AN OFFSHORE JACK-UP INSTALLATION, ASSEMBLY AND METHOD

An offshore installation including a powerplant adapted for powering an electricity distribution network of the offshore installation and an exhaust processing module . The exhaust processing module has an input connected to the powerplant for receiving exhaust gas comprising carbon dioxide from the powerplant, a carbon dioxide capture module arranged to separate carbon dioxide from the exhaust gas, and an output for outputting the separated carbon dioxide. The exhaust processing module is powered by the powerplant, and the outlet of the carbon dioxide capture module is connected to a storage facility for temporary storing the separated carbon dioxide.

The present invention relates to an offshore jack-up installation, assembly and method.

BACKGROUND

Offshore oil and gas production platforms and drilling installations require energy to perform production and drilling operations. Under normal circumstances, fuel gas such as natural gas is obtained by the production platform is combusted in a gas-fired powerplant on the production platform. The combustion generator supplies power to meet the energy needs of the production platform and/or the drilling installation.

However, burning the fuel gas to power the production platform and/or the drilling installation causes carbon dioxide emissions as well as other undesirable gases. In some coastal areas, production platform and/or the drilling installation are required to reduce their carbon dioxide emissions during operation.

One proposal is to electrify the production platform and/or the drilling installations such that they do not burn fossil fuels during operation. However, electrification requires a plentiful supply of electricity generated from renewable sources in order to reduce the carbon dioxide emissions from the operation of the production platform and/or the drilling installation.

One another proposal is to pump carbon dioxide into an existing oil and gas reserve. This enhances the oil and gas recovery (EOR/EGR) from the oil and gas reserve. However, the oil and gas absorb the carbon dioxide and therefore the recovered oil and gas must be processed to remove the absorbed carbon dioxide. The removal of the absorbed carbon dioxide increases the energy required and increases the carbon dioxide emissions of the production platforms and/or the drilling installations.

Another proposal is discussed in “Offshore power generation with carbon capture and storage to decarbonise mainland electricity and offshore oil and gas installations: A technoeconomic analysis” S Roussanaly et al Applied Energy 233-234 (2019) p478-494. This proposal discusses a floating platform which receives natural gas from a pipeline and stores captured carbon dioxide below the seabed. A problem with this is that the floating platform must be positioned close to an existing natural gas pipeline or another suitable supply of processed fuel-gas. Furthermore, the floating platform must be specially designed to operate in harsh weather conditions. For example, the mooring ropes or the dynamic positioning system must be increased in size and capacity to maintain the position of the floating platform within allowable excursions for harsh weather. The floating rig may also be limited by the minimum water depth in which it can operate.

The proposal also discloses a fixed installation option whereby natural gas is extracted from a gas field and converted to electricity on the fixed installation. Carbon dioxide is then stored below the seabed. A problem with a fixed installation is that the installation and decommissioning of the fixed installation takes significant time and resources. This is problematic if the oil and gas field is marginal with a limited expected lifetime. This means that if the oil and gas field is depleted, the fixed installation cannot be easily moved to provide power to production platforms elsewhere.

Examples of the present invention aim to address the aforementioned problems.

According to an aspect of the present invention, there is an offshore jack-up installation comprising a hull; a plurality of moveable legs engageable with the seafloor, wherein the offshore installation is arranged to move the legs with respect to the hull to position the hull out of the water when the legs engage the seafloor; an exhaust processing module arranged to receive exhaust gas comprising carbon dioxide, the exhaust module arranged to process carbon dioxide in the exhaust gas and to output processed carbon dioxide to at least one other offshore installation for storage in carbon dioxide storage pocket in the seabed.

Optionally, the offshore jack-up installation comprises a powerplant and the exhaust of the powerplant is outputted from the powerplant to the exhaust processing module.

Optionally, the offshore jack-up installation comprises at least one output power port arranged to output power to the at least one other offshore installation or to an onshore electricity distribution network.

Optionally, the offshore jack-up installation comprises at least one input fuel gas duct for receiving fuel gas from the at least one other offshore installation.

Optionally, the exhaust processing module is in fluid communication with another powerplant mounted on the at least one other offshore installation and the exhaust of the other powerplant is outputted to the exhaust processing module.

Optionally, the powerplant on the offshore jack-up installation or the powerplant mounted on the at least one other offshore installation powers the exhaust processing module.

Optionally, the exhaust processing module comprises a carbon dioxide capture module arranged to separate carbon dioxide from the exhaust gas.

Optionally, the carbon dioxide capture module is a scrubber mounted in a flue gas exhaust duct.

