This paper describes the evolution of the design leading to the selection, development and delivery of Stones disconnectable Buoyant Turret Mooring (BTM) buoy. The optimization process leading to the selection and configuration of the BTM buoy is discussed, with particular focus given to the mooring- riser system payloads supported by the BTM when in the disconnected state.
A hybrid design, featuring syntactic foam buoyancy modules integrated into a steel structural skeleton, and incorporating a minimal number of steel ballast tanks, was selected over a conventional all steel buoyant hull structure. The selected design provides for a protective steel cage for the buoyancy modules, and a structural path for mooring-riser system loads into the Floating Production, Storage and Offloading (FPSO), while a large number of syntactic foam blocks are secured within the steel frame to provide adequate buoyancy to meet the in-service performance requirements. A qualitative discussion about the advantages of the selected geometry and hybrid steel-foam design is presented, including the performance characteristics of disconnection, submergence equilibrium and ballasting.
Beyond the design evolution considerations including concept selection and optimization, attention is given to manufacturing, constructability, offshore installation and operability under the latest US Gulf of Mexico (GOM) regulatory regime. The buoy's transit voyage from Singapore to the GOM for the initial offshore integration with the FPSO necessitated Transport and Installation (T&I) requirements which were embedded into the design and integration of all BTM buoy components. Buoy ballasting and de-ballasting strategy after mooring hookup and riser connection played a pivotal role in sizing critical components and equipment. In this context, the paper will explore the interrelations between design and operations in order to optimize the loading requirements.
The design decisions leading to the selection of geometries, materials and configurations of the largest and deepest offshore mooring installation are discussed. A novel solution is developed to accommodate a complex deepwater installation with a large payload mooring-riser system. Feedback on onshore fabrication and offshore integration and operations are presented.
AbstractOil and natural gas producers continuously strive to control costs, and that goal becomes even more important when market conditions are challenging. To maximize the return on their capital investment and continue to extract reserves on legacy fields, many owners and operators are looking for ways to extend the service lives of aging assets.The Neptune Spar was the first production spar platform in the world, when it was installed in 1996. Currently owned and operated by Noble Energy, the unit continues producing at Viosca Knoll 826 in the Gulf of Mexico. As the platform ages, there is an interest in extending its service life to allow continued operation in the field. As requested by Noble Energy, ABS Group initiated a life extension assessment project.This paper describes the process of the Neptune Spar life extension assessments and challenges encountered during the process. One of the critical aspects of the life extension process is regulatory approval. Since the life extension for floating production platforms is a relatively new trend in the offshore industry, the regulatory compliance process is still under development, and this project is providing a significant contribution to the development of guidance and criteria.The purpose of a life extension assessment is to understand the history of the facility and its current physical condition to determine its structural integrity and outline what is needed for the unit to be maintained for safe and responsible extended service. The life extension project began with a roadmap for life extension assessments that included conducting baseline inspections, reviewing historic inspection and repairs records, undergoing gap analyses that compared the spar's current condition with the original design premise and calculations, and performing additional engineering analyses.As part of the regulatory approval process, the U.S. Bureau of Safety and Environmental Enforcement (BSEE) and the U.S. Coast Guard (USCG) require that a Certified Verification Agent (CVA) verify the entire process of life extension and submit reports that document findings and recommendations. ABS served as the CVA. During the life extension assessment process, ABS Group and Noble Energy consistently coordinated with ABS, BSEE and USCG.Based on the life extension assessments, ABS has granted class certificate for the life extension of this platform. The process of the spar's life extension assessment provides industry with a better understanding of the technical requirements for life extension of other floating production assets, which will have a long-term impact on future asset intergrity management for these types of facilities in deep water.
