bluuebunny/crossref_metadata_2025_split huggingface dataset:
Girassol - The Umbilicals and Flowlines - Presentation and challenges
Authors: Rouillon Jacky 
Published: October 2008

Abstract
The Girassol field development, offshore Angola in 1,400m of water, has stringent operating requirements due to flow assurance issues and the need for flexibility. The result was the selection of new riser and flowline concepts with numerous qualifications for materials and equipment. This paper details how these concepts - freestanding riser towers, insulated flowline bundles and a mid-depth export system - met project requirements.
UFL has demonstrated that solutions could be developed in a short timeframe. These concepts will be used as a reference for other deepwater developments and while alternative solutions may be chosen, the challenges will be similar.

UFL system presentation
The umbilical and flowline network, part of the Girassol development, is made up of the following main systems:

Production system
The production system comprises five production loops. Thirteen manifolds are installed in 'daisy chains' along these loops. Up to two production wells can be tied in to each manifold.
Each of the production loops is made up of two sections: the production bundle on the seabed bottom and the production riser integrated within the riser towers connected to the FPSO.

Production bundles
Each of the five production loops consists of several production bundles interconnecting the manifolds (refer to the overall field layout).
In total there will be 11 production bundles with eight installed during the first phae of the offshore operations carried out during 2001.
Each production bundle contains (Fig.5):Two by 8in production flowlines.One by 2in service line.These lines are contained within two semi cylindrical modules of syntactic buoyancy foam, which ensure the thermal insulation of the pipes.One by 30in carrier pipe housing the insulation foam, the production and service lines.
The carrier pipe ensures the mechanical protection, the corrosion protection and contributes to the overall thermal performance of the system as it avoids exchanges of seawater with the external environment. The carrier pipe is entirely closed and full of inhibited water.
The weight in air is 550kg/m with a submerged weight in production condition is in the range of 90kg/m. Each bundle is equipped at each end with a sled (Fig. 6), which is used for the installation by seabottom tow and also as structural support to perform the tie-in of the spools connecting the bundles to the manifolds.
The length of the production bundles varies from 700m to 3,000m. The lengths have been determined on the basis of the subsea field layout, but are limited by the bollard pull of the towing spread used for installation.

Production risers
The 8in and 2in risers, which are a continuation of the pipelines in the production bundles, are integrated within freestanding riser towers (Fig. 1 and 3).
Each production riser is equipped with a 3in gas lift line with an entry point at the bottom of the riser tower.
Development of the Prince Field
Authors: Koon J.R. , Heijermans Bart , Wybro P.G. 
Published: October 2008

Abstract
This paper covers the development of the Prince (formerly known as Sunday Silence) Field. The paper outlines how the lease operator and owners in conjunction with turnkey contractors succeeded in developing a relatively small oil field (in deepwater terms) in an environment of low oil prices. This work included the first application of the "MOSES" Tension Leg Platform. The "MOSES" TLP is the first of a new 4th generation in TLP designs that introduces a new hull configuration offering the industry improved platform motions, lower cost, and less fabrication time than other deepwater platform concepts. The successful completion of the development of the Prince Field proves that the industry can execute innovative deepwater development projects on a lump sum contract basis in record setting time frames without costly overruns.

Introduction
The Prince Field is an oil discovery with associated gas located in Ewing Bank Block 958, 959, and 1003, 80 miles offshore Louisiana in a water depth of 1490 ft. (Reference Figure 1) The three leases are unitized in the Ewing Bank Block 1003 Unit. The Prince Field was developed by means of four (4) predrilled wells that were completed and tied back via top tensioned risers to dry trees located on a MOSES TLP. Oil and associated gas are processed to pipeline specifications on the platform and exported via two (2) export steel catenary risers (SCR). The pipelines and SCR's were pre-laid in April 2001, and the TLP was installed in July 2001. The first riser was installed and the initial well was brought on-stream in September 2001.
The development of the Prince Field can be characterized by the following industry trendsetting activities:The Prince Field was the first deepwater field that received royalty relief under the Deepwater Royalty Relief Outer Continental Royalty Relief Act.A MOSES TLP was selected for the Prince Field development after four competitive bids had been reviewed. This marked the first time in the Gulf of Mexico that competitive bidding was used for a turnkey deepwater floating platform concept selection and the first time that the MOSES TLP was selected.The SCR's designed for the Prince Field development are the world's shallowest SCRs suspended from a floating platform. Additional details are provided in the paper listed in the reference section 1.The Prince Field development marks the first time that the working interest owner in the leases (El Paso Production GOM, Inc.) decided to contract with a pipeline and platform infrastructure company (El Paso Energy Partners, L.P.) to have El Paso Energy Partners own and operate the deepwater platform and process production from the field for a fee. This arrangement lowered the development costs and made it possible for El Paso Production GOM, Inc. to develop the field with a deepwater platform in lieu of a subsea tie-back.The TLP hull is the first use of a new 4th generation TLP design that offers the industry a new alternative with dry tree or wet tree capability.
Composite Risers and Tethers: The Future for Deep Water TLPs
Authors: Botker Stig , Johannessen Thomas B. 
Published: October 2008

