WO2023167593A1 - Hydrocarbon production system with reduced carbon dioxide emission - Google Patents

Hydrocarbon production system with reduced carbon dioxide emission Download PDF

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Publication number
WO2023167593A1
WO2023167593A1 PCT/NO2023/050047 NO2023050047W WO2023167593A1 WO 2023167593 A1 WO2023167593 A1 WO 2023167593A1 NO 2023050047 W NO2023050047 W NO 2023050047W WO 2023167593 A1 WO2023167593 A1 WO 2023167593A1
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WO
WIPO (PCT)
Prior art keywords
production system
hydrocarbon production
offshore hydrocarbon
ammonia
power source
Prior art date
Application number
PCT/NO2023/050047
Other languages
French (fr)
Inventor
Arild SAMUELSBERG
Bengt Olav Neeraas
Original Assignee
Equinor Energy As
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Equinor Energy As filed Critical Equinor Energy As
Publication of WO2023167593A1 publication Critical patent/WO2023167593A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
    • E21B41/0007—Equipment or details not covered by groups E21B15/00 - E21B40/00 for underwater installations
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
    • F02C3/20—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products
    • F02C3/22—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products the fuel or oxidant being gaseous at standard temperature and pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
    • F02C3/20—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products
    • F02C3/26—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products the fuel or oxidant being solid or pulverulent, e.g. in slurry or suspension
    • F02C3/28—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products the fuel or oxidant being solid or pulverulent, e.g. in slurry or suspension using a separate gas producer for gasifying the fuel before combustion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0203—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels characterised by the type of gaseous fuel
    • F02M21/0206—Non-hydrocarbon fuels, e.g. hydrogen, ammonia or carbon monoxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/22—Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/22—Fuel cells in which the fuel is based on materials comprising carbon or oxygen or hydrogen and other elements; Fuel cells in which the fuel is based on materials comprising only elements other than carbon, oxygen or hydrogen
    • H01M8/222—Fuel cells in which the fuel is based on compounds containing nitrogen, e.g. hydrazine, ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B2035/448—Floating hydrocarbon production vessels, e.g. Floating Production Storage and Offloading vessels [FPSO]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63H—MARINE PROPULSION OR STEERING
    • B63H21/00—Use of propulsion power plant or units on vessels
    • B63H2021/003—Use of propulsion power plant or units on vessels the power plant using fuel cells for energy supply or accumulation, e.g. for buffering photovoltaic energy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/06—Integration with other chemical processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
    • C01B3/047—Decomposition of ammonia
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/30—The power source being a fuel cell
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P80/00—Climate change mitigation technologies for sector-wide applications
    • Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Definitions

  • the present invention relates to a method of operating a hydrocarbon production system with reduced carbon dioxide (CO2) emission.
  • the invention further extends to a corresponding hydrocarbon production system, to a method of forming such a hydrocarbon production system and to a method of retrofitting an existing hydrocarbon production system for conformity with the hydrocarbon production system of the invention.
  • Hydrocarbon production systems and in particular offshore hydrocarbon production facilities, often comprise one or more gas turbine engines (GTE) for local power generation at the production system.
  • GTE gas turbine engines
  • a portion of the hydrocarbon gases produced may be combusted in the GTE to produce power for the operation of the production system.
  • the exhaust gases produced from the combustion comprising a significant portion of carbon dioxide, are vented to the atmosphere.
  • KR 20210007791 A discloses an offshore structure including an integral fuel cell capable of producing power from hydrogen, which may optionally be mixed with other fuels.
  • US 2017/0218727 A1 discloses a land-based fracking system powered by gas turbine engines fuelled by a combustible liquid fuel source.
  • a method of operating an offshore hydrocarbon production system comprising a power source configured to provide power to the offshore hydrocarbon production system, the method comprising using ammonia as an energy source for the power source in order to provide power to the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system and hence the step of using the ammonia as an energy source for the power source takes place on/at the unit that is separate from the remainder of the offshore hydrocarbon production system.
  • ammonia As an energy source, the byproducts of using ammonia as an energy source (e.g. as fuel in a combustion engine or as fuel for a fuel cell) are nitrogen (N2) and water (H2O). No carbon dioxide (CO2) is produced and vented to the atmosphere as in various prior art scenarios where hydrocarbon gas is combusted for power production. As such, emission of carbon dioxide to the atmosphere (and the detrimental environmental impacts associated therewith) through operation of the hydrocarbon production system in accordance with the first aspect of the invention is reduced and may in fact be totally avoided (i.e.
  • the method of the first aspect of the invention can result in operation of the hydrocarbon production system with net-zero carbon dioxide emissions).
  • the method of the first aspect thus provides a far less environmentally harmful method of operation of a hydrocarbon production system as compared to known methods of operation because the nitrogen and water produced as byproducts have little to no detrimental environmental impact, at least as compared to carbon dioxide.
  • the power source may hence be positioned on/at the unit that is separate from the remainder of the offshore hydrocarbon production system.
  • a unit that is separate from the remainder of the offshore hydrocarbon production system defines an entity/structure that is a separate offshore entity/structure from the remainder of the hydrocarbon production system. That is to say, the unit is effectively an entity, the primary structure/construction of which, is separated by a body of water from the remainder of the offshore hydrocarbon production system. Accordingly, whilst the unit would still be connected with the remainder hydrocarbon production system (e.g. through electrical/power connections, utilities connections, walkways, etc.), the unit is a separate and distinct entity from the remainder of the hydrocarbon production system. Examples of the unit, as further discussed below, include vessels (ships), independent offshore platforms, buoys or spar buoys, floaters or rigs.
  • the power source may be a combustion engine.
  • the combustion engine may be a gas turbine engine.
  • the combustion engine may be a gas engine (i.e. gaseous-fuelled engine), e.g. a two-stroke, four-stroke, six-stroke or wankel rotary engine.
  • the gas engine may be a V-type engine, e.g. a V18 engine.
  • the combustion engine may be specifically configured to combust ammonia or hydrogen (i.e. the design, operation and performance of the combustion may be specifically selected, tuned, designed etc. for optimal combustion of ammonia/hydrogen). The use of hydrogen or ammonia as a fuel for the combustion engine is described in greater detail below.
  • the step of using the ammonia as an energy source for the power source may comprise fuelling the combustion engine with ammonia and/or combusting the ammonia in the combustion engine.
  • the step of using the ammonia as an energy source for the power source may comprise: cracking the ammonia to form hydrogen; and fuelling the power source with the hydrogen (e.g. combusting the hydrogen in the combustion engine).
  • the by-products from this overall process i.e. nitrogen from the step of cracking and water from the use of hydrogen as a fuel
  • the method remains less environmentally harmful than prior art methods that are reliant on hydrocarbon fuels as discussed above.
  • the power source may be a fuel cell.
  • the power source may be an ammonia powered fuel cell.
  • the step of using the ammonia as an energy source for the power source may comprise fuelling the ammonia powered fuel cell with the ammonia.
  • the fuel cell may be a hydrogen powered fuel cell.
