The Greece–Italy Interconnector (IGI) will consist of a new 210 km offshore pipeline that will connect the Greek and Italian natural gas transportation systems, and a 590 km pipeline to be constructed onshore in Greece. It is designed to ultimately form part of the Interconnection Turkey–Greece–Italy (ITGI) pipeline project, which will allow Italy and the rest of Europe to import natural gas from the Caspian Sea and the Middle East.

The offshore section of the IGI, known as the Poseidon project, will complete the natural gas corridor through Turkey, Greece and Italy following the inauguration of the 296 km Turkey – Greece Pipeline in 2007.

The 590 km onshore section of the IGI that remains to be implemented in Greece will be constructed by Greece’s public gas corporation, DEPA subsidiary The Hellenic Gas Transmission System Operator (DESFA), and will run from Komotini to the IGI Poseidon metering station in Thesprotia.

The 42 inch diameter pipeline will have a capacity of 15 Bcm/a of gas and will include the construction of three compressor stations at Kipi, Komotini, and at Nea Mesimbria, Thessaloniki.

DEPA and Edison have entered discussions with natural gas suppliers in the Caspian area, and specifically in Azerbaijan, for the supply that will be transmitted through the pipeline system.

Onshore design

Penspen is providing the basic engineering design for the onshore section of the pipeline including pipeline, compressor stations, metering/regulation stations and the SCADA system.

The scope of works includes:

• 590 km of 42 inch diameter high-pressure gas pipeline from Komotini in Eastern Greece to Variko where the pipeline ties in to the offshore section of the IGI project;
• Valve and scraper stations;
• Three compressor stations initially at Kipi, Komotini and Nea Messimvria;
• Two metering/regulating stations to supply gas to the existing natural gas transmission system at Komotini and Nea Messimvria;
• A dedicated SCADA/control and telecommunications facilities for the new pipeline system; and,
• Latest technology security and access control systems for all facilities.

The design documents for the four discrete elements of the project have now been issued and the project, which is progressing according to schedule, is due to be completed in the last quarter of 2011.

In terms of technical challenges on the project, Penspen said “The length of the pipeline and the various different types of terrain do need to be taken into account, but specialists have conducted surveys of the various pipeline routing options and the optimum proposed route has been identified, avoiding natural reserves and protected areas.”

Offshore survey

The detailed marine survey contract has been awarded to Fugro Geoconsulting. The surveying services are required for the identification of a feasible seabed pipeline route between the Greek and Italian landfall points and production of alignment drawing sheets covering a survey corridor along the route.

Survey requirements include hydrographic, geophysical, and geotechnical surveys to provide an accurate digital terrain model, seabed mapping, and sub-seabed information to support the pipeline's design and installation.

The proposed route is approximately 200 km in length, of which approximately 70 per cent is in water greater than 150 m and 40 per cent is in water depths greater than 1,000 m, while the maximum depth along the route reaches nearly 1,400 m. Two steep continental slopes exist between the Greek and Italian continental shelves, and these and the deepwater area in the centre of the route, will require detailed geohazard assessment.

Fugro will be responsible for permitting, safety, access, environmental matters, and operational control of the entire services. The offshore survey will be completed using a deepwater survey vessel equipped with the appropriate specialist equipment required for deep-water survey, cable crossing surveys and other special surveys. Specialist geotechnical equipment for seabed sampling and coring will be required with laboratory testing of samples to be carried out on completion of data collection. High-resolution seismic data acquisition for geohazard purposes will also be required.

The nearshore surveys, which are typically carried out between the landfalls and 20 m water depth, will require a specialist nearshore survey vessel as well as a shallow-water geotechnical drilling rig. Topographical, geophysical and geotechnical survey will also be required onshore in the vicinity of each landfall.

Construction on the IGI is scheduled to begin in 2012 and it is anticipated that the pipeline will be brought online mid-2015.