steam turbines in a single or a combined cycle mode.

8. The system according to any of the preceding claims, wherein the secondary power grid (3) further comprises at least one battery (60) configured to store electrical power.

9. The system according to any one of the preceding claims, wherein the plurality of secondary power sources (9, 10, 11) additionally comprises at least one or more secondary gas turbines (16), and the number of secondary power sources (9, 10, 11) is larger than a number of the secondary gas turbines (16).

10. The system according to any of the preceding claims, further comprising a controller (70) configured to monitor the consumer electrical power demand and the electrical power availability at the plurality of primary and secondary power sources and to control the switch device (40) based on a result of monitoring.11 . The system according to claim 10 when dependent on claim 9, wherein the controller (70) is configured to control operation of the at least one secondary gas turbine (16) based on the consumer electrical power demand and the electrical power availability.

12. A method (100) for assisting renewable power sources adoption in a FPSO (50) comprisingArranging (110) a primary power grid (2) comprising a plurality of primary power sources (5, 6, 7, 8) connected to one or more first type FPSO consumers (20) arranged at least partially on the FPSO (50);Arranging (120) a secondary power grid (3) to couple to the primary power grid (2) at a coupling point (4), the secondary power grid (3) comprising a plurality of secondary power sources (13, 14,15) connected to one or more second type FPSO consumers (30) arranged optionally on the FPSO (50), at least one of the second number of secondary power sources (9, 10) configured to supply green electrical power converted from a renewable energy, wherein a number of second type FPSO consumers (20) consists in 10 to 50% of a total load of FPSO consumers corresponding to a combined load of the first type and the second type FPSO consumers (20, 30), the method further comprising:Coupling (140) or decoupling (160) the secondary power grid (3) and the primary power grid (2) at the coupling point (40) for electrical power to transfer from the secondary power grid (3) into the primary power grid (2) or vice-versa based on the first type FPSO consumer and the second type FPSO consumer electrical power demand and an electrical power availability (130, 150) at the plurality of primary and secondary power sources.

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