  • using the ammonia as an energy source for the power source may comprise: cracking the ammonia to form hydrogen; and fuelling the hydrogen powered fuel cell with the hydrogen.
  • the hydrocarbon production system may comprise or consist of an offshore hydrocarbon production facility.
  • the hydrocarbon production facility may be a hydrocarbon production platform, e.g. an unmanned hydrocarbon production platform, or a floating, production, storage and offloading vessel (FPSO).
  • FPSO floating, production, storage and offloading vessel
  • hydrocarbon production system is a system that is specifically configured for the production and/or processing of hydrocarbons (e.g. oil, natural gas, etc.).
  • hydrocarbons e.g. oil, natural gas, etc.
  • the hydrocarbon production system will comprise a degree of production equipment and/or a degree of processing equipment configured for processing or part-processing the produced hydrocarbons.
  • the power source may provide electrical power for the hydrocarbon production system. If the power source is a combustion engine, this may entail use of an electrical generator connected to the engine or which the combustion engine forms part of.
  • the optional combustion engine may additionally and/or alternatively be configured to provide motive power for the hydrocarbon production system.
  • the combustion engine may be configured to directly power components of the hydrocarbon production system, e.g. to provide a direct drive to a compressor of the hydrocarbon production system and/or other rotating components of the hydrocarbon production system.
  • the hydrocarbon production system may comprise a plurality of power sources. Each power source may be configured to provide power for the hydrocarbon production system.
  • the method may comprise: using the ammonia as an energy source for some or all of the plurality of the power sources to provide power for the hydrocarbon production system.
  • the method may comprise, prior to the step of using ammonia, storing the ammonia at the hydrocarbon production system. This may occur on/at the same unit where the ammonia is used as an energy source. Alternatively, the ammonia may be stored at a different site, e.g. on/at the remainder of the hydrocarbon production system or at a further, separate unit.
  • Storing the ammonia at the hydrocarbon production system may comprise storing the ammonia in a storage tank or tanks.
  • the storage tank(s) may be configured for storing ammonia at an elevated pressure, for example liquefied ammonia at ambient temperature conditions (e.g. between 0°C and 40 °C).
  • the storage tank(s) may be configured to store the ammonia at between 5 barg - 20 barg, for example at 5 barg, 10 barg, 15 barg or 20 barg.
  • the exact pressurised conditions that the storage tank(s) are configured to store the ammonia at may be selected dependent on the ambient temperature of the ammonia (optionally as a liquid) to be stored therein, the tolerances of the storage tank and/or the tolerance of the equipment used for loading and unloading the ammonia into the storage tank(s).
  • the step of storing the ammonia may comprise storing the ammonia as a liquid, optionally as a liquid at ambient temperature conditions.
  • the method may comprise the step of liquefying ammonia, optionally at ambient temperature conditions, prior to storing the ammonia.
  • storing and/or liquefying ammonia at ambient temperature conditions requires the ammonia to be pressurised at pressures far above ambient pressure conditions with the exact pressure conditions being determined by the specific ambient temperature of the ammonia.
  • Ambient temperature conditions may be any temperature between 0°C - 40 °C.
  • the pressure required in order to liquefy the ammonia and/or store the ammonia as a liquid may be between, for example, 5 barg - 20 barg, with the exact pressure required being determined by the ambient temperature selected.
  • the step of using the ammonia as an energy source for the power source takes place at a unit that is separate from the remainder of the offshore hydrocarbon production system.
  • combusting ammonia in the combustion engine may take place on/at the separate unit of the hydrocarbon production system.
  • the optional step of storing the ammonia may take place on/at the separate unit of the hydrocarbon production system. If present, the generator may be provided on the separate unit.
  • the separate unit may be a modular unit of the hydrocarbon production system.
  • the modular unit may be self-contained and (easily/readily) separable from the remainder of the hydrocarbon production system.
  • modular it is meant that the separate unit may be considered to constitute a module that is self-contained and that can be readily conjoined with and split apart from the remainder of the hydrocarbon production system. That is to say, a modular unit is not integral with the remainder of the hydrocarbon production system. Any connections between the modular unit and the remainder of the hydrocarbon production system may hence be readily reversible (i.e. they are designed to be reversible) such that the modular unit is readily disconnected from the remainder of the hydrocarbon production system (e.g. through electrical/power connections, utilities connections, walkways, etc.).
  • the method may comprise supplying the power produced at the power source from the separate unit to the remainder of the hydrocarbon production system (e.g. via a power/electrical connection, such as a cable - more on this feature below).
  • the separate unit may be a separate facility from the portion of the hydrocarbon production system where hydrocarbon producing operations are carried out.
  • the separate unit may be a separate floating unit/facility situated adjacent, e.g., a production platform or a floating, production storage and offloading (FPSO) vessel that constitutes the remainder of the hydrocarbon production system.
  • FPSO floating, production storage and offloading
  • Having a separate unit, and in particular a separate modular unit is advantageous since it can be easily installed/retrofitted in combination with an already existing hydrocarbon production system (i.e. a brownfield facility) in order that the invention of the first aspect can be implemented without significant downtime in production at the already existent hydrocarbon production system.
  • This also means that minimal modification is required to the already existing hydrocarbon production system for the invention to be employed other than maybe the decommissioning and/or removal of an already existent power source (e.g. gas turbine engine). Such modification/replacement may not be necessary however.
  • the separate modular unit can be moved and used in combination with other already existing hydrocarbon production systems, e.g. after reserves have been depleted at a first system.
  • the separate unit may form part of a plurality of hydrocarbon production systems. That is to say, a plurality of different hydrocarbon production systems (including the hydrocarbon production system to which the method of the first aspect relates) may comprise a common (single) separate unit (e.g. a common single, modular unit).
  • the common, single unit may provide power to each of the plurality of hydrocarbon production systems.
  • the single separate unit may take the form of a floating unit/facility situated adjacent and connected to a plurality of production platforms, production facilities and/or FPSOs and may provide power for each of the connected production platforms, production facilities and/or FPSOs.
  • the single unit may be termed an energy hub given that it acts as an energy source for a plurality of systems.
  • the single unit may be connected to the remainder of the/each hydrocarbon production system via appropriate cabling.
  • the cabling may be configured to supply electrical AC power of 50 Hz -60 Hz frequency and/or at a power of 7 MW from the single unit to the remainder of the/each hydrocarbon production system.
  • the method of the first aspect may be employed at a brownfield production facility or at a greenfield production facility.
  • the ammonia may be grey ammonia, green ammonia and/or blue ammonia.
  • the method may comprise, prior to the step of using the ammonia as an energy source for the power source and optionally prior to the optional step of storing, transporting the ammonia to the hydrocarbon production system.
  • the step of transporting may make use of a tanker/vessel.
  • the hydrocarbon production system may also comprise a steam engine configured to provide power to the hydrocarbon production system.
  • the steam engine may be configured to run in a combined cycled with the combustion engine. That is, the exhaust gases from combustion at the combustion engine may be used to heat water which drives the steam engine to produce power for the hydrocarbon production system.
