Liquefied natural gas production facility on a gravity-based structure

Abstract

The present invention relates to a production facility and can be used for the development of an integrated onshore and offshore liquefied natural gas (LNG) production complex on gravity-based structures. The liquefied natural gas (LNG) production complex comprises at least two gravity-based structures (GBS) 4-6, each of which houses a natural gas liquefaction production line 1-3 using a mixed refrigerant, the natural gas liquefaction production line 1-3 including a feed gas receiving and processing facility, a gas condensate stabilization facility, a gas dehydration and mercury removal facility, a wide-fraction light hydrocarbon (WFLH) extraction facility, a refrigerant treatment and compression system, and a liquefaction facility, at least one production line 1 (2, 3) on the GBS 4 (5, 6) includes a fractional distillation facility for producing mixed refrigerant components from NGLs, and at least one respective GBS 4 (5, 6) has at least one storage tank for each mixed refrigerant component. Each GBS 4 (5, 6) has at least one LNG storage tank. At least one GBS 4 (5, 6) has at least one Stable Gas Condensate (SGC) storage tank. At least one GBS has an extension 7 (8) for shipping LNG and SGC to gas carriers. At least one of the tanks for each mixed refrigerant component has a pipeline connection to the refrigerant treatment and compression system of each production line to form a single mixed refrigerant component replenishment system. At least one SGC storage tank has a pipeline connection to the condensate stabilization facility of each production line to form a single SGC storage and shipping system. The LNG storage tank has a pipeline interconnection to form a single LNG storage and shipping system. The present invention allows for the avoidance of excessive equipment duplication by developing a shared technology system for the entire complex.

Description

[Technical field]

[0001] The present invention relates to production facilities and may be used for the development of integrated onshore and offshore Liquefied Natural Gas (LNG) production complexes on gravity-based structures. [Background technology]

[0002] There are several types of onshore and offshore hydrocarbon processing plants, for example natural gas liquefaction plants (LNG plants) on floating and gravity-based foundations.

[0003] A common design is the LNG production complex, which is a floating natural gas production, processing, liquefaction, LNG storage and offloading facility. Floating installations for production, storage, and offloading of LNG (FLNG) are used for offshore gas field development and are installed directly in the offshore area using anchoring and / or moorings. Such floating installations cannot be operated in offshore locations with severe ice conditions because the drifting ice makes reliable positioning of the floating installation necessary to connect to the valves on the underwater pipes impossible, therefore floating LNG plant application is limited to offshore area development in ice-free ocean. Moreover, the production capacity of floating installations is limited by the size of the floating installation, which can only accommodate a single production line, requiring a complete set of main and auxiliary equipment to support the line operation, while at the same time limiting the critical equipment sparing options.

[0004] One example of an LNG plant on a gravity-based structure (GBS) is the Onshore LNG Production, Storage, and Shipping Plant (US 2016 / 0231050 A1, publication date: 2016 / 08 / 11), where the liquefaction equipment is installed on the top deck of the gravity-based structure, and the plant capacity can be expanded by installing additional equipment in the existing area of ​​the GBS top slab and / or by using additional process equipment mounted on their own dedicated foundation structures that rest on the seabed or on shore near the GBS that houses most of the process equipment. This design has the following disadvantages: 1. Larger size GBS to accommodate additional equipment. 2. Equipment belonging to the same production line is distributed over several locations, which means longer pipe and cable runs and more complex plant operations. 3. Equipment duplication in case of capacity expansion. 4. The equipment of individual production lines cannot be used for sparing purposes for the production complex as a whole.

