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Crossing the Black Sea

05th April 2013

While the South Stream gas pipeline will enable Russia to continue catering to Europe’s increasing gas needs, the ambitious project entails a matching technological feat – crossing the Black Sea

Crossing the Black Sea
Crossing the deep abyssal plain of the Black Sea, with a depth of up to 2,250 m will no doubt prove a technological challenge

Long used to being the big boy on the gas block, Russia, and in particular its state-owned energy giant Gazprom, the world’s largest holder of gas reserves, is now being forced to contemplate a future where it no longer maintains the upper hand in the global gas chessboard.


Shale revolution chills Gazprom

Major shale gas finds in the US and elsewhere have forced Gazprom to lower contract prices in order to stay competitive. The International Energy Agency (IEA) last year went so far as to predict in one of its reports that the push to unlock large unconventional oil and gas reserves in the US would allow it to surpass Russia as the world’s largest producer of gas by 2017.


In turn, this has allowed Europe to consider lowering its dependence on Russian gas. However, some reports say Europe’s dependence on gas is expected to increase in the next thirty years. The UK, for instance, is estimated to import 50-80 per cent of its gas needs by 2020, according to Jonathan Stern, chairman and senior research fellow at The Oxford Institute for Energy Studies.


This suggests that, in effect, Europe will remain a strategic hub for competition within the gas market. For Michael Engell-Jensen, executive director of the International Association of Oil & Gas Producers (OGP), such dominance will remain with Russia for the time being. “In my opinion, Europe will continue to rely substantially on Russian gas for the foreseeable future,” he tells OGT. But such dominance cannot be maintained without a matching network of pipeline infrastructure.


South Stream, a Russian priority

Russia’s South Stream gas pipeline is therefore of crucial importance both to Europe’s and the Kremlin’s energy security in this respect, as it will allow it to increase the flow of gas to the region’s countries.


A spokesperson for Gazprom Group’s Information Directorate tells OGT: “Europe will need an ever more pervasive network of gas transmission facilities to satisfy the growing energy demand. South Stream will contribute considerably to satisfying this need. It will provide a direct link between hydrocarbon suppliers and consumers, ensure delivery of extra gas volumes and make an invaluable contribution to enhancing European energy security.”


Gazprom and Eni own a 50 per cent and 20 per cent stake in the USD 18.25bn project, respectively, while Germany’s Wintershall and France’s EDF each own 15 per cent. Russia is expected to provide around half of the funds required to put the project on wheels.


The 900 km long and over 2 km deep South Stream will carry Russian gas to southern Europe through the Black Sea. Some 63 billion cubic meters per annum will run through the sea to Bulgaria, from where the route will go to Serbia, Hungary and Slovenia, and on to northern Italy.


But for Stern, South Stream’s potential prevalence in the European energy market is not a given. “Even if they [the parties] decide to go ahead, South Stream will not reach full volumes until 2020,” he tells OGT. Nonetheless, first gas is expected to run through South Stream by late 2015 and according to Russian estimates it could meet as much as 10 per cent of Europe’s annual gas needs by 2020.


It comes as no surprise that Russia would endeavour to cut to the chase and kick off construction of the South Stream gas pipeline last year already. Construction in Russia was initially scheduled to start in 2013 but was pushed forward to December 2012, following Turkey’s permission for the gas pipeline to be built under its waters in the Black Sea.

The challenges ahead

The sections of South Stream’s on land will be built by Gazprom in conjunction with local companies. While onshore construction in Russia began in late 2012, Gazprom estimates construction in Bulgaria to ensue only in June of this year.

South Stream Transport B.V. will be the operating company in charge of the underwater section of the gas pipeline, which will run through the Black Sea. South Stream Transport expects to start laying pipe in 2014, after receiving all of the necessary approvals from the countries involved.


Some of the world’s most challenging geographical locations where famous pipelines have been laid include the North Sea, the Mediterranean Sea, West Africa, and South America. However, crossing the deep abyssal plain of the Black Sea, with a depth of up to 2,250 m will no doubt prove a technological challenge for the parties involved, a challenge perhaps only matched by Blue Stream, the Russia-Turkey pipeline built between 2001-2002 through the same area. In addition, countries looking to expand their energy infrastructure networks in order to feed increasing demand at home will no doubt draw insight from the obstacles overcome in the South Stream project.


Firstly among the list of challenges in building a pipeline across the Black Sea is both the laying of the pipes themselves and the choice of appropriate pipe-laying vessels. The latter have been identified by South Stream Transport as special ultra-deepwater (UDW) vessels.


“Since the Black Sea is up to 2,250 metres deep, special ultra-deepwater (UDW) vessels with dynamic positioning to lay the gas pipelines will be needed,” the company says. “Conventional anchor vessels cannot lay pipes in such an environment, making the availability and selection of the right UDW vessels absolutely crucial.”


Secondly – and perhaps the biggest game-changer in the underwater section of the South Stream project –, the proposed plan envisages a combination of pipe diameter and water depth never before achieved in the global oil and gas industry. The current industry benchmark for pipe diameter-water depth correlation is set at 24 in. for depths of up to 2,150 m or 32 in. to up to 1,400 m. South Stream is considering laying pipes of 32 in. at a record breaking depth of 2,250 m, as the introduction of a 32 in. instead of a 24 in. pipe allows for roughly double the gas throughput.


For large diameter pipeline projects, wall thickness design is of the utmost importance. In South Stream, the planned wall thickness is 39 mm which, coupled with the desired 32 in. of diameter, will allow for only two possible pipe manufacturing processes: JCOE and UOE. In the former, pipe plates are formed to a J-shape through a pressed module, and then to a C-shape until the plate acquires an O-shape, after which the pipe is subject to a process of cold expansion. In UOE, cold expansion follows a process in which the plate is formed into U-shape and O-shape using a pressed module.


Furthermore, these ambitious pipe specifications will have to withstand the risk of pipeline spanning and geohazards, risks which are significant when considering the rugged and steep continental slopes leading into the deep-waters of the Black Sea.  

Pipeline spanning occurs when actual span lengths exceed the allowable length, which may result in pipeline damage. This can be corrected through subsea intervention methods such as shoulder shaving and support placements.


Geohazards consist of natural seabed characteristics which jeopardise the overall integrity of subsea pipelines through unstable slopes, faults, mudflows, gas-expulsions and other relevant features which require extensive survey and engineering.  A feasibility survey on the proposed pipeline has identified earthquake-induced slope stability and mass gravity flows as the major risks faced on the eastern and western continental slopes of the Black Sea.


The above are simply some of the obstacles which South Stream will face during its development. From the use of an ambitious pipe diameter at never before attempted water depths, the choice of wall thickness design as well as adequate pipe lay vessels on to having to overcome harsh seabed conditions and aggressive subsea environments – all parties will have to consider the best options and technologies as well as the Black Sea’s geological constraints through detailed project planning, surveying and engineering.

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