Optionally, the exhaust processing module comprises a carbon dioxide processing module arranged to compress, cool, dewater, liquify and/or store the separated carbon dioxide.

Optionally, the offshore jack-up installation comprises a steam generator.

Optionally, the generated steam is used for heating the carbon dioxide in the exhaust processing module.

Optionally, the steam generator is in fluid communication with another offshore installation and the generated steam is used for heating offshore oil and gas production equipment.

Optionally, the steam generator is in fluid communication with a steam-methane reforming module.

Optionally, the steam-methane reforming module is in fluid communication with the exhaust processing module.

Optionally, the steam-methane reforming module is in fluid communication with a pipeline for pumping generated hydrogen directly to shore or via an H2tanker vessel.

Optionally, the offshore jack-up installation comprises an air separation module configured to output concentrated oxygen to powerplant on the offshore jack-up installation or the powerplant mounted on the at least one other offshore installation.

Optionally, the at least one other offshore installation is one or more of the following: a production platform, a wellhead platform, a jack-up drilling rig, a semi-submersible rig or a drilling vessel.

Optionally, the at least one other offshore installation stores the outputted processed carbon dioxide in a carbon dioxide storage pocket remote from submarine oil and gas reserves.

Optionally, the carbon dioxide is pumped via a subsea pipe to a submerged wellhead.

Optionally, the carbon dioxide storage pocket in the seabed is a saline aquifer, an active oil and gas field, or a depleted oil and gas field.

Optionally, the exhaust processing module comprises an auxiliary input port arrange to receive carbon dioxide from a vessel or from a subsea pipeline.

Optionally, the offshore jack-up installation comprises accommodation for the offshore jack-up installation operations and/or for the operations of at least one other offshore installation.

In another aspect of the invention there is an offshore installation assembly comprising a production platform in fluid connection with a submarine oil and gas reserve and arranged to generate fuel gas and the production platform is in fluid connection with a carbon dioxide storage pocket in the seabed; and an offshore jack-up installation comprising a hull; a plurality of moveable legs engageable with the seafloor, wherein the offshore installation is arranged to move the legs with respect to the hull to position the hull out of the water when the legs engage the seafloor and positioned adjacent to a production platform; a powerplant for burning fuel gas received from the production platform and arranged to generate power; an exhaust processing module arranged to receive exhaust gas comprising carbon dioxide in fluid communication with an exhaust port of the powerplant, the exhaust processing module arranged to process carbon dioxide from the exhaust of the powerplant; and the exhaust processing module is arranged to output processed carbon dioxide to the production platform for storage in the carbon dioxide storage pocket.

In another aspect of the invention, there is provided a method of operating an offshore jack-up installation, the offshore jack-up installation having an exhaust processing module arranged to receive exhaust gas comprising carbon dioxide, the method comprising moving an offshore jack-up installation adjacent to a production platform; connecting the exhaust processing module to the production platform; connecting the production platform to a carbon dioxide storage pocket in the seabed; processing carbon dioxide in the exhaust gas; outputting processed carbon dioxide to the production platform; and storing the processed carbon dioxide in the carbon dioxide storage pocket.

In yet another aspect of the invention, there is an offshore jack-up installation comprising a hull; a plurality of moveable legs engageable with the seafloor, wherein the offshore installation is arranged to move the legs with respect to the hull to position the hull out of the water when the legs engage the seafloor; and an exhaust processing module arranged to receive exhaust gas comprising carbon dioxide, the exhaust module arranged to process carbon dioxide in the exhaust gas and to output processed carbon dioxide for storage.

Various other aspects and further embodiments are also described in the following detailed description and in the attached claims with reference to the accompanying drawings, in which:

FIG.1shows a side view of an offshore jack-up installation100according to an example. In some examples, the offshore jack-up installation100is a retrofitted jack-up former drilling rig.

The offshore jack-up installation100is floatable and comprises a hull102. The hull102comprises a plurality of legs104which extend through the hull102and engage the seabed106. The legs104comprise spudcans110which are arranged to engage the seabed106. The offshore jack-up installation100is shown in an operational position with the hull102being positioned above the surface of the water108. The offshore jack-up installation100is moveable between different locations.

When the offshore jack-up installation100moves between locations, the plurality of the legs104are retracted and the offshore jack-up installation100is sailed to the new location. The offshore jack-up installation100can be towed with one or more tugboats (not shown). In some examples, the offshore jack-up installation100is moved adjacent to one or more offshore installations or rigs116,118,130as shown in step700ofFIG.19.FIG.19shows a flow diagram of the method of operation of an offshore jack-up installation100according to an example.

