DESIGN AND CONSTRUCTION OF GRAVITY BASED …

1 Paper PS6-7 AND CONSTRUCTION OF GRAVITY BASED structure AND modularized LNG TANKS FOR THE ADRIATIC LNG TERMINAL Lisa B. Waters Project Manager Terminale GNL Adriatico Srl Chuck V. Mueller GBS DESIGN Site Manager Paul C. Hellen LNG Tank DESIGN Site Lead Gary L. Hurst GBS Engineering Lead ExxonMobil Development Company ABSTRACT CONSTRUCTION is under way on the world s first offshore LNG storage and re-gasification terminal, to be installed and operated in the Northern Adriatic Sea, about 17 kilometers east of Porto Levante, Italy. The Adriatic LNG (ALNG) Terminal is designed to deliver 8 billion standard cubic meters of gas into the Italian gas grid via a 30" pipeline to shore. Start-up of the terminal is targeted for 2008. The terminal is a large GRAVITY BASED structure (GBS), housing two steel LNG storage tanks and a topsides re-gasification facility. The overall dimensions of the GBS are 180m long, 88m wide, and 47m high, resting on the seabed at 29m mean sea level.

2 The two 9% Nickel (9%Ni) steel LNG storage tanks each measure 155m long, 33m wide, and 28m high. Each tank weighs approximately 4500mt; the constructed weight of the terminal will be approximately 290,000mt. This paper summarizes key aspects of the DESIGN and CONSTRUCTION of the concrete GBS and modularized LNG storage tanks, whose CONSTRUCTION were both initiated in early 2005. It will discuss some of the unique engineering aspects associated with the facility s global DESIGN , including: The seismic and metocean considerations that govern the terminal DESIGN . The DESIGN of the first-of-a-kind 125,000 cubic meter modularized storage tanks, and the engineering challenges associated with their installation and operation inside a confined GBS structure . The CONSTRUCTION of the concrete GBS in Algeciras, Spain, and how this relatively undeveloped site was converted to support the CONSTRUCTION of a 250,000mt concrete structure , the integration of two 10,000mt LNG tanks and 20,000mt topsides facilities, and marine operations required to initiate transportation of the completed facility to the Adriatic.

3 The unique challenges of the fabrication of the 9%Ni LNG tanks in Ulsan, Korea, and their transportation to the Algeciras site. Paper PS6-7 The Adriatic LNG (ALNG) Terminal is an offshore LNG storage and re-gasification terminal under development by Terminale GNL Adriatico Srl, an Italian company owned by Qatar Petroleum, ExxonMobil, and Edison. The ALNG Terminal is now under CONSTRUCTION and, in 2008, will be installed in the Northern Adriatic Sea, about 17 kilometers east of Porto Levante, Italy. The terminal is designed to deliver an annual average of billion standard cubic meters of gas. Gas will be delivered to shore via a 30" pipeline which will be tied into the Italian gas grid. A computer rendering of the ALNG Terminal is shown in Figure 1. Eighty percent (80%) of the terminal capacity is reserved for supply of LNG into Italy from Qatar s North Field. Ras Laffan Liquefied Natural Gas Company Ltd.

4 (II), (RasGas), a joint venture between Qatar Petroleum and ExxonMobil, will supply the LNG from its facilities under a 25-year Sales and Purchase Agreement (SPA). The remaining twenty percent (20%) of terminal capacity is available for third party supplies. Start-up of the terminal is targeted for 2008. The ALNG Terminal will establish a number of industry "firsts" including: First offshore LNG import terminal First concrete " GRAVITY BASED structure " (GBS) used as an LNG terminal First application of proprietary Modular LNG storage tank technology First application of specially adapted LNG offloading arms designed to improve operability in more exposed metocean conditions Figure 1. Adriatic LNG Terminal Paper PS6-7 TERMINAL DESCRIPTION The ALNG Terminal is a unique facility utilizing innovative technology to provide a safe and efficient offshore LNG offloading, storage, and re-gasification capability. The terminal is a large GRAVITY BASED structure (GBS) resting on the seabed at 29 meters mean sea level.

5 The structure is 180 meters long by 88 meters wide, with a height of about 47 meters. Approximately 90,000 cubic meters of concrete will be required to build the GBS. Constructed weight of the facility is approximately 290,000mt; the installed weight after adding solid ballast at the installation site is over 640,000mt. The GBS will contain two LNG storage tanks with a total working capacity of 250,000 cubic meters, approximately twice the capacity of a conventional LNG carrier. The recently developed Modular LNG (MLNG) tank technology is being used to enable the tanks to be constructed in parallel with the GBS structure , while meeting all required safety and performance standards. Approximately 20,000 mt of topsides and mooring facilities will be installed directly on the GBS structure . Major process equipment will include four in-tank LNG pumps, five high-pressure send-out pumps, four Open Rack Vaporizers (ORV's) which use seawater as the heating medium, a Waste Heat Recovery LNG Vaporizer (WHRV) which uses waste heat from the turbine generators, and two Boil Off Gas (BOG) compressors.