[0005] The closest complex design to the proposed one would have three LNG plants on gravity-based structures (GBS), each housing an individual production line (Arctic LNG 2 Project. Environmental, Social and Health Impact Assessment. Non-Technical Overview. Ramboll Prepared by the CIS. August 2020, pp. 10-12. http: / / arcticspg.ru / %D0%A0%D0%B5%D0%B7%D1%8E%D0%BC%D0%B5%20%D0%BD%D0%B5%D1%82%D0%B5%D1%85%D0%BD%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%BE%D0%B3%D0%BE%20%D1%85%D0%B0%D1%80%D0%B0%D0%BA%D1%82%D0%B5%D1%80%D0%B0 / Arctic%20LNG%202%20NTS%20v3_final%20report_RUS_clean.pdf). The LNG plant comprises three gravity-based structures (GBS), each housing a natural gas liquefaction line utilizing a mixed refrigerant, the natural gas liquefaction line including a gas condensate stabilization facility, a mercury removal facility, an acid gas removal and dehydration facility, a wide fraction of light hydrocarbons (WFLH) extraction facility, a liquefaction facility, and a fractional distillation facility for producing the mixed refrigerant components from the WFLH, each GBS having at least one LNG storage tank and at least one stable gas condensate (SGC) storage tank, each GBS also having at least one tank for each mixed refrigerant component and LNG and SGC shipping outriggers.

[0006] A drawback of this facility is that the process equipment is tripled across the three production lines, as well as the inability to use individual line equipment as a whole for sparing of the production complex equipment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US 2016 / 0231050 A1 [Non-patent literature]

[0008] [Non-Patent Document 1] Arctic LNG2 Project. Environmental, Social and Health Impact Assessment. Non-technical Overview. Prepared by Ramboll CIS. August 2020, pages 10-12. http: / / arcticspg.ru / %D0%A0%D0%B5%D0%B7%D1%8E%D0%BC%D0%B5%20%D0%BD%D0%B5%D1%82%D0%B5%D1%85%D0%BD%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%BE%D0%B3%D0%BE%20%D1%85%D0%B0%D1%80%D0%B0%D0%BA%D1%82%D0%B5%D1%80%D0%B0 / Arctic%20LNG%202%20NTS%20v3_final%20report_RUS_clean.pdf Summary of the Invention [Problem to be solved by the invention]

[0009] The proposed invention provides a solution to the technical problem of equipment duplication in an LNG production complex with two or more production lines, each housed on a dedicated GBS. [Means for solving the problem]

[0010] The technological advances achieved by this invention allow for the avoidance of excessive equipment duplication by developing shared technology systems for the entire complex. Also, some design options for the complex allow for necessary sparing of critical systems by using equipment on one GBS to maintain the operation of production lines housed on other GBS.

[0011] The technical result is provided as a liquefied natural gas (LNG) production complex with at least two GBSs, each of which houses a natural gas liquefaction production line using a mixed refrigerant, the natural gas liquefaction production line including a feed gas receiving and processing facility, a gas condensate stabilization facility, a gas dehydration and mercury removal facility, a wide fraction light hydrocarbon (WFLH) extraction facility, a refrigerant processing and compression system, and a liquefaction facility, at least one GBS production line includes a fractional distillation facility for producing mixed refrigerant components from the WFLH, and at least one respective GBS has at least one storage tank for each mixed refrigerant component. Each GBS has at least one LNG storage tank. At least one GBS has at least one Stable Gas Condensate (SGC) storage tank. At least one GBS has an extension for shipping the LNG and SGC to a tanker.

[0012] In accordance with the present invention, at least one of the tanks for each mixed refrigerant component has a pipeline connection to the refrigerant processing and compression system of each production line to form a single mixed refrigerant component replenishment system, at least one SGC storage tank has a pipeline connection to the condensate stabilization facilities of all production lines to form a single SGC storage and shipping system, and the LNG storage tank has a pipeline interconnection to form a single LNG storage and shipping system.

[0013] The following design options exist for the complex:

[0014] The complex may comprise two GBSs, with fractional distillation equipment installed on one or each of the two production lines, and at least one of the tanks for each mixed refrigerant component installed in one or each of the two GBSs.

[0015] The complex may include at least three GBSs, with fractional distillation equipment installed on at least two production lines, and at least one of each of the tanks for each mixed refrigerant component installed in at least two respective GBSs.

[0016] In the case of a two GBS complex, at least one of the SGC storage tanks is located in one or each of the two GBS.

[0017] In the case of a complex of three or more GBS, at least one SGC storage tank will be installed in at least two of the GBS.

[0018] Moreover, in the case of a complex of three or more GBS, outriggers for shipping LNG and SGC are available on at least two of the GBS.

[0019] Each production line may be equipped with a nitrogen system including an air separation facility, a nitrogen storage tank, and a nitrogen vaporizer, with one of the production lines also having a back-up air separation facility, and the nitrogen systems having pipeline interconnections to form a single nitrogen supply system.