Abstract
The present paper describes the extension of well proven TLP technology to applications in ultra deep waters. It is concluded that the careful optimisation of the TLP hull and topside as well as the use of composite risers and tethers lead to economical and technically feasible TLP solutions at water depths as large as 3000 m.
The paper addresses the following subjects:TLP technology and hydrodynamic optimizationComposite risers and tethers impact on overall TLP designComposite riser and tether design and fabricationStatus on the composite tether and riser development program which is ongoing through the Conoco/Kvaerner Composite AllianceMInstallation of composite tethersA case study including cost estimates

Introduction
The TLP concept has proven to be suitable in both harsh and benign climate conditions during the last two decades. TLPs have been chosen at water depths down to approximately 1300 m. However, for water depths larger than this, the weight of conventional tether and riser systems becomes large and begins to dominate the entire global configuration of the TLP. This may result in a solution which is not feasible either from an economical or a technical point of view.
Alternative floating dry completion units have recently been introduced for large water depths. In particular the Spar buoy concept has been successful in the Gulf of Mexico. The alternative solutions are, however, technically challenging, typically involving large relative motion between the dry wellheads and the floater as well as significant offshore work prior to installation.
In 1995, Kvaerner and Conoco established a Composite Alliance with the aim of exploring the business potential of composite solutions in the offshore and shipbuilding industries. It was concluded in a holistic study that the largest potential lies in the development of composite risers and tethers. As a result, two large development programmes were initiated, namely the CompRiser programme initiated in 1996, and the CompTether programme initiated in 1998. The main objective of the two programmes is to qualify the technology by prototype testing and offshore demonstration.
The application of composite tethers and risers go a long way in resolving the main concerns of employing TLPs for deep water applications. This fact, together with the excellent track record of the TLP and the prospects for new deep water field developments, led to the initiation of a development project within Kvaerner Oil & Gas (KOGAS) in 1999. The main objective was to improve the economy of TLP solutions and to extend the water depth range for economical and technically feasible TLP solutions down to 3000 m both for harsh and benign environments.
This goal was achieved by bringing in new ideas for the overall configuration, construction and installation of the TLP, and by using composite materials for the fabrication of tethers and risers. The present paper summarises the main conclusions from this development project and the composite development projects.
Maureen Refloat Project: Challenges to Control Weight and Stability Through a Decommissioning Project
Authors: Røed Kristian , Karlsen Kristin , Davies Richard 
Published: October 2008

Abstract
This paper gives a brief summary of the methods, actions and decisions involved in maintaining control of Maureen Alpha's weight, centre of gravity and hydrostatic stability through the decommissioning process.
The process described herein is an example on "backwards" engineering, retracing a structure's history and deciding how to handle the information, rather than adapting a design to given parameters and constraints.