AbstractThe Stones Field FPSO design provided many challenges in the design of the disconnectable Buoy Turret Mooring (BTM), including the 2900m (9500ft) water depth (the world's deepest floating production system), the first use of steel lazy wave risers from a BTM system, the local environment which included Rossby Topographic Wave currents along the Sigsbee Escarpment, and especially the efficient and safe mating and un-mating of two large floating bodies at sea without use of support vessels.The paper covers the overall philosophy of the disconnect/reconnect operation of the turret/buoy, and then describes the major design challenges encountered. The major system components will be described. The functional aspects of the disconnection and reconnection will be discussed, with discussion of how the particular challenges of the project drove the design.A sequence of increasingly complex model tests was used to guide the design. These initially included forced motion and drop tests to define the hydrodynamic properties of the buoy and the hydrodynamic near-field interaction of the buoy and a fixed FPSO turret. Later tests modeled the full system in waves while disconnecting and reconnecting. The model test results were then used to calibrate a numerical simulation which was used to refine and validate the design. A follow-on paper by Carrico and Leverette (2017) describes the test programs in detail.
Williams Field Services (WFS) use of the classic Spar hull form for the deepwater field development projects is the first classic Spar hull since ExxonMobil installed the Diana/Hoover Spar in 2000. Since that time, 14 Truss Spars and one Cell Spar have been installed. Learnings from those Spars along with increases in the metocean condition since 2000, significant increases in topside payload during detailed design, support of the five initial SCRs on a porch at the keel plus the decision to fabricate the hull in a US graving dock provided new challenges for the Naval Architects from design through to hull installation.
The paper discusses the key drivers, constraints and criteria that had to be reconciled into a floating system with acceptable global motions, acceptable horizontal trim and robust characteristics for changes in topside payload and CGs. Examples of these sometimes conflicting design requirements include: the increased hull freeboard which was driven by the new metocean condition which then led to a higher topside VCG, a 30% increase in the topside's maximum operating payload between the end of FEED and midway into final design yet the depth and length of the graving dock dictated that these changes had to be accommodated without increasing either the diameter or draft of the hull. This paper presents the challenging results of the model tests and their impacts on the design of the mooring system as well as the very close tolerances in trim and stability for the tow out of the graving dock and then to site.
Historically, FPSO’s have been the floating production solution of choice in Asia. Until 2012 only one Spar (Malaysia) and one TLP (Indonesia) has been installed. No Semisubmersible production units have been installed in South East Asia to date.
In the coming decade a large number of deepwater fields will be developed. We will see a large increase of TLPs, Spars & Semisubmersibles entering into operation. FPSO, TLP, Semisubmersible and Spar are proven solutions with mature technology and successful experience. They have been used for deepwater oil and gas production over many years worldwide. Different concepts bring with it advantages and limitations.
Before a field development concept is selected many design parameters need to be evaluated.
The primary drivers to be examined for concept selection are:
• Water Depth - Major impact on mooring design
• Reservoir Shapes - Drilling requirements
• Metocean Conditions
• Well access requirements - Dry tree or wet tree.
• Availability of infrastructure and market location
• Platform Drilling
• Implication on Cap-Ex, Op-Ex for each concept
This paper discusses the selection criteria for application in Asia and also addresses design, fabrication and installation challenges. It will discuss the recent trend towards using Tender Assisted Drilling versus a permanently installed drilling facility and the associated challenges and solutions.
The Liuhua 11-1 oil field, to date, the largest oil field in the South China Sea, is located in approximately 310 meter of water. It was the first deepwater field in the South China Sea originally developed by a consortium of Amoco, CNOOC and Kerr-McGee in 1995. The development includes a Floating Production System (FPS) with a subsea production system, and a Floating Production Storage Offloading (FPSO) located approximately 3km northwest of the FPS. The development of a nearby field, the Liuhua 4-1, about 11km away from Liuhua 11-1, was approved in early 2010 and produced in 2012 through the Liuhua 11-1 FPS facilities via subsea tieback, which requires to FPS life extension and topsides capacities upgrading for another 15 years. There are significant technical challenges for the life extension and dry dock upgrade of the FPS, as well as the subsea tie-back of the Liuhua 4-1 field. The FPS mooring and subsea control risers need to be disconnected and reconnected after the FPS drydock. The new 11km subsea pipeline between two oil fileds, control umbilical and electrical cable risers need to be installed. The FPS upgrade project started in 2010 and completed successfully in 2012 with the reconnection of the mooring and risers to the FPS. Both the Liuhua 11-1 and the Liuhua 4-1 fields are currently producing. This paper gives an overview of the Liuhua11-1 and Li uhua4-1 development as a case study for South China Sea deepwater development and also discusses the technology and project execution for developing nearby marginal fields.
