Address:

Otto Nielsens veg 10

P.O.Box 4125 ValentinlystNO-7450 Trondheim, Norway

Phone: +47 7359 5500

Fax: +47 7359 5776

E-mail: marintek@marintek.sintef.no

Internet: www.marintek.sintef.no

NORWEGIAN MARINE TECHNOLOGY RESEARCH INSTITUTE

ISSN 0801-1818

1 - April - 2006

Contents:

MARINTEK boosts Houston operation ... 1

Turnaround optimi-zation - experiences from RAPID project . 2

Applying SIMLA for evaluation of pipeline stability during installation .... 4

Technical condition of valves .................. 5

Model testing of floating wind turbine facility ...................... 6

Change management – adopting the MTO perspective .............. 7

Underwater position measurements ......... 8

Houston is the oil capital of the world, as is confirmed by a steadily rising level of activity over the past several years. “Everyone” is in Houston, from oil companies to engineering companies and suppliers. Projects all over the world are developed and managed out of Hou-ston. Subjects that attract significant attention include deep water, LNG and extreme hydrody-namic loads. For many years MARINTEK has been heavily involved in technology develop-ment in these and other fields. The hurricanes in the Gulf of Mexico last summer also triggered the industry’s interest in taking another look at the design regimes for risers, pipelines and mooring systems. MARINTEK has a role to play also in this critical area.

Since its opening in 1998, MARINTEK (USA), Inc. has been an important means for MARINTEK to serve its Houston-based clients and offshore development projects. The focus was on marketing and sales, primarily of its laboratory services. Last spring, MARINTEK’s Board of Directors approved a business plan for MARINTEK (USA), Inc. that suggested a new mode of operation for the Houston office: MARINTEK (USA), Inc. should offer services that would be performed locally. The services would be based on MARINTEK software and competencies, including:

MARINTEK boosts Houston operationMARINTEK’s subsidiary in Houston, Texas, MARINTEK (USA), Inc., has entered a new mode of operation since last summer. From being a sales and marketing office primarily promoting MARINTEK’s laboratory services, the company now offers MARINTEK’s expertise as well as local resources for technical services and techno-logy development to customers in Houston and the Gulf of Mexico region.

Cont. on page 2

MARINTEK plays an important role in model testing and verification of moorings and risers for deep water floating installations.

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Norway is the world’s third largest net exporter of crude oil, and a significant supplier of gas to the European market. Statoil is a Norwegian integrated oil and gas company, with more than 25,000 employees worldwide, and with a large number of off-shore production plants, pipelines and land-based facilities. As part of an improvement campaign that is focusing on increased production and reduced maintenance and operational costs, MARINTEK is collaborat-ing with Statoil Research and Development on a project related to turnaround strategies and maintenance that requires shutdown. The project is called RAPID, which stands for “Remove Activities, Prolong Interval and Decrease duration”.

Statoil’s facilities are subject to turna-rounds on a regular basis. The facilities are all linked together in a complex produc-

tion infrastructure that comprises every stage from wells to market. There are

Turnaround optimization - experiences from RAPID project

Since 2003, MARINTEK has been engaged by Statoil to challenge turnaround strategies and the execu-tion of maintenance that requires shutdown. The project was launched because turnarounds are the largest single contributor to reduced produc-tion in Statoil.

Photo: Svein Harald Ledaal, Statoil.

Advanced technical services in marine hydrodynamics and structural engineer-ing

Analyses and calculations: - Extreme loads (slamming, sloshing

etc.) - Special hydrodynamic situations

and/or special structures

Simulation services: - Marine operations - Behaviour and performance of marine

structures, vessels and terminals - Pipelaying

Software sales and support

MARINTEK (USA), Inc. moved into new offices in Houston in December last year. From these offices MARINTEK (USA), Inc., alone or together with MARINTEK (Norway),

offers a variety of technical services, from specialist studies to JIPs on technology development. The basis for the services is the company’s competence in marine hydrodynamics, structural engineering and operations technology (maintenance and logistics/supply-chain management) devel-oped at MARINTEK in Trondheim over the past 50 years. This expertise is avail-able in the form of a series of high-quality computer programs, many of which are regarded as industry standards.

MARINTEK (USA), Inc.11999 Katy Freeway, Suite 490Houston, TX, 77079, USA

Tel. 281-854-2589 Fax 281-854-2588 E-mail: info@marintekusa.com

MARINTEK boosts Houston ...Cont. from page 1

Cont. next page

MARINTEK (USA), Inc. has moved into new offices.

Heidrun TLP.

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differences between offshore and onshore turnaround practice. Onshore, the typical interval between turnarounds is five years, the duration is four weeks and the scope, around 150,000 man-hours. Offshore, the typical interval is between one and two years, the duration is two to three weeks and it involves between 14,000 and 90,000 man-hours of work. The work is performed by a single contractor offshore and onshore by a group of individual contractors for each work package. Offshore turnaround planning is typically constrained by weather conditions, the availability of skilled person-nel, transport of spares, personnel and materials (supply ship, helicopter), offshore berths, offshore storage capacity and avail-able workspace.

In our concept we have worked along three axes: Removing activities that may lead to production losses, prolonging intervals between such activities and decreasing the duration of both activities and the whole turnaround process.

Remove activities

Removing activities reduces the scope of the turnaround and opens the possibility of shorter turnarounds. Some of the solutions/results provided are:

Work Scope Challenge – a systematic approach to challenging the scope of work. The methodology is programmed and implemented in the maintenance management administration system SAP.

Utilization of unplanned production shutdowns – when an unforeseen shutdown occurs the managers have only a short time to respond. Tradition-ally, quick return to full production is stressed and maintenance is only included if possible. The methodol-ogy includes guidelines to challenge the existing mindset by extending the shutdown period to perform additional maintenance that requires shutdown, if this can be shown to be cost-effec-tive. This requires that all activities are well documented, prepared and known by the involved parties. The strategy is ambitious and requires procedures, tools and training to support the deci-sion-makers and the support chain.

Improved or new inspection methods – mapping of methodologies that are capable of verifying the technical condition of process equipment without having to open it (shutdown or reducing production).

Improved or new methods to perform “hot work” during operation – survey-

Photo: Kjetil Alsvik. Statoil.

ing “hot work” technology, e.g. welding habitats, hot tapping, various methods of cold cutting/grinding etc.

Prolong intervals

Under this heading condition monitoring once again becomes important. Since one important component of the maintenance performed during a turnaround is mechani-cal condition assessment, there is a need for better, more widespread use of condition monitoring. This aspect also includes map-ping methods for temporary repair of minor faults in pipework with a view to making it last until the next repair opportunity.

Decrease duration

The duration of a turnaround offshore is normally determined by a few critical jobs (critical path). Some of the solutions/results provided are:

Methodology to challenge critical jobs - by restructuring the tasks and improve maintainability it is possible to cut down the duration considerably.

Mapping of Cleaning In Place (CIP) tech-nology - many larger tasks are related to tanks and pressure vessels and involves cleaning. Utilizing and preparing for the use of CIP technology offers the poten-tially considerable time savings.

Modeling and optimization

The RAPID project has focused on optimizing shutdowns/turnarounds on individual offshore platforms (“bottom-up approach”). Another approach is to optimize shutdown/turnarounds seen from a corporate level, from wells to market (“top-down approach”). MARINTEK and Statoil Research and Development have now launched efforts to develop a decision-sup-port tool to improve long-term planning from a “top-down” perspective.

MARINTEK contact:TomAnders.Thorstensen@marintek.sintef.noTurnaround at Sleipner - modification of the deluge system.

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By utilising SIMLA, which has been devel-oped by MARINTEK for Norsk Hydro, the contribution from bending stiffness of the pipe can be included, and the constraints of the pipe aft of the touchdown will be simulated in a realistic way, as the software makes use of a proper 3D terrain model. Furthermore, instability at specific loca-tions is not necessarily regarded as critical if it can be shown that the pipe slides into a stable configuration. Utilizing recently developed functionality in SIMLA (the FEED approach), sliding of the pipe can be studied numerically.

Recommended analysis procedure

When SIMLA is applied for the evaluation of laying stability the recommended analysis and evaluation procedure is as follows:

I. Agree on geotechnical input to be used in the analysis

II. Convert geotechnical input to pipe/soil interaction models

III. Screening analysis A. Identify possible challenging areas

IV. Evaluation of challenging areas in view of:

A. Contact force build-up B. Soil type C. Seabed topography

V. Apply the FEED analysis approach for the remaining challenging areas

A. Determine whether sliding might be a problem

Screening analysis

This approach is used to screen potentially critical locations with respect to stability. The SIMLA screening approach can be regarded as a repeated sequence of static solutions in which the pipe configuration is stepped along a planned numerical route. The correct pipe properties and soil stiff-ness parameters are mapped to the model as a function of the kilometre point (KP) for the current location.

The result of a screening analysis is illus-trated in Figure 2. As the plot shows, the capacity curve indicating the available fric-tion factor will vary depending on location.

As can also be seen from Figure 2, at some

areas along the route the calculated neces-sary friction factor (red curve) crosses the available capacity curve. Such locations need to be examined in more detail.

FEED analysis

The FEED approach has been developed for detailed study of particularly challenging areas. In this model the lay vessel is moved and new elements are introduced from the vessel. This approach thus provides a more physically correct analysis where the history of a node in the finite element model is known. In this case axial friction, as well as on-bottom sliding and possible yielding of pipe material, can be modelled.

Applying SIMLA for evaluation of pipeline stability during installation

Due to the rough seabed terrain in the deepwater area of the Ormen Lange field (Figure 1) stability during installa-tion is an important issue.

Simplified 2D evaluation methods do not take the con-tribution from bending stiffness of the pipe into account. In large-diameter pipes, bending stiffness will distribute the lateral reaction force from the seabed over a signifi-cant length in the touchdown area, and this therefore needs to be taken into account when evaluating stability during installation.

Figure 1. The Ormen Lange deepwater area.

Figure 2. Results from a SIMLA screening analysis – Stability vs KP.

Cont. next page

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As mentioned above, this approach allows the pipe to slide relative to the pipe route. In such cases it is important to note that even if the pipe has been evaluated as unstable relative to the centre-line of the pipe route, it may still be stable within the route corridor.

Figure 3 shows a close-up of a specific pipe route location with a 10 m wide route corri-dor and with the pipe configuration being a result of a FEED analysis. Initial contact has been established to the left of the centre-line.

However, since the route enters a right-hand curve at this location, and since the FEED analysis approach allows for lateral sliding of the pipe, the as-laid pipe configuration ends up to the right of the route centre-line.

The FEED approach makes it possible to evaluate lateral stability within the route cor-ridor, which offers more flexibility in particu-larly challenging areas. If this approach is used for screening purposes, the result will typically be that some of the peaks in the calculated necessary lateral friction factor are removed.

Figure 3. Pipe sliding within route corridor.

While testing whether or not the valve can be closed is a relatively simple task, determining the internal leakage rate is quite complex. Traditional methods require clos-ing the valves for a lengthy period of time, which in many cases necessitates closing production and leading to high testing costs.

A CORD project led by MARINTEK is at-tempting to identify and test methods and technologies for determining the technical condition of ESDVs with regard to internal leakage. A number of companies offer condition-monitoring technology based on

leakage detection by acoustics or dynamic pressure. Such systems have been installed on several installations on the Norwegian continental shelf, but maintenance per-sonnel are reluctant to base maintenance decisions on the measurements from these systems. It is therefore necessary to carry out tests under controlled conditions to de-termine the ability of available technologies and methods to provide qualitative and/or quantitative measures of internal leakage through the valves.

MARINTEK is currently building facilities at SINTEF’s Multiphase Laboratory at Tiller

Technical condition of valvesOffshore installations are fitted with special purpose valves that section the processing plant into segments in case of an emergency (Emergency Shut Down Valves, ESDV), the purpose being to limit the quantity of hydrocarbons which could leak and sustain a fire. The valves must be tested periodically with regard to function (i.e. ability to close) and internal leakage.

in Trondheim with the aim of carrying out testing in 2006, and the test programme start-up is expected to take place in April.

MARINTEK contact:Anders.Valland@marintek.sintef.no

MARINTEK contact: Egil.Giertsen@marintek.sintef.no

Leakage detection by comparing noise in cavity with flowline noise.

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Our model was built to a scale of 1:47. Model production was challenging due to strict weight limitations. The rotor blades for the wind turbine had to be made from carbon fibre and epoxy, and vacuum casting was used in order to obtain the correct shape.

Model testing of floating wind turbine facilityMARINTEK carried out model testing of a 5MW floating wind turbine facility for deepwater locations (>300 m) on contract for Norsk Hydro in October/November 2005. The full-scale structure measures almost 202 m from the keel to the top of the tower and the radius of the rotor is 61.5 m. The struc-ture is to be held in place by three mooring lines, each split into two delta-lines at the upper end.

The floating wind turbine model in still water. Note the reflections from the position measure-ment devices mounted on the column.

The floating structure behaved well in waves. We tested four different sea states with wave heights ranging from Hs = 3 m to Hs = 14 m.

The main objectives of the tests were to study the behaviour of the structure under loading from waves and wind, investigate the effects of various ways of controlling the power output and finally, to provide data for verification and validation for computer simulation programs.

The conventional way of controlling the power output of a wind turbine, when the relative wind speed is high, is to keep the rotation speed constant and adjust the pitch angle of the rotor blades. This approach introduces negative damping in the system. Such negative damping is not particularly dramatic for land-based structures, but might have important consequences for the dynamics of floating structures. In order to investigate the effect of negative damping in the model tests, it was necessary to obtain the same thrust characteristics as in full scale. Due to scale effects, the thrust level in the model tests was lower than in full scale, but the slope of the thrust-versus-windspeed curve was reproduced well in the model tests, thus enabling us to study the effect of negative damping introduced by the rotor.

It is clear from the model tests that the method, by which the wind turbine power output is controlled, has an impact on the pitch response of the floating structure.

MARINTEK contact:Rune.Yttervik@marintek.sintef.no

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Working together in new ways, using new communication technology and work-ing closer with personnel with different competence are all challenging tasks. It is important to take into account the human and organisational aspects in these change processes. The term MTO (Man, Technology and Organisation) covers these aspects.

Together with SINTEF and IFE, MARINTEK has developed a methodology called CORD MTO. This development project has been supported by Statoil, Hydro, ConocoPhil-lips and BP, and these companies are the owners of the methodology. CORD MTO is primarily an assistant to the change pro-cesses involved in Integrated Operations. The methodology was primarily developed

Change management – adopting the MTO perspectiveThe offshore industry is focusing on e-operation, remote operation and Integrated Operations. Preparation for tail production from some installations and the introduction of new technology are two reasons for these new opera-tional modes. Cost-effective tail production is a chal-lenge, and new technology such as fibre-optic cables, condition monitoring equipment and new communication systems have introduced new operational opportunities. Integrated Operation means more than remote opera-tion or e-operation; it also implies closer cooperation between the land and offshore organisations, not to mention interdisciplinary cooperation.

working environment and work organisa-tion. The application of the CORD MTO methodology is run by a dedicated project team which may bring in representatives from the operators. The methodology is divided into three main steps; • Operational experience review• Analysis and allocation of functions• Work organisation.

The mapping and clarification of visions and goals is an important part of an iterative process.

The CORD MTO methodology has been tested by the oil companies throughout 2005. The pilots highlighted various aspects, from reallocation of functions from offshore to onshore facilities, to the use of new “cooperation rooms”. More advanced multidisciplinary cooperation requires additional competence and know-ledge and one project focused on the need for collaboration training in order to be prepared for Integrated Operations.

More advanced technology and equipment for condition monitoring is an important part of Integrated Operation. Maintenance performance will change and these change processes will be the main area of focus on CORD MTO methodology in MARINTEK in the near future. MARINTEK will also evaluate the use of CORD MTO for change manage-ment processes in the shipping industry. Successful implementation of new techno-logy depends on a thorough consideration of man, technology and organisational aspects.

MARINTEK contact:Lisbeth.Hansson@marintek.sintef.no

Participants and collaboration in Integrated Operations.

to support the change process involved in reallocating functions between offshore and onshore facilities, but the application area has later proved to be highly suitable for change processes in general. The MTO perspective is an essential aspect of the methodology.

The CORD MTO methodology employs scenarios to analyse functions and pos-sible function allocations (between man and machine and between, for example, onshore and offshore facilities), and ensures that both normal operating condi-tions and operational discrepancies are subjected to analysis. The methodology provides a good foundation for detailed design and later verification of the resulting

Schematic overview of the CORD MTO method.

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Measurement principle

The principle for optical 3D measurements is simple: Let two cameras observe the same object point, for example a marker on a model. Each camera observes the object point at a specific image position. If we know the camera positions and orientations and the focal lengths of the camera objec-tives, we can use these 2D image positions to calculate lines of sight from each camera to the marker. The 3D position of the marker is found where the lines of sight intersect.

Real systems

Of course, there are more details to a real measurement system than this: The positions and orientations of the cameras, for example, have to be determined by a separate calibration process. The optical aberrations of the cameras must also be

corrected. And special markers are needed to make the detection process robust.

6DOF

In order to calculate the position and orien-tation (six degrees of freedom, abbreviated 6DOF) of a model in the global coordinate system we must equip it with three or more markers having known 3D positions in the model’s local coordinate system.

Measuring under water

When we employ this measurement system under water several further issues emerge:

Camera housingThe cameras must be placed in watertight housings.

MarkersFor our traditional in-air measurements we use both passive markers made of retro-reflective material and active markers that emit light themselves. The latter alterna-tive has a longer measurement range. It is difficult to make such active markers for use under water, so at pre-sent we use the passive variant. This means that we need to select a retro-reflective material that has

optimal mechanical and optical properties for underwater use.

LightIn order to maximise the measurement range the light used to illuminate the markers must be optimized to have as little absorption in water as possible.

The air-water interfaceThe cameras sit in air inside their hous-ings and observe the submerged markers through a glass window. This distorts the image geometry, and the image linearization algorithm must correct for this effect.

Project status

Last year we built prototype watertight camera housings, while Qualisys equipped the cameras with new light sources and modified the imaging linearization algorithm. The test results were very promising. We cali-brated the system successfully and made sev-eral measurements with good measurement accuracy. Based on the experience gained from the tests, Qualisys and MARINTEK will now make further optimizations, and we plan to have an operational system later this year.

Applications

Some areas in which underwater position measurement is of great interest are- subsea installations- risers/flowlines motions and interactions- motions of subsurface bodies

MARINTEK contact:Jorn.Jensen@marintek.sintef.no

Qualisys contact:fredrik.muller@qualisys.se

Underwater position measurementsMARINTEK has measured the position and orientation of ship and platform models optically for nearly 25 years. Until 1998 we used a measurement system developed here at MARINTEK. Since then we have used a commercial system produced by the Swedish company Qualisys AB (www.qualisys.com).

There is currently a growing interest in position measurements for underwa-ter models. Therefore we are now cooperating with Qualisys to modify the measurement system so that it can operate under water.

Camera mounted in watertight housing.

Sketch of the measurement principle.

Calibration of measurement system.