Offshore General Introduction Analysis

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ESDEP WG 15A

STRUCTURAL SYSTEMS: OFFSHORE

Lecture 15A.1: Offshore Structures:

General IntroductionOBJECTIVE/SCOPE

To identify the basic vocabulary, to introduce the major concepts for offshore platform structures, and to explain where the basic structuralrequirements for design are generated.

PREREQUISITES

None.

SUMMARY

The lecture starts with a presentation of the importance of offshore hydro-carbon exploitation, the basic steps in the development process (fromseismic exploration to platform removal) and the introduction of the major structural concepts (jacket-based, GBS-based, TLP, floating). The

major codes are identified.

For the fixed platform concepts (jacket and GBS), the different execution phases are briefly explained: design, fabrication and installation.Special attention is given to some principles of topside design.

A basic introduction to cost aspects is presented.

Finally terms are introduced through a glossary.

1. INTRODUCTION

Offshore platforms are constructed to produce the hydrocarbons oil and gas. The contribution of offshore oil production in the year 1988 to theworld energy consumption was 9% and is estimated to be 24% in 2000.

The investment (CAPEX) required at present to produce one barrel of oil per day ($/B/D) and the production costs (OPEX) per barrel are

depicted in the table below.

World oil production in 1988 was 63 million barrel/day. These figures clearly indicate the challenge for the offshore designer: a growingcontribution is required from offshore exploitation, a very capital intensive activity.

Figure 1 shows the distribution of the oil and gas fields in the North Sea, a major contribution to the world offshore hydrocarbons. It alsoindicates the onshore fields in England, the Netherlands and Germany.

Condition CAPEX $/B/D OPEX $/B

Conventional

Average 4000 - 8000 5

Middle East 500 - 3000 1

Non-Opec 3000 - 12000 8

Offshore

North Sea 10000 - 25000 5 - 10

Deepwater 15000 - 35000 10 - 15

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2. OFFSHORE PLATFORMS

2.1 Introduction of Basic Types

The overwhelming majority of platforms are piled-jacket with deck structures, all built in steel (see Slides 1 and 2).




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Slide 1 : Jacket based platform - Southern sector North Sea

Slide 2 : Jacket based platform - Northern sector North Sea

A second major type is the gravity concrete structure (see Figure 2), which is employed in the North Sea in the Norwegian and British sectors.




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A third type is the floating production unit.

2.2 Environment

The offshore environment can be characterized by:

water depth at location soil, at seabottom and in-depth wind speed, air temperature waves, tide and storm surge, current ice (fixed, floes, icebergs) earthquakes (if necessary)

The topside structure also must be kept clear of the wave crest. The clearance (airgap) usually is taken at approximately 1,50 m, but should beincreased if reservoir depletion will create significant subsidence.

2.3 Construction

The environment as well as financial aspects require that a high degree of prefabrication must be performed onshore. It is necessary to design tolimit offshore work to a minimum. The overall cost of a man-hour offshore is approximately five times that of an onshore man-hour. The cost ofconstruction equipment required to handle loads, and the cost for logistics are also a magnitude higher offshore.

These factors combined with the size and weight of the items, require that a designer must carefully consider all construction activities betweenshop fabrication and offshore installation.

2.4 Codes

Structural design has to comply with specific offshore structural codes. The worldwide leading structural code is the API-RP2A [1]. The recentlyissued Lloyds rules [2] and the DnV rules [3] are also important.

Specific government requirements have to be complied with, e.g. in the rules of Department of Energy (DoE), Norwegian Petroleum Direktorate(NPD). For the detail design of the topside structure the AISC-code [4] is frequently used, and the AWS-code [5] is used for welding.




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In the UK the Piper alpha diaster has led to a completely new approach to regulation offshore. The responsibility for regulatory control has beenmoved to the Health and Safety Executive (HSE) and the operator has to produce a formal safety assessment (TSA) himself instead of complyingwith detailed regulations.

2.5 Certification and Warranty Survey

Government authorities require that recognized bodies appraise the aspects of structural integrity and issue a certificate to that purpose.

The major certification bodies are:

Det norske Veritas (DnV) Lloyds Register of Shipping (LRS) American Bureau of Shipping (ABS) Bureau Veritas (BV) Germanischer Lloyd (GL)

Their requirements are available to the designer [2, 3, 6, 7, 8].

Insurance companies covering transport and installation require the structures to be reviewed by warranty surveyors before acceptance. Thewarranty surveyors apply standards, if available, on a confidential basis.

3. OFFSHORE DEVELOPMENT OF AN OIL/GAS FIELD

3.1 Introduction

The different requirements of an offshore platform and the typical phases of an offshore development are summarized in [9]. After several initialphases which include seismic field surveying, one or more exploration wells are drilled. Jack-up drilling rigs are used for this purpose for waterdepths up to 100 - 120 m; for deeper water floating rigs are used. The results are studied and the economics and risks of different development

plans are evaluated. Factors involved in the evaluation may include number of wells required, fixed or floated production facilities, number ofsuch facilities, and pipeline or tanker off-loading.