Jung, Sung-Ryng (Offshore Engineering Team 1 Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Park, Sung-Hwan (Offshore Engineering Team 1 Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Kang, Nam-Gu (Offshore Engineering Team 1 Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Lee, Gi-Tae (Offshore Engineering Team 1 Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Moon, Hae-Am (Offshore Engineering Team 1 Daewoo Shipbuilding & Marine Engineering Co., Ltd.) | Kim, Jin-Tae (Offshore Engineering Team 1 Daewoo Shipbuilding & Marine Engineering Co., Ltd.)
This paper deals with verification of the structural adequacy by 3-D local fine mesh technique and beam analysis for FPSO (Floating, Production, Storage and Offloading) hull appurtenances and adjacent offshore area structures. The FPSO was designed to satisfy the strict COMPANY’s own requirements and common Class rule requirements in in-place and towing condition. Therefore, the importance of general description note which covers objectives, design principles, design conditions, methodologies and evaluation methods at the early design stage is higher and higher. In order to investigate the structural fit for purpose of offshore structures, 3-D fine mesh analysis or beam analysis approach had been carried out by using well-recognized software.
DSME was awarded to accomplish the engineering, procurement, construction and installation of the FPSO from one of oil majors in the latter half of 2007. The FPSO has been designed and will be constructed in Okpo ship yard of Daewoo Shipbuilding and Marine Engineering Co., Ltd. In the latter middle of 2010, it will be towed to the operation site as shown in Figure 1(Refer to the full paper). After arriving on site, offshore hook-up operations such as mooring campaign and riser connection works will be done for first oil. Oil field, which lies in Block 17, is located in offshore Angola, approximately 40 km to the east of Dalia FPSO and 200 km to shore. The filed is consisting of two (2) independent groups of reservoirs:
* Miocene reservoirs, in 600 m to 900 m water depth,
* Oligocene reservoirs, in 1000 m to 1200 m water depth
The purpose of the FPSO is to accommodate the various topside equipment, utilities and bulks for oil and gas processing. And it is intended to store the produced oil for a certain time until the oil is offloaded into the offloading tanker.
Saad, Arthur Curty (Petrobras) | Joao, Leonardo Vilain (Petrobras) | Loureiro, Rodrigo Reis (Petrobras) | de Brandao, Renilton (Petrobras) | Filho, Remo Zauli Machado (Petrobras) | Lopes, Clovis (Sevan Marine) | Gioppo, Heitor Luiz (Sevan Marine do Brasil Ltda)
The world's first floating, production, storage and offloading (FPSO) mono-column type platform was installed in June 2007 in the Piranema field, located offshore Sergipe state, Brazil, in 1,090 meters water depth. The unit is equipped with a process plant capable of handling 30,000 bpd (41 to 44º API) of crude, and capacities for 2,400,000 Nm3/day gas compression and 300,000 barrels oil storage. It was designed, built and commissioned by Sevan Marine according to the novel concept. The unit is currently being operated by Sevan Marine for Petrobras under a long-term charter contract.
A Technical Cooperation Agreement, between Petrobras and Sevan Marine to investigate the mono-hull concept since initial tank tests, also allowed monitoring motions and environmental data since the platform was commissioned, under a project led by Petrobras Research and Development Center.
This paper is intended to provide information on the motion behavior of a mono-hull production platform in real environmental conditions, and presents a comparison among data acquired from field measurements and results from numerical simulations as well as from model tests performed during the design phase. Other FPSO key functionalities are also addressed in this paper, such as the offloading operations and mooring system performance.