[0020] Each production line may be equipped with an air compressor installation, two of the production lines having a backup air compressor installation, and the air compressor installations having pipeline interconnections to form a single compressed air supply system.

[0021] Each production line may be equipped with an air dryer installation, two of the production lines having a backup air dryer installation, and the air dryer installations having pipeline interconnections to form a single dry air system.

[0022] It is preferred that each GBS has a power plant, all the power plants have cable interconnections to form a single power system, each power plant has a gas turbine generator (GTG), and two of the power plants each have a back-up GTG. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 shows the structure of the production complex on the GBS. [Diagram 2] FIG. 1 is a diagram showing the mechanism of the GBS production line as viewed from above. [Diagram 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 2 is a vertical cross-sectional view BB of FIG. [Diagram 5] FIG. 1 illustrates the mechanism of the SGC storage and shipping system. [Figure 6] FIG. 1 illustrates the mechanism for the WFLH fractional distillation and mixed refrigerant component replenishment system. [Figure 7] FIG. 1 illustrates an arrangement of an LNG storage and shipping system. [Figure 8] FIG. 1 shows a diagram of the nitrogen system mechanism. [Figure 9] FIG. 1 illustrates the mechanism of a power supply system. [Figure 10] FIG. 2 is a diagram showing the mechanism of an air compressor installation. [Figure 11] FIG. 2 shows the mechanism of an air dryer installation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] A liquefied natural gas (LNG) production complex on a gravity based structure (GBS) is a combination of process, engineering and auxiliary equipment for the production, storage and shipment of LNG and SGC. A complex may include two or more production lines on a gravity based structure (GBS).

[0025] The drawing shows an exemplary complex with three production lines 1, 2, 3, each on a dedicated GBS 4, 5, 6 (Figure 1). Each production line 1 (2, 3) with its respective GBS 4 (5, 6) is a prefabricated item made in a specialized company and then towed floating to the installation site of each production line 1 (2, 3). The production line 1 (2) on the GBS 4 (5) may have an overhang 7 (8) for shipping the product to a tanker (Figure 2). At the site, the GBSs 4-6 are installed near a dedicated wharf area on a dedicated underbase foundation 22 on the seabed (Figures 3, 4). The production lines 1-3 on the GBSs 4-6 are interconnected by piping and cabling installed on a viaduct 9, which allows the integration of the production lines 1-3 into a single production complex. Each GBS is also connected to shore by viaducts and bridges, allowing installation of the respective piping and cable installations to shore, as well as ease of access to the production complex and rapid personnel evacuation, without the aid of underwater pipelines and / or long overwater viaducts. The short distance to shore allows for simpler and cheaper integration with onshore facilities, including hydrocarbon fields, from which feedstock is supplied to the production complex.

[0026] On shore, near production lines 1-3, a high-pressure flare 10 and a common economy 11 are installed to be shared by the entire complex (Figure 1).

[0027] Each production line 1-3 is the top side (modularized process equipment) on GBS 4-6 (Fig. 2, 3 and 4). The main process equipment where the gas processing and liquefaction process sequence is completed are the inlet facility equipment 28 including the raw gas receiving and processing equipment and the gas condensate stabilization equipment, the gas dehydration equipment 29 and the mercury removal equipment 30, the WFLH extraction equipment 31 and the fractional distillation equipment 32, the gas liquefaction equipment 33, the mixed refrigerant compressor equipment 34 and 35, the boil-off gas compressor equipment 36, the fuel gas equipment 37 and the heat transfer medium system equipment 38 (Fig. 2).

[0028] The main process equipment on both sides of the GBS as well as the power plant 43, emergency diesel generators 44, nitrogen system equipment 45, air compressor equipment 46 and air dryer equipment 47 have pipelines, cable trays and bridge connections via interconnection modules 39-42.

[0029] The GBS 4-6 are three-dimensional structures made from reinforced concrete, whose function is storage for extracted and processed raw gas, as well as for auxiliary substances and materials. They form the basis of the top side (production lines 1-3) and are designed to be placed on the seabed of a body of water with the help of their own weight. The GBS central part 12 is a rectangular prism with a top slab 13 (Figures 3 and 4).

