bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultra-Deepwater Steel Hybrid-Riser Concept for Offshore Brazil
Authors: Andueza A. , Stefen S.F. , Silve R.M. 
Published: October 2008

Abstract
Petrobras has around 17.3 billions barrels of oil reserves being half of them under more than 1000 meters water depth. In addition, 60% of offshore exploratory concessions are also deeper than 1000 meters water and half of these concessions at more than 2000 meters. Therefore, the future Brazilian oil discoveries should be located offshore in ultra-deep waters. Beyond 2000 meters water depth flexible riser technology is so far not proved. Therefore, the new challenge is to develop an ultra-deep water hybrid riser technology in order to incorporate these reserves in the Company's assets.
This paper shows a preliminary technical feasibility study considering a hybrid riser configuration for a typical deep water field in Campos Basin, Offshore Brazil. The water depth is 1800 meters and the riser is attached to a turret at bow FPSO (Floating Production Storage & Offloading) vessel. The results indicate an attractive alternative design concept that fulfil some typical difficulties related to ultra-deep waters such as high vertical loads on the production floating unit.
The analysis methodology uses the Finite Element Method through commercial computer codes packages MSC/Patran and Abaqus. The hydrodynamic loads are computed through programming using PCL (Patran Command Language).
The strength of the pipe under bending, tension and external pressure is considered through the standard DNV OS-F101 [1]. This standard is proposed specifically for the analysis of submarine pipelines.

Introduction
The steel hybrid riser concept [2,3,4,5] is composed by a SCJ (Steel Catenary Jumper) connected to a SSVR (Self-Standing Vertical Riser) through a goose neck spool piece, as shown in Figure 1. The connection of the two rigid risers is provided by a typical flex-joint. The SSVR requires a subsurface buoy at the top to keep its vertical stability. In addition, the SCJ is attached at the base of a bow turret of a typical FPSO built on the hull of a former VLCC (Very Large Crude Carrier). At the seabed the connection is modeled as a hinge, however, a taper joint or a flexjoint could be considered based on a further local analysis not included in this paper.
One of the main advantages of such configuration is that it eliminates entirely riser soil interaction, therefore, any TDP (Touch Down Point) design constraints. Another important advantage is that the concept is made completely of steel pipes, which gives more flexibility in terms of construction and procurement.
The proposed configuration in this work was defined through the analysis of the results of a preliminary study of several simulations.
The System Specification is described below:WD (Water depth) = 1800 metersPipe Outer Diameter = 12.75 inPipe wall thickness = 1 inPipe material: API 5L X65SCJ length = 1700 metersSSVR length = 800 metersBuoy upthrust = 1470 kNFlex joint connecting SCJ top and FPSOFlex joint connecting SCJ and SSVROperational offset: 10% of water depthAccidental offset: 15% of water depthVLCC ship with turret system
Analysis of Splices used in Large Synthetic Ropes
Authors: Leech C.M. , Flory J. 
Published: October 2008

Abstract
The analysis of eye splices used in synthetic rope is considered by categorising splice geometries and then developing the modelling for each type. The three splices considered are commonly used in wire ropes and are applied to six round one aramid ropes; the splices are the long or transmission splice, the admiralty or locktuck splice and the Liverpool splice. The geometry of each is analysed and then applied to determine the load capability for each type. The internal friction and contact forces are also discussed.

Introduction
Large synthetic ropes are widely used in many traditional structural applications. These ropes are terminated and this can be achieved by a variety of mechanisms. Their ends can be cast into in epoxy fittings or terminations, they can be gripped or they can be spliced either to another rope or to themselves forming an eye. Analyses haves been conducted on the strength and life of these ropes, but little analysis has been done on the splicing of these ropes. This paper describes three splice geometries and introduces the analysis associated with each.
Modern synthetic ropes vary in construction and in the constituent fibre materials. The assembly geometries consist of the oldest geometry namely twisting of strands around a core axis, of braiding and plaiting of strands, and of layering of groups of strands. The strands are formed by twisting, braiding or plaiting of yarns and these yarns are formed from textile or rope yarns that in turn are assembled from the smallest fibre groups. Thus the development of the rope from the basic component is achieved through a hierarchical tree, in which the geometry of assembly is the link between consecutive levels.
The material components used in modern polymer fibre ropes have a range of properties that can be exploited in rope construction, namely strength, stiffness, creep and relaxation, fatigue life, shock and impact resistance, and friction for internal energy absorption, fibre abrasion and rope integrity.
Much has been done in recent years on the analysis of rope performance, fatigue and internal heating. However, the analysis of termination of such ropes by splicing has not been done before. The following splices are considered.
The long (transmission) splice for twisted structures is achieved by stagger cutting each strand in the standing end and laying in its path a strand from the joining splice end. This is the simplest splice geometry. The analysis for the splice integrity requires an estimate of the contact friction.
The Admiralty (locktuck) splice uses a braid geometry formed by weaving the strands from the standing end with those of the splice. Contact is enforced at the crossover points and friction again ensures that the splice does not disintegrate.
Suspension Transport In Southern Alaskan Coastal Waters
Authors: Wright F.F. 
Published: October 2008