  • the method may comprise running the steam engine in a combined cycle with the combustion engine to provide power for the hydrocarbon production system. This step of running the steam engine in a combined cycle may comprise using the exhaust gases from the combustion at the combustion engine to heat water into steam; and driving a steam engine to produce power for the hydrocarbon production system.
  • the steam engine may be situated on/at the separate unit.
  • an offshore hydrocarbon production system comprising a power source configured to provide power for the offshore hydrocarbon production system; wherein the offshore hydrocarbon production system is arranged to use ammonia as an energy source for the power source in order to provide power for the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
  • the method of the first aspect of the invention may be a method of operating the hydrocarbon production system of the second aspect of the invention.
  • the hydrocarbon production system of the second aspect may be in accordance with the hydrocarbon production system discussed above in relation to the first aspect of the invention and may comprise any optional features thereof.
  • a method of retrofitting an existing offshore hydrocarbon production system comprising: decommissioning and/or removing an existent power source at the offshore hydrocarbon production system: installing at the offshore hydrocarbon production system a new power source configured to provide power for the offshore hydrocarbon production system; and configuring the offshore hydrocarbon production system to use ammonia as an energy source for the power source; wherein the new power source is provided on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
  • the step of installing at the offshore hydrocarbon production system a new power source may comprise providing or installing the separate unit comprising the new power source.
  • a platform or vessel on which the new power source is provided may be provided adjacent and connected to the existing hydrocarbon production system.
  • the existing hydrocarbon production system may be a brownfield production system.
  • the hydrocarbon production system resulting from the method of the third aspect may be a hydrocarbon production system in accordance with the second aspect, optionally inclusive of any optional feature thereof.
  • a method of assembling an offshore hydrocarbon production system comprising providing equipment and infrastructure configured for the production and/or processing of hydrocarbons; providing a power source configured to provide power for the offshore hydrocarbon production system; and configuring the offshore hydrocarbon production system to use ammonia as an energy source for the power source; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
  • the hydrocarbon production system resulting from the method of the fourth aspect may be a greenfield production system.
  • the hydrocarbon production system resulting from the method of the fourth aspect may be a hydrocarbon production system in accordance with the second aspect, optionally inclusive of any optional feature thereof.
  • a plurality of offshore hydrocarbon production systems that comprise a common power source situated on a single, modular unit and that is configured to provide power for each of the plurality of offshore hydrocarbon production systems; wherein the plurality of offshore hydrocarbon production systems are arranged to use ammonia as an energy source for the common power source in order to provide power for each of the plurality of offshore hydrocarbon production systems.
  • One or all of the hydrocarbon production systems of the fifth aspect may be in accordance with the hydrocarbon production system of the second aspect, optionally including any optional features thereof.
  • One or all of the hydrocarbon production systems of the fifth aspect may be operated in accordance with the first aspect, optionally including any optional features thereof.
  • a method of operating a plurality of offshore hydrocarbon production systems comprising a common power source situated on a single, modular unit and configured to provide power for the plurality of offshore hydrocarbon production systems, the method comprising using ammonia as an energy source for the common power source in order to provide power for the plurality of offshore hydrocarbon production systems.
  • the plurality of hydrocarbon production systems of the sixth aspect may be in accordance with the fifth aspect, optionally inclusive of any optional features thereof.
  • a method of operating an offshore hydrocarbon production system comprising a power source (e.g. a combustion engine) configured to provide power for the offshore hydrocarbon production system, the method comprising fuelling the power source with the ammonia (e.g. combusting the ammonia in the combustion engine) to provide power (e.g. electrical power) for the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
  • a power source e.g. a combustion engine
  • a method of operating a hydrocarbon production system comprising a power source configured to provide power for the hydrocarbon production system, the method comprising using ammonia as an energy source for the power source in order to provide power for the hydrocarbon production system.
  • This further aspect of the invention may comprise any of the compatible features discussed above in relation to the other aspects of the invention.
  • a hydrocarbon production system comprising a power source configured to provide power for the hydrocarbon production system; wherein the hydrocarbon production system is arranged to use ammonia as an energy source for the power source in order to provide power for the hydrocarbon production system.
  • This still further aspect of the invention may comprise any of the compatible features discussed above in relation to the other aspects of the invention.
  • Figure 1 is a schematic depiction of an offshore floating facility connected to a tanker and to three separate production facilities;
  • Figure 2 is a cross-sectional view of the offshore floating facility of Figure 1;
  • Figure 3 shows a gas engine of a generator positioned on the offshore floating facility of Figures 1 and 2;
  • Figure 4 is a pressure enthalpy chart for ammonia.
  • FIG 1 shows an offshore floating facility 1 that is connected by three separates cables 3a, 4a, and 5a to three separate production facilities 3, 4, 5.
  • Production facility 3 is an offshore production platform 3
  • production facility 4 is another offshore production platform 4, whilst production facility 5 is a floating, production, storage and offloading (FPSO) 5.
  • FPSO floating, production, storage and offloading
  • Each production facility 3, 4, 5 is situated at its own respective hydrocarbon reservoir and is arranged to permit production of hydrocarbons from its respective reservoir via suitable production and processing equipment.
  • the cables 3a, 4a, 5a are each electrical power cables 3a, 4a, 5a that are configured for carrying electrical power from the offshore floating facility 1 to each of the production facilities 3, 4, 5 in order to provide power thereto, as will be described in further detail below.
  • a tanker 2 Also connected to the offshore floating facility 1 is a tanker 2.
  • the tanker 2 is connected to the offshore floating facility 1 via two separate conduits 2a, 2b that are each arranged to carry a fluid, specifically ammonia, between the tanker 2 and the offshore floating facility 1 as will be described in greater detail below.
  • the conduits 2a and 2b are reversibly connected to the tanker 2 as discussed in further detail below.
  • the offshore floating facility 1 has a predominantly ship shaped hull 101.
  • the storage tanks 103 are arranged to store liquid ammonia therein at ambient temperature conditions and, consequently, at pressures of between 5 barg - 20 barg (the exact pressure of storage being dependent on the ambient temperature conditions as discussed below with reference to Figure 4).
  • the hull 101 also comprises a plurality of generators 105 that each comprise a gas engine 107.
  • Each gas engine 107 is a V18 engine which is specifically configured to combust gaseous ammonia therein. Motive power produced by each engine 107 drives electricity generation at each generator 105.
  • Each of the generators 105 are connected to the cables 3a, 4a, 5a in a manner that permits electrical power produced at the generators 105 to be passed via the cables 3a, 4a, 5a to the production facilities 3, 4, 5.
  • the tanker 2 comprises a plurality storage tanks (not shown) correspondent to the storage tanks 103 on-board the offshore floating facility 1.
  • the storage tanks on the tanker 2 are arranged to store liquid ammonia therein at ambient temperature conditions and, consequently, at pressures of between 5 barg - 20 barg (the exact pressure of storage being dependent on the ambient temperature conditions).
  • the storage tanks on-board the tanker 2 are loaded with ambient temperature liquid ammonia at an onshore site remote from the offshore floating facility 1 and the production facilities 3, 4, 5.