[0030] On the sides of the central portion 12 along its periphery, the GBS has protruding portions 14 with vertical outer walls. The GBS central portion 12 and the protruding portions 14 share a base slab 15, the protruding portions 14 being lower than the central portion 12.

[0031] The GBS central portion 12 is divided into compartments by vertical longitudinal and transverse walls 16. Some of the compartments, e.g., compartments 17 and 18, are used for product (LNG and SGC) storage, while other compartments, e.g., compartments 19, 20 and 21, are used for ballast water. The GBS protruding portion 14 is divided into compartments 20 along the GBS periphery by vertical walls perpendicular to the outer wall of the GBS protruding portion 14, and compartments 20 are also included in the ballast system.

[0032] The GBS top slab 13 has a reinforced concrete support 24 on which the top modules are mounted.

[0033] The GBS 4-6 are able to remain afloat during transportation on water to the site of the integrated production complex and are able to withstand the effects of ice in ice conditions. Changing the state of the GBS 4-6 from floating to stationary at the installation site on the foundation 22 is ensured by filling the ballast compartments 19, 20, 21 with water.

[0034] To prevent abrasion of the bottom below the GBSs 4-6 and the bottom of the body of water, seabed reinforcements 23, such as gabions or other similar devices, may be placed on the water bed around the GBSs 4-6 (Figure 3).

[0035] The technological processes of the GBS LNG production complex have no fundamental differences from the mixed refrigerant-based process technologies used in onshore plants. Each process production line for the liquefaction of natural gas using mixed refrigerants includes an inlet facility 28, which contains equipment for receiving and processing the feed gas and for stabilizing the gas condensate. The feed gas and condensate from the field are piped through a viaduct 9 to the inlet facility 28, where the receiving of the feed gas, pressure control, separation of the liquid condensate (hydrocarbons and water), removal of carbon dioxide, hydrogen sulfide, methanol and other impurities from the feed gas and stabilization of the gas condensate take place.

[0036] The stabilized gas condensate (SGC) is approximately 75,000 m 3 The raw material is then pumped to a storage tank with a capacity of 10 ...

[0037] The SGC storage and delivery system (FIG. 5) is common for the entire production complex, and condensate can be pumped between at least two production lines through an onshore pipeline, making it possible not to have an SGC storage tank at each GBS. If the complex comprises two GBSs, the SGC storage tank can be located in any one of the two GBSs or in both of the two GBSs. If the complex consists of at least three GBSs, the SGC storage tank is located in at least two GBSs, in this example only GBSs 4 and 5, where SGC is also sent for storage from the third production line 3, which does not have a condensate storage tank.

[0038] The treated feed gas is sent continuously to a dehydration plant 29 and a mercury removal plant 30 where mercury, moisture, and residual methanol are removed from the treated feed gas before it is sent to a wide fraction light hydrocarbon (WFLH) extraction plant 31. In the WFLH extraction plant 31, ethane, propane, butane, and NGL fractions are extracted from the treated gas before it is sent for liquefaction.

[0039] At least one production line has a WFLH fractional distillation installation 32. The ethane, propane and butane produced in said installation are used for mixed refrigerant component replenishment purposes. A mixed refrigerant component replenishment system 48 is common for the entire complex. The refrigerant components can be pumped between the production lines through an onshore pipeline. If the complex has two GBS and two production lines, the fractional distillation installation can be placed on either of the production lines or on both of the production lines. If the complex consists of at least three production lines, it is sufficient to place the fractional distillation installation on at least two of the at least three production lines. In this example, the fractional distillation installation is installed on the first and second production lines 1 and 2 (FIG. 6), where the hydrocarbons extracted from the gas are fractionally distilled, resulting in the production of ethane, propane and butane portions. The remaining stabilized heavy hydrocarbons are sent to the SGC storage tank, i.e., to the section 18.

