bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon Fiber Composite Tendons for Deepwater Tension Leg Platforms
Authors: Sparks C. , Zivanovic I. , Sparks Freyssinet , Luyckx J. , Sparks Soficar , Hudson W. 
Published: October 2008

Abstract
The paper presents new technology for the tendons of deepwater Tension Leg Platforms (TLPs) based on Carbon Fiber Composites. The technology, named 3C-TendonsTM, has been developed by the group comprising Freyssinet, Soficar, Bostik Findley, Institut Français du Pétrole and Doris Engineering. The technology solves the problems of weight and fatigue which become critical for TLPs in very deep water. The tendons are made up of multiple numbers of subelements each of which comprises 19 rods, all of which are spoolable for transport. For the complete tendon, the partners have opted for parallel rods and sub-elements for technical reasons explained in the paper. Final installation is by the method of tow-out and upending.

Introduction - Background to TLP tendons
When designing the tendons of a TLP the designer has the triple technical objective of ensuring that:maximum loads at the tendon top ends do not exceed acceptable values;cumulative fatigue damage due to fluctuating axial stresses is acceptable;bottom end effective tension remains positive at all times and hence that tendon buckling is avoided. Tendon pretension in particular has to be chosen to avoid such buckling.

Tendon pretension
Tendon pretension can be considered as part of the total load on the platform. There is therefore considerable motivation to reduce its value as far as possible. This involves firstly minimising the apparent weight in water of the tendons.
All TLPs constructed to date are anchored by steel tendons which, in virtually all cases, have been composed of hollow tubes. These have been left air filled at atmospheric pressure to reduce their weight in water. The tendons of the Jolliet TLP (528m depth) were almost neutrally buoyant with a D/t ratio of 30. For subsequent TLPs in water depths down to 1200m lower values of D/t (20-25) have had to be used because of the combined effect of external pressure and axial loads.
As water depth increases towards the ultra-deep the D/t ratio has to be even further reduced to prevent collapse from external pressure. This leads to heavy tendons if the crosssection is maintained constant and hence requires a significant increase in displacement of the TLP to support the additional load. An alternative is to use "stepped tendons" for which the diameter is increased in steps towards the upper end. This is equivalent to incorporating buoyancy in the upper part of the tendon itself.
The other alternative is to fabricate the tendons from a different, naturally lightweight material, such as carbon fiber composite. The weight of such composite (specific gravity 1.59) is only slightly greater than that of water. Hence carbon composite tendons do not require buoyancy to be incorporated in the tendon to reduce their weight in water. Furthermore they are capable of resisting external water pressure without collapse and their resistance to static and fatigue loads is significantly better than steel.
Model Test Experience on Vortex Induced Vibrations of Truss Spars
Authors: van Dijk Radboud , Magee Allan , van Perryman Steve , van Gebara Joe 
Published: October 2008

Abstract
In order to evaluate the Vortex Induced Vibration (VIV) response of truss Spars and to optimize their strake configuration several model test programs have been carried out at MARIN. The results show that it is possible to optimize the strake design of Spars to obtain minimum VIV-response. The results of the model tests also suggest that modeling details, such as appendages, can have an influence on the Vortex Induced Vibrations. In order to reliably predict the full-scale VIV-behavior of the prototype Spar these details must therefore be accurately represented on the model. Furthermore, damping of attached structures such as the truss on a truss Spar can significantly contribute to the reduction of VIV. Loads on such structures have been measured in the model tests.
An important aspect that needs consideration in VIV model testing is effect of model scale on the Reynolds number. Roughness can be added to the hard tank of the Spar to minimize scale effects. The paper discusses possible scale effects and the effect of hull roughness on model test results. The repeatability of VIV model tests and reliability of these tests in representing the full-scale situation is discussed. The effect of Spar heading with respect to the current direction as well as current speed will be discussed.

Introduction
Since 1996 Spars have been used as production platforms in the Gulf of Mexico. Vortex Induced Vibrations (VIV) of the Spar are an important consideration in mooring system design. The Vortex Induced Vibrations of Spars are typically reduced by adding helical strakes to the Spar hull. The effectiveness of the strakes must be verified in the design stage of the Spar. At present numerical tools are not capable of accurately predicting VIV-behavior of Spars. Model tests are therefore currently the most practical method to verify and optimize the strake design.
A new development in Spar design is the so-called truss-Spar (Refs 1 & 2). In order to evaluate the VIV-behavior of this type of Spars dedicated model tests have been conducted on several truss Spars.