As soon as exploitation is decided and approved, there are four main technical activities, prior to production:

engineering and design fabrication and installation of the production facility drilling of production wells, taking 2 - 3 months/well providing the off loading system (pipelines, tankers, etc.).

The drilling and construction interaction is described below for two typical fixed platform concepts.

3.2 Jacket Based Platform for Shallow Water

First the jacket is installed. The wells are then drilled by a jack-up drilling unit standing close by with a cantilever rig extending over the jacket.Slide 3 shows a jack-up drilling unit with a cantilever rig. (In this instance it is engaged in exploratory drilling and is therefore working inisolation.)

Slide 3 : Cantilevered drilling rig: Self-elevating (jack-up) exploration drilling platform.

Design and construction of the topside are progressed parallel to the drilling, allowing production to start soon after deck installation. For furtherwells, the jack-up drilling unit will be called once again and will reach over the well area of the production deck.

As an alternative to this concept the wells are often accommodated in a separate wellhead platform, linked by a bridge to the production platform(see Slide 1).




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3.3 Jacket and Gravity Based Platform for Deep Water

The wells are drilled from a drilling rig on the permanent platform (see Slide 2). Drilling starts after the platform is built and completelyinstalled. Consequently production starts between one and two years after platform installation.

In recent years pre-drilled wells have been used to allow an earlier start of the production. In this case the platform has to be installed exactlyabove the pre-drilled wells.

4. JACKETS AND PILE FOUNDATION

4.1 Introduction

Jackets, the tower-like braced tubular structures, generally perform two functions:

They provide the substructure for the production facility (topside), keeping it stable above the waves. They support laterally and protect the 26-30 inch well conductors and the pipeline riser.

The installation methods for the jacket and the piles have a profound impact on the design.

4.2 Pile Foundation

The jacket foundation is provided by open-ended tubular steel piles, with diameters up to 2m. The piles are driven approximately 40 - 80 m, andin some cases 120 m deep into the seabed.

There are basically three types of pile/jacket arrangement (see Figure 3):

Pile-through-legconcept, where the pile is installed in the corner legs of the jacket.

Skirt pilesthrough pile sleeves at the jacket-base, where the pile is installed in guides attached to the jacket leg. Skirt piles can be grouped inclusters around each of the jacket legs.

Vertical skirt pilesare directly installed in the pile sleeve at the jacket base; all other guides are deleted. This arrangement results in reducedstructural weight and easier pile driving. In contrast inclined piles enlarge the foundation at the bottom, thus providing a stiffer structure.

4.3 Pile Bearing Resistance

Axial load resistance is required for bearing as well as for tension. The pile accumulates both skin friction as well as end bearing resistance.




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Lateral load resistance of the pile is required for restraint of the horizontal forces. These forces lead to significant bending of the pile near to theseabed.

Number, arrangement, diameter and penetration of the piles depend on the environmental loads and the soil conditions at the location.

4.4 Corrosion Protection

The most usual form of corrosion protection of the bare underwater part of the jacket as well as the upper part of the piles in soil is by cathodicprotection using sacrificial anodes. A sacrificial anode (approximate 3 kN each) consists of a zinc/aluminium bar cast about a steel tube and

welded on to the structures. Typically approximately 5% of the jacket weight is applied as anodes.

The steelwork in the splash zone is usually protected by a sacrificial wall thickness of 12 mm to the members.

5. TOPSIDES

5.1 Introduction

The major functions on the deck of an offshore platform are:

well control support for well work-over equipment separation of gas, oil and non-transportable components in the raw product, e.g. water, parafines/waxes and sand support for pumps/compressors required to transport the product ashore power generation

accommodation for operating and maintenance staff.

There are basically two structural types of topside, the integrated and modularized topside which are positioned either on a jacket or on aconcrete gravity substructure.

5.2 Jacket-based Topsides

5.2.1 Concepts

There are four structural concepts in practice. They result from the lifting capacity of crane vessels and the load-out capacity at the yards:

the single integrated deck (up to approx 100 MN) the split deck in two four-leg units the integrated deck with living quarter module the modularized topside consisting of module support frame (MSF) carrying a series of modules.

Slide 4 shows an integrated deck (though excluding the living quarters and helideck) being moved from its assembly building.

Slide 4 : Integrated topside during load out

5.2.2 Structural Design for Integrated Topsides

For the smaller decks, up to approximately 100 MN weight, the support structure consists of trusses or portal frames with deletion of diagonals.

The moderate vertical load and shear per column allows the topside to be supported by vertical columns (deck legs) only, down to the top of thepiles (situated at approximately +4 m to +6 m L.A.T. (Low Astronomic Tide).