  • the tanker 2 then travels to a site of the offshore floating facility 1 (e.g. as shown in Figure 1) whilst the liquid, ambient temperature ammonia is maintained as such within the storage tanks. This is achieved by ensuring that the storage tanks remain suitably pressurised during transit of the tanker 2.
  • the conduits 2a, 2b are connected to the tanker 2.
  • Liquid ammonia is then offloaded from the tanker 2 to the offshore floating facility 1 via the conduit 2a and is transferred into the storage tanks 103 on-board the offshore floating facility 1 for storage therein.
  • the transfer between the tanker 2 and the storage tanks 103, and the subsequent storage therein, is carried out whilst maintaining, as far as possible, the ammonia as a liquid at ambient temperature conditions.
  • the interior of the storage tanks 103 may be under ambient pressure conditions and be filled with air and/or gaseous ammonia left over as a remnant from a previous stock of ammonia.
  • the vaporised portion of the ammonia is separated off from the liquid ammonia at the offshore floating facility 1 and is transferred back to the tanker 2 via the conduit 1b.
  • This gaseous ammonia can then be re-condensed on board the tanker 2 at ambient temperature conditions and subsequently transferred back to the offshore facility 1 via the conduit 1a for storage thereon.
  • the gaseous ammonia can be stored aboard the tanker 2 for transit back to, e.g., an on shore site. Once all of the liquid ammonia has been offloaded from the tanker 2, the conduits 2a, 2b are disconnected. The tanker 2 then travels away from the offshore floating facility, optionally back to an onshore site for further loading and transport of ammonia.
  • the liquid ammonia stored within the storage tanks 103 aboard the offshore floating facility 1 is used as a fuel to power the gas engines 107 comprised as part of generators 105.
  • the storage tanks 103 on-board the floating facility 1 serve as a buffer storage for fuel for the generators 105.
  • the liquid ammonia stored within the storage tanks 103 is sent from the tanks 103 to an inlet of the engines 107.
  • the liquid ammonia is vaporised, either passively as a natural result of depressurisation that occurs during transit and/or actively via a suitable vaporiser, into a gaseous form.
  • the ammonia can then be appropriately introduced into the gas engine 107 for combustion therein.
  • Combustion of the ammonia in the engines 107 drives electricity generation at the generators 105.
  • the electrical power (e.g. rated at 7 MW) produced at the generators 105 is then transferred via the cables 3a, 4a, 5a from the offshore floating facility 1 to the production facilities 3, 4, 5 and is used to power operations at the production facilities 3, 4, 5, including powering the production and processing equipment situated thereat.
  • the offshore floating facility 1 thus acts as an energy hub for a plurality of hydrocarbon production facilities 3, 4, 5 and serves to provide power for production and other operations that occur at each facility.
  • the floating facility 1 is thus comprised as part of a plurality of hydrocarbon production systems, wherein the remainder of each system is formed by a respective production facility 3, 4, 5.
  • Figure 4 shows a pressure-enthalpy chart for ammonia. Pressure is represented along the y-axis whilst enthalpy is represented along the x-axis.
  • the region below the saturation line 61 (termed ‘saturation dome’) represents where any addition of enthalpy will cause additional liquid ammonia to vaporize instead of raising the temperature of the ammonia.
  • the red lines on the chart indicate constant temperatures and, whilst not depicted therein, it can be deduced from the temperature values given either side of the saturation dome that the temperature lines would be at a complete horizontal through the saturation dome.
  • the green lines on the chart each represent a constant ratio of vapour mass to total mass of the ammonia.
  • the region 63 shown in blue represents where ammonia is at ambient temperature conditions (i.e. 0°C - 40 °C) within the saturation dome. Within region 63 the vast majority of ammonia would be in a liquid state whilst being at ambient temperature conditions as can be deduced from the ratios of vapour mass to total mass of the ammonia in this region. The ambient temperature liquid ammonia that is stored in the storage tanks as discussed above would typically fall within region 63 of the pressure-enthalpy chart.

Abstract

A method of operating an offshore hydrocarbon production system, the offshore hydrocarbon production system comprising a power source (107) configured to provide power for the offshore hydrocarbon production system, the method comprising using ammonia as an energy source for the power source (107) in order to provide power for the offshore hydrocarbon production system; wherein the power source (107) is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system and hence the step of using the ammonia as an energy source for the power source (107) takes place on/at the unit that is separate from the remainder of the offshore hydrocarbon production system.

Description

HYDROCARBON PRODUCTION SYSTEM WITH REDUCED CARBON DIOXIDE EMISSION
The present invention relates to a method of operating a hydrocarbon production system with reduced carbon dioxide (CO2) emission. The invention further extends to a corresponding hydrocarbon production system, to a method of forming such a hydrocarbon production system and to a method of retrofitting an existing hydrocarbon production system for conformity with the hydrocarbon production system of the invention.
Hydrocarbon production systems, and in particular offshore hydrocarbon production facilities, often comprise one or more gas turbine engines (GTE) for local power generation at the production system. Typically, a portion of the hydrocarbon gases produced may be combusted in the GTE to produce power for the operation of the production system. The exhaust gases produced from the combustion, comprising a significant portion of carbon dioxide, are vented to the atmosphere.
The significant detrimental impacts that carbon dioxide emission has on the environment are notoriously well-known. There is therefore a general desire, where possible, to reduce carbon dioxide emission to the environment and, as time goes on, this desire only grows. The regulations surrounding operation of hydrocarbon production systems reflects this growing desire, with mandates on the reduction of the ‘carbon footprint’ for such systems being introduced by the various regulatory bodies.
KR 20210007791 A discloses an offshore structure including an integral fuel cell capable of producing power from hydrogen, which may optionally be mixed with other fuels.
US 2017/0218727 A1 discloses a land-based fracking system powered by gas turbine engines fuelled by a combustible liquid fuel source.
In accordance with a first aspect of the invention, there is provided a method of operating an offshore hydrocarbon production system, the offshore hydrocarbon production system comprising a power source configured to provide power to the offshore hydrocarbon production system, the method comprising using ammonia as an energy source for the power source in order to provide power to the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system and hence the step of using the ammonia as an energy source for the power source takes place on/at the unit that is separate from the remainder of the offshore hydrocarbon production system.
For the production of power, the method of the first aspect is reliant on ammonia (NH3) as an energy source. As the skilled person will appreciate, the byproducts of using ammonia as an energy source (e.g. as fuel in a combustion engine or as fuel for a fuel cell) are nitrogen (N2) and water (H2O). No carbon dioxide (CO2) is produced and vented to the atmosphere as in various prior art scenarios where hydrocarbon gas is combusted for power production. As such, emission of carbon dioxide to the atmosphere (and the detrimental environmental impacts associated therewith) through operation of the hydrocarbon production system in accordance with the first aspect of the invention is reduced and may in fact be totally avoided (i.e. the method of the first aspect of the invention can result in operation of the hydrocarbon production system with net-zero carbon dioxide emissions). The method of the first aspect thus provides a far less environmentally harmful method of operation of a hydrocarbon production system as compared to known methods of operation because the nitrogen and water produced as byproducts have little to no detrimental environmental impact, at least as compared to carbon dioxide.