Vortex Induced Vibrations
A blunt structure placed in a flow (either air or water) will experience an oscillating force due to the shedding of vortices. This phenomenon is studied and discussed extensively (e.g. Ref. 3). If this structure is able to move in the flow Vortex Induced Vibrations (VIV) can occur. The predominant direction of these motions is transverse to the direction of the flow. Large steady state type oscillations occur when the vortex shedding frequency coincides with a natural frequency of the structure. This is known as 'lock-in'. For offshore structures these vortex induced vibrations could add to the fatigue damage of mooring and risers, shortening the total fatigue life and also increase the overall drag on the structure. Experience has shown that in offshore structures cylindrical objects such as risers, calm buoys and Spars are most susceptible to VIV, but also other shapes can exhibit VIV-behavior.
Seabed Located Drilling Rig - ITF Pioneer Project
Authors: Ayling L.J. , Jenner J.W. , Neffgen J.M. 
Published: October 2008

Abstract
ITF Pioneer Project PX 1017 is the Feasibility Study of a drilling rig that is located on the sea bed. The new Seabed Drilling Rig (SDR) and its Rig Support Vessel (RSV) are simpler and considerably less expensive than previous attempts to re-locate a land rig subsea. (See CAD Illustration.)There are no rigid risers between SDR and RSV.The SDR is largely insensitive to weather and the RSV has a far larger envelope in which to operate.The SDR is modular and can be deployed through a normal moon pool in the RSVThe SDR uses standard drilling procedures and jointed tubulars;The main control of mud circulation, to and from the well, is at the seabed.This SDR technology leapfrogs current 'riserless drilling' technology, but applies many useful lessons learned.The projected costs, per well drilled, compare favorably with floating drilling in as little as 1,000ft (300m) of water and do not increase significantly with water depth.Reductions in current well construction costs of up to 30% appear feasible in 3,500ft (1,100m) water depth.Reductions in current well construction costs in excess of 30% appear feasible in 7,500ft (2,300m) water depth.Locating the Rig on the seabed apparently offers the best technical and economic solution for drilling in 10,000ft (3,000m) water depth and, because of its low depth sensitivity, the technology can be extended to 20,000ft (6,000m.) water depth. The step change in economics is due to a new method of handling all tubulars & tubular assemblies, plus a new mud control system combined with the Continuous Circulation System (presented in OTC Paper 14269 in 2002).
Results, so far, indicate that there are no apparent show stoppers. Detail Design is planned for 2003/2004 with a prototype operating in 2006.

Introduction
In conventional offshore drilling, the drilling rig is located above the water surface; on the deck of a 'bottom supported'installation such as a submersible, jack-up, or fixed platform, or on the deck of a 'floating unit', such as a semi submersible, or drill ship.
Drilling from 'bottom supported' installations provides similar conditions to drilling on land. 'Floaters' have to contend with the relative motion between the drilling unit and seabed by tensioning the riser, with its telescopic joint and flexible hoses at the surface and flex or ball joint above the sub-sea BOP stack. The drill string must also be maintained in a constant position in the hole by the use of a heave compensator in the derrick.
The equipment necessary to handle the marine riser, drill string and casing becomes exponentially heavier and more costly with increasing water depth, to the extent that semis and drillships, capable of drilling in up to 10,000ft (3,000m) of water, now cost of the order of ﹩350 million to ﹩500 million to build.
Installation of metallic tube umbilicals in 3,000 meters water
Authors: Dieumegard C. , Fellows P. 
Published: October 2008

Abstract
This paper discusses the design and the installation of steel tube umbilicals for service in 3000 metres water depth. Designs of functional components and umbilical cross sections to cope with the specific requirements of the ultra deep water are reviewed in terms of availability and qualification status. Current installation practice is then reviewed and its inherent limitations are outlined - Limitations which may well be reached sooner rather than later. This paper proposes some means by which these limits can be increased.

Introduction
This paper discusses the development of steel tube umbilicals for service in 3000 metres. Design and qualification status of functional components and umbilical cross section arrangement are reviewed. Areas where further developments are needed are identified, and solutions are proposed to cope with the specific requirements of the ultra deep water.
In a second part, limitations of the current installation practice; conventional 'overboarding' using installation chutes are outlined. Limitations on installation depth achievable with current installation constraints, in terms of tensioner track length and chute radius, are examined.
This paper proposes some means by which these limits can be increased. Predictive modelling of the radial stiffness of umbilical bundles is reviewed and practical methods of increasing radial stiffness, to permit higher values of clamping pressure within the tensioner, are outlined.