[0040] For storing the mixed refrigerant components in at least one GBS, separate tanks 27 are provided in at least two GBSs in the case of at least three GBSs, in this example the first and second GBSs 4 and 5, at least one tank for each mixed refrigerant component is used for mixed refrigerant component replenishment in all three production lines 1 to 3, including the production line 3 that does not have a fractional distillation installation and a mixed refrigerant component storage tank (Figure 6). The WFLH extracted in the third GBS 6 is either returned to the treated gas stream to the liquefaction installation or sent to the WFLH fractional distillation installation installed in the GBS 4 or 5. If the complex has two GBSs, the tanks for each mixed refrigerant component can be located in one or two GBSs with fractional distillation installations. In the case of at least three GBSs, having fractional distillation installations and tanks for each mixed refrigerant component in at least two production lines (1 and 2) makes it possible to ensure the redundancy of this crucial equipment. All tanks 27 for each mixed refrigerant component have pipeline connections to the refrigerant processing and compression systems of each production line to form a single mixed refrigerant component replenishment system 48.

[0041] The treated gas is sent to the liquefaction facility 33, which is equipped with three coil-wound heat exchangers in series that are used to cool the gas, followed by throttling and generation of the liquefied portion (LNG) and boil-off gas. Three mixed refrigerants with different compositions are used for gas cooling in the heat exchangers, which are mixtures of nitrogen, methane, ethane, propane, and butane. The liquefied gas is sent to the LNG storage tanks 25 housed in each GBS 4-6. The LNG storage tanks 25 have pipeline interconnections to form a single LNG storage and shipping system. The LNG storage and shipping system (Figures 7, 10) is common for the entire production complex and LNG can be pumped between the tanks 25 located in the various GBSs through onshore pipelines, allowing maximum use of the total tank capacity.

[0042] Each of GBS4 to 6 is 115,000m 3 The production complex will house at least one or preferably two tanks 25 for the storage of LNG, each having a capacity of about 690,000 m. This brings the total capacity of the tanks 25 in the production complex to about 690,000 m. 3 Membrane tanks are used for LNG storage. In this case, a tank 25 consisting of a steel membrane made of stainless steel or Invar (Fe-Ni alloy), separated from the concrete structure by an insulating layer, is installed in the concrete compartment 17 (figures 3, 4). The insulating layer is placed directly on the top slab 13, the intermediate slab 26 and the GBS walls 16 and transfers the loads from the tank 25 and its LNG contents to the above-mentioned enclosure. The GBS slabs and walls thus act as support structures for the membrane tank 25, which is integrated into a single structure with the support structures. To prevent leakage, the bottom and sides of the membrane tank 25 have a secondary barrier, which is an additional membrane installed in the insulating layer.

[0043] Tanks for the storage of the mixed refrigerant component ethane have a similar membrane structure but smaller capacity. GBS 4 and 5 each have a capacity of approximately 1,200 m 3The system has one ethane tank with a capacity of 10 ...

[0044] The self-supporting tanks installed in the GBS4 and 5 compartments are used for the other mixed refrigerant components, namely butane and propane. The two GBS4 and 5 each have a capacity of 280 m 3 and one tank for the storage of butane, each with a capacity of 280 m 3 and one tank for the storage of propane, with a capacity of 1000 L / s (Figures 3 and 6).

[0045] Tanks 27 for each mixed refrigerant component are located within the GBS as close as possible to the associated process equipment where those components are used, allowing for optimization of pipeline length and mass, electrical heat tracing, and insulation.

[0046] The refrigerant is processed and compressed in mixed refrigerant compressor units 34 and 35 (FIG. 2). Each of the three mixed refrigerant loops has two parallel strings, A and B, in the form of two separate units with 50% of the full capacity. This allows the production complex to operate at 50% capacity even if half of the compressor units are shut down.

[0047] Each installation has two compressors on one shaft and on one frame. Each such pair of compressors is driven by one gas turbine driver, which reduces the number of gas turbine drivers. All drivers have the same capacity and are fully integrated, which simplifies operation and repair of all drivers.