Since the step of using the ammonia as an energy source for the power source takes place on/at a unit that is separate from the remainder of the offshore hydrocarbon production system, the power source may hence be positioned on/at the unit that is separate from the remainder of the offshore hydrocarbon production system.
In the context of the invention, a unit that is separate from the remainder of the offshore hydrocarbon production system defines an entity/structure that is a separate offshore entity/structure from the remainder of the hydrocarbon production system. That is to say, the unit is effectively an entity, the primary structure/construction of which, is separated by a body of water from the remainder of the offshore hydrocarbon production system. Accordingly, whilst the unit would still be connected with the remainder hydrocarbon production system (e.g. through electrical/power connections, utilities connections, walkways, etc.), the unit is a separate and distinct entity from the remainder of the hydrocarbon production system. Examples of the unit, as further discussed below, include vessels (ships), independent offshore platforms, buoys or spar buoys, floaters or rigs. The power source may be a combustion engine. The combustion engine may be a gas turbine engine. Alternatively, the combustion engine may be a gas engine (i.e. gaseous-fuelled engine), e.g. a two-stroke, four-stroke, six-stroke or wankel rotary engine. The gas engine may be a V-type engine, e.g. a V18 engine. The combustion engine may be specifically configured to combust ammonia or hydrogen (i.e. the design, operation and performance of the combustion may be specifically selected, tuned, designed etc. for optimal combustion of ammonia/hydrogen). The use of hydrogen or ammonia as a fuel for the combustion engine is described in greater detail below.
The step of using the ammonia as an energy source for the power source may comprise fuelling the combustion engine with ammonia and/or combusting the ammonia in the combustion engine.
The step of using the ammonia as an energy source for the power source may comprise: cracking the ammonia to form hydrogen; and fuelling the power source with the hydrogen (e.g. combusting the hydrogen in the combustion engine). It will be appreciated that in a scenario where the ammonia is first cracked and the resultant hydrogen is used as fuel (e.g. combusted in the combustion engine), the by-products from this overall process (i.e. nitrogen from the step of cracking and water from the use of hydrogen as a fuel) remain the same as when the ammonia is directly used as fuel for the power source. As such, the method remains less environmentally harmful than prior art methods that are reliant on hydrocarbon fuels as discussed above.
The power source may be a fuel cell. For example, the power source may be an ammonia powered fuel cell. As such, the step of using the ammonia as an energy source for the power source may comprise fuelling the ammonia powered fuel cell with the ammonia.
Alternatively, the fuel cell may be a hydrogen powered fuel cell. In such a scenario, using the ammonia as an energy source for the power source may comprise: cracking the ammonia to form hydrogen; and fuelling the hydrogen powered fuel cell with the hydrogen.
It will be noted that even in scenarios of the first aspect of the invention where a hydrogen fuel cell is used to power the hydrocarbon production system (rather than using the ammonia as a fuel directly for a combustion engine or an ammonia powered fuel cell) the by-products from the overall process (i.e. nitrogen and water) remain the same and hence the first aspect of the invention remains less environmentally harmful than prior art methods. Nitrogen is output as a byproduct at the cracking stage whilst water is output as a by-product from the hydrogen fuel cell.
The hydrocarbon production system may comprise or consist of an offshore hydrocarbon production facility. The hydrocarbon production facility may be a hydrocarbon production platform, e.g. an unmanned hydrocarbon production platform, or a floating, production, storage and offloading vessel (FPSO).
It will be understood by the skilled person that a hydrocarbon production system is a system that is specifically configured for the production and/or processing of hydrocarbons (e.g. oil, natural gas, etc.). As such, the hydrocarbon production system will comprise a degree of production equipment and/or a degree of processing equipment configured for processing or part-processing the produced hydrocarbons.
The power source may provide electrical power for the hydrocarbon production system. If the power source is a combustion engine, this may entail use of an electrical generator connected to the engine or which the combustion engine forms part of. The optional combustion engine may additionally and/or alternatively be configured to provide motive power for the hydrocarbon production system. For example, the combustion engine may be configured to directly power components of the hydrocarbon production system, e.g. to provide a direct drive to a compressor of the hydrocarbon production system and/or other rotating components of the hydrocarbon production system.
The hydrocarbon production system may comprise a plurality of power sources. Each power source may be configured to provide power for the hydrocarbon production system. The method may comprise: using the ammonia as an energy source for some or all of the plurality of the power sources to provide power for the hydrocarbon production system.
The method may comprise, prior to the step of using ammonia, storing the ammonia at the hydrocarbon production system. This may occur on/at the same unit where the ammonia is used as an energy source. Alternatively, the ammonia may be stored at a different site, e.g. on/at the remainder of the hydrocarbon production system or at a further, separate unit.
Storing the ammonia at the hydrocarbon production system may comprise storing the ammonia in a storage tank or tanks. The storage tank(s) may be configured for storing ammonia at an elevated pressure, for example liquefied ammonia at ambient temperature conditions (e.g. between 0°C and 40 °C). The storage tank(s) may be configured to store the ammonia at between 5 barg - 20 barg, for example at 5 barg, 10 barg, 15 barg or 20 barg. The exact pressurised conditions that the storage tank(s) are configured to store the ammonia at may be selected dependent on the ambient temperature of the ammonia (optionally as a liquid) to be stored therein, the tolerances of the storage tank and/or the tolerance of the equipment used for loading and unloading the ammonia into the storage tank(s).
The step of storing the ammonia may comprise storing the ammonia as a liquid, optionally as a liquid at ambient temperature conditions.
The method may comprise the step of liquefying ammonia, optionally at ambient temperature conditions, prior to storing the ammonia.
The skilled person will appreciate that storing and/or liquefying ammonia at ambient temperature conditions requires the ammonia to be pressurised at pressures far above ambient pressure conditions with the exact pressure conditions being determined by the specific ambient temperature of the ammonia. Ambient temperature conditions may be any temperature between 0°C - 40 °C. As such, the pressure required in order to liquefy the ammonia and/or store the ammonia as a liquid may be between, for example, 5 barg - 20 barg, with the exact pressure required being determined by the ambient temperature selected.
Conventionally, liquefaction of ammonia and/or storage of ammonia as a liquid is carried out at ambient pressure conditions and hence, as will be understood by the skilled person, at low temperature conditions that are significantly below ambient temperature conditions. In the context of the invention however, whilst possible it is less viable and advantageous to liquefy and store ammonia at temperature conditions significantly below ambient temperature conditions. This is because there is significant complexity and expenditure, both operational and capital, associated with the equipment, personnel and processes required to produce and maintain ammonia as a liquid at such temperature conditions and at ambient pressure conditions. In an offshore scenario, limited space also means that it may not be viable to provide the necessary infrastructure to produce liquefied ammonia at ambient pressure conditions.