Introduction
On June 26th 2001, eighteen years after its installation, the 110 000- tonne Maureen Alpha steel gravity platform was refloated in UK waters, and the three-days tow towards Stord, Norway initiated. Maureen, which was owned by Phillips Petroleum Co UK, had been the largest offshore steel platform in the North Sea. Aker Maritime was awarded the contract for removal of the platform in 1999.
Accurate weight data were essential in the calculation of the platform's floating stability, which was a highly critical factor during the ascent from the seabed to floating condition with very little water plane area.
This paper will cover the approaches to the following challenges encountered in the weight and stability analyses:The accuracy and reliability of the 18-year old as-built and as-installed documentation.Weight and buoyancy changes during platform service time. Scanning of lifting logs and the search for undocumented changes.Production system residues. Definition of the weight of remaining mud, scale and liquid. How thorough is the cleaning of the pipes and tanks?
Undocumented changes to the substructure:Weight and nature of marine growth on the structure.Water inside the lattice frame. Sluiced in upon installation, how to evacuate the structure before refloat, and how to cope with remaining water volumes.How to account for wax and residues in the storage tanks.Sacrificial anodes. How much is left?Breached lattice members. Full, half full or still dry?Stairs, ladders and walkways under deck partially destroyed by waves.The application of "allowance for uncertainty". A considerable amount of weight and stability contributing items were indefinable and had to be accounted for by means of statistics. Assuming worstcase scenarios would never have allowed the re-float operation to take place.Stability criteria. DNV rules define the operation as a "transient phase", hence applicable stability criteria had to be defined by the Main Contractor, based on weather limitations, maximum inclination limits and the decision that clashes with seabed structures were to be avoided.
More detailed descriptions of the Maureen platform and the history and particulars of the re-float project in general, can be found in /1/.
All units referred to in the text are SI standard metric units.

Reference systems
Given a set of data where virtually every figure is subject to doubt with variable levels of influence on the total, the first task is to define some fixed reference to hang all obtained results on.
Design Criteria and Inspection Strategy for FPSO's
Authors: François Michel , Frorup Ulrik 
Published: October 2008

Abstract
The FPSO's now under operation or construction are mainly ship-shaped structures. However these units differ significantly from oil trading tankers for their service conditions, being in continuous operation at sea and Site specific as opposed to ocean trading. Therefore, Classification Rules for FPSO's are providing complement, and provide the necessary input, before application of the Ship Rules that are the standard reference for shipyards.
A FPSO is constantly in loading/unloading process and loading conditions have to be carefully studied, taking into account both operating requirements, and future maintenance and inspection requirements.
As a FPSO is a site specific unit, study of the loads induced by waves is to be performed, and comparison of the results with the standard requirements for trading ship will provide the data required for the application of (ship) Class Rules.
Given Operator's objectives of a vessel in continuous operation at sea, and no dry-docking for the intended service life, durability is an essential consideration, with implication on design for e.g. accessibility, corrosion protection and corrosion margins, and Fatigue strength.
Tools are available, at the design stage, to perform strength and fatigue evaluations of the structure, and help in design. The database thus obtained will provide, during vessel operation, a compliance management tool for the hull structure.
Issues in this paper are discussed based on the experience gained in new-built but also converted FPSO's actually moored in various areas of the globe like West Africa, China and Brazil.

Introduction
The FPSO's (Floating Production Storage and Offloading Units) now under operation or construction worldwide are mainly ship-shaped structures purpose-built or converted by shipyards based on their know-how and application of Classification Societies Rules.
The Classification Societies were established during the 19th century with the development of the shipping industry, to provide independent information on the actual condition of the ships, and to develop Rules for Classification of Ships including design, construction and maintenance/surveys requirements.
With the development of international conventions, Flag states have recognized their competence and technical expertise and have often delegated their technical inspections to them.
This has helped Classification Societies to harvest and compile unrivalled knowledge in terms of ocean-going structures and safety at sea. Then, the development of an expertise in offshore installations was considered as a natural extension of their duty of encouraging the protection of life and environment at sea.
Global Performance of Floating Production Systems
Authors: Garrett D.L. , Chappell J.F. , Gordon R.B. 
Published: October 2008

ABSTRACT
Fully coupled global analysis of Floating Production Systems, including the vessel, mooring and risers is described. Modeling procedures for each component, including hydrodynamic modeling, characterization of the environment and element length selection for mooring lines and risers, are presented. Simulation requirements for both Frequency Domain and Time Domain analysis are presented. This includes criteria for selection of frequency content and simulation length.
Results for two Floating Production Systems are presented. The first is a Gulf of Mexico spar with taut-leg mooring and top-tensioned risers in a water depth of 6,000 ft. The second is a spread moored West Africa FPSO with steel catenary risers in 4,500 ft water depth. Modeling of each is described. Results for vessel motions, riser stresses, and mooring line tensions are presented, including detailed comparisons of Time Domain and Frequency Domain results.