[0048] Ethane, propane, and butane extracted from WFLH in fractional distillation facility 32 and stored in tanks 27 for replenishment in GBS1 and 2 are used to produce refrigerants. Methane replenishment is done using treated feed gas and boil-off gas. Nitrogen for refrigerant replenishment is produced in integrated nitrogen system facility 45, which includes air separation facility 49 with air purification and dehydration system, liquid nitrogen storage tank 50, and liquid nitrogen vaporizer 51 (Figure 8). Production line 1 houses integrated air separation facilities 49 in 2 x 100% configuration (one facility in operation and one facility on standby), production lines 2 and 3 are equipped with air separation facilities 49 in 1 x 100% configuration. Nitrogen production redundancy for the entire production complex is ensured by production line 1 and the ability to pump nitrogen between production lines. In addition to mixed refrigerant make-up, nitrogen is used to produce the inert medium and gas cushion, purging, compressor dry gas seals, and as a backup source of purge gas.

[0049] The boil-off gas generated in the liquefaction plant 33, the LNG storage tanks 25 and also in the cargo tanks of the gas carrier during shipment is sent to the boil-off gas compressor plant 36 for boil-off gas compression and supply. The boil-off gas is partly used for processing in the fuel gas plant 37 and is mainly consumed by the gas turbine and mixed refrigerant compressor plant in the power plant.

[0050] The power supply system is common for the whole production complex (Fig. 9). The system is based on a gas turbine power plant 43 in each production line 1-3. Each power plant 43 in production lines 1 and 2 has three gas turbine generators (GTG) 52, two in operation and one on standby, production line 3 has two GTG 52. The GTG 52 of the power plants and the turbine drivers of the mixed refrigerant compressors use integrated gas turbines, which makes the equipment easier and cheaper to operate and service. The gas turbines are equipped with facilities for recovering waste heat to be used for heating the heating medium in the heating medium system facilities 38.

[0051] An emergency diesel generator 44 serves as a standby power source. Since the power plants 43 across the three production lines are subsumed into a single power system with the aid of cables running through the viaduct 9, an N+2 generation sparing configuration is made possible.

[0052] A similar sparing principle is used for the air compressors and air dryers for which the air supply systems across the three production lines are interconnected.

[0053] On production lines 1 and 2, the air compressor installations 46 are installed in a 3 x 50% configuration (two in operation and one on standby), while the air compressor installations 46 on production line 3 are installed in a 2 x 50% configuration (Figure 10). Sparing of the air compressor installations on production line 3 is ensured by the back-up capacity of production lines 1 and 2.

[0054] An air dryer installation 47 is installed on each production line, two of the production lines also have a backup air dryer installation. On production lines 1 and 2, these installations are installed in a 3 x 50% configuration (two in operation and one on standby), and an air dryer installation is installed on production line 3 in a 2 x 50% configuration (Figure 11). Sparing of the air dryer installation 47 on production line 3 is ensured by the backup air dryer installation 47 on production lines 1 and 2. The dry air is used to increase the pressure in the gas turbine engine and to provide an air barrier for the coupling of the gas turbine driver of the mixed refrigerant compressor.

[0055] LNG is shipped to tankers for transporting liquefied gas via vents 7 and 8 installed on some production lines, for example only on production lines 1 and 2 and GBS 4 and 5 (Figure 1). The same vents 7, 8 are used for SGC shipments. The product of production line 3 is shipped at the vents of production lines 1 and 2 via the LNG and SGC storage and shipping system.

[0056] Shipping outriggers 7, 8 are structurally integrated with the GBS 4, 5 and top side. Fenders and a technical platform with loading arms, as well as other marine and process equipment enabling LNG and SGC shipping, are installed on the overhang 14 on the berthing side of the GBS. Mooring equipment for tanker berthing is installed on the berthing side of the GBS. The water area near the outriggers 7, 8 may have a seabed reinforcement 23 that protects the bottom soil from abrasion by ship propellers (Figure 3).

[0057] The production lines 1-3 are interconnected by viaducts 9 and cables and pipelines running over the dockland. The same viaducts 9 are used to connect the production complex to fields and other onshore facilities. [Explanation of symbols]