The offshore jack-up installation100comprises a main deck112, an accommodation structure114for housing personnel. The accommodation structure114can be used for housing personnel working on the offshore jack-up installation100or one or more adjacent offshore installations116,118,130. Advantageously, this means that additional offshore installations providing accommodation for the production platform116are not needed. By providing the accommodation structure114on the offshore jack-up installation100, the carbon dioxide emissions generated from providing the hotel load required for the accommodation structure114can be captured by an exhaust processing module132thereby reducing potentially further emissions vented to the atmosphere. The exhaust processing module132will be discussed in further detail below.

The main deck112of the offshore jack-up installation100may be used for storing equipment used in operations of adjacent offshore installations116,118,130. For example, the main deck112can be used to store equipment used in production operations on a production platform116or drilling operations on an offshore drilling rig118. In some examples, there is a bridge (not shown) extending between the offshore jack-up installation100and the adjacent offshore installations116,118,130. The bridge can comprise a walkway, electrical connections, flue gas ducting, fuel gas pipes and any other suitable cable connection or pipe between the offshore jack-up installation100and the adjacent offshore installations116,118,130.

The production operations on a production platform116or drilling operations on an offshore drilling rig118are known and will not be discussed in any further detail hereinafter.

The offshore jack-up installation100has a powerplant120. In some examples, the powerplant120comprises at least one combustion generator for generating electricity. In some examples, the combustion generator is a gas turbine generator (not shown) or a diesel generator. The gas turbine generator is arranged to burn natural gas or any other fuel gas such as methane, hydrogen etc. and generate electricity. In some examples, there is a plurality of gas turbine generators. For example, there can be two, three, four, five, six, seven, or eight or any number of gas turbine generators.

In some examples, the offshore jack-up installation100optionally comprises a fuel gas storage tank (not shown) for storing fuel gas to be burnt in the powerplant120.

In some examples, powerplant120is arranged to generate an electrical supply for the offshore jack-up installation100and other adjacent offshore installations116,118,130such as the production platform116and the offshore drilling rig118. The offshore rig performs power consuming operations, and these are powered from an electricity distribution network (microgrid). The electricity distribution network normally operates as an autonomically network in a so-called “island mode”. According to the invention, the powerplant120powers the electricity distribution network, and the powerplant120is often based on several diesel generators. The offshore drilling rig118can optionally be a semisubmersible rig (not shown) positioned by mooring and/or anchor system and/or a dynamic positioning system. In some examples, the powerplant120has a generation capacity of several hundreds of Megawatts of combined electrical and thermal power. A significant fraction of the total power by the powerplant120may be for generating steam for both electrical power generation (e.g. by exhaust heat recovery) and for heating purposes. The CC absorbent-regenerative system, as discussed below, for dissolving the CO2 out of the absorbents may require considerable heating and may be in excess of what is achievable by exhaust heat recovery. In some other examples, the powerplant120has a generation capacity of between 400 MW to 800 MW. In other examples the powerplant120as a generation capacity of 150 MW, 200 MW, 300 MW, 400 MW, 500 MW, 600 MW, 700 MW, 800 MW, 900 MW, 1000 MW. In other examples, the powerplant120can have any suitable capacity such that it can generate electricity or generate electricity and heating for both the offshore jack-up installation100(e.g. for powering the on-board carbon capture and processing systems, as discussed below) and other adjacent offshore installations116,118,130. The exhaust processing module132discussed below which is configured to capture carbon from exhaust may require between 20% to 30% of the power generated by the powerplant120.

In this way, the offshore jack-up installation100comprises at least one output power port124arranged to output power to the at least one other offshore installation116,118,130. An electrical cable122is connected between the output power port124and the production platform116. This means that the powerplant120can generate electricity and provide power to the production platform116. Additional cables126,128can optionally be provided to provide power to other adjacent installations such as a wellhead platform130and the offshore drilling rig118. The additional cables126,128can be daisy-chained between the different adjacent offshore installations116,118,130. Alternatively, the additional cables126,128can each extend from the offshore jack-up installation100in a hub-spoke arrangement (not shown).

The production platform116as shown inFIG.1comprises a large production platform powerplant300(as shown inFIG.3) which is typically 50-100 MW or more. In some examples, the production platform powerplant300may be entirely shut-down or decommissioned. In this example, all production facilities of the production platform116are powered and heated (by steam) from the powerplant120of the offshore jack-up installation100(this is discussed in more detail with respect toFIGS.13,1415and16). In some examples, excess electrical power generated by the powerplant120can be sent to shore. Transmission of excess power to shore will be discussed in further detail below with respect toFIGS.8,9,13,14,15and16.