5.2.3 Structural Design for Modularized Jacket-based Topsides




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A major modularized topside weighs 200 to 400 MN. In this case the MSF is a heavy tubular structure (Figure 4), with lateral bracing down tothe top of jacket.

5.3 Structural Design for Modularized Gravity-based Topsides

The topsides to be supported by a gravity-based substructure (see Figure 2) are in a weight range of 200 MN up to 500 MN.

The backbone of the structure is a system of heavy box-girders with a height of approximately 10 m and a width of approximately 12 - 15 m (seeFigure 5).




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The substructure of the deck is rigidly connected to the concrete column and acts as a beam supporting the deck modules. This connectionintroduces wave-induced fatigue in the deck structure. A recent development, foreseen for the Norwegian Troll platform, is to provide a flexibleconnection between the deck and concrete column, thus eliminating fatigue in the deck [10].

6. EQUIPMENT AND LIVING QUARTER MODULES

Equipment modules (20-75 MN) have the form of rectangular boxes with one or two intermediate floors.

The floors are steel plate (6, 8 or 10 mm thick) for roof and lower floor, and grating for intermediate floors.

In living quarter modules (5-25 MN) all sleeping rooms require windows and several doors must be provided in the outer walls. This requirementcan interfere seriously with truss arrangements. Floors are flat or stiffened plate.

Three types of structural concepts, all avoiding interior columns, can be distinguished:

conventional trusses in the walls. stiffened plate walls (so called stressed skin or deck house type). heavy base frame (with wind bracings in the walls).

7. CONSTRUCTION

7.1 Introduction

The design of offshore structures has to consider various requirements of construction relating to:

1. fabrication.2. weight.3. load-out.4. sea transport.5. offshore installation.6. module installation.7. hook-up.8. commissioning.

A documented construction strategy should be available during all phases of the design and the actual design development should be monitoredagainst the construction strategy.




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Construction is illustrated below by four examples.

7.2 Construction of Jackets and Topsides

7.2.1 Lift Installed Jackets

The jacket is built in the vertical (smaller jackets) or horizontal position (bigger jackets) on a quay of a fabrication site.

The jacket is loaded-out and seafastened aboard a barge. At the offshore location the barge is moored alongside an offshore crane vessel.

The jacket is lifted off the barge, upended from the horizontal, and carefully set down onto the seabed.

After setting down the jacket, the piles are installed into the sleeves and, driven into the seabed. Fixing the piles to the jacket completes theinstallation.

7.2.2 Launch Installed Jackets

The jacket is built in horizontal position.

For load-out to the transport barge, the jacket is put on skids sliding on a straight track of steel beams, and pulled onto the barge (Slide 5).

Slide 5 : Jacket being loaded onto barge by skidding

At the offshore location the jacket is slid off the barge. It immerses deeply into the water and assumes a floating position afterwards (see Figure6).




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Two parallel heavy vertical trusses in the jacket structure are required, capable of taking the support reactions during launching. To reduce forcesand moments in the jacket, rocker arms are attached to the stern of the barge.

The next phase is to upright the jacket by means of controlled flooding of the buoyancy tanks and then set down onto the seabed. Self-upendingjackets obtain a vertical position after the launch on their own. Piling and pile/jacket fixing completes the installation.

7.2.3 Topsides for a Gravity-Based Structure (GBS)

The topside is assembled above the sea on a temporary support near a yard. It is then taken by a barge of such dimensions as to fit between thecolumns of the temporary support and between the columns of the GBS. The GBS is brought in a deep floating condition in a sheltered site, e.g.a Norwegian fjord. The barge is positioned between the columns and the GBS is then deballasted to mate with and to take over the deck from the

barge. The floating GBS with deck is then towed to the offshore site and set down onto the seabed.

7.2.4 Jacket Topsides

For topsides up to approximately 120 MN, the topside may be installed in one lift. Slide 6 shows a 60 MN topside being installed by floatingcranes.




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Slide 6 : Installation of 60MN K12-BP topside by floating crane

For the modularized topside, first the MSF will be installed, immediately followed by the modules.

7.3 Offshore Lifting

Lifting of heavy loads from barges (Slide 6) is one of the very important and spectacular construction activities requiring a focus on the problemwhen concepts are developed. Weather windows, i.e. periods of suitable weather conditions, are required for these operations.

7.3.1 Crane Vessel

Lifting of heavy loads offshore requires use of specialized crane vessels. Figure 7 provides information on a typical big, dual crane vessel. Table1 (page 16) lists some of the major offshore crane vessels.

7.3.2 Sling-arrangement, Slings and Shackles




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Notes:

1. Rated lifting capacity in metric tonnes.2. When the crane vessels are provided with two cranes, these cranes are situated at the vessels stern or bow at approximately 60 m distance

c.t.c.

1. 3. Rev = Load capability with fully revolving crane.

Fix = Load capability with crane fixed.

7.4 Sea Transport and Sea Fastening

Transportation is performed aboard a flat-top barge or, if possible, on the deck of the crane vessel.