[0058] 1 Production line (GBS top side) 2 Production line (GBS top side) 3 Production line (GBS top side) 4 GBS 5 GBS 6 GBS 7. Extension for tankers 8. Extension for tankers 9. Interconnecting Viaduct 10 High Pressure Flare 11 General Economy Objects 12 GBS central part 13 Top slab of central section of GBS 14 GBS protrusion 15 GBS foundation slab 16 GBS Vertical Wall 17 LNG storage compartment 18 SGC Storage Area 19 Internal ballast compartment 20 External ballast compartment 21 Internal ballast compartment below intermediate support slab of LNG storage tank 22 GBS Underbase Foundation 23 Submarine reinforcement 24 Top support 25 LNG storage tanks 26 Support slab for LNG storage tank 27 Mixed refrigerant component storage tank 28 Entrance facilities 29 Gas dehydration equipment 30 Mercury removal equipment 31 WFLH Extraction Facility 32 Fractional distillation equipment 33 Gas liquefaction equipment 34 Mixed refrigerant compressor equipment (Line A) 35 Mixed refrigerant compressor equipment (Line B) 36 Boil-off gas compressor equipment 37 Fuel Gas Equipment 38 Heating medium system equipment 39 First Interconnection Module 40 Second Interconnection Module 41 Third Interconnection Module 42 Fourth Interconnection Module 43 Power Plant 44 Emergency diesel generator 45 Nitrogen System Equipment 46 Air Compressor Equipment 47 Air dryer equipment 48 Mixed refrigerant component replenishment system 49 Air Separation Plant 50 Nitrogen Storage Tank 51 Nitrogen vaporizer 52 Gas Turbine Generator 53 Docklands 54 Undersea 55 Water surface

Claims

1. A liquefied natural gas (LNG) production complex comprising at least two gravity-based structures (GBS), each of the at least two GBS housing a natural gas liquefaction production line using a mixed refrigerant, the natural gas liquefaction production line including feed gas receiving and processing equipment, gas condensate stabilization equipment, gas dehydration and mercury removal equipment, wide fraction light hydrocarbon (WFLH) extraction equipment, a refrigerant treatment and compression system, and liquefaction equipment; At least one GBS production line includes a fractional distillation facility for producing a mixed refrigerant component from the WFLH; at least one respective GBS having at least one storage tank for each mixed refrigerant component; Each GBS has at least one LNG storage tank; At least one GBS has at least one stable gas condensate (SGC) storage tank; In a complex, at least one GBS has an extension for LNG and SGC shipments, at least one of the tanks for each mixed refrigerant component has a pipeline connection to the refrigerant processing and compression system of each production line to form a single mixed refrigerant component replenishment system; At least one SGC storage tank has a pipeline connection to the condensate stabilization equipment of each production line to form a single SGC storage and shipping system; The LNG storage tanks have pipeline interconnections to form a single LNG storage and shipping system. Characterized in that Complex facility.

2. 2. The complex according to claim 1, characterized in that the complex comprises two GBSs, the fractional distillation installation is installed on one or each of the two production lines, and at least one tank for each mixed refrigerant component is installed in one or each of the two GBSs.

3. 2. The complex according to claim 1, characterized in that the complex comprises at least three GBSs, the fractional distillation installations are installed on at least two production lines, and at least one of each tank for each mixed refrigerant component is installed in at least two respective GBSs.

4. 2. The complex of claim 1, characterized in that said complex comprises two GBSs, and at least one SGC storage tank is installed in one or each of said two GBSs.

5. 2. The complex of claim 1, wherein the complex comprises at least three GBSs, and wherein at least one SGC storage tank is located in at least two GBSs.

6. 2. The complex of claim 1, wherein said complex comprises at least three GBSs, and said LNG and SGC shipping ports are available on at least two GBSs.

7. 2. The complex of claim 1, wherein each production line is equipped with a nitrogen system including an air separation plant, a nitrogen storage tank, and a nitrogen vaporizer, one of the production lines also having a back-up air separation plant, the nitrogen systems having pipeline interconnections to form a single nitrogen supply system.

8. 2. The complex of claim 1, wherein each production line is equipped with an air compressor installation, two of said production lines having backup air compressor installations, said air compressor installations having pipeline interconnections to form a single compressed air supply system.

9. 2. The complex of claim 1, wherein each production line is equipped with an air dryer installation, two of said production lines having backup air dryer installations, said air dryer installations having pipeline interconnections to form a single dry air system.

10. 2. The complex of claim 1, wherein each GBS houses a power plant, all said power plants having cable interconnections to form a single power system, each power plant having a Gas Turbine Generator (GTG), and two of said power plants each having a back-up GTG.

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