INTRODUCTION
Development of deepwater fields requires complex systems for production and export of oil and gas. These can include combinations of steel catenary risers, flexible flowlines, top tensioned risers, and hybrid risers, connected to one or more moored floating structures ("floaters") such as spars, TLPs, semisubmersibles, and ships. The floater may be moored with either catenary or taut legs.
Coupled analysis includes detailed models of the floater, the mooring lines and the risers in a single model. A single model can include a floater, 12-16 mooring lines and 20 or more risers, resulting in models with more than 10,000 degrees of freedom. Stochastic analysis is used to calculate the response to wind, wave and current loads. For fatigue analysis, there may be more than 1,000 load cases. Efficient, accurate modeling is needed to produce the results needed for design.
Recommendations for developing efficient, accurate models for both Time Domain and Frequency Domain analysis are presented. The criteria have been developed over many years of modeling and analysis of Floating Production Systems.

COUPLED ANALYSIS METHODOLOGY
The coupled analysis for the examples was performed using Stress Engineering Services' RAMS (Rational Approach to Marine Systems) software. The modeling criteria are not restricted to RAMS, but are generally applicable.
RAMS uses a consistent cubic finite element representation of an elastic rod [1] to model risers, TLP tethers and mooring lines. The element includes axial and bending stiffness. Bending stiffness varies linearly and tension varies quadratically along the axis of the rod. The external load model accounts for weight, buoyancy, internal fluids and hydrodynamic loads. A generalized Morison model is used to compute hydrodynamic loads. Seabed contact is simulated by nonlinear spring and friction models. The finite element method uses a displacement formulation that allows for large element displacements and rotations in three-dimensional space, while strains are assumed to be moderate.
Environment Severity Factors and Their Applications in FPSO Hull Strength Assessment
Authors: Zhao Chuntian , Wu Jer-Fang , Huang Ken , Shin Yung 
Published: October 2008

Abstract
This paper presents an approach to conduct the scantling design and strength assessment for a ship-shaped FPSO to be stationed at a specific site. By introducing the Environment Severity Factors (ESFs), the effects of the site-specific wave conditions and the mooring/risers as well as the topsidestructures on the loads of FPSO hull structure can be considered while the strength analyses and criteria can be kept as simple as those used in the design of ocean-going tankers. The determination of ESFs is based on the direct calculation of wave-induced and motion-induced loads. The determinations and applications of ESFs for two common types of wave conditions are discussed, in which:wave conditions can be represented by a wave spectrum of simple-form or by the long-term wave scatter diagram consisting of wave spectra of simple-form, such as JONSWAP wave spectrum andBretschneider wave spectrum.Wave conditions cannot be represented by a wave spectrum of simple-form, for example, for the cases that both seas (wind or storm generated waves)and swells exist.
The latter becomes more complicated if the seas and swells propagate in different directions, which may occur in some offshore areas such as offshore Brazil and West of Africa. For the design and analysis of an FPSO conversion, the ESF concepts can also be used in assessing the fatigue damage accumulated during the past route services as an ocean-going tanker. The proposed approach for the strengthassessments can be applied to both the newly built and the converted FPSOs. This approach can facilitate the hull scantling design and strength assessment.

Introduction
A Floating Production, Storage and Offloading system (FPSO) is a popular type of vessel used in the offshore oil production. An FPSO may be a newbuild or a conversion from an oil tanker, which has been in service for some years. The discussion of the proposed approach covers both types of FPSOs.
In general, FPSO design is more complicated and time consuming than tanker design for the following reasons:FPSO design requires the application of site-specific environmental conditions, while tanker design applies unrestricted-service wave conditions, which are rule-based for all ocean-going tankers. The rule-based design is generally much simpler than the case-by-case design. Besides, FPSO design also needs to consider the specific transit and installation conditions.FPSO design criteria will not be the same as those for tankers. For example, tanker design uses 20-year extreme wave conditions, while FPSO design uses 100-year waves.FPSOs have more complicated structural configurations. The effects of mooring/riser system and topside structures need to be considered in the FPSO hull design. Due to the interaction of these design considerations, the hull structure design may need to go through several iterations.