The Gulf of Mexico (GOM) has gone through many waves of exploration and development, each time reinventing and pushing the boundaries. Finally, the realization of crossing boundaries and combining United States and Mexico GOM into "One GOM" commercially and technically is within reach. One GOM resource base - discovered remaining to be produced and prospective - is reaching 50 billion barrels of oil equivalent (BBOE). New plays in the U.S. GOM and the opening of the Mexican GOM, coupled with innovative technological and commercial models and increasing interest from the investment community, are poised to drive value and keep this resource base and production growing further. This manuscript sets the stage for the panel discussion scheduled for 9.30am to 12.00pm, Thursday, May 3, 2018 at the Offshore Technology Conference (OTC). The panelists are oil company executives representing small to large independents and integrated oil companies along with service providers as follows: Tim Duncan, President and CEO, Talos Energy LLC Bjorn Inge Braathen, SVP Exploration, Statoil Niall McCormack, Vice President Exploration, BHP Billiton Petroleum Martin Stauble, Vice President Exploration, Shell Lorna Campbell, Mexico Exploration Manager, ExxonMobil Mark Cizek, Vice President, Williams Stein Rasmussen, Chief Strategy Officer, SBM Offshore Sandeep Khurana, Sr. Manager, Granherne (A KBR Company) and Julie Wilson, Director, Wood Mackenzie

Corus Tubes was the sole supplier of 457mm (18 inch) linepipe for the Williams Perdido Norte project. At 2514msw Perdido is one of the deepest large diameter export pipelines in the world. The depth of the pipeline coupled with the severely undulating seabed bathymetry, made it one of the most challenging projects completed to date. In total, 312.3km of 457mm (18 inch) outside diameter linepipe was delivered in thicknesses ranging from 19.1mm to 27.0mm; dimensions well beyond the production capabilities of most UOE mills. The characteristics of the UOE process are described below. At its UOE pipe mill in Hartlepool, UK, Corus Tubes has over 15 years of experience in deepwater pipe manufacturing technology. During the Perdido Norte contract, this experience enabled the manufacture of pipe to the highest quality. For the pipeline to be installed, survive and perform at 2514msw Corus Tubes worked closely with Williams to ensure that the pipe was manufactured with the optimum properties for the installation and operational conditions. The resulting pipe product exceeded its specified requirements in terms of dimensional control and mechanical properties. Pipe of this quality, apart from ensuring deepwater integrity, helps realise tangible benefits during the installation phase by offering a high level of product consistency that facilitates welding. Despite demanding offshore welding defect acceptance criteria, pipeline fabrication was successfully completed with very low levels of repair, attributable in part to the quality of the pipe produced. This paper documents the factors that led to the successful design and supply of the Perdido Norte linepipe. Corus Tubes' technical achievements will be described in detail from collaboration in terms of pipe specification, through plate selection and supply, to eventual pipe manufacture and delivery. Furthermore, this paper concludes with a summary by Williams of how the pipe performed during installation and finally offers a joint vision of future challenges and advances that will drive pipeline technology into ever-deeper waters. Introduction In 2002, a major oil and gas discovery was made at the Great White Field in the Gulf of Mexico. The discovery, located about 350 km south of Galveston, Texas in the Alaminos Canyon Block 857 had water depths of over 2514m (Figure 1). The partners in the field held interests in several surrounding blocks in water depths up to 2895m. The decision was made to utilise a common floating production facility, the Perdido Regional Development Host, and to export the oil and gas through a pipeline network. Williams contracted with the oil operating company to build and operate the Perdido Norte oil and gas export pipelines. Both deepwater export pipelines were to be based on a 457mm (18 inches) diameter UOE design. Gas export from the Perdido Regional Development Host was to be via a 168km line to tie into Williams existing Seahawk gas gathering system, allowing transportation of approximately 265 million cubic feet per day. Heavier hydrocarbon products would be exported via a 120km oil line to tie into Exxon Mobil's Hoover Offshore Oil Pipeline System (HOOPS).

The majority of Spar hulls have been fabricated overseas on skid ways and transported stateside for quayside offloading using submersible Heavy Lift Vessels. For the Williams Gulfstar 1 FPS (GS1) Floating Production System (FPS) we elected to construct the hull in a graving dock and tow it directly to the installation site. This paper will describe the unique fabrication and installation techniques that were used to build a classic Spar hull within a graving dock, rather than using the traditional skid way and overseas-transport approach. It will also describe the GS1 hull installation campaign including tow to site, upending, and hull and mooring installation. The overall fabrication approach for the GS1 hull was a stateside program utilizing Gulf of Mexico fabricators. The fabrication portion of the paper will focus on the construction methodology for the hull, including the lessons learned incorporated into the design before the start of construction, as well as those realized during construction that were implemented at site to improve both cost and schedule. The major challenges addressed will include modular fabrication, dimensional control, and sequencing and lifting the modular blocks into the graving dock using one of the world’s largest onshore cranes. The GS1 installation planning and execution experience will be described with focus on a record-breaking installation program with specific identification of the considerable benefits realized by using a temporary work deck for pull-in of all mooring lines and risers. This paper highlights lessons learned, both good and bad, through the unique fabrication and installation approaches used to safely fabricate and install GS1. These lessons learned are applicable to engineers and planners for the fabrication and installation of a Spar-based FPS.

Corus Tubes was the sole supplier of 457mm (18 inch) linepipe for the Williams Perdido Norte project. At 2514msw Perdido is one of the deepest large diameter export pipelines in the world. The depth of the pipeline coupled with the severely undulating seabed bathymetry, made it one of the most challenging projects completed to date. In total, 312.3km of 457mm (18 inch) outside diameter linepipe was delivered in thicknesses ranging from 19.1mm to 27.0mm; dimensions well beyond the production capabilities of most UOE mills. The characteristics of the UOE process are described below.At its UOE pipe mill in Hartlepool, UK, Corus Tubes has over 15 years of experience in deepwater pipe manufacturing technology. During the Perdido Norte contract, this experience enabled the manufacture of pipe to the highest quality. For the pipeline to be installed, survive and perform at 2514msw Corus Tubes worked closely with Williams to ensure that the pipe was manufactured with the optimum properties for the installation and operational conditions. The resulting pipe product exceeded its specified requirements in terms of dimensional control and mechanical properties.Pipe of this quality, apart from ensuring deepwater integrity, helps realise tangible benefits during the installation phase by offering a high level of product consistency that facilitates welding. Despite demanding offshore welding defect acceptance criteria, pipeline fabrication was successfully completed with very low levels of repair, attributable in part to the quality of the pipe produced. This paper documents the factors that led to the successful design and supply of the Perdido Norte linepipe. Corus Tubes' technical achievements will be described in detail from collaboration in terms of pipe specification, through plate selection and supply, to eventual pipe manufacture and delivery. Furthermore, this paper concludes with a summary by Williams of how the pipe performed during installation and finally offers a joint vision of future challenges and advances that will drive pipeline technology into ever-deeper waters.