Pipe technology and installation equipment for frontier deep water projects

摘要

Project perspectives in new offshore districts are targeting water depths of 3000-4500 m in open ocean. Field development is often located in the proximity, not far from the toe of the continental slopes. In many circumstances the preferred option for exporting the products is the subsea pipeline, routed across the complex features of the continental slopes. Export pipelines from such fields are therefore large diameter pipes with thick walls to meet deep water strength criteria. Current projects show that material and linepipe technology are at the upper bound of what can be produced within the stringent criteria imposed by the application. Installation implies heavy lay spans that require large vessels as well as high capacity handling and pipe lay equipment. Specific upgrading of existing lay vessels cannot exceed certain limits and proven technology as high strength steel wire cables cannot implicitly provide adequate answers to the needs. Further, in case of huge fields, the development is progressive and the early pipelines include In-Line Structures that allow to accomodate future links to adjacent fields. The challenge is to lay along routes where features and bottom roughness require careful procedures to meet the established targets e.g. specific location of subsea structures in relation to pipeline alignment and their verticality.