Subsea 7 delivered three papers in the Underwater Deep Riser Systems Session at this year’s OTC on 8 May, in Houston, USA.

The first paper is titled ‘COBRA: An uncoupled riser system for ultra deepwater in harsh environments’. Subsea 7 and Statoil present this paper on a new un-coupled riser concept, the Catenary Offset Buoyant Riser Assembly (COBRA). This consists of a catenary riser section with a long, slender buoyancy module on top which is tethered down to the seabed. COBRA is an efficient riser arrangement for host platforms with large motions, e.g. FPSO or semi-submersibles.

The second paper by Subsea 7 is on ‘High strength carbon steel and CRA lined pipe for reel-lay installation’ with Vallourec and Mannseman Tubes and BUTTING. The paper looks at the use of high strength steel, Grade X80, and the significant benefits it offers , including a reduction in pipeline weight and savings in material and fabrication costs. Similarly, reel-lay is a cost effective offshore installation method for high strength steel.

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