The module requires fixing to the barge (see Figure 9) to withstand barge motions in rough seas. The sea fastening concept is determined by thepositions of the framing in the module as well as of the "hard points" in the barge.

7.5 Load-out

7.5.1 Introduction

For load-out three basic methods are applied:

skidding platform trailers shearlegs.

7.5.2 Skidding




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Skidding is a method feasible for items of any weight. The system consists of a series of steel beams, acting as track, on which a group of skidswith each approximately 6 MN load capacity is arranged. Each skid is provided with a hydraulic jack to control the reaction.

7.5.3 Platform Trailers

Specialized trailer units (see Figure 10) can be combined to act as one unit for loads up to 60 - 75 MN. The wheels are individually suspendedand integrated jacks allow adjustment up to 300 mm.

The load capacity over the projected ground area varies from approximately 55 to 85 kN/sq.m.

The units can drive in all directions and negotiate curves.

7.5.4 Shearlegs

Load-out by shearlegs is attractive for small jackets built on the quay. Smaller decks (up to 10 - 12 MN) can be loaded out on the decklegs pre-positioned on the barge, thus allowing deck and deckleg to be installed in one lift offshore.

7.6 Platform Removal

In recent years platform removal has become common. The mode of removal depends strongly on the regulations of the local authorities.Provision for removal should be considered in the design phase.

8. STRUCTURAL ANALYSIS

8.1 Introduction




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The majority of structural analyses are based on the linear theory of elasticity for total system behaviour. Dynamic analysis is performed for thesystem behaviour under wave-attack if the natural period exceeds 3 seconds. Many elements can exhibit local dynamic behaviour, e.g.compressor foundations, flare-stacks, crane-pedestals, slender jacket members, conductors.

8.2 In-place Phase

Three types of analysis are performed:

Survival state, under wave/current/wind attack with 50 or 100 years recurrence period.

Operational state, under wave/current/wind attack with 1 or 5 years recurrence period, under full operation. Fatigue assessment. Accidental.

All these analyses are performed on the complete and intact structure. Assessments at damaged structures, e.g. with one member deleted, andassessments of collision situations are occasionally performed.

8.3 Construction Phase

The major phases of construction when structural integrity may be endangered are:

Load-out Sea transport Upending of jackets Lifting.

9. COST ASPECTS

9.1 Introduction

The economic feasibility of an offshore project depends on many aspects: capital expenditure (CAPEX), tax, royalties, operational expenditure(OPEX).

In a typical offshore field development, one third of the CAPEX is spent on the platform, one third on the drilling of wells and one third on thepipelines.

Cost estimates are usually prepared in a deterministic approach. Recently cost-estimating using a probabilistic approach has been developed andadopted in major offshore projects.

The CAPEX of an installed offshore platform topside amounts to approximately 20 ECU/kg.

9.2 Capital Expenditure (CAPEX)

The major elements in the CAPEX for an offshore platform are:

project management and design material and equipment procurement fabrication transport and installation hook-up and commissioning.

9.3 Operational Expenditure (OPEX)

In the North Sea approximately 20 percent of OPEX are required for offshore inspection, maintenance and repair (IMR).

The amount to be spent on IMR over the project life can add up to approximately half the original investment.

IMR is the area in which the structural engineer makes a contribution by effort in design, selection of material, improved corrosion protection,accessibility, basic provisions for scaffolding, avoiding jacket attachments dangerous to divers, etc.

10. DEEP WATER DEVELOPMENTS

Deep water introduces a wide range of extra difficulties for the operator, the designer and constructor of offshore platforms.

Fixed platforms have recently been installed in water of 410 m. depth, i.e. "Bullwinkle" developed by Shell Oil for a Gulf of Mexico location.The jacket weighed nearly 500 MN.

The maximum depth of water at platform sites in the North Sea is approximately 220 m at present. The development of the Troll field situated inapproximately 305 m deep water is planned for 1993.




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In the Gulf of Mexico and offshore California several fixed platforms in water depths of 250 - 350 m are in operation (Cerveza, Cognac). Exxonhas a guyed tower platform (Lena) in operation in 300 m deep water.

An option for deeper locations is to use subsea wells with flowlines to a nearby (approximately maximum 10 km) fixed platform at a smallerwater depth. Alternatively subsea wells may be used with flexible risers to a floating production unit. Subsea wells are now feasible for 300 - 900m deep water. The deepest wells have been developed off Brasil in moderate weather conditions.

The tension leg platform (TLP) seems to be the most promising deepwater production unit (Figure 11). It consists of a semi-submersiblepontoon, tied to the seabed by vertical prestressed tethers. The first TLP was Hutton in the North Sea and recently TLP-Jolliet was installed at a530 m deep location in the Gulf of Mexico. Norwegian Snorre and Heidrun fields have been developed with TLPs as well.