6 One of the in-tank LNG pumps, one high-pressure LNG pump, and one ORV serve as spare equipment. Three gas turbine generators will provide approximately Mega Watts (MW) of electric power. Living quarters will be provided on the terminal for up to 60 people. Figure 2 depicts the DESIGN of the Topsides facilities. Maintenance BuildingLiving QuartersElectrical & InstrumentBuilding (EIB)Power Generation & Heat RecoveryOpen Rack Vaporizers (ORV)& HP Sendout PumpsBoil-off Gas CompressorsLoading Platform w/ Loading ArmsConcrete / GBS Mooring DolphinsBerthingStructuresMaintenance BuildingLiving QuartersElectrical & InstrumentBuilding (EIB)Power Generation & Heat RecoveryOpen Rack Vaporizers (ORV)& HP Sendout PumpsBoil-off Gas CompressorsLoading Platform w/ Loading ArmsConcrete / GBS Mooring DolphinsBerthingStructures Figure 2. Topsides Layout of ALNG Terminal Paper PS6-7 facilities will accommodate a variety of modern LNG carrier sizes. Unloading of an LNG carrier will occur approximately once every three days in order to sustain continuous operation of the terminal.

7 Tanker berthing will be limited to daylight hours, but cargo unloading can continue throughout the night. Total turnaround time for the large tankers is 18 - 24 hours. Tanker mooring is accomplished through the use of mooring hooks installed on the GBS terminal and two 10,000mt concrete mooring dolphins installed on either end of the terminal. A 30-inch diameter, 40-km long pipeline (15 km sea line, 10 km wetlands, 15 km onshore/farmland) will transport gas to shore and onward to a metering station at Cavarzere. As a separate project and investment, Edison will build a new 84-km section of pipeline from Cavarzere to Minerbio for delivery of the gas to the Italian grid. Figure 3. ALNG Terminal Location and Pipeline Route ALNG TERMINAL PROJECT EXECUTION SUMMARY The concrete GBS is being constructed in a large casting basin at the Campamento site near Algeciras, Spain. Installation, hook-up, mechanical completion, and commissioning of the LNG tanks and the topsides equipment will also occur in the casting basin.

8 Once this is all accomplished, the casting basin will be flooded and the bund wall removed thereby enabling the completed terminal to be floated out and towed to the final installation site, approximately 1700 nautical miles away. MINERBIOMETER STATION @ CAVARZEREPORTO VIROSEA LINELANDFALLMINERBIOALNG TERMINALMETER STATION @ CAVARZEREPORTO VIROSEA LINELANDFALLP aper PS6-7 installation at site the terminal will initially be re-ballasted with water to provide sufficient foundation stability for a seasonal storm (10-year return period). Moderate underbase suction will be established temporarily through a number of filters installed in the base slab. Then, terminal on bottom weight of the terminal will be increased by replacing the water with a slurry of 350,000 mt of solid ballast material. Once this is accomplished, the terminal will have sufficient on-bottom weight to provide foundation stability for 100-year storm conditions.

9 Once ballasting and final on-site commissioning are completed, cool-down of the tanks will commence, with the introduction of the first load of LNG from a berthed carrier. Upon completion of the cooldown, the ALNG terminal will be able to re-gasify LNG stored in its tanks and export the gas to shore via pipeline. While the major concrete CONSTRUCTION work and the integration and completion of the ALNG terminal are being done in Spain, components of the terminal are being engineered, procured, and fabricated in other part of Spain and countries throughout the world, including Korea, the United States, Canada and Europe. Figure 4. Worldwide Project Locations 9% Ni PlateBelgiumProject HeadquartersMilan, Italy External Affairs Regulatory Commercial Project Management OperationsTopsides FabricationCadiz, SpainTopsidesHouston, TX Engineering ProcurementGBS CONSTRUCTION SiteAlgeciras, Spain LNG Tanks Integration Topsides Integration Mechanical Completion CommissioningLNG TerminalAdriatic Sea Installation Commissioning Start-up OperationsRasGasDoha, QatarLNG SupplyLNG TanksDarlington, UK Engineering ProcurementLNG TanksVancouver, BC Structural DESIGN Transportation AnalysisSunnyvale, CA Structural AnalysisGBS & Mooring DolphinsOslo, Norway Engineering ProcurementPipelineFano, Italy Engineering Procurement CONSTRUCTION Mgmt.

10 CommissioningMooring DolphinsVenice, Italy ConstructionLNG Tank FabricationUlsan, South Korea9% Ni PlateBelgiumProject HeadquartersMilan, Italy External Affairs Regulatory Commercial Project Management OperationsTopsides FabricationCadiz, SpainTopsidesHouston, TX Engineering ProcurementGBS CONSTRUCTION SiteAlgeciras, Spain LNG Tanks Integration Topsides Integration Mechanical Completion CommissioningLNG TerminalAdriatic Sea Installation Commissioning Start-up OperationsRasGasDoha, QatarLNG SupplyLNG TanksDarlington, UK Engineering ProcurementLNG TanksVancouver, BC Structural DESIGN Transportation AnalysisSunnyvale, CA Structural AnalysisGBS & Mooring DolphinsOslo, Norway Engineering ProcurementPipelineFano, Italy Engineering Procurement CONSTRUCTION Mgmt. CommissioningMooring DolphinsVenice, Italy ConstructionLNG Tank FabricationUlsan, South KoreaPaper PS6-7 , SAFETY AND ENVIRONMENT (HSE) Commitment The Adriatic LNG Project is committed to delivering a safe, reliable and operable facility at minimum cost through simple and effective DESIGN .