Alternatively, the production platform powerplant300is maintained in an operational status. In this case, all the exhaust ducting (not shown) of the production platform powerplant300is rerouted to the offshore jack-up installation100for exhaust processing. In this case, the powerplant120on the offshore jack-up installation100is not be required or alternatively the powerplant120runs in parallel. In some examples where the offshore jack-up installation100comprises the powerplant120, the powerplant120may be smaller than the production platform powerplant300and arranged to only power and heat the carbon capture and processing systems. This will be discussed in further detail below with respect toFIGS.4and5.

The offshore jack-up installation100comprises an exhaust processing module132.

The exhaust processing module132is configured to generate a clean exhaust with no or significantly reduced carbon dioxide content. The exhaust processing module132comprises a carbon dioxide capture module134and a carbon dioxide processing module142as shown inFIG.3. The exhaust processing module132in other examples can comprise additional processing modules for treating the exhaust gas and/or the carbon dioxide.

As will be understood from other examples discussed below, the carbon dioxide capture module134is optional and a flow of carbon dioxide gas is pumped directly to the carbon dioxide processing module142. Other examples which do not use a carbon dioxide capture module134will be described below.

In some examples, the carbon dioxide capture module134is a scrubber mounted in series with a flue-gas exhaust system136. Carbon dioxide scrubbing is a well-known technology used for removal of carbon dioxide from the exhaust of power plants fired by fossil fuels. The primary technology applied involves the use of various amines, e.g. monoethanolamine. Cold solutions of these organic compounds bind carbon dioxide, and the binding is reversed at higher temperatures. This means that the carbon dioxide capture module134is integral with the flue-gas exhaust system136. Thereby the exhaust gas flowing through the flue-gas exhaust system136also flows through the carbon dioxide capture module134. The flue-gas exhaust system136is in fluid communication with an exhaust outlet of the powerplant120. Alternatively or additionally the flue-gas exhaust system136and the carbon capture module134can be in fluid communication with the production platform powerplant300. In this case, exhaust outlets from either the powerplant120on the offshore jack-up installation100or from the production platform powerplant300are connected to the flue -gas exhaust system136and the exhaust processing module132. In this way, exhaust flue gases from either the powerplant120on the offshore jack-up installation100or from the production platform powerplant300pass through the carbon capture module134. The flue136is connected to the production platform powerplant300via large heavy ducting144across the connecting bridge between the offshore jack-up installation100and the production platform116.

The carbon dioxide capture module134is arranged to receive exhaust gas comprising carbon dioxide from the powerplant120. The carbon dioxide capture module134carries out post-combustion carbon capture. In some examples, the exhaust gas comprising carbon dioxide is received from the production platform powerplant300. Accordingly, the exhaust is the emissions resulting from burning the fuel gas during combustion in the gas turbine generator.

The carbon dioxide processing module142receives the separated carbon dioxide from the carbon dioxide capture module134. The carbon dioxide processing module142processes the captured carbon dioxide so that it is suitable for storage in a carbon dioxide storage pocket200in the seabed106.

In order to make the captured carbon dioxide suitable for undersea storage, the carbon dioxide processing module142is configured to carry out one or more processes on the captured carbon dioxide. The carbon dioxide processing module142is arranged to carry out one or more of the following on the carbon dioxide: compression, cooling, de-watering, liquefaction and temporary storage. Carbon dioxide in liquid state can only exist at a pressure above 5.1 atm, in the temperature range between 31.1° C. (temperature of critical point) and −56.6° C. (temperature of triple point). The carbon dioxide processing module142can serve as an import/export hub for carbon dioxide on and off the offshore jack-up installation100. The carbon dioxide processing module142may also receive (or export) carbon dioxide from/to tanker vessels and/or seabed pipelines from/to shore facilities. Thereafter, the carbon dioxide processing module142cryogenically pumps the carbon dioxide over to the production platform116and/or the wellhead platform130for well injection.

The exhaust processing module132is electrically connected to the powerplant120. Accordingly, the powerplant120powers the exhaust processing module132. In some examples, depending on the carbon dioxide load the exhaust processing module132uses, an estimated 20-30% of the generated heat and power load. The exhaust processing module power load132is “parasitic” for powering the carbon capturing and -processing systems from capture to injection into the well. The powerplant120is arranged to generate more power than the electrical load of the exhaust processing module132during operation. Alternatively, the production platform powerplant300can power the exhaust processing module132if the production platform powerplant300generates excess power.