Thus, it is particularly advantageous (though optional) in the context of the invention of the first aspect to store liquid ammonia at ambient temperature conditions. As noted above, this requires the ammonia to be pressurised at pressure conditions above ambient conditions; however, the pressurisation required is associated with significantly reduced complexity and expenditure, both operational and capital, in terms of the equipment, personnel and processes involved and hence is particularly suited to offshore scenarios.
The step of using the ammonia as an energy source for the power source takes place at a unit that is separate from the remainder of the offshore hydrocarbon production system. For example, combusting ammonia in the combustion engine may take place on/at the separate unit of the hydrocarbon production system. As above, the optional step of storing the ammonia may take place on/at the separate unit of the hydrocarbon production system. If present, the generator may be provided on the separate unit.
The separate unit may be a modular unit of the hydrocarbon production system. The modular unit may be self-contained and (easily/readily) separable from the remainder of the hydrocarbon production system. By modular it is meant that the separate unit may be considered to constitute a module that is self-contained and that can be readily conjoined with and split apart from the remainder of the hydrocarbon production system. That is to say, a modular unit is not integral with the remainder of the hydrocarbon production system. Any connections between the modular unit and the remainder of the hydrocarbon production system may hence be readily reversible (i.e. they are designed to be reversible) such that the modular unit is readily disconnected from the remainder of the hydrocarbon production system (e.g. through electrical/power connections, utilities connections, walkways, etc.).
Since the step of using the ammonia as an energy source for the power source takes place at a unit that is separate from the remainder of the offshore hydrocarbon production system, the method may comprise supplying the power produced at the power source from the separate unit to the remainder of the hydrocarbon production system (e.g. via a power/electrical connection, such as a cable - more on this feature below).
As noted above, the separate unit may be a separate facility from the portion of the hydrocarbon production system where hydrocarbon producing operations are carried out. For example, the separate unit may be a separate floating unit/facility situated adjacent, e.g., a production platform or a floating, production storage and offloading (FPSO) vessel that constitutes the remainder of the hydrocarbon production system.
Having a separate unit, and in particular a separate modular unit, is advantageous since it can be easily installed/retrofitted in combination with an already existing hydrocarbon production system (i.e. a brownfield facility) in order that the invention of the first aspect can be implemented without significant downtime in production at the already existent hydrocarbon production system. This also means that minimal modification is required to the already existing hydrocarbon production system for the invention to be employed other than maybe the decommissioning and/or removal of an already existent power source (e.g. gas turbine engine). Such modification/replacement may not be necessary however. It furthermore means the separate modular unit can be moved and used in combination with other already existing hydrocarbon production systems, e.g. after reserves have been depleted at a first system.
The separate unit may form part of a plurality of hydrocarbon production systems. That is to say, a plurality of different hydrocarbon production systems (including the hydrocarbon production system to which the method of the first aspect relates) may comprise a common (single) separate unit (e.g. a common single, modular unit). The common, single unit may provide power to each of the plurality of hydrocarbon production systems. For example, in an offshore scenario, the single separate unit may take the form of a floating unit/facility situated adjacent and connected to a plurality of production platforms, production facilities and/or FPSOs and may provide power for each of the connected production platforms, production facilities and/or FPSOs. In such a scenario, the single unit may be termed an energy hub given that it acts as an energy source for a plurality of systems.
The single unit may be connected to the remainder of the/each hydrocarbon production system via appropriate cabling. The cabling may be configured to supply electrical AC power of 50 Hz -60 Hz frequency and/or at a power of 7 MW from the single unit to the remainder of the/each hydrocarbon production system.
The method of the first aspect may be employed at a brownfield production facility or at a greenfield production facility.
The ammonia may be grey ammonia, green ammonia and/or blue ammonia.
The method may comprise, prior to the step of using the ammonia as an energy source for the power source and optionally prior to the optional step of storing, transporting the ammonia to the hydrocarbon production system. The step of transporting may make use of a tanker/vessel.
In scenarios where the hydrocarbon system comprises a combustion engine, the hydrocarbon production system may also comprise a steam engine configured to provide power to the hydrocarbon production system. The steam engine may be configured to run in a combined cycled with the combustion engine. That is, the exhaust gases from combustion at the combustion engine may be used to heat water which drives the steam engine to produce power for the hydrocarbon production system. As such, the method may comprise running the steam engine in a combined cycle with the combustion engine to provide power for the hydrocarbon production system. This step of running the steam engine in a combined cycle may comprise using the exhaust gases from the combustion at the combustion engine to heat water into steam; and driving a steam engine to produce power for the hydrocarbon production system. The steam engine may be situated on/at the separate unit.
In a second aspect of the invention, there is provided an offshore hydrocarbon production system, the offshore hydrocarbon production system comprising a power source configured to provide power for the offshore hydrocarbon production system; wherein the offshore hydrocarbon production system is arranged to use ammonia as an energy source for the power source in order to provide power for the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
The method of the first aspect of the invention, including any optional features thereof, may be a method of operating the hydrocarbon production system of the second aspect of the invention.
The hydrocarbon production system of the second aspect may be in accordance with the hydrocarbon production system discussed above in relation to the first aspect of the invention and may comprise any optional features thereof.
In a third aspect of the invention, there is provided a method of retrofitting an existing offshore hydrocarbon production system, the method comprising: decommissioning and/or removing an existent power source at the offshore hydrocarbon production system: installing at the offshore hydrocarbon production system a new power source configured to provide power for the offshore hydrocarbon production system; and configuring the offshore hydrocarbon production system to use ammonia as an energy source for the power source; wherein the new power source is provided on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
The step of installing at the offshore hydrocarbon production system a new power source may comprise providing or installing the separate unit comprising the new power source. For example, a platform or vessel on which the new power source is provided may be provided adjacent and connected to the existing hydrocarbon production system.
The existing hydrocarbon production system may be a brownfield production system.
The hydrocarbon production system resulting from the method of the third aspect may be a hydrocarbon production system in accordance with the second aspect, optionally inclusive of any optional feature thereof.
In a fourth aspect, there is provided a method of assembling an offshore hydrocarbon production system, the method comprising providing equipment and infrastructure configured for the production and/or processing of hydrocarbons; providing a power source configured to provide power for the offshore hydrocarbon production system; and configuring the offshore hydrocarbon production system to use ammonia as an energy source for the power source; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
The hydrocarbon production system resulting from the method of the fourth aspect may be a greenfield production system.
The hydrocarbon production system resulting from the method of the fourth aspect may be a hydrocarbon production system in accordance with the second aspect, optionally inclusive of any optional feature thereof.
In accordance with a fifth aspect, there is provided a plurality of offshore hydrocarbon production systems that comprise a common power source situated on a single, modular unit and that is configured to provide power for each of the plurality of offshore hydrocarbon production systems; wherein the plurality of offshore hydrocarbon production systems are arranged to use ammonia as an energy source for the common power source in order to provide power for each of the plurality of offshore hydrocarbon production systems.
