In 1993, Richard D’Souza (Fellow), the principal author and his co-authors presented a landmark paper reviewing the Semisubmersible Floating Production System (FPS) technology at the SNAME centennial meeting in New York. (D’Souza et al., 1993a). The paper captured the twenty year progression of the FPS beginning with the Argyll field in the UK Sector of the North Sea in 80 meters of water that was converted from a semisubmersible Mobile Offshore Drilling Unit (MODU) and began producing in 1975. During this period about twenty five FPSs were installed, primarily in the North Sea and Brazil. Most were converted from semisubmersible MODUs. The deepest was in 625 m, the largest displacing 45,000 mt and the maximum oil rate was 70,000 bopd.
Over forty FPSs have been installed since then, most of which are purpose built platforms. The technology has expanded to a maximum water depth of 2400 m, displacements exceeding 150,000 mt and production rates of 300,000 boepd. The inherent versatility and flexibility of the FPS to adapt to a wide range of water depths, payloads, metocean conditions and future expansion, has resulted in the FPS superseding the Tension Leg Platform (TLP) and the Spar platform as the most widely used floating production platform after the Floating Production Storage and Offloading (FPSO) platform. Its field development applications range from marginal reservoirs to giant deepwater oil and gas fields across the globe.
This paper, authored by Richard D’Souza with a new team of co-authors, is a sequel to the 1993 paper and is intended as a historical and technical archive of the evolution of the FPS technology in the ensuing twenty five years. It highlights the importance of the Naval Architect and Ocean Engineer whose role has evolved from a peripheral to a major player in the design, fabrication and installation of the FPS. This paper has two objectives. One is to inform Operators and Contractors engaged in developing deepwater fields by providing a historical overview of lessons learned and technology evolution of the FPS. The other is to inspire graduate and post graduate Naval Architects and Ocean Engineers to consider a career in the offshore industry where they will have an impactful role in shaping the future of deepwater floating production platforms.
Recent mooring research indicates that fiber ropes with higher strength and higher stiffness would benefit floating offshore platforms in water depths beyond 2000 meters in terms of reduced offset and reduced weight in comparison with polyester rope mooring. More advanced fibers with high strength and high stiffness are also entering into market. The industry has used high strength and high stiffness ropes for temporary moorings and mobile offshore drilling unit moorings. However, high strength and high stiffness fiber ropes have not yet been used for permanent moorings. This paper summarizes studies conducted by the industry on the high strength and high stiffness fiber ropes. An overview is provided for the existing research results, testing conducted, application guidelines, rope qualification processes, project experience, lessons learnt and the challenges of using high strength and high stiffness ropes for permanent moorings. Based on the industry experience of using polyester rope for permanent mooring and knowledge gained on high strength and high stiffness rope, this paper provides recommended assessments that could facilitate the application of high strength and high stiffness ropes for permanent deepwater moorings.
This paper is based on work performed during design, implementation and operation of the Cascade and Chinook fields in ultra-deep waters of the U.S. Gulf of Mexico. It describes how Regulatory compliance was accomplished for this the first Floating Production Storage and Offloading System in the Gulf of Mexico and the decision making towards selecting a disconnectable Floating Production Storage and Offloading System and critical activities from award to operation of this innovative disconnectable Ultra Deep Water FPSO in over 8,200 feet of water, making it the deepest moored FPSO. It is an Early Production System (EPS) that will establish production potential prior to installing the full production facility for the production potential anticipated. Crude is offloaded by tandem offloading to Jones Act shuttle tankers.
The path Petrobras took, from applying for approval from the U.S. Regulatory Agencies for the use of a Floating Production Storage and Offloading system (FPSO) with tandem offloading to purchase of the Cascade and Chinook (C&C) fields and to produce both fields with a FPSO, was challenging in many ways.
Petrobras accepted the challenges of having to incorporate new technology, breaking records in the process to achieve production in these ultra deep water fields, complying with Regulatory Agencies requirements that did not necessarily have language in the regulations that were specifically applicable for an FPSO in U.S. waters and to install an EPS FPSO to produce in gulf of Mexico where no FPSO had ever produced before.
FPSO technology for use as a production facility was considered state-of-the-art worldwide but was not yet accepted in the U.S. Gulf of Mexico (USGoM), when Petrobras embarked on the project to install the first FPSO in USGoM, realizing it would be a challenge. Petrobras development strategy was to produce C&C fields from a common facility. Petrobras successfully achieve their goal of producing the C&C fields with the first FPSO in the USGoM. The EPS FPSO, BW Pioneer, is currently producing from both these fields.
This paper will provide insights into the path taken to successfully complete this challenging project that included; close cooperation with US Regulatory Agencies to accept FPSO production facilities, changes in ownership of the fields, submission for approval of concept to the MMS and USCG, steps in the project to get the leased EPS FPSO to the field and tools to assist operations and production.
Subsequent to completion of the C&C project, the US Regulatory Agencies preference has shifted from a permanently moored FPSO (as evaluated in the EIS) to a disconnectable FPSO (as approved for C&C fields).