Umbilical Design for 3,000 meters water depth
Metallic tube. Tube wall thicknesses are determined according to the ISO-13628-5 standard (which takes into account hoop and radial stress, end cap effect and tensile load). The Collapse resistance (vs. buckle propagation) of the tube is checked according to well-recognised standards such as API 1111 or BS 8010.
Metallic tubes have an intrinsic high resistance to collapse. Therefore in shallow water the governing factor for the determination of the tube wall thickness is the combined effect of pressure and axial tension. However for deep and ultra deep water the collapse resistance (based on the buckle propagation pressure) can be the main factor for the design of the tube wall thickness. It is therefore critical for the umbilical designer to know the exact function of each tube, the characteristics of the conveyed fluid, and the possibility for a tube to be empty, or filled with gas.
Figure 1 presents the tube wall thickness calculated as per ISO-13628-5 standard for several types of tube (from 1" to 2" ID, all 5ksi DWP - SMYS = 620MPa) designed for dynamic application in several water depths (from 500m to 3,000m) and considering the tube designed to be collapse resistant or not.
Subsea Tree Installation, Lessons Learned on a West Africa Development
Authors: Voss Robert , Moore Tony 
Published: October 2008

Abstract
A Subsea Production Development Project was undertaken in West Africa. The Development is a subsea production project in 1200 ft of water. Twenty-eight subsea Horizontal Trees (HT) were installed from 1999 through 2002 in four drill centers over several campaigns. A remaining five trees are scheduled for future installation.
A project was undertaken to review and analyze the field service reports for each of these installations. The scope of this review included the subsea tree, tubing hanger, crown plug, internal tree cap, and debris cap. Ancillary operations such as wear bushing retrieval, bop test tool, straddle sleeve, and bore protector were also included. Other subsea equipment and interfaces were not subject to this analysis in order to maintain focus on the tree itself.
The review of this data had several purposes:To compare the equipment and activity performances against related variables such as rig, personnel, well condition, and environmental conditions.For benchmarking, to establish mean and standard deviations of installation times and other key variable data such as landing loads, pull-out forces, etc.A critical review of the installation procedures against the actual field reports to look for "hidden factories" and other undocumented activities. Based on this review, the procedures were revised to both optimize the process, and ensure the required performance data is recorded.To establish a standard electronic format for the future collection of field tree installation data. This on-line database will be used to maintain baseline performance statistics, identify equipment performance trends, and formally address field failures for complete resolution. The field data will be back-loaded into this existing WELS (Well Electronic Log System) database, and all future tree installations will use this format. This paper will document the results of the West Africa installation data analysis, including:Presenting the installation data in chart and graph format.Drawing conclusions about the equipment performance and effectiveness of the procedures.Making recommendations as to the requirements for a tree installation data collection system.

Introduction

Project and Field Description
The field, discovered May 1997, is located in West Africa in about 1200 ft of water. The operator for and on behalf of joint venture partners decided to develop the first of three phases as a fast-track early production system. First oil was in December 1999, 30 months after discovery and 15 months after contract awards.
Refer to Figure 1 for an illustration of the full field development.
The field is a full subsea development with a local FPSO host. The nature of the field dictated multiple drill centers and pressure maintenance on the natural drive reservoirs. The subsea architecture is a traditional cluster system with discrete wells surrounding central manifolds at each of the three major drill centers. Another key aspect of this development was the desire to maintain a Zero-flare environment for the produced gas.
Cryogenic Flexible for Offshore LNG Transfer
Authors: Cox P.J.C. , Gerez J.-M. , Biaggi J.-P. 
Published: October 2008

Abstract
This paper addresses the conception, development and testing of a cryogenic flexible, and its integration and qualification as part of an overall offshore transfer system. This technological advance has been made possible by Joint Industry Projects (J.I.P.), sponsored by both major Oil & Gas companies, and shipping & service companies. Development is ongoing and an industry Specification is one of the main aims.

Introduction
The industry trend towards the offshore production and transfer of LNG has lead to the requirement for innovative solutions to ensure safety in a marine environment and acceptable operating envelopes between the production units and the shuttle tankers. One solution is the use of a cryogenic flexible as part of an integrated transfer system, for both loading and offloading. The main part of this paper is dedicated to the cryogenic flexible itself, whilst a short second part discusses the system approach.

1.0 Cryogenic Flexible
1.1 Design Basis The characteristics of Liquefied Natural Gas, in particular its temperature of -163°C and the large volumes involved, means that the traditional methods and materials used for the manufacturing of flexibles for offshore use in the Oil and Gas Industry are not acceptable, and that alternative techniques must be used.
At the initial stage of its development, no industry standard existed, however in order for one of the recognised Certification authorities to have a basis upon which to eventually propose such a standard, reference was made to the following:Oil Companies International Marine Forum (OCIMF) "Guide to Purchasing Manufacturing and Testing of Loading and Discharge Hoses for Offshore Moorings", 1991 (OCIMF 91)British Standards (BS), "Specifications for Hose and Hose Assemblies for Liquefied Petroleum Gas", BS 4089, 1989.British Standards (BS), "Flexible Metallic Hose Assemblies", BS 6501, 1991Expansion Joint Manufacturers AssociationCode des Appareils et Pression These parameters cover both the loading and gas return conditions.
The prototype design, whilst being a 16- full bore flexible, allows full extrapolation of all results up to an internal diameter of 24-.
The minimum service life is set at 5 years with a safety factor of 10 relative to fatigue life. Where possible, materials with a proven track record within cryogenic applications were chosen.
A Study on Suction and Scouring of Sit-On-Bottom Type Offshore Structure
Authors: Ninomiya Katsuya , Tagaya Kozo , Murase Yoshihide 
Published: October 2008

