Warren R. True
Pipeline/Gas
Processing Editor
Efforts to move more Algerian gas to Europe have hit full stride this year.
Planning is well under way for the Maghreb Europe pipeline, a second gas line from North Africa, this time across the Strait of Gibraltar into Spain. Construction on most segments will begin this summer (Fig. 1).
Meanwhile, construction is nearly complete to double capacity on the original Trans Mediterranean gas pipeline from Algeria across the Sicily Channel to Italy.
MORE GAS FOR EUROPE
The second natural gas pipeline to be laid across a portion of the Mediterranean Sea will run 865 miles from Algeria's Hassi R'Mel gas field in the Sahara desert, across northern Morocco, through the Strait of Gibraltar to Cordoba, Spain, for connection to the Spanish gas transmission grid (Fig. 1).
Expansion could eventually take gas to Portugal, France, and Germany. Algeria's state oil company Sonatrach has signed gas-supply contracts with Portugal and Germany and extended French contracts by 15 years (OGJ, Feb. 22, 1903, Newsletter, and p. 42).
In its $1.5 billion first stage, the Maghreb Europe gas line will be able to move approximately 700 MMcfd with later added compression to expand capacity to 1.8 bcfd.
The line will be installed in four sections.
- The 530 km (330 mile), 48 in. first section will run from Hassi R'Mel, Algeria, to the Algerian border with Morocco (east of the Moroccan town of Berguent).
In August of last year, Sonatrach let a $450 million contract to Bechtel Corp., Houston, to engineer and construct the segment. The contract also calls for installation of a fiber optic telecommunication and control system along the pipeline (OGJ, Aug. 9, p. 23).
Bechtel says that the 48-in., X 70 line pipe will be supplied in three sizes: 0.500 in., 0.562 in., and 0.875 in. W.T.
Europipe Daval, Dunkerque, France, will supply 110 km (68.3 miles) of pipe in all three thicknesses (29.5 km of 0.875 in., 22.5 km of 0.562 in., and 58 km of 0.500 in.).
Also supplying 0.500 in. W.T. pipe are Siderurgica de Tubo Soldado (S.T.S.), Vitoria, Spain (180 km), Sider of Annaba, Algeria (130 km), and Anabib of Ghardaia, Algeria (130 km).
The pipe will be externally coated by 3 mm of extruded polyethylene; an epoxy resin will coat the pipe internally. It will be able to handle 70 bar (1,015 psi) of pressure at the Hassi R'Mel injection point and will free flow to the Morrocan border.
- Current plans call for a Spanish group to finance the second 335 mile section from the Algeria Morocco border to near Tangier at the Strait of Gibraltar. A Moroccan-Spanish combine will handle construction (OGJ, June 1, 1992, p. 38).
The 48 in. OD, 0.5600.810 in. W.T., Grade X 70 pipe will be supplied by Europipe (Mannesman Handel A.G.), Dusselforf, and Ilva Lamiere e Tubi, Genoa. It will be coated externally with 3 mm of polyethylene and internally with 60 mils of dry film epoxy. Cathodic protection will be by impressed current.
Metra Gaz, Casablanca, says that two compressor stations are under consideration, at the Algerian Moroccan border and close to Tangier. Total installed power at each would consist of two 32,500 hp gas turbine centrifugal compressors supplied by Cooper Rolls.
Metra Gaz expects to begin construction in June with first gas flowing at the end of 1995.
Near Tangier and the compressor station, a gas-handling terminal will also be located 20 m above mean sea level and 500 m from subsea pipeline landfall in a flat area called Dalar Er Raouli.1
- In February 1993, Omegaz, the joint venture which will own the line, awarded a contract for management, detailed design, and procurement of the 30 mile third section subsea portion of the line to a J.P. Kenny/Intecsa joint venture.
J.P. Kenny and Intecsa are engineering and design firms based, respectively, in the U.K. and Spain.
J.P. Kenny preliminarily sees the system as twin, 22-in. lines (Grade API 5L X-65). Wall thicknesses will vary according to shore (1.016 in.), shallow water (0.584 in.), or deepwater (0.788 in.). Each line will be designed to operate at 155 bar (approximately 2,250 psi).