In some examples, the carbon dioxide capture module134performs reactive absorption of carbon dioxide using monoethanolamine as solvent for the exhaust in the flue136. The exhaust gas is cooled to e.g. between 35° C. to 65° C. and the cooled exhaust gas is sent to a packed bed absorber comprising the monoethanolamine solvent.

The monoethanolamine solvent comprising the absorbed carbon dioxide is passed to a regenerator (not shown) requiring considerable re-heating where carbon dioxide is released. The carbon dioxide is then compressed and dehydrated. After compression to 80 bar, the carbon dioxide is cooled with cooling water and then pumped to 110 bars. At this point, the carbon dioxide is suitable for undersea storage. The storage process will be discussed in further detail below.

In some examples, the exhaust processing module132can comprise any suitable process for removing carbon dioxide from the exhaust of the powerplant120. Whilst a process using a monoethanolamine solvent is described, any other suitable solvent can be used. Other such methods of removing carbon dioxide will be discussed hereinafter.

One example will now be discussed in reference toFIGS.2and3.FIGS.2and3respectively show a schematic representation of the offshore jack-up installation100and a close-up of the offshore jack-up installation100.FIGS.2and3show an example whereby the offshore jack-up installation100is adjacent to the production platform116and the production platform powerplant300provides power and optionally heat/steam to the exhaust processing module132.

The production platform powerplant300receives fuel gas from a fuel gas storage tank302. The production platform powerplant300then burns the fuel gas in on or more gas turbines and generates electricity and steam heating for the oil and gas separation processes. The offshore jack-up installation100is electrically connected to the production platform116with electric cable122. In this way, the production platform116can supply at least some or all of the electrical energy that the offshore jack-up installation100needs to operate.

The production platform116sends flue gas to the exhaust processing module132on the offshore jack-up installation100via the ducting144.

As shown inFIG.2, the production platform116is connected to an oil and gas reserve202via a riser210and is arranged to extract fuel gas e.g. natural gas from the oil and gas reserve202. Extraction of the oil and gas using the production platform116is known and will not be discussed in any further detail.

The production platform powerplant300is in fluid connection with the exhaust processing module132as discussed in reference toFIG.1. Accordingly, the exhaust from the production platform powerplant300is sent to the exhaust processing module132. The carbon dioxide capture module134extracts carbon dioxide from the exhaust as shown in step706ofFIG.19and as previously discussed.

Once the carbon dioxide has been separated from the exhaust gas, the remaining exhaust gas can be vented into the atmosphere or further processed. For example, the exhaust processing module132may comprise one or more further modules for processing the exhaust gas. For example, the remaining exhaust gas can be passed through a scrubber (not shown) for removing SOx or NOx emissions. In some examples, the exhaust gas from the powerplant120or the production platform powerplant300can be passed through the SOx or NOx scrubber before the exhaust gas is processed by the exhaust processing module132. The SOx and NOx scrubbers are known and will not be discussed in any further detail.

The offshore jack-up installation100is further connected to the production platform116with a carbon dioxide pipe206as shown inFIGS.2and3. The output port138from the carbon dioxide processing module142is connected to the production platform116via the carbon dioxide pipe206as shown in step702inFIG.19. The carbon dioxide pipe206is arranged to receive a gaseous or liquid form of carbon dioxide from at least one output port138in fluid communication with the exhaust processing module132. The carbon dioxide pipe206can be constructed from a corrosive resistant material such as stainless steel to withstand the corrosive properties of the carbon dioxide. In this way, the production platform116can receive the separated carbon dioxide for subsequent submarine storage as shown in step708ofFIG.19.

The production platform116is in fluid connection with a carbon dioxide storage pocket200in the seabed106as shown in step704inFIG.19. The carbon dioxide storage pocket200is stable and capable of retaining the carbon dioxide pumped into it. The carbon dioxide is then stored in the carbon dioxide storage pocket200as shown in step710ofFIG.19. The production platform116is connected to the carbon dioxide storage pocket200via a carbon dioxide riser208. Similar to the carbon dioxide pipe206, the carbon dioxide riser208can be constructed from a corrosive resistant material such as stainless steel to withstand the corrosive properties of the carbon dioxide. The carbon dioxide storage pocket200comprises a well cap to ensure that the carbon dioxide is retained within the carbon dioxide storage pocket200. The well cap comprises a Christmas tree (not shown) or other suitable valve mechanism for allowing carbon dioxide to be pumped into carbon dioxide storage pocket200and retaining the carbon dioxide therein.

