North Adriatic LNG Terminal

The North Adriatic LNG terminal (Isola di Porto Levante) is a major import terminal positioned off the north-east coast of Italy – 17km offshore in 30m of water – between Venice and Punta della Maestra in Rovigo.

The terminal was inaugurated in October 2009 and provides the Italian gas market with LNG supplied from RasGas II train 4 in Qatar. Italian consumption is projected to rise by 50% in the next decade.

Italy will be able to rely on the delivery of about 6.4 billion cubic metres of natural gas a year for 25 years.

The $900m terminal receives LNG ships (145,000m³ in size) nine miles offshore every three days, and regasifies and transmits gas to an onshore metering station where it enters the Italian grid.

Adriatic LNG is an Italian company set up to build and operate the platform; it is owned by affiliates of Qatar Petroleum (45%), ExxonMobil (45%) and Edison (10%). The Italian energy company Edison is 90% owned by ExxonMobil and Qatar Petroleum.

The reception terminal, which was designed to receive up to six million tonnes of LNG per year, consists of a gravity base structure (GBS), which is a type of artificial island to be installed in shallow water and is the first of its kind in the world. Due to its size, (180m x 88m x 48m) the GBS was constructed within a ‘casting basin’ or dry dock. On completion of the construction, the dock was flooded and the caisson floated to its subsequent mooring in the Adriatic Sea.

Capacity for Italian gas market

A total of 80% of the terminal capacity (4.7mta of LNG) is allocated to Edison for 25 years. Edison signed a sale and purchase agreement with RasGas II covering this commitment. The remaining 20% of capacity will be available to third-party users.

The Adriatic LNG platform is one of only two being constructed. The second platform, also an Italian project, involves the mooring of a floating storage and regasification unit (FSRU) off the coast of Livorno.

The Adriatic LNG terminal will benefit the country’s economy. It was declared of national interest by the programme drafted by the National Energy and Environment Conference, organised by ENEA on behalf of the Italian Government in 1998.

Adriatic LNG platform construction

The North Adriatic LNG project began in October 2003 and the major contractor for the GBS LNG terminal was Aker Kvaerner. Aker Kvaerner was awarded the $21m front-end engineering design (FEED) contract in January 2004. It was also awarded the contract to conduct detailed design and planning activities ($50m) in June 2004.

The concrete casing of the Adriatic LNG terminal was constructed at the Aker Kvaerner yard in an existing dry dock in Campamento in the bay of Algeciras in the south of Spain.

Arup Spain was the project manager and also undertook designing of various aspects of the infrastructure. Arup Spain entered into a framework agreement with its client Aker Kvaerner, to carry out various work activities ranging from designing the infrastructure, civil works, site supervision of the deepening of the dry dock to advising on Spanish health and safety regulations, regulatory issues and negotiation with utility companies.

Acciona, a Spanish engineering company, worked on the construction of certain aspects of the project. The GBS terminal is a concrete platform structure 180m long, 88m wide and almost 50m high. The deck of the GBS provides space for an accommodation block with 60 beds, utility systems such as power generators and 8,000t of process equipment for LNG regasification.

The structure is equipped with berthing and mooring systems for unloading LNG and can accommodate LNG carrier vessels with capacities up to 152,000m³ of LNG. Necso Madrid and Gleitz Salzburg are responsible for formwork engineering services on the platform.

Storage tanks

Hyundai Heavy Industries (HHI) of South Korea completed the construction of two large LNG storage tanks for the new Adriatic LNG gravity-based structure in mid-2006.

Each of the rectangular tanks, which are made from 9% nickel steel, weighs 4,800t and has a capacity of 250,000m³. The tanks are protected with high-resistance concrete double walls with inert materials (sand) between the walls.

Skanska Whessoe of Darlington, UK, designed the tanks and subcontracted the $110m fabrication project to HHI.

HHI is using special barges to ship the tanks, each split into six modules, to Aker Kvaener yard in southern Spain where the GBS terminal is being built. The tanks were assembled and placed within the concrete casing of the GBS terminal.

What happens to the gas?

The terminal receives only two or three tankers a week and transfers LNG into the two special tanks. The platform then regasifies the LNG as a controlled process.

After vaporisation on the terminal, the LNG is sent to shore through a 30in (76cm) diameter natural gas pipeline laid under the seabed to avoid interference with the environment and maritime activities.

The pipeline’s landfall is south of the Levante Po River mouth near Scanno Cavallari and continues underground onshore to the metering station that connects it to the national grid.

Snamprogetti, an ENI affiliate, was the contractor for the pipeline. An onshore logistics base along the Levante Po provides support for the terminal’s operations.

Offloading gas at the terminal

FMC Technologies of France was responsible for the construction of the all-metal LNG offloading system for the project. All-metal marine loading arms were designed and supplied to meet the operating requirements for LNG carriers exposed to wave conditions.

The special offshore all-metal loading system provided a viable solution for loading / unloading operations in exposed conditions without having to construct breakwaters.

Wave-induced motions of LNG carriers while at the terminal necessitate the use of a cable targeting system to ensure that operators are able to safely and reliably connect to and disconnect from the manifold flange.

The targeting system was tested in full scale during the yard erection test and it was also evaluated during the comprehensive Failure Mode Effect and Criticality Analysis (FMECA) that was conducted prior to EPC.

Upstream enhancements

Qatar Petroleum and ExxonMobil are making upstream investments associated with the project. These include a wellhead platform with an expected seven wells, pipelines, a 4.7mta LNG train at Ras Laffan City (that went onstream in February 2010) and five conventional LNG tankers to supply the new LNG terminal.