The lines will be coated with 0.240 in. coal tar enamel corrosion coating and between 1.6 and 4.0 in. con crete coating and will be protected by a cathodic protection system. They will traverse water depths down t 388 m (1,273 ft).
J.P. Kenny says the seabed along the proposed route is generally bedrock with little or no sedimentary cover in the deeper sections. The topography is very rugged which will require extensive span rectification along the route.
Currents are complex at this location with Atlantic water flowing through the strait at higher levels and Mediterranean water flowing in an opposite direction at lower levels. Currents in both directions are particularly swift, says J.P. Kenny.
Tenders for line pipe manufacture and construction were issued in September and October with installation set for September 1994 through March 1995.
First gas flow for this segment is targeted for October 1995.
- Spain's Enagas will lay the fourth section from landfall in Spain west of Gibraltar to Cordoba. Additionally, Spain's Industry Ministry will spend $5.25 billion on the country's gas infrastructure of which $972 million are earmarked for the Maghreb Spain line (OGJ, June 1, 1992, p. 38).
Enagas reports that this portion will consist of a 158-mile (255 km), 48 in. section and a 12 mile (19 km), 36 in. section. Operating pressure will be 1,160 psi (80 bar) in API 5L Grade X 70 pipe, 0.636 in. and 0.348 in. W.T. pipe.
Major contractors on this portion of the Maghreb Europe line are Heymo ple, Mardrid, for its engineering; Mannesmann, Dusselforf, and Ilva, Genoa, for the pipe; Cirtubo, Burgos, for the coating; and Nuovo Pignone, Florence, for the line's valves (API 6D).
Engineering of the line was scheduled for completion last month, according to Enagas, as materials are being marshalled between September 1993 and December 1994.
Construction is set to begin in May with commissioning by late 1995 or January 1996.
DEMAND GROWTH
Slightly more than 10 years after commissioning of the original Trans Mediterranean gas pipeline (OGJ, Nov. 26, 1979, p. 66; Feb. 9, 1981, p. 39;), construction to double its capacity to 26 billion cu m/year (bcmy; 2.5 bcfd) from the present 12.5 bcmy began in 1992 and continues this year.
Work has progressed simultaneously in Tunisia, the Sicily Channel, Sicily, the Strait of Messina, and along the Italian peninsula (Fig. 2).
Addition of from one to three compression units after 1995 could boost capacity to 2.9 bcfd.
The expansion is in response to growth of natural-gas consumption in Italy. Since 1983 when Algerian gas began flowing through the first Trans Mediterranean gas pipeline, gas consumption in Italy has increased by 70% to exceed 50 bcmy, according to SNAM SpA, Milan, the Italian gas-transmission company.
Simultaneously, the nation wide distribution network of gas pipelines has expanded to 23,000 km (more than 14,280 miles).
Today in Italy, natural gas meets 25% of energy needs and is forecast to meet a third of energy needs by 2000, with 80 bcmy consumed.
The largest growth is in electric generation both because the increasing efficiency of the processes used makes it cheaper and because natural gas today is the cleanest source of energy available, says SNAM. In this sector consumption could reach 25 30 bcmy.
Consumption in the industrial sector is also forecast to grow.
EXPANSION WORK
Expansion of the Trans-Mediterranean pipeline consists of the laying of more than 2,200 km (1,366 miles) of new pipelines from the Algerian Tunisian border to Minerbio, Italy. Completion of the project is set for 1996.
But even by the end of 1993, the system was able to carry 7 billion cu m/year (245 bcf/year; 671 MMcfd).
The new pipeline will parallel the full length of the first one, except for the stretch crossing the Strait of Messina and the stretch between Melizzano, in Campania, and Gallese, north of Rome.
In the first case, the divergence results from the impossibility of widening the original arrival point at Favazzina. In the second case, it results from the necessity of taking the pipeline near to the storage center at San Salva, near the Adriatic Sea.
SNAM says that the considerable experience gained in building and operating the first pipeline for 10 years is being put to good use in the construction of the new line.
To provide the energy necessary to transmit the gas along the entire 2,000 km of pipeline, compressor stations already in place are being upgraded and new ones added.