In some examples, the carbon dioxide storage pocket200is a saline aquifer, an active oil and gas field, and/or a depleted oil and gas field. Carbon dioxide may be permanently stored in the carbon dioxide storage pocket200. In this way, the carbon dioxide is retained and prevented from escaping into the atmosphere.

Advantageously, this means that the offshore jack-up installation100can generate all the electricity for an offshore installation and at the same time the carbon dioxide generated from the electricity generation can be captured and stored. By using an offshore jack-up installation100, the time to move and install the offshore jack-up installation100with power production and carbon capture capability is quicker. In some examples, a converted jack-up drilling rig may be used for the offshore jack-up installation100. The converted jack-up drilling rig is modified and the cantilever and drilling facilities are removed. A prefabricated powerplant120and an exhaust processing module132are then installed on the converted jack-up drilling rig which operates as discussed in reference to the Figures.

In some examples, there is a walkway (not shown) between the offshore jack-up installation100and the adjacent offshore installations116,118,130. In some examples, the walkway is wide enough to receive a forklift truck. This means that e.g. palletized equipment can be conveniently moved between the offshore jack-up installation100and the adjacent offshore installations116,118,130. This means that the main deck112of the offshore jack-up installation100can be used for extra storage space for equipment of the adjacent offshore installations116,118,130.

One example will now be discussed in reference toFIGS.4and5.FIGS.4and5respectively show a schematic representation of the offshore jack-up installation100and a close-up of the offshore jack-up installation100.

The examples as shown inFIGS.4and5are the same as the examples discussed in reference toFIGS.2and3except that the offshore jack-up installation100comprises a powerplant120for powering and heating the exhaust processing module132, the offshore jack-up installation100utilities and hotel facilities.

In some examples, the powerplant120may comprise one or more diesel generators with additional steam boilers. The powerplant120provides electrical power and heating to the exhaust processing module132. The powerplant120is in fluid communication with the exhaust processing module132. Accordingly, flue gas from exhaust from the powerplant120is sent to the exhaust processing module132.

The powerplant120operates independently from the production platform powerplant300. This means flue gas from both the powerplant120and the production platform powerplant300are sent to the exhaust processing module132.

The carbon dioxide is then captured, processed and stored as previously discussed in reference toFIGS.2and3.

One example will now be discussed in reference toFIGS.6and7.FIG.6shows a schematic diagram of an offshore jack-up installation100according to an example.FIG.7shows a schematic a close-up of the offshore jack-up installation100.

The examples as shown inFIGS.6and7are the same as the examples discussed in reference toFIGS.4and5except that the offshore jack-up installation100comprises a gas turbine powerplant120for powering and heating the exhaust processing module132.

The offshore jack-up installation100comprises a powerplant120and an exhaust processing module132as discussed in reference toFIG.1. The offshore jack-up installation100further comprises a fuel pipe204connected between the offshore jack-up installation100and the production platform116for supplying fuel (e.g. fuel gas) to the powerplant120.

The powerplant120may be an optimized high-efficiency co-generation powerplant incorporating waste heat recovery steam generation and highly integrated with the carbon capture system for achieving the optimum balance of fuel efficiency and carbon capture.

Advantageously, this is made possible by an integrated modular architecture of the powerplant120and carbon capture systems of the exhaust processing module132and the large deck112space and load-carrying capacity of the offshore jack-up platform100. This is opposed to what may usually be accommodated on a fixed installation production platform, where such systems would have to be retrofitted and installed in-between planned shut-down of the oil and gas production facilities.

The production platform116sends fuel gas to the powerplant120on the offshore jack-up installation100via the fuel pipe204. The powerplant120then burns the fuel gas and generates electricity and steam heating.

One example will now be discussed in reference toFIGS.8and9.FIGS.8and9respectively show a schematic representation of the offshore jack-up installation100and a close-up of the offshore jack-up installation100.

The examples as shown inFIGS.8and9are the same as the examples discussed in reference toFIGS.8and9, except that the offshore jack-up installation100generates excess electricity which is exported onshore.

In some examples, the offshore jack-up installation100is connected to an onshore electricity distribution grid600via a subsea cable602. Furthermore, subject to the capacity of the powerplant120, the offshore jack-up installation100could also be connected by subsea power cables and send power to multiple other production platforms and drilling rigs116,118,130further away from the offshore jack-up installation100. In this way, the offshore jack-up installation100can generate cleaner electricity for both onshore and offshore electricity demands.