One or all of the hydrocarbon production systems of the fifth aspect may be in accordance with the hydrocarbon production system of the second aspect, optionally including any optional features thereof. One or all of the hydrocarbon production systems of the fifth aspect may be operated in accordance with the first aspect, optionally including any optional features thereof.
In a sixth aspect, there is provided a method of operating a plurality of offshore hydrocarbon production systems, the plurality of offshore hydrocarbon production systems comprising a common power source situated on a single, modular unit and configured to provide power for the plurality of offshore hydrocarbon production systems, the method comprising using ammonia as an energy source for the common power source in order to provide power for the plurality of offshore hydrocarbon production systems.
The plurality of hydrocarbon production systems of the sixth aspect may be in accordance with the fifth aspect, optionally inclusive of any optional features thereof.
In a further aspect of the invention, there is provided a method of operating an offshore hydrocarbon production system, the offshore hydrocarbon production system comprising a power source (e.g. a combustion engine) configured to provide power for the offshore hydrocarbon production system, the method comprising fuelling the power source with the ammonia (e.g. combusting the ammonia in the combustion engine) to provide power (e.g. electrical power) for the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
In yet a further aspect of the invention, there is provided a method of operating a hydrocarbon production system, the hydrocarbon production system comprising a power source configured to provide power for the hydrocarbon production system, the method comprising using ammonia as an energy source for the power source in order to provide power for the hydrocarbon production system. This further aspect of the invention may comprise any of the compatible features discussed above in relation to the other aspects of the invention.
In still a further aspect of the invention, there is provided a hydrocarbon production system, the hydrocarbon production system comprising a power source configured to provide power for the hydrocarbon production system; wherein the hydrocarbon production system is arranged to use ammonia as an energy source for the power source in order to provide power for the hydrocarbon production system. This still further aspect of the invention may comprise any of the compatible features discussed above in relation to the other aspects of the invention.
Certain embodiments of the invention will now be described, by way of example only, and with reference to the figures, in which:
Figure 1 is a schematic depiction of an offshore floating facility connected to a tanker and to three separate production facilities;
Figure 2 is a cross-sectional view of the offshore floating facility of Figure 1;
Figure 3 shows a gas engine of a generator positioned on the offshore floating facility of Figures 1 and 2; and
Figure 4 is a pressure enthalpy chart for ammonia.
Figure 1 shows an offshore floating facility 1 that is connected by three separates cables 3a, 4a, and 5a to three separate production facilities 3, 4, 5. Production facility 3 is an offshore production platform 3, production facility 4 is another offshore production platform 4, whilst production facility 5 is a floating, production, storage and offloading (FPSO) 5. Each production facility 3, 4, 5 is situated at its own respective hydrocarbon reservoir and is arranged to permit production of hydrocarbons from its respective reservoir via suitable production and processing equipment. The cables 3a, 4a, 5a are each electrical power cables 3a, 4a, 5a that are configured for carrying electrical power from the offshore floating facility 1 to each of the production facilities 3, 4, 5 in order to provide power thereto, as will be described in further detail below.
Also connected to the offshore floating facility 1 is a tanker 2. The tanker 2 is connected to the offshore floating facility 1 via two separate conduits 2a, 2b that are each arranged to carry a fluid, specifically ammonia, between the tanker 2 and the offshore floating facility 1 as will be described in greater detail below. The conduits 2a and 2b are reversibly connected to the tanker 2 as discussed in further detail below.
As can be seen in greater detail with reference to Figure 2, the offshore floating facility 1 has a predominantly ship shaped hull 101. Housed with the hull 101 are two storage tanks 103. The storage tanks 103 are arranged to store liquid ammonia therein at ambient temperature conditions and, consequently, at pressures of between 5 barg - 20 barg (the exact pressure of storage being dependent on the ambient temperature conditions as discussed below with reference to Figure 4). The hull 101 also comprises a plurality of generators 105 that each comprise a gas engine 107. Each gas engine 107, further details of which can be seen in Figure 3, is a V18 engine which is specifically configured to combust gaseous ammonia therein. Motive power produced by each engine 107 drives electricity generation at each generator 105.
Each of the generators 105 are connected to the cables 3a, 4a, 5a in a manner that permits electrical power produced at the generators 105 to be passed via the cables 3a, 4a, 5a to the production facilities 3, 4, 5.
The tanker 2 comprises a plurality storage tanks (not shown) correspondent to the storage tanks 103 on-board the offshore floating facility 1. The storage tanks on the tanker 2 are arranged to store liquid ammonia therein at ambient temperature conditions and, consequently, at pressures of between 5 barg - 20 barg (the exact pressure of storage being dependent on the ambient temperature conditions).
In use, the storage tanks on-board the tanker 2 are loaded with ambient temperature liquid ammonia at an onshore site remote from the offshore floating facility 1 and the production facilities 3, 4, 5. The tanker 2 then travels to a site of the offshore floating facility 1 (e.g. as shown in Figure 1) whilst the liquid, ambient temperature ammonia is maintained as such within the storage tanks. This is achieved by ensuring that the storage tanks remain suitably pressurised during transit of the tanker 2. Once at the site of the offshore floating facility 1 , the conduits 2a, 2b are connected to the tanker 2. Liquid ammonia is then offloaded from the tanker 2 to the offshore floating facility 1 via the conduit 2a and is transferred into the storage tanks 103 on-board the offshore floating facility 1 for storage therein.
The transfer between the tanker 2 and the storage tanks 103, and the subsequent storage therein, is carried out whilst maintaining, as far as possible, the ammonia as a liquid at ambient temperature conditions. This requires the transfer and subsequent storage in the tanks 103 to be carried out at suitably pressurised conditions. It may not however be possible to maintain all ammonia in a liquid state during this transfer and subsequent storage. For example, prior to introduction of liquid ammonia from the tanker 2 to the storage tanks 103, the interior of the storage tanks 103 may be under ambient pressure conditions and be filled with air and/or gaseous ammonia left over as a remnant from a previous stock of ammonia. As such, initial introduction of the pressurised liquid ammonia at ambient temperature conditions into the storage tanks 103 will result in an initial depressurisation of some liquid ammonia such that it is vaporised into a gaseous form. Soon after however, the storage tanks 103 will pressurise sufficiently such that further introduced ammonia will remain in a liquid state at ambient temperature conditions.
In the event of vaporisation of any portion of the ammonia during its transfer between the tanker 2 and the offshore floating facility 1 , (e.g. after initial introduction into the storage tanks 103 as discussed above) then the vaporised portion of the ammonia is separated off from the liquid ammonia at the offshore floating facility 1 and is transferred back to the tanker 2 via the conduit 1b. This gaseous ammonia can then be re-condensed on board the tanker 2 at ambient temperature conditions and subsequently transferred back to the offshore facility 1 via the conduit 1a for storage thereon. Alternatively, the gaseous ammonia can be stored aboard the tanker 2 for transit back to, e.g., an on shore site. Once all of the liquid ammonia has been offloaded from the tanker 2, the conduits 2a, 2b are disconnected. The tanker 2 then travels away from the offshore floating facility, optionally back to an onshore site for further loading and transport of ammonia.