Abstract
The authors made reports on the study of the same subject at Offshore Technology Conference held in 1971 1). The conclusions that were announced at the Conference are as follows:As to the suction under freeing-on-bottom of the sit-on-bottom type offshore structure which settles on the sea bed soft cohesive soil:An effective shape of the bottom of the structure against suction is n.The suction mechanism became clear to obtain' practical formulas of the suction force when the suction breaker was not used.As to the scouring by the waves or the tidal current when the sit-on-bottom type offshore structure settles on the sandy soil:A skirted hemispheric leg is most effective against scouring.The characteristics of scouring by the waves or the tidal current became clear. But in the above reports it Was noted that the following problems still remained unsolved:
But in the above reports it was noted that the following problems still remained unsolved:As to Suction: In the formula for obtaining the suction force there are still some unobvious elements.As to Scouring: The method to assume the scouring on the prototype has not been studied yet. The authors made more detailed studies to solve these problems, and have obtained the following conclusions:
The authors made more detailed studies to solve these problems, and have obtained the following conclusions:As to Suction: The suction force consists of the side friction, the viscous force and the bottom adhesion, and the Cogitative calculation became possible of each of these forces.Side Friction: The important factor is the time that the offshore structure is left on the sea bottom after settling, and the relation between the side friction and the settling-time of the structure Was obtained.Viscous Force: The important factors are the width or the diameter of the bottom settling on the sea bed F the pulling velocity and 'the viscosity of soil; and the relation between these three factors and the viscous force Was obtained.Bottom Adhesion Force: The bottom adhesion force depends on the cohesion of soil and the settling-time of the structure, and the relation between these two was obtained.
Wash Pipe Or No Wash Pipe? That is The Question
Authors: Pineda Francisco , Traweek Bryce , Curtis James 
Published: October 2008

Abstract
Conventional gravel pack or frac pack completions typically require the use of wash pipe to act as a conduit for fluid returns as well to carry a shifting mechanism to open or close a return port. Using properly sized wash pipe can enhance the placement of the gravel across the entire annular space and the formation. It can be used in conjunction with a shifting mechanism and a sliding sleeve to force the fluid returns to pass through the bottom of the screen. It can allow a washdown capability while running the assembly into hole. In specialty systems, it can even act as a pumping conduit for post-gravel pack stimulation.
However, the use of wash pipe, especially in long horizontal wells, means the loss of valuable rig time due to make up and break up of the wash pipe, or recovery if the wash pipe is stuck. Economic considerations, along with completion efficiencies, are especially important on deepwater completions. Not using wash pipe reduces rig time, generating significant cost savings, and also eliminates the risk of sticking it.
This paper reviews conventional wash pipe applications and describes new systems that accomplish the same goal with a minimum amount of wash pipe or no wash pipe at all.

Uses of Wash Pipe
The production of formation sand into a well is one of the oldest problems plaguing the oil and gas industry because its adverse effects on well productivity and equipment.1
Gravel packing and frac packing are the methods of choice for sand control. In combination with sand screens they provide downhole filters to prevent production of formation sand. During the execution of these methods, a properly sized sand or proppant has to be placed in the formation as well as the annulus of the screen-casing or screen-open hole using a gravel pack packer assembly with a gravel pack service tool and wash pipe inside the sand screen, with its bottom hanging as close as possible to the end of the screen. This configuration aids the placement of the sand or proppant by allowing the gravel pack fluids to travel down the tubing, through and out the ports of the gravel pack service tool and assembly, down the blank/screen-casing or open hole annulus, into the perforations or open hole, through the screen, up the wash pipe and gravel pack service tool, and into the gravel pack packer-casing annulus.
Wash pipe can also be use as a conduit to allow washdown capabilities when installing screens or liners. In isolation systems, wash pipe is used to run shifting tools to activate sliding sleeves in order to achieve returns during gravel packing.
There are also other economic factors to consider when using wash pipe, such as the valuable rig time necessary for making up, running in and breaking up, especially in horizontal wells, and also in the unfortunate case of fishing if the wash pipe becomes stuck.

Wash Pipe Selection Criteria
Proper selection criteria include strength, material, connection type, and diameter.