11. CONCLUDING SUMMARY

The lecture starts with the presentation of the importance of offshore hydro-carbon exploitation, the basic steps in the development process(from seismic exploration to platform removal) and the introduction of the major structural concepts (jacket-based, GBS-based, TLP,floating).

The major codes are identified. For the fixed platform concepts (jacket and GBS), the different execution phases are briefly explained: design, fabrication and installation.

Special attention is given to the principles of topside design. A basic introduction to cost aspects is presented. Finally terms are introduced within a glossary.

12. GLOSSARY OF TERMS

AIR GAP Clearance between the top of maximum wave and underside of the topside.




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CAISSONS See SUMPS

CONDUCTORS The tubular protecting and guiding the drill string from the topside down to 40 to 100m under the sea bottom. After drilling itprotects the well casing.

G.B.S. Gravity based structure, sitting flatly on the sea bottom, stable through its weight.

HOOK-UP Connecting components or systems, after installation offshore.

JACKET Tubular sub-structure under a topside, standing in the water and pile founded.

LOAD-OUT The operation of bringing the object (module, jacket, deck) from the quay onto the transportation barge.

PADEARS (TRUNNIONS) Thick-walled tubular stubs, directly receiving slings and transversely welded to the main structure.

PADEYES Thick-walled plate with hole, receiving the pin of the shackle, welded to the main structure.

PIPELINE RISER The piping section which rises from the sea bed to topside level.

SEA-FASTENING The structure to keep the object rigidly connected to the barge during transport.

SHACKLES Connecting element (bow + pin) between slings and padeyes.

SLINGS Cables with spliced eyed at both ends, for offshore lifting, the upper end resting in the crane hook.

SPREADER Tubular frame, used in lifting operation.

SUBSEA TEMPLATE Structure at seabottom, to guide conductors prior to jacket installation.

SUMPS Vertical pipes from topside down to 5-10 m below water level for intake or discharge.

TOPSIDE Topside, the compact offshore process plant, with all auxiliaries, positioned above the waves.

UP ENDING Bringing the jacket in vertical position, prior to set down on the sea bottom.

WEATHER WINDOW

A period of calm weather, defined on basis of operational limits for the offshore marine operation.

WELLHEAD AREA Area in topside where the wellheads are positioned including the valves mounted on its top.

13. REFERENCES

[1] API-RP2A: Recommended practice for planning, designing and constructing fixed offshore platforms.

American Petroleum Institute 18th ed. 1989.

The structural offshore code, governs the majority of platforms.

[2] LRS Code for offshore platforms.

Lloyds Register of Shipping.

London (UK) 1988.

Regulations of a major certifying authority.

[3] DnV: Rules for the classification of fixed offshore installations.

Det Norske Veritas 1989.

Important set of rules.

[4] AISC: Specification for the design, fabrication and erection of structural steel for buildings.

American Institute of Steel Construction 1989.

Widely used structural code for topsides.




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[5] AWS D1.1-90: Structural Welding Code - Steel.

American Welding Society 1990.

The structural offshore welding code.

[6] DnV/Marine Operations: Standard for insurance warranty surveys in marine operations.

Det norske Veritas June 1985.


[7] ABS: Rules for building and classing offshore installations, Part 1 Structures.

American Bureau of Shipping 1983.


[8] BV: Rules and regulations for the construction and classification of offshore platforms.

Bureau Veritas, Paris 1975.


[9] ANON: A primer of offshore operations.

Petex Publ. Austin U.S.A 2nd ed. 1985.

Fundamental information about offshore oil and gas operations.

[10] AGJ Berkelder et al: Flexible deck joints.

ASME/OMAE-conference The Hague 1989 Vol.II pp. 753-760.

Presents interesting new concept in GBS design.

14. ADDITIONAL READING

1. BS 6235: Code of practice for fixed offshore structures.

British Standards Institution 1982.

Important code, mainly for the British offshore sector.

2. DoE Offshore installations: Guidance on design and construction, U.K. Department of Energy 1990.

Governmental regulations for British offshore sector only.

3. UEG: Design of tubular joints (3 volumes).

UEG Offshore Research Publ. U.R.33 1985.

Important theoretical and practical book.

4. J. Wardenier: Hollow section joints.

Delft University Press 1981.

Theoretical publication on tubular design including practical design formulae.

5. ARSEM: Design guides for offshore structures welded tubular joints.

Edition Technip, Paris (France), 1987.

Important theoretical and practical book.

6. D. Johnston: Field development options.




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Oil & Gas Journal, May 5 1986, pp 132 - 142.

Good presentation on development options.

7. G. I. Claum et al: Offshore Structures: Vol 1: Conceptual Design and Hydri-mechanics; Vol 2 - Strength and Safety for Structural design.

Springer Verlag, London 1992.

Fundamental publication on structural behaviour.

8. W.J. Graff: Introduction to offshore structures.

Gulf Publishing Company, Houston 1981.