The liquid ammonia stored within the storage tanks 103 aboard the offshore floating facility 1 is used as a fuel to power the gas engines 107 comprised as part of generators 105. As such, the storage tanks 103 on-board the floating facility 1 serve as a buffer storage for fuel for the generators 105.
Specifically, the liquid ammonia stored within the storage tanks 103 is sent from the tanks 103 to an inlet of the engines 107. During transit between the tanks 103 and the gas engine 107 the liquid ammonia is vaporised, either passively as a natural result of depressurisation that occurs during transit and/or actively via a suitable vaporiser, into a gaseous form. In its gaseous form, the ammonia can then be appropriately introduced into the gas engine 107 for combustion therein.
Combustion of the ammonia in the engines 107 drives electricity generation at the generators 105. The electrical power (e.g. rated at 7 MW) produced at the generators 105 is then transferred via the cables 3a, 4a, 5a from the offshore floating facility 1 to the production facilities 3, 4, 5 and is used to power operations at the production facilities 3, 4, 5, including powering the production and processing equipment situated thereat.
The offshore floating facility 1 thus acts as an energy hub for a plurality of hydrocarbon production facilities 3, 4, 5 and serves to provide power for production and other operations that occur at each facility. The floating facility 1 is thus comprised as part of a plurality of hydrocarbon production systems, wherein the remainder of each system is formed by a respective production facility 3, 4, 5.
Figure 4 shows a pressure-enthalpy chart for ammonia. Pressure is represented along the y-axis whilst enthalpy is represented along the x-axis. The region below the saturation line 61 (termed ‘saturation dome’) represents where any addition of enthalpy will cause additional liquid ammonia to vaporize instead of raising the temperature of the ammonia. The red lines on the chart indicate constant temperatures and, whilst not depicted therein, it can be deduced from the temperature values given either side of the saturation dome that the temperature lines would be at a complete horizontal through the saturation dome. The green lines on the chart each represent a constant ratio of vapour mass to total mass of the ammonia.
The region 63 shown in blue represents where ammonia is at ambient temperature conditions (i.e. 0°C - 40 °C) within the saturation dome. Within region 63 the vast majority of ammonia would be in a liquid state whilst being at ambient temperature conditions as can be deduced from the ratios of vapour mass to total mass of the ammonia in this region. The ambient temperature liquid ammonia that is stored in the storage tanks as discussed above would typically fall within region 63 of the pressure-enthalpy chart.

Claims

Claims:
1. A method of operating an offshore hydrocarbon production system, the offshore hydrocarbon production system comprising a power source configured to provide power for the offshore hydrocarbon production system, the method comprising using ammonia as an energy source for the power source in order to provide power for the offshore hydrocarbon production system; wherein the power source is located on/at a unit that is separate from the remainder of the offshore hydrocarbon production system and hence the step of using the ammonia as an energy source for the power source takes place on/at the unit that is separate from the remainder of the offshore hydrocarbon production system.
2. A method as claimed in claim 1 , wherein the power source is a combustion engine and wherein the step of using the ammonia as an energy source for the power source comprises combusting ammonia in the combustion engine.
3. A method as claimed in claim 2, wherein the offshore hydrocarbon production system comprises a steam engine and the method comprises running the steam engine in a combined cycle with the combustion engine to provide power for the offshore hydrocarbon production system.
4. A method as claimed in claim 1 , wherein the power source is a fuel cell.
5. A method as claimed in claim 4, wherein the fuel cell is an ammonia powered fuel cell, and wherein the step of using ammonia as an energy source for the power source comprises fuelling the ammonia powered fuel cell with ammonia.
6. A method as claimed in claim 4, wherein the fuel cell is a hydrogen powered fuel cell, wherein the step of using ammonia as an energy source for the power source comprises: cracking the ammonia to form hydrogen; and fuelling the hydrogen powered fuel cell with the hydrogen.
7. A method as claimed in any preceding claim, wherein the separate unit is a single, modular unit of the offshore hydrocarbon production system that is self-contained and separate from the remainder of the offshore hydrocarbon production system, and the method comprises supplying the power produced at the power source from the modular unit to the remainder of the offshore hydrocarbon production system.
8. A method as claimed in claim 7, wherein the remainder of the offshore hydrocarbon production system comprises a production platform or FPSO, and wherein the modular unit is a floating facility situated adjacent and connected to the production platform or FPSO.
9. An offshore hydrocarbon production system comprising a power source configured to provide power for the offshore hydrocarbon production system; wherein the offshore hydrocarbon production system is arranged to use ammonia as an energy source for the power source in order to provide power for the offshore hydrocarbon production system; wherein the power source is on a unit that is separate from the remainder of the offshore hydrocarbon production system.
10. An offshore hydrocarbon production system according to claim 9, wherein the power source is a combustion engine that is configured to combust ammonia to provide power for the offshore hydrocarbon production system.
11. An offshore hydrocarbon production system according to claim 10, comprising a steam engine configured to run in a combined cycled with the combustion engine to provide power to the offshore hydrocarbon production system.
12. An offshore hydrocarbon production system according to claim 9, wherein the power source is a fuel cell. An offshore hydrocarbon production system according to claim 12, wherein the fuel cell is an ammonia powered fuel cell. An offshore hydrocarbon production system according to claim 12, wherein the fuel cell is a hydrogen powered fuel cell, and wherein the offshore hydrocarbon production system comprises an ammonia cracker in communication with the hydrogen powered fuel cell, the ammonia cracker being configured to crack ammonia to produce hydrogen and to communicate the hydrogen to the hydrogen powered fuel cell. An offshore hydrocarbon production system according to any of claims 9 to 14, wherein the separate unit is a single, modular unit that is self-contained and separate from the remainder of the offshore hydrocarbon production system. An offshore hydrocarbon production system as claimed in claim 15, wherein the remainder of the offshore hydrocarbon production system comprises a production platform or FPSO and wherein the modular unit is a floating facility situated adjacent and connected to the production platform or FPSO. A method of assembling an offshore hydrocarbon production system, the method comprising providing equipment and infrastructure configured for the production and/or processing of hydrocarbons; and providing a power source configured to provide power for the offshore hydrocarbon production system; wherein the offshore hydrocarbon production system is arranged to use ammonia as an energy source for the power source in order to provide power for the offshore hydrocarbon production system; and wherein the power source is provided on/at a unit that is separate from the remainder of the offshore hydrocarbon production system. A method of retrofitting an existing offshore hydrocarbon production system, the method comprising: decommissioning and/or removing an existing power source at the offshore hydrocarbon production system: installing at the offshore hydrocarbon production system a new power source configured to provide power for the offshore hydrocarbon production system; and configuring the offshore hydrocarbon production system to use ammonia as an energy source for the power source; wherein the new power source is installed on/at a unit that is separate from the remainder of the offshore hydrocarbon production system.
PCT/NO2023/050047 2022-03-02 2023-03-02 Hydrocarbon production system with reduced carbon dioxide emission WO2023167593A1 (en)

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