Additionally, the offshore jack-up installation100in some examples is optionally arranged to receive carbon dioxide from a vessel140or from a separate pipeline612connected to an onshore source of carbon dioxide. This means that the offshore jack-up installation100can facilitate storage of carbon dioxide generated remote from the offshore installations. When the offshore jack-up installation100receives carbon dioxide from a vessel140or a pipeline, the carbon dioxide can be mixed with the processed carbon dioxide from the carbon dioxide processing module142.

Another example will now be described in reference toFIGS.10and11.FIGS.10and11respectively show a schematic diagram of an offshore jack-up installation100and a close-up schematic diagram according to another example.

FIGS.10and11are the same as shown inFIGS.9and10except that the offshore jack-up installation100supplies power to a plurality of adjacent offshore installations.FIGS.10and11optionally do not have connections to shore, but in another example, the arrangement shown inFIGS.10and11can comprise the connections to shore as discussed in reference toFIGS.8and9.

WhilstFIG.10shows a wellhead platform130, there can be any arrangement of other adjacent offshore installations. This can include any number of production platforms, wellhead platforms, drilling platforms or any other offshore installation.

FIG.1shows an example of the offshore jack-up installation100being electrically connected to the production platform116with electric cable122. The other adjacent wellhead platform130, and the offshore drilling rig118are electrically connected to the offshore jack-up installation100by electrical cables126,128. In this way, the offshore jack-up installation100can supply at least some or all of the electrical energy that the production platform116and the other adjacent offshore installations need to operate.

The wellhead platform130in some examples is connected to a carbon dioxide storage pocket200similar to the production platform116as discussed in reference toFIGS.1and2. The capture and storage of the carbon dioxide is the same as previously discussed. As mentioned above, the wellhead platform130is connected to the production platform116. The flow of carbon dioxide and/or fuel gas to and from the wellhead platform130is via the production platform116. In this way, the wellhead platform130can provide fuel gas to the offshore jack-up installation100and receive carbon dioxide from the offshore jack-up installation100via the production platform116. The production platform116controls the operation of the wellhead platform130and the flow of carbon dioxide thereto. Accordingly, one or more of the pipes and cables connecting the offshore jack-up installation100and the adjacent offshore installations116,130can be shared e.g. for fuel gas, carbon dioxide and/or electricity.

Additional floating or fixed offshore installations can be connected to the offshore jack-up installation100. For example, a drilling jack-up rig118, a semisubmersible rig (not shown) or drilling vessel (not shown) can be electrically connected to the offshore jack-up installation100.

In some examples, the separated carbon dioxide can be stored in a carbon dioxide storage pocket remote from the production platform116and the offshore jack-up installation100. In a less preferred example, the carbon dioxide can be pumped via a subsea carbon dioxide pipe (not shown) to a submerged wellhead (not shown) for the remote carbon dioxide storage pocket (not shown). However, the production platform116(and/or a wellhead platform130) is preferred as the transmission hub for any carbon dioxide being deposited underground because the infrastructure of the production platform116is more suitable for pumping carbon dioxide beneath the seabed106.

One example will now be discussed in reference toFIGS.12and13.FIGS.12and13respectively show a schematic representation of the offshore jack-up installation100and a close-up of the offshore jack-up installation100.

The examples as shown inFIGS.12and13are the same as the examples discussed in reference toFIGS.10and11, except that the offshore jack-up installation100generates excess electricity and heat to power the production platform116.

In this example, the production platform powerplant300has been permanently decommissioned, removed, or is offline for e.g. maintenance. Accordingly, the production platform116is not able to provide its own electricity or heating requirements as necessary to run the oil and gas production and export systems. Instead, the powerplant120on the offshore jack-up installation100generates both electrical power and steam for the production platform116.

The offshore jack-up installation100is connected to the production platform116via an electrical cable122as previously discussed. Furthermore, a steam duct400is connected between the offshore jack-up installation100and the production platform116.

The steam outputted from the powerplant120is pumped to the production platform116and the steam is used to heat the production equipment402. Use of steam for heating in the oil production process on a production platform116is known and will not be discussed in any further detail.

One example will now be discussed in reference toFIGS.14and15.FIGS.14and15respectively show a schematic representation of the offshore jack-up installation100and a close-up of the offshore jack-up installation100.

The examples as shown inFIGS.14and15are the same as the examples discussed in reference toFIGS.12and13, except that the offshore jack-up installation100generates excess electricity which is supplied to shore and/or to other oil and gas installations in the area.

The connections to the shore are the same as discussed in reference toFIGS.8and9.

One example will now be discussed in reference toFIG.16.FIG.16shows a close-up schematic of the offshore jack-up installation100.

The example as shown inFIGS.16is the same as the examples discussed in reference toFIGS.14and15, except that the offshore jack-up installation100comprises a modified exhaust processing module132and an air separation unit500. In this way, the offshore jack-up installation100comprises an oxyfuel combustion generator.

The air separation unit500modifies the atmosphere in which the powerplant120burns the fuel gas. The air separation unit500removes the nitrogen from the air and concentrates the oxygen content of the air. The separated nitrogen can be vented directly to the atmosphere. In some examples, the air separation unit500sends pure oxygen or a gas comprising mostly of oxygen to the powerplant120. This means that only water-steam and carbon dioxide are the by-products from the combustion of the fuel gas in the powerplant120.

Accordingly, the exhaust comprises highly concentrated carbon dioxide once the water has been condensed from the steam. This means that the carbon dioxide capture module134e.g. a scrubber is not required and purification of the carbon dioxide is easier. Instead, the exhaust comprising de-watered carbon dioxide is processed by the carbon dioxide processing module142. This is similar to the previously discussed examples. The processed carbon dioxide is then liquified and pumped for undersea storage.

The condensate water by-product may be discharged directly overboard or exported to the production platform116for injection into a dedicated water-injection well, e.g. for enhanced oil or gas recovery.

WhilstFIG.16shows electrical and carbon dioxide pipe connections to the shore, these connections are optional. The air separation unit500can be used without the shore connections.

One example will now be discussed in reference toFIG.17.FIG.17shows a close-up schematic of the offshore jack-up installation100.

The example as shown inFIGS.17is the same as the examples discussed in reference toFIGS.2and3, except that the offshore jack-up installation100generates hydrogen fuel, e.g. by a steam methane reforming (SMR) process.

Similar to the examples discussed in reference toFIGS.2and3, the production platform powerplant300sends flue gas and power to the offshore jack-up installation100.

The offshore jack-up installation100comprises a boiler800or any other suitable means for generating steam. The boiler800burns fuel gas received from the production platform116for generating the steam.

The generated steam is then sent to a steam methane reforming module802. Accordingly, the carbon dioxide is captured before the fuel (e.g. hydrogen) is burnt. At the same time, the carbon dioxide generated from the boiler800is captured by the carbon dioxide capture module134as previously discussed.

The steam methane reforming module802generates hydrogen which is stored and/or pumped onshore via a pipeline or transported by an H2tanker vessel. Accordingly, the offshore jack-up installation100can create hydrogen fuel for consumption in onshore markets whilst capturing the carbon dioxide from the generated hydrogen.

One example will now be discussed in reference toFIG.18.FIG.18shows a close-up schematic of the offshore jack-up installation100.

The example as shown inFIGS.18is the same as the examples discussed in reference toFIG.17, except that the offshore jack-up installation100comprises a powerplant120. In this example, the powerplant120provides power to the exhaust processing module132rather than the production platform powerplant300. This is similar to the powerplant120discussed in reference to e.g.FIGS.4and5.

One example will now be discussed in reference toFIG.20.FIG.20shows a close-up schematic of the offshore jack-up installation100.FIG.20is the same as the example discussed in reference toFIGS.4and5except that the offshore jack-up installation100may not be connected to an adjacent production platform116or other offshore installation for carbon dioxide injection into an undersea storage.

Instead, the carbon dioxide processing module142cryogenically pumps the liquid carbon dioxide via a riser208for direct injection into a well under the seabed below the rig. In this way, the offshore jack-up installation100is directly connected to the carbon dioxide storage pocket200in the seabed106.

In another example, the carbon dioxide processing module142cryogenically pumps the liquid carbon dioxide into a pipeline902for export to shore or to a platform further away from the offshore jack-up installation100.

In another example, the carbon dioxide processing module142cryogenically pumps the liquid carbon dioxide into a temporary storage facility900onboard the rig, until the carbon dioxide may be offloaded to a carbon dioxide tanker vessel140for export. Similar to the example described inFIGS.4and5, the powerplant120provides power and heat/steam to the exhaust processing module132.

The exhaust processing module132can be reduced in size to provide more space on the deck112of the offshore jack-up installation100. In some examples, the offshore jack-up installation100can be a drilling jack-up rig.

In other examples, the offshore installation100may be a floating rig, i.e. a drilling-semisubmersible or a drillship.

This means that the offshore drilling rig100may be a stand-alone/independent facility that can carry out drilling- and other well operations and also capture carbon from exhaust gases.

In another embodiment, two or more embodiments are combined. Features of one embodiment can be combined with features of other embodiments.

Embodiments of the present invention have been discussed with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the invention.