Abstract
Sporadic. large-volume transport of suspended silts and clays characterizes the inshore sedimentary regime of southern Alaska. Both in fiords and on the open shelf there is rapid deposition of an undistinguished periglacial mud which is carried as discrete layers n, in, and under the seasonally stratified waters of the region. This phenomenon, analogous to spring floods in temperate areas, is particularly important in late summer and autumn when thermohaline stratification of the coastal waters is most pronounced. Within a given coastal water column there are routinely two or more water masses with density contrasts as great as 4 g/l. Such density surfaces are quite adequate to support the highly turbid glacial run-off waters of the region, which rarely contain more than 0.5 g/l suspended sediment. Much of the suspended material travels in individual bolusses which behave as water asses, sinking to a level corresponding to their effective density and gradually losing their load by settling and flocculation. Apparently internal turbulence within a bolus tends to maintain relatively coarse particles in suspension for considerable periods. This accounts for the transport of silts and even fine sands across sills in fiords and even beyond the continental shelf, in contrast to classic turbidity current transport which tends to be strictly controlled by sea floor topography. Both the turbid waters and the discontinuous currents associated with this mode of sedimentation may be critical factors in the conduct of diver or submersible operations in inshore waters where appropriate conditions exist.

Introduction
Ancient mariners often navigated by the appearance of turbid river waters at the sea surface considerable distances from shore. Modern aerial and satellite photographs have demonstrated that this phenomenon is extremely common; fresh river waters bearing considerable loads of suspended sediment spread many miles from shore (Stevenson, 1969). This suspension transport is due to the relative density differences between the cold, saline seawater and the warmer, fresh river water, despite theconsiderable quantities of suspended material in the fresh water. A similar phenomenon has been observed by divers and deep submersibles at the sea floors of the continental shelf and slope where rather slow down-slope movement of turbid waters, quite distinct from classic turbidity currents, is often seen (Moore, 1969). Within the deep sea, persistent turbid layers carrying very dilute suspensions of fine clay particles have been reported by various observers. Discrete turbid water layers capable of carrying large quantities of suspended sediment supported on density interfaces within the water column have been postulated (Gould, 1951; Stetson and Smith, 1938).
Multiple turbid layers within the water column have been observed in southern Alaskan fiords (Wright, 1970). It is believed that this may be a very significant agency of sediment transport, not merely within fiords but also on the shelf and slope.
The Blake Development Project proves the flexibility of FPSOs in the successful completion of a schedule driven modification to a producing FPSO
Authors: Soeters Mireille , Reynolds Keith , van  Elk Harry 
Published: October 2008

Abstract
The Bleo Holm is an FPSO owned and operated by Bluewater, leased by Talisman for operation of the Ross & Parry Fields located in the North Sea. After discovery of the nearby Blake Field and evaluation of several development concepts a tieback of the Blake field to the Bleo Holm FPSO was selected.
In order to be able to produce the Blake field through the Bleo Holm, extensive modifications to the Bleo Holm facility were required that would only be possible to implement during a shutdown period. Without production during the shutdown period the owners of the Ross & Parry Fields would be subject to a loss of oil revenue. Minimisation of the shutdown period was therefore absolutely essential and was reflected in the execution schedule that became the project driver.
This paper describes the development of the project during all its phases (concept, engineering, construction and commissioning) and highlights how the construction schedule, being the main driver, influenced decisions taken during the course of the project.
The paper also discusses the flexibility of the FPSO concept and the benefits the Blake Field Tie-in to the Bleo Holm provided to the field owners and to Bluewater.