Good general introduction to offshore structures.

9. B.C. Gerwick: Construction of offshore structures.

John Wiley & Sons, New York 1986.

Up to date presentation of offshore design and construction.

10. T.A. Doody et al: Important considerations for successful fabrication of offshore structures.

OTC paper 5348, Houston 1986, pp 531-539.

Valuable paper on fabrication aspects.

11. D.I. Karsan et al: An economic study on parameters influencing the cost of fixed platforms.

OTC paper 5301, Houston 1986, pp 79-93.

Good presentation on offshore CAPEX assessment.

Previous |Next | Contents




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PRODUCT FAMILY BROCHU

SACSAnalysis PackagesDesign and Analysis Software for Offshore Structures & Vessels

Offshore Structure Enterprise:The Professional Static Offshore package contains

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Offshore Structure Advanced:The Professional Static Topsides package contains capabilities

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Offshore Structure:The Professional Static Analysis package contains capabilities

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SACS ANALYSIS PACKAGES

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Interactive Fatigue, Dynamic Response, and Wave Response. It

requires the use of the Offshore Structure, Offshore Structure

Advanced, or Offshore Structure Enterprise package.

Wind:Wind Turbine Package

The Wind Turbine package is comprised of the following packages

necessary for wind turbine platform design: Offshore Structure

Enterprise, Pile Structure Design, Collapse, and Fatigue Enterprise.

The package also contains the SACS interfaces to the GH Bladed and

FAST wind turbine aero-elastic modules. Full automation including

multi-core analysis capability is included for efficient analysis of a

large number of time history simulations.

Marine:Marine Installation Add-On

The Marine Installation Add-on package permits launch and upending

analysis. The package includes the Launch and Flotation program

modules, and requires the use of the Offshore Structure, Offshore

Structure Advanced, or Offshore Structure Enterprise package.

Marine Enterprise:Hull Modeling and Meshing, Motions,and Stability Analysis

The Marine Enterprise Add-on provides modeling and meshing

of vessel hulls, calculation of stability, and prediction of vessel

motions. It can be used for new or existing FPSO studies, as well

as for transportation and installation analysis. It links with the Tow

module for calculation of motions induced loads and downstream

code checking and fatigue calculations. The package contains

the Hull Modeler, Hull Mesher Motions, and Stability modules,

and requires the use of the Offshore Structure, Offshore Structure

Advanced, or Offshore Structure Enterprise package.

Ship Impact Analysis

Motions prediction on an FPSO.

Parametric Study for the Fatigue Design of a Wind Turbine

Transition Piece

The following add-on modules extend the functionality of any of the three Offshore Structure suites.


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SACS Executive:Common Interface to Program Suite

Controls and connects all elements of the SACS system

Launches all SACS interactive programs

Executes all batch program analyses

Allows access to all SACS system configuration settings,

including system file location and security key settings

Includes command line help and power buttons for the most

commonly executed tasks

Specifies analysis options without changing data input file

Precede:Interactive Full Screen Graphics Modeler

Model generation capabilities include geometry, material

and section properties, and loading

Automatic input error detection

Maintains data backup

Beam and/or finite element modeling including plate

and shell elements

Automatic offshore jacket and deck generation

User defined input units

Cartesian, cylindrical, or spherical mesh generation

Automatic weight or load generation including gravity, pressure,

and skid mounted equipment loads

Seastate data generation capabilities

Extensive plotting and reporting capabilities

Code check parameter generation including K-factors and

compression flange unbraced lengths

Allows SACS model files to be converted into 3D SAT file format

compatible with AutoCAD, and other CAD systems

Physical member support capabilities

Professional and other ACIS-enabled CAD packages

Supports full 3D geometry and section properties

Allows SACS model files to be ported directly to a PDMS macro

file, which creates the 3D model in PDMS

Supports PDMS section libraries in addition to creating PDMS

sections for sections defined in the SACS model

Logging functionality

ISM Export to ProSteel and other steel detailing systems

Data Generator:Interactive Data Generation for all Programs

Intelligent full screen editor that labels and highlights data fields

and provides help for data input

Form-filling data input available as well as full screen mode

Automatic data checking

Seastate:Environmental Loads Generator

Ability to view plot files on screen

Sends viewed plots to printer/plotter

Supports HP-GL, Postscript, DXF, Windows devices

Metafile (WMF), and SACS NPF plot file

Allows plot size, character size, margins, formats, etc.

Ability to modify chart settings

Full implementation of API 21stedition

Supports five wave theories

Current included or excluded

Generates load due to wind, gravity, buoyancy,

and mud flow

SACS has applications for all types of offshore structures & vessels

Offshore System Types

1. Fixed Platforms

2. Compliant Tower

3. Tension Leg Platforms

4. Semi-Submersibles

5. FPSOs

The following software modules extend the functionality of any of the three Offshore Structure suites and are either

included within those packages or available as add-on modules. Please consult your Bentley representative for product

specifics relative to your needs.


