Hutton Tension Leg Platform Research Articles

Heave-Restrained Platform Reduces Costs and Eases Operations

Heave-Restrained Platform Reduces Costs and Eases Operations

886294 Hutton tension leg platform foundations: prediction of driven pile behaviour : Jardine, R J; Potts, D M Geotechnique V38, N2, June 1988, P231–252

886294 Hutton tension leg platform foundations: prediction of driven pile behaviour : Jardine, R J; Potts, D M Geotechnique V38, N2, June 1988, P231–252

886293 Hutton tension leg platform foundations: measurement of pile group axial load-displacement relations : Jardine, R J; Hight, D W; McIntosh, W Geotechnique V38, N2, June 1988, P219–230

886293 Hutton tension leg platform foundations: measurement of pile group axial load-displacement relations : Jardine, R J; Hight, D W; McIntosh, W Geotechnique V38, N2, June 1988, P219–230

Hydrocyclones: A Solution to Produced-Water Treatment

Summary Progressing into deeper water and more hostile environments in the search for new oil and gas reserves has placed an increasing demand on the industry to develop lighter, more compact, and more efficient process equipment to replace their traditional counterparts. A recent application of cyclone technology for liquid/liquid separation of oil from produced water has shown considerable promise during extensive field testing. This paper outlines the basic construction and principle of operation of the deoiling hydrocyclone and discusses system design, early operational experiences, and test results from the first full-scale commercial application of the four-in-one hydrocyclone concept on the Murchison platform. In addition, and of perhaps more significance, early results from field tests of the larger 60-mm [2.4-in.] cyclones on the Hutton tension leg platform (TLP), where conventional equipment was adversely affected by platform motion, are discussed.

Hutton tension leg platform foundations: prediction of driven pile behaviour

This Paper describes an approach to the prediction of axial load-displacement relationships for large piled foundations. The method is based on effective stress principles and attempts to take account of the effects of pile installation and equilibration, the possible formation of an interface zone (with reduced frictional strength) near the pile shaft and strongly non-linear soil constitutive behaviour. The theoretical and experimental background of the topic is reviewed and the approach then applied in a finite element analysis of the piled foundations of the Hutton tension leg platform. A superposition procedure is used to estimate group behaviour from predictions made for a single pile. The results are found to give a close match with the four independent foundation compliance parameters measured on-site during platform installation. L'article décit une méthode pour prevoir les relations charge/tassement axiales pour des pieux de grandes dimensions. Cette méthod est basée sur les principes de contrainte effective et tente de tenir compte des effets de l'installation et de l'équilibration des pieux, de la formation éventuelle d'une région d'interface (à resistance par frottement réduite) près du fût du pieu et du comportement constitutif fortement non-linéaire du sol. La base théorique et expérimentale du sujet est passée en revue et la méthode est appliquée à une analyse par éléments finis des pieux d'une plateforme à pieds de traction type Hutton. On emploie une procédure de superposition pour évaluer le comportement du groupe à partir des prédictions faites pour un pieu simple. Les réultats s'accordent bien avec les quatre paramètres indépendants de correspondance des fondations mesurés en place au tours de l'installation du pieu.

Hutton tension leg platform foundations: measurement of pile group axial load-displacement relations

This Paper describes the development of sensitive foundation instrumentation and its use in monitoring the foundation behaviour of the Hutton Tension Leg Platform The TLP installation sequence allowed the pile groups’ initial load-deflexion behaviour to be observed in an almost ideal way, with known large forces being applied as point loadings in a controlled sequence. High quality data were obtained, and these have been used to interpret axial loadsettlement and moment-rotation relationships for the pile groups. Relationships have been determined for displacements with respect to both local and remote datum positions. In general, the foundation response was far stiffer than that expected from the predictive methods routinely used by the offshore industry. L'article décrit la mise au point d'une instrumentation sensitive des fondations et son emploi pour tracer le comportement des plateformes à pieds de traction type Hutton. Le processus d'installation d'une telle plateforme permit l'observation sous des conditions presqu'idéales du comportement initial chargement-deplacement de la part des groupes depieux, de grandes forces connues étant appliquées comme charges ponctuelles dans une séquence contrôlée. Des donnnées de haute qualité furent obtenues et utilisées pour interpréter les rapports charge/tassement et moment/rotation axiaux pour les groupes de pieux. Des relations furent definies pour des déplacements en rapport à des positions de repère locales et lointaines. En général léponse des fondations était beaucoup plus rigide que celle déduit des méthodes de prédiction couramment employées par l'industrie en mer.

Hutton TLP Marine Operations

This paper reviews the planning and execution of the marine operations for the Hutton tension leg platform (TLP), including well template installation, site preparation, foundation installation, temporary anchorages, mating, major tows, and TLP installation. Planning the work to meet project objectives resulted in the use of a number of new techniques and advanced equipment applications. These included underwater pile hammers and special acoustic equipment to provide positioning information during underwater operations. However, the detailed planning that preceded each operation enhanced the effectiveness of the equipment significantly. Further, it contributed materially to the attainment of first oil only 22 days after TLP installation.

Response of Tension Leg Buoy to Vertical Seismic Excitations

The tension leg platform (TLP) has been studied since the 1970 s by Paulling et al., but has not been used so practically excepting Hutton TLP in the North Sea. The main reason is reliability on the strength of the tether. Therefore, most studies on TLP have related to the strength of the tether. The wave response of TLP and the tension of the tether were studied by Paulling, and Yoshida.Since TLP has been said to be an aseismatic structure, the earthquake force has not been considered on designing as an external force to the tether. It is true that the horizontal component of the earthquake can be ignored because the flexural stiffness of the tether is nearly zero. However, the tension fluctuation of the vertical component of the earthquake is an important factor on designing. Studies on the earthquake load of TLP is only little described in Penzien's paper, but it has not yet been clarified. The authors have made for years theoretical and experimental investigations on the earthquake response of TLP.In TLP motion analysis, the problem is usually simplified by idealizing the tether as simple springs. While this approximation appears to be generally adequate for shallow waters. The relative weight ratio (tether/platform) increases very rapidly as the water depth increases. Thus, it is necessary to treat the TLP under the earthquake as a continuous system rather than as a rigid body.In this study, motion equations on a tension leg buoy (TLB), taking the tether weight into consideration, were prepared to clarify the earthquake response.

Requirements for a Nondestructive Inspection System for the Hutton Tension Leg Platform (TLP) Mooring System

The mooring system is one of the most critical and novel aspects of the Hutton tension leg platform (TLP) design. The tension lines of the TLP mooring system are subjected to severe fatigue loading conditions making the continuous assessment of their integrity an essential part of the production operation. To ensure that the mooring system is performing as designed and—more importantly—that no critical damage has been sustained, an in-situ nondestructive examination (NDE) system is being developed. The inspection system requirements to not only detect but also size possible defects in the mooring system’s heavy-walled components necessitates sophisticated ultrasonic transducers be developed. In addition, a variety of micro, mini, and supermini-computers are required to process the large amount of data required to accurately size defects in the body of the components and in the threaded connections. This paper outlines the inspection requirements for the tension legs. The various concepts considered for the in-situ inspection are also discussed. Additionally presented is the ultrasonic inspection concept being developed for this inspection system.

Evaluation of Structural Steel Castings for the Hutton Tension Leg Platform

The use of steel castings as major structural elements of the Hutton tension leg platform represents a relatively novel concept. In order to ensure that these castings would provide adequate service, an extensive testing program was undertaken to assess variations in chemical composition and mechanical properties of prototype castings. In addition, a rigorous acceptance procedure for production castings was developed. The results of these programs showed that steel castings possessed adequate strength and toughness. Also, a welding procedure was developed which consistently produced sound weld repair and satisfactory joints between cast and plate steel.

Selection and Evaluation of High-Strength Steel for Hutton TLP Tension Leg Elements

The development of the tension leg platform (TLP) for the Hutton Field in the North Sea represents the first application of this deepwater concept. The use of vertical tension legs as the mooring system is the most novel part of the TLP design. One of the unique features of the tension legs is the use of 92.5-mm (3.64-in.) thick tubulars forged from 3 1/2 percent Ni-Cr-Mo-V high-strength steel (795 MPa (115.3 ksi) minimum yield strength) as mooring elements. Because of the importance of these elements to the survival of the TLP, the chemical composition and the steelmaking procedure were critically examined and optimized. In addition, extensive evaluation of the corrosion fatigue behavior of the steel was undertaken. This paper discusses the basis for the steel selection and specification, the results of the rigorous corrosion fatigue test program, and the assessment of the variation of properties along the length and through the thickness of full-size components. These results illustrate the suitability of the proposed high-strength steel for the mooring system application and establish confidence in both steelmaking and quality control procedures.

Advanced Offshore Oil Platforms

Four innovative offshore platforms that are designed to withstand 100-foot waves in waters 600-feet deep are described. These platforms are: (1) Stratfjord B Concrete Gravity-Base Platform; (2) Magnus Steel-Template-Jacket Platform; (3) Hutton Tension-Leg Platform; and (4) Block 280 Guyed Tower. The Statfjord B platform, designed in Norway, rests on four massive concrete columns with storage tanks at the base. It depends solely on its own mass for stability. The Magnus platform, designed by the British, is the heaviest offshore platform yet fabricated, weighing 41,000 tons. Two of the platform's four legs will incorporate flotation chambers so that the structure can be floated to its site in the North Sea. The Hutton structure, also designed in England, will consist of a buoyant hull tethered to the sea floor by slender steel tubes at its four corners. The first platform of its type, the Hutton structure is also destined for the North Sea. The US designed Block 280 guyed tower is designed for service in the Gulf of Mexico in water 1000 feet deep. It will be pinned to the sea floor by a spokelike array of 20 steel cables, each one more than 3000 feet long. The tower and its guysmore » will weigh 43,000 tons, slightly more than the Magnus steel-template jacket and more than four time as much as the Eiffel Tower. At a cost of approximately $2.6 billion, the Magnus is the most expensive offshore platform to date. The Statfjord B was put into production in 1982. The Magnus is scheduled for oil production in 1983. The Hutton and the Block 280 will both be producing in 1984. (JMT)« less

The Hutton TLP: A Preliminary Design

Summary This paper presents a preliminary design for a tension leg platform (TLP) to develop the U.K. Hutton field. A platform (TLP) to develop the U.K. Hutton field. A structural design is described with results of performance analyses and model tests. Designs of the facilities, the tension leg system, the foundations, and the well systems also are included. Introduction The TLP that is being designed for the U. K. Hutton field will support all functional requirements for drilling, oil production, personnel accommodation, and ancillary production, personnel accommodation, and ancillary services. The Hutton field lies 144.8 km (90 miles) northeast of the Shetland Islands in 147-m (482-ft) water depth.The TLP is a floating structure connected to anchors fixed in the seabed by vertical mooring lines (tension legs) at each corner of the platform (Fig. 1). These vertical mooring lines virtually eliminate the vertical plane motions of heave, pitch, and roll, while the lateral movements in surge, sway, and yaw are compliantly restrained. Buoyancy is provided by the vertical columns and the horizontal pontoons connecting the bottoms of these columns. An excess of buoyancy greater than the platform weight keeps the mooring lines in tension for all platform weight keeps the mooring lines in tension for all weather and all loading conditions. Column height is sufficient to support the deck above the wave crest elevations for all tide and wave conditions when the TLP is fixed to the seabed foundations by the tension legs.The TLP is installed permanently in the sense that it can resist the effects of extreme environmental conditions and continue operations in the same manner as conventional fixed platforms. The fabrication, outfitting, hookup, and commissioning of the facilities can be completed in onshore fabrication yards and/or inshore completion sites. All components are designed for a minimum of 20 years' service life. Key components such as tension legs and well riser tensioners are simple and intrinsically reliable, have backups, and are replaceable for inspection and maintenance. Individual well risers connect each well to the TLP. These individually tensioned risers safely and reliably withstand the effects of extreme environmental conditions without the need to be disconnected.In the early 1970's, a team of Conoco engineers analyzed subsea production systems for deep water. As a result, they recommended that designs be developed to provide above-water platform space to accommodate provide above-water platform space to accommodate drilling and production facilities in deep water. The tension leg platform was recognized as a potential system with a cost that should be relatively insensitive to water depth. An intensive study concluded that this concept was feasible and could be designed to be reliable.As a consequence of these studies, another in-depth design study was carried out in 1977 on the application of a TLP for development of the Hutton field. In addition, the application of a semisubmersible early production system was investigated. Following a production system was investigated. Following a comprehensive investigation of alternative development methods, including a steel jacket structure, the team recommended the use of a TLP to develop Hutton. The development plan calls for nine wells to be drilled with a plan calls for nine wells to be drilled with a semisubmersible drilling rig before TLP installation. The remaining wells will be drilled from the TLP while previously completed wells are being produced.The development of new technology is greatly enhanced by application to a specific, real project. TLP development studies prior to the Hutton field design study necessarily included numerous alternative solutions. For example, the TLP could be anchored by a gravity base, driven piles, or drilled and grouted piles. Specific environmental conditions, water depth, and soil characteristics can minimize the consideration of certain alternatives before detailed and costly studies are made. The most feasible or preferred solution can be selected early and designers can proceed directly to detailed engineering studies. Vendor support is obtained more easily for a specific real project for which there is a visible and timely application of their effort.This paper describes a preliminary design for the Hutton TLP. JPT P. 208