Introduction
The Bleo Holm FPSO (Floating Production Storage and Offloading Facility) is located in the North Sea 100km North East of Aberdeen in the Moray Firth. The Bleo Holm FPSO is owned and operated by Bluewater and leased to Talisman Energy and partners Nippon Oil, Intrepid and Kerr McGee, for production of the Ross & Parry fields. The field is located in license blocks 13/28a and 13/29a and has estimated recoverable reserves of 50 to 70 million barrels of oil. From sub-sea well completions and flexible risers, well fluids are delivered to the Bleo Holm where, after separation into oil, gas and water, oil is stored in the cargo tanks. The resultant gas is compressed for gas lift and export and the cleaned water is routed overboard. First oil from the Ross & Parry Fields was achieved 19th April 1999. The Blake field, in license blocks 13/24 and 13/29, laying approximately 10 km North from the Bleo Holm location, was discovered in mid 1997. The Blake field, operated by BG Group, is owned by BG Group and partners Paladin and Talisman Energy. The recoverable reserves of the Blake Field were estimated to be approximately 80 million barrels of oil.
Initially a dedicated production facility for the Blake Field Development was considered and, following technical, economic and safety evaluations of the various solutions an FPSO concept was selected as the most favourable. As a result of the fall in oil price in 1998 a standalone development was no longer considered economically viable and the concept of a subsea tie-back to a host facility was generated. The following facilities were identified as having the potential.
Development of a Deep Sea FPSO Suitable for the Gulf of Mexico Area
Authors: Park In-Kyu , Shin Hyun-Soo , Chung Hoe-Woo , Beek Johan W.F. 
Published: October 2008

Abstract
An overall conceptual design development of a deep sea FPSO suitable for the Gulf of Mexico area is described. The oil storage capacity was determined after the market screening by analyzing the answers to questionnaires submitted to potential field operators. The locations of turret, accommodation, topsides, flare boom and offloading equipment have been studied carefully before selecting the final location on the general arrangements. The basic drawings of general arrangements, lines, mid-ship section, accommodation layout and outfitting systems are developed. The basic hydrostatic calculations, stability, motions, mooring, structural and riser analyses are also carried out. The model tests are carried out at 2-dimensional wave flume for roll motion and wave model basin for global performances. In order to reduce the roll motion, a box-like mid-ship section is adopted with projected bilge keels. The model tests confirmed the expected good motion performances. A turret moored, one million barrels storage capacity, double hull FPSO is found to be most suitable in the Gulf of Mexico.

Introduction
The Gulf of Mexico was the last offshore oil field area not open for FPSOs. The absence of FPSOs from the GoM is partly due to the well-developed production and pipeline infrastructure. Another reason is the relative prevalence of gas developments in the GoM. As production enters deeper water and far away from any export infrastructure, the demand for FPSOs gets stronger. The final threshold to open the GoM for FPSOs was a safety confirmation. MMS (the Minerals Management Services) have expressed concerns about FPSO deployment, which have focused on the performance of offloading operations and the vessels' survivability during hurricanes in the GoM. According to the EIS (Environmental Impact Statement) recently issued by MMS, potential sitespecific impacts are essentially the same as with other deepwater development and production systems. The FPSO has been widely used as a most competitive production system concept in other offshore fields where infrastructure is not sufficient, or where the fields are marginal. As the water depth for offshore fields increases, more offshore operators have selected the FPSO concept. Considering the size of the oil reservoirs in the GoM, FPSOs will be widely adopted by the main operators.
On December 31st 2001 the MMS announced its decision to allow the industry to propose using FPSOs in the central and western Gulf of Mexico.
This paper presents an overall conceptual design development of a deep sea FPSO suitable for the Gulf of Mexico area. The locations of turret, accommodation, topsides, flare boom and offloading equipment have been studied carefully before selecting the final location on the general arrangements. Environmental conditions in the Gulf of Mexico, such as hurricanes, ultra-deep water depth and loop currents, required special consideration in the dimensioning and arrangements.
Reducing Spatial Aliasing in Wave-Equation Multiple Attenuation
Authors: Jiao Jianwu , Leger Pierre , Stevens John 
Published: October 2008

Abstract
Multiples are a major problem in offshore seismic exploration. Wave-equation methods are a popular tool for multiple attenuation, but behave poorly in the presence of spatial aliasing. This paper will propose a method to reduce the effect of spatial aliasing. It does this by first applying a linear transformation to the wave equation. This transformation reduces dips in the data, but does not involve approximations, nor does it change the form of the equation. Wave extrapolation is then performed using an efficient Kirchhoffstyle phase-shift operation. The modeled multiples are adaptively subtracted from the original traces with a multichannel constrained filter. The proposed method has givengood results on a data set from the East Coast of Canada.