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Marine growth, flooded, and non-flooded members

RAO and acceleration loading including non-structural weights

Moving loads generation

Diameter, Reynolds number, and wake encounter effects

dependent drag and inertia coefficients

Weight load cases

Forces on non-structural bodies

Deterministic and random wave modeling for dynamic response

Member hydrodynamic modeling for static and dynamic analysis

SACS IV Solver:Static Beam and Finite Element Analysis

Beam elements including tubulars, tees, wide flanges,

channels, angles, cones, plate and box girders, stiffened

cylinders, and boxes

Solid and plate elements (isotropic and stiffened)

Discrete Kirchoff Theory (DKT) thin-plates

Isoparametric 6-, 8-, and 9-node shell elements

Library of AISC, U.K., European, German, Chinese, and

Japanese cross sections, as well as user-defined libraries

Member, plate and shell local and global offsets

Beam and finite element thermal loads

Elastic supports defined in global or reference joint

coordinate system

Specified support joint displacements

Unlimited load cases

P-delta effects

Master/slave DOF

Post:Beam and Finite Element CodeCheck and Redesign

Beam and plate element code check and redesign

API (including 21stedition), AISC, LRFD, Norsok, Eurocode 3,

Canadian, DNV, British Standards, and Danish DS449code check

Plate panel checks in accordance to DnV-RP-C201

Creates updated model with redesigned elements

Modify code check parameters

Load combination capabilities

Supports codes from 1977 to present

Detailed and summary reports

Hydrostatic collapse analysis

Span (multi-member effects)

ISO 19902

Joint Can:Tubular Joint Code Check and Redesign

Present and past codes including latest API

21stedition, supplement 2, and LRFD, Norsok, DS449,

and Canadian

API earthquake and simplified fatigue analysis

ISO 19902

Connection strength (50 percent) check

Overlapping joints analyzed Minimum and extreme seismic analysis

Postvue:Interactive Graphics Post Processor

Interactive member and tubular joint code check

and redesign, with the option to print code check

details for latest AISC, ASD and LRFD, API,

ISO 19902 codes

Display shear and bending moment diagrams

Display deflected shapes for static and dynamic analyses

Color plate stress contour plots Code check and redesign by individual or group

of elements

Supports same codes as post module

Extensive reporting and plotting capabilities

Color-coded results and unity check plots

Creates updated input model file for re-analysis

Labels UC ratio, stresses, and internal forces

on elements

Automatic Joint Meshing


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Concrete:Reinforced Concrete Code Checkand Redesign

Rectangular, Circular, Tee, and L cross sections

Beam, bi-axial beam-column, slab, and wall elements supported

Multiple reinforcement patterns can be specified

Code check per ACI 318-89 (Revised 1992)

Shear reinforcement check and redesign

Reinforcement development length check

Deflection and creep calculation

Second order/P-delta analysis capabilities

Fatigue:Fatigue Life Evaluation and Redesign

Spectral, time history, and deterministic fatigue analysis

Cyclic stress range calculation procedures include wave search,

curve fit, and interpolation

SCF calculations recommended by API (including 21sted.

supplements), HSE, DNV, DS449 and Norsok Codes

Automatic redesign

API (including 21st ed. supplements), AWS, HSE, and Norsok

thickness dependent recommended S-N curves

Multiple run damage accumulation

Pierson-Moskowitz, JONSWAP, Ochi-Hubble double peak,

simplified double peek, and user-defined spectra

Automated or user-specified connection details

Pile fatigue analysis

Creates wave spectra from scatter diagram

Uses Paris equation to predict crack growth rate due to

cyclic stresses

Load path dependent joint classifications

Includes wave spreading effects

Reservoir (rain flow) cycle counting method ISO 19902

Interactive Fatigue:Interactive Fatigue Life Evaluation

Shows the 3D view of the connection and allows braces to be

selected with the mouse

Reads connection defaults when joint and/or brace is/are

selected, thus eliminating the need to calculate and display

SCFs before viewing capacity or modifying properties

Recognizes all SCF and S-N options available in the batch program

Allows SCF theory to be changed for any type connection, including

in-line connections and connections with user defined SCFs

Reports have been expanded and reworked to make them

easier to read

Reports and plots can be displayed on the screen and/or

saved to a file

Automatic redesign

GAP:Non-linear Analysis With One-way Elements

Accurate simulation of load out or transportation analysis using

one-way elements

Tension or compression gap elements with initial gap

General non-linear elements

Friction element

PSI:Non-linear Soil, Pile, and Structure Interaction

Beam column effects included

Non-uniform piles

P-Y and T-Z curves, axial adhesion and springs

API P-Y, T-Z, skin friction and adhesion data generated from soil

properties per API

API P-Y / T-Z Soil

API Adhesion Soil

User Defined P-Y / T-Z Soil

User Defined Adhesion Soil

PSI:


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Full structural analysis and pile code check API, LRFD, Norsok,

HSE, DS449, Canadian, and DNV

Offset P-Y & T-Z curves for mudslides

Full plotting and graphical representation of soil data and results,

including stresses, P-Y, T-Z curves

Soil liquefaction effects

Pile:Isolated 3D Pile Analysis

Beam column and pile batter effects included

Uses PSI soil data

Optional pile head springs

Specify force at or below pile head

Specify pile head displacements

Specified pile head forces or displacements

Automatic generation of linear equivalent pile stubs for dynamic

or static analysis


Same plotting and code check features as PSI

Superelement:Automated Substructure Creationand Application

Unlimited number of superelements

Up to 1,000 interface joints per superelement

Translation and rotation of superelements

User defined stiffness matrices

Full stress recovery

Superelements can contain other superelements

Translation and rotation of superelements

Combine:Common Solution File Utility

Combines dynamic and static results from one or multiple

solution files

Combines results from analyzes having different member,

plates, etc.

Superimposes mode shapes

Worst-case combination of dead loads with

earthquake response

Determine extreme wave loads from input spectra

Large Deflection (LDF):Large Deflection Analysis

Iterative solution for geometric

Solves plate membrane problems

Accounts for P-delta effects nonlinearities

Collapse:Non-linear Collapse Analysis

Linear and non-linear material behavior

Non-linear springs

Sequential load stacking capability

Activate and deactivate elements

Joint flexibility options

Non-linear Elasto-plastic Deformations


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Impact analysis with automatic unloading, built-in DnV ship

indentation curves and energy absorption functionality

Load cases may contain loading and/or specified displacements

Includes geometric nonlinearities

Plastic members and finite elements

Includes piles with non-linear soils and plasticity


Plastic DKT plates

Dynpac:Dynamic Characteristics

Householder-Givens solution

Guyan reduction of non-essential degrees of freedom

Lumped or consistent structural mass generation

Automatic virtual mass generation

Complete seastate hydrodynamic modeling

User input distributed and concentrated mass

Non-structural weight modeling

Full 6 DOF modes available for forced response analysis

Wave Response:Dynamic Wave Response

Deterministic and random waves

Pierson-Moskowitz, Jonswap, Ochi-Hubble, and user wave spectra

Harris, Von Karmon, and Kaimal wind spectra

Fluid-structure relative velocity and acceleration accounted for

Modal Acceleration and non-linear fluid damping Closed form steady state response in the frequency domain

Equivalent static load output for accurate stress recovery

Zero crossing and RMS responses

Time history analysis of wave and wind and time history load

Buoyancy dynamic loads included

Stress, internal load, base shear, and overturning momenttransfer function plots available

Full coupling with Fatigue program

Elastic dynamic response of floating structures including stingers

Input and output Power Spectral Densities with

Probability Distributions

Special features for wind turbine analysis

Dynamic Response:General Dynamic Response and Earthquake Analysis

Frequency domain analysis

Time history, response spectrum or PSD-based

driven input

Time history and harmonic-force driven input

SRSS, CQC and peak modal combinations

API response spectra library and user input spectra

Wind spectral loading capability

Structural and fluid damping

Vibration analysis with multiple input points with

user specified frequencies and phasing

General periodic forces decomposed by Fourier analysis

Ice dynamics analysis

Engine/compressor vibration analysis

Response spectrum output at any joint

Stability and Upending Analysis

Dual Hook Capabilities

Buoyancy Tanks, Valves,

User Defined Buoyancy

Flotation and Upending Analysis


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Find out about Bentleyat: www.Bentley.com/Offshore

Contact Bentley1-800-BENTLEY (1-800-236-8539)

Outside the US +1 610-458-5000

Global Office Listingswww.bentley.com/contact

System Requirements

Processor:Core 2 processor or better

Operating System:Windows 7 or Windows 8

RAM:Minimum 2 GB of RAM

Hard Disk:

Minimum 2 GB of free hard disk spaceDisplay:Graphics card supporting Open GL

128 MB RAM or greater video

card with 1280x1024 or higher

video resolution

SACS

Equivalent static load and incremental load output

resulting from earthquake, ship impact, dropped object

and blast analysis. This loading can be used for

subsequent linear static analysis or for non-linear

collapse analysis

Ship impact analysis

Dropped object analysis

Launch:

Jacket Launch Analysis Full launch motion time history analysis including

hydrodynamic forces in all directions

Time history of jacket and barge motions

All phases of launch included

Unbalanced loads generated for any position

Launch sequence plot capability including barge and

jacket silhouette for designated steps

Anchor restraints

Flotation:Jacket Flotation and Upending Analysis

Color coded snapshots of each upending step

Stability and upending analyses

Initial floating and on bottom positions provided

Upending steps can include multiple commands

Dual hook capabilities

Buoyancy tanks, valves, user-specified buoyