Deepwater Pipelines Installation Risks and Challenges

Abstract

With the advent of next cycle of stabilization and steady increment of oil and gas prices, the deepwater blocks which were marginalized due to high development cost, are beginning to appear as a lucrative proposition again. Globally new oil and gas production is focused in remote locations which are also challenging to operate. Deepwater, ultra-deepwater, tight oil and shale gas are great examples of this. In last two decades, exploration & production players have made rapid progress in pushing the depth of subsea production. The on-going development of new hydrocarbon discoveries in different deepwater regions creates significant opportunities for the pipeline industry. Also, the need of the ‘oil & gas markets’ to get well connected with the ‘oil & gas producers’ is leading its way to the announcements of long distance deepwater pipelines in a record water depth of up to 3500 m in the recent past. Gearing up for this challenge, this paper broadly elucidates the deepwater pipeline installation risks and challenges, such as selection of the line pipe to sustain high external over-pressure and tensile stresses generated due to installation forces, selection of external coating system, capability requirement of installation vessels with high tensioner capacity to hold the long catenary of thick-walled pipe, pipeline configuration control and prevention against accidental flooding while laying, challenges in touch-down point monitoring and buckle detection, seabed intervention requirement & methodologies and new evolving testing & commissioning philosophies required for ensuring the integrity of the deepwater pipelines after installation. This paper also covers the findings of installation analysis, for S-lay configuration, performed for deepwater pipelines with varying water depths. This paper intends to bring awareness among the "oil and gas fraternity" regarding challenges involved in ultra-deepwater pipelines and discusses the technical advancements made in this segment and the need of further works for bringing the installation of pipelines in ultra-deepwater one step closer.