Introduction
The basic model in seismic processing assumes that reflection data consists of primaries only. If multiples are not removed they can be misinterpreted as, or interfere with, primaries. Therefore the attenuation of multiple reflections has been an important research subject and many methods have been developed. The methods can be classified into two types: those that exploit the periodic nature of multiples, and those that exploit the moveout differences between multiple and primary reflections.
The first category includes predictive deconvolution in the x-t or ?-? domain. Predictive deconvolution assumes that the multiples are periodic within an application window and that the primary events are not - that is, the multiples can be predicted and thereby subtracted from the seismic records. In the prestack x-t domain, water bottom multiples are periodic only for zero offset traces and flat-water bottoms. To achieve periodicity of multiples for far-offset traces, transforms such as the ?-? transform or the radial trace method must be applied. Still, for shallow water depths (shorter period multiples), periodicity only holds in a limited window. Predictive deconvolution can introduce spurious events and needs to be applied with care. It is more effective for removing "ringing" multiple energy than longer period waterbottom multiples.
The second category includes methods in the F-K, K-L and ?-? domains. While these methods are routinely used and can be very effective, there have a number of problems. All of these methods lose effectiveness when the velocity discrimination between primary events and multiples is small. This is the case at near offsets where there is little or no separation of primary and multiple events, and at all offsets when there is little velocity difference. Their effectiveness is further reduced when the seismic events violate the modeling assumptions (non-hyperbolic events for F-K and K-L, or non-parabolic events after NMO for ?-?).
Recently there has been interest in techniques based on wave theory, which can be considered extensions of conventional predictive deconvolution. Multiples are predicted by either wavefield extrapolation1,2,3 or wavefield inversion4. They are then subtracted from the original data.
Tandem Mooring LNG Offloading System
Authors: Poldervaart L. , Queau J.P. , Van Wyngaarden Wim 
Published: October 2008

Abstract
The attractiveness of placing a natural gas liquefaction plant on a vessel moored at or close to an offshore field is known. This vessel can either be part of an oil development in which it liquefies associated gas or a stand alone development of a gas field. In the associated gas case, the Floating LNG (FLNG) unit makes certain oil developments feasible by turning the associated gas disposal into a moneymaking opportunity. In the gas field case, the FLNG makes remote offshore field production economic. The safe reliable transfer of this LNG in open sea, possibly harsh, environment has however not been possible. The proposed LNG Offloading Arm (LOA) effectively combines proven technology and operating experience to effect the safe and reliable transfer of LNG between tandem moored vessels or between a fixed tower and LNG carrier in up to 5 meter significant seas. The concept is based on the experience of mooring systems surviving 100 years storms, dis-connectable mooring systems in typhoon areas and work performed on cryogenic swivels. The LOA structure consists of "vertical" and "horizontal" arm section with swivels to provide articulations required to follow the relative motions between the FLNG and the tandem moored LNG carrier. The vertical section is supported from a cantilevered rotating structure on the back of the FLNG vessel or on a fixed tower. The horizontal section connects the LNG carrier to the lower end of the vertical section. Each section is composed of a central pipe for LNG transfer and a large diameter outer pipe structure also used as the vapor return from the LNG carrier. The LNG carrier can be passivelymoored using gravity restoration by weights located in the horizontal section of the loading arm or DP assisted using both the arm and the LNG carrier thruster system.

Introduction
The technology for cryogenic liquefaction and storage of LNG on an offshore floating vessel is known. The safe reliable ship to ship transfer of this LNG in an open sea, possibly harsh, environment has however not been possible. SBM having experience in both the supply and operation of mooring systems put this experience to work in the development of a Tandem LNG Offloading system. The philosophy adopted for this development was to keep the design simple and whenever possible stick to components that had a known track record.
Having over 40 years experience in the design, supply, and operation of Single Point Mooring (SPM) systems and Floating Production Storage and Offloading (FPSO) systems the value of simple robust design was well understood and applied to this LNG Arm development. Known technology and operational experience either directly or indirectly applied to the Arm include soft yoke or gravity moorings (Fig. l), articulated fluid transfer arms (Fig. 2), cryogenic swivels (Fig. 3a and b) and tandem mooring systems (Fig. 4).