Medgaz: Pipeline Construction • Minimised Spanning; And, • Minimised Locations of High Stress and Potential Upheaval Initiators
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ProJects ProJects The reception terminal in Almería. • Ensured pipelay feasibility by both S- and J-lay vessels; Medgaz: pipeline construction • Minimised spanning; and, • Minimised locations of high stress and potential upheaval initiators. in the ultra deep Intec contracted US-based company D’Appolonia to carry out the geohazard Challenging seabed topography, pipelay depths reaching 2,155 m below water level and deep water evaluation for the Medgaz Pipeline. cable crossings were just some of the obstacles successfully navigated by the team of engineers and D’Appolonia says that the primary pipeline construction workers on the Medgaz Pipeline. technical issues associated with the project were: • Seismic hazards; • Fault rupture hazards; and, he 24 inch diameter, 210 km Medgaz group of major multinational companies • Landslide risks. Pipeline commenced transporting gas that comprise of Iberdrola, Endesa, and The work undertaken by D’Appolonia Tfrom the Algerian port of Beni Saf to a GDF Suez. provided the basis for selection of a route landing point near Almeria on Spain’s coast In the years between the initial that minimised geohazard risk, particularly in March 2011. feasibility and the renewed interest in in continental shelf break slope areas. The pipeline, which has the capacity the project, more advanced engineering Residual geohazard risks were determined Offshore gas pipeline pre-commissioning tests in Beni Saf. to transport 8 Bcm/a of gas, is supplied technologies had been developed, making to be at acceptable levels for pipeline with gas from the Hassi R’mel field in it possible to execute the sophisticated construction and operation. Algeria, through a 547 km, 48 inch diameter work required to successfully complete the Following the completion of FEED in pipeline which was constructed as part of project. Design ensure an optimised and safe design for 2004, the offshore route length was the project. In Spain, a 48 inch diameter In 2001, CEPSA and Sonatrach formed The Saipem 7000 arrives at the port of Almeria. In June 2003, Intec Engineering (now Medgaz. 197.65 km. Approximately 49 per cent of the pipeline connects Medgaz to the Spanish MEDGAZ S.A to design, construct and Intecsea) was awarded the contract to Intec said that issues specific to the pipeline was to be constructed at depths gas network. operate the Medgaz Pipeline. perform front-end engineering and design Medgaz Pipeline included geohazards greater than 1,000 m, with the maximum The idea of building a direct gas pipeline named C-Surveyor I, which operated (FEED) for the pipeline. Intec’s scope of associated with steep continental shelf water depth reaching 2,155 km. The design between Algeria and Europe arose in the Survey and mapping totally autonomously, without any physical work for the contract included the design margins and the bio-diverse coastal areas of included 17 pipeline curves and five 1970s. Feasibility studies were conducted In 2002 the first marine survey was connection to the parent ship, carrying out and engineering of the offshore pipeline, Spain and Algeria, both of which cater for in-service cable crossings, which were all at that time, however technical limitations completed by C&C Inc. This survey was its 50-hour missions 40 m above the seabed. the shore approaches and the short onshore fishing and tourism industries. greater than 1,000 m in length. prevented the construction and operation of conducted to seek a suitable pipeline After successfully completing this pipeline sections to the onshore terminals Intec was required to provide a Intec’s pipeline design included a a gas pipeline in ultra-deep waters. corridor between Algeria and Spain. The phase, which required overcoming a at either end of the trunkline. design that: crossing of the Yusuf Fault at kilometre More than two decades later, Spain’s two survey vessels, Odin Finder and Rig number of geological obstacles in record- Intec built on lessons learned from its • Minimised environmental impact; point (KP) 74 and also required construction growing demand for natural gas combined Supporter, used the most current seabed breaking water depths exceeding work on the Bluestream and Mardi Gras • Minimised pipeline route length; across a number of steep slopes (up to with its own limited indigenous petroleum mapping technologies at the time including 2,100 m, a suitable pipeline corridor was deep water pipelines, capturing relevant • Avoided seabed obstructions; 14˚) between KP 71 and KP 77. resources prompted CEPSA and Sonatrach the most modern multi-beam equipment found crossing the Alborán Sea area in the experience of pipeline design, fabrication • Avoided geohazards; to reassess the project in association with a mounted on an unmanned submarine Western Mediterranean. and installation in ultra-deepwater to • Minimised the number of crossings; ConTinued on page 34 ›› 32 PiPelines international | JUne 2011 PiPelines international | JUne 2011 33.