Constructing the World's Longest Subsea Pipeline, Langeled Gas Export

Abstract

Abstract Langeled is part of the development of the Ormen Lange Gas field, operated by Hydro in the development phase and by Norske Shell in the operating phase. At plateau level, the Ormen Lange field will produce around 20 billion Sm3 gas per year, which is equivalent to 20 % of UK gas demand at the time of start-up of the gas deliveries. The gas will be transported through the world's longest subsea pipeline over a distance of nearly 1200 kilometers, from Nyhamna on the west coast of Norway, via the Sleipner field in the North Sea, to Easington in the UK. The Langeled project was developed by Statoil on behalf of the operator, Hydro, using personnel from both companies. This paper covers the main technical, organizational and logistical challenges faced in developing the project. Key conceptual tasks, the massive construction task involving two of the world's largest pipe-laying vessels over two seasons; the logistics of producing, coating and transporting 100,000 pipe joints, the challenging riser installation and modification works on the Sleipner field and finally, the landfall and terminal construction in Easington UK are described. Introduction Ormen Lange is a large gas field located 120 km off the west coast of mid-Norway. The field has been developed with two subsea templates and with two 30" flowlines to shore at Nyhamna, where a gas treatment facility is being built. Hydro is the development operator, while Norske Shell will operate the field and the plant in the future. As part of the Ormen Lange development, a dedicated large diameter export pipeline, called Langeled, has been installed to transport dry gas from Nyhamna to the east coast of England in order to supply gas to the UK market. The Langeled development project has been managed by Statoil on behalf of Hydro. Gassco, operating all the main gas export pipelines from the Norwegian continental Shelf, on behalf of the owners, is taking over the operator ship of Langeled in the operational phase. This was effective from September 1st 2006, when the Langeled South became operational. Langeled is a 1200 km long pipeline from Nyhamna to Easington on the east coast of England, which is tied into the Sleipner field about midway across the North Sea. The northern half consists of a 42" diameter 250/215 bar pipeline, whilst the southern half from Sleipner to the UK comprises a 44" diameter 157 bar pipeline. This paper will highlight the main challenges of the project;system description and concept selectionlandfall in UKright of wayenvironmental challengesexecution and market strategyconstruction and marine operationsmodifications and tie-in to Sleipnertie-in, testing and Ready for Operation (RFO) activitiessafety during the construction phase System description and concept selection. Market considerations. The main driver for the concept selection of a gas field development is the market considerations. In case of Ormen Lange, several possible market scenarios and locations were evaluated.