Every station has a spare compression unit so that flow rates are not being decreased during maintenance work. Each unit is completely autonomous, running on gas taken from the same pipeline.
Measures are planned to reduce the environmental impact of the stations to a minimum, says SNAM.
TWO PARTS
From a technical standpoint, the new project can be divided into two parts: the landlines in Tunisia, in Sicily, and on the Italian peninsula; and the subsea stretches of the Sicily Channel and the Messina strait.
LAND SECTIONS
In the stretches on land, the new line will be 1,200 mm (48 in.) OD and from 1625.9 mm (0.640 1.04 in.) W.T., depending on demands imposed by the zones in which it will be placed, says SNAM.
State of the art techniques such as horizontal drilling, microtunnel, and vertical shaft construction, have been studied for river crossings, railway lines, motorways, and steeply inclined slopes.
SNAM says that special attention is being paid to ensure that the natural surroundings can be reconstructed when the work finishes.
- The 230 mile, 48 in. Tunisian section is more than half complete.
The 64 mile north section (Qued R'Mel to Cape Bon) and the 62 mile south section (Feriana Sbeitla) are in operation.
As of the end of summer 1993, in the 103 mile central section (Sbeitla Qued R'Mel), 56 miles of the route had been prepared for installation, 42 miles of linepipe welding had taken place, and 37.3 miles of pipe had been laid.
At the three compressor stations (Cape Bon, Feriana, and Sbikha) turbocompressors have been installed. At Sbikha, one unit began operation in early June 1993.
And at the Cape Bon station, assembly of two units was finished and firing tests completed in July 1993.
Also at Feriana, assembly of the new unit is complete.
- Basic design for the entire 900 mile, 48 in. Italian section was completed last year.
By the end of 1993, as much as 261 miles (430 km) of pipe were installed and readied for hydrostatic testing.
In December 1992, almost 180 miles (289 km) of Ene had been installed and commissioned for operation.
Excavation and assembly contracts for the remaining portions of work have been awarded and construction has begun.
Pipe (API Grade X 65) has been supplied by Europipe and Ilva: 16 in. OD x 1.02-in. W.T. The pipe has an exterior coating of polyethylene and an interior coating of epoxy. In rocky areas, a sand bed was employed in lieu of rockshield (Fig. 3).
Compressor station construction on the Italian section will be virtually complete by yearend.
At Enna, building and mechanical mounting works are under way and on schedule. Electrical installation work has been started, with the fitting of the wiring.
Last fall, Nuovo Pignone was completing the mounting of the turbocompressor (PGT 25).
At Messina and Tarsia, design has been completed and bid competition readied for the civil works while that for the mechanical mounting was prepared in fourth quarter 1993.
Building permission has been obtained; work will start July 1994.
In the compressor station in Messina, a combined cycle plant is planned which will use exhaust heat from the gas turbines to drive a 5-mw (6,500 hp) compressor with a steam turbine.
At Montessana sulla Marcellana, design of the plant was completed last year.
Construction suffered delay because of problems with the local authorities over environmental concerns, but construction is continuing, says SNAM, including hydrostatic testing of much of the pipe already laid.
Electrical instrumentation has been installed and building works are continuing.
At Melizzano, Nuovo Pignone has completed the mechanical mounting of the turbocompressor (PGT 25).
Building works and mechanical mounting were put out to tender in the final months of 1993.
At Gallese, building works and mechanical mounting for the turbocompressor are installed. Preliminary tests prior to operation are under way.
And at Terrnuova Bracciolini, the first two turbocompressors were placed in operation in March 1993. Final building works are in progress and mechanical mounting of the third turbocompressor is under way and will be operating by yearend.
In Sicily, construction of 350 km of 48 in. pipe has been planned from Mazara del Vallo (west) to Messina (east) to run adjacent the existing 48 in. line.
To date, 159 km have been laid. By the end of this year, 65 km of additional line win have been laid. Construction began in 1992 and will be complete in 1996.
MARINE SECTIONS
In the Sicily Channel, where maximum sea depth exceeds 600 m, bathymorphological surveys using both underwater and surface equipment were carried out along the new pipeline routes by visual and instrumental inspections.
Meteorological and oceanographic information was also collected to complete and integrate the same studies conducted for the laying of the first 20 in. lines more than 10 years ago.
The two new pipelines lie on average 40 50 m from the previous ones. Each line's nominal diameter is 26 in. and 0.875 1.01 in. (22.2 25.4 mm) W.T. Thicker (1.62 in. 41 mm) buckle arrestors are placed in the deepest stretches of the line.
The external anti corrosion protection is extruded lateral bank polyethylene with a minimum thickness of 3.5 mm. The internal coating is of epoxide material 60100 K thick.
In the shallower stretch, less than 250 m deep, the pipelines are weighted with gunite 40 80 mm thick to ensure stability in areas with sea currents.
The laying of the offshore section of the first of the two new 26 in. lines (the fourth and fifth lines to be laid) was completed by the Saipem Castoro Sei in January 1993 with the abandonment of the draw head 1.6 km from the coast at Cape Feto, Sicily.
In May 1993, excavation was completed for the landings, followed in May June by the laying of sections of the fourth and fifth lines and the tie in of the fourth line t its offshore section.
The hydraulic test of the fourth line was conducted from beach to beach.
Construction (pipeline laying, excavation, testing) was contracted out to Saipem and carried out to the design and under supervision of Snamprogetti.
ILVA SpA, Taranto, Italy, supplied the 22.2 mm pipes; Mannesmann, Germany, the 25.4 mm pipes; Mannesmann/E.B.K., Germany, the buckle arrestors; and Bac Bergsoe, Denmark, the anodes.
Scop, Italy, and Vetco Inspection GMBH, Germany, carried out the technical control on the supply of pipes.
Laying of the fifth line, the offshore section, Saipem Castoro Sei was under way in November December of last year and scheduled for completion by yearend.
After this, tie in of the offshore fifth line with the section already completed at the Cape Feto landing will be effected, thus completing the construction of the pipeline.
Suppliers of services and materials are the same as for the fourth line.
The fifth line is due for purging from air to gas by summer 1994.
STRAIT OF MESSINA
In the Strait of Messina, where maximum depth of the sea bed exceeds 400 m, bathymorphological and oceanographic surveys were conducted to identify the routes of the new pipelines, which do not follow that of the previous 20 in. lines laid 10 years ago.
The two new pipelines run parallel to each other an average 30 m apart.
Their nominal diameter is 26 in. with 0.875 1.1 in. W.T. (22.2 and 28.0 mm). Sections of thicker buckle suppressors are inserted in the deepest sections.
The external anti corrosion protection and gunite weighting are similar to that found on the lines in the Sicily Channel.
The laying of the two new lines was completed by Saipem's Castoro Sei in February 1993. Between March and June 1993, excavations were carried out for the coastal landings where in June the pipeline sections for each landing were laid (Fig. 4).
At the beginning of July, the tie ins for the new fourth and fifth lines were finished. These lines were subsequently successfully connected hydraulically an then dried in September an October.
Work is under way to finish reburying the landings with restoration of the sea bed's original profile.
Suppliers of the materials for the pipelines in the Strait of Messina are the same as for the Sicily Channel.
Construction was carried out by the Saipem Associazione Temporanea di Impresa Saipem A.G./E.M.C. Ltd. consortium with design and under supervision of Snamprogetti.
Work is still in progress and due to be completed by spring on the terminals: new terminals at PaLmi and at Faro Superiore.
CONTROL CENTERS
The entire pipeline and all the compressor stations will be operational by summer and remotely controlled from the dispatching center in San Donato Milanese for the Italian stretch and from the station in Cape Bon for the stretch in Tunisia.
Both dispatching centers are manned continually by specialist personnel.
Alongside the pipeline will operate a telecommunications network consisting of radio links and a fiberoptic transmission line.
Computers in both dispatching centers will continuously receive data (measurements and signals) relating to operating conditions from the stations along the pipeline. These win be compared with reference data and parameters and all anomalous conditions displayed on control monitors.
REFERENCE
- Baker, D.W., J.P. Kenny & Partners Ltd., "Pipelines across the Straits of Gibraltar," presented to the Deep Offshore Technology Conference, Monte Carlo, Nov. 8 9, 1993.
Copyright 1994 Oil & Gas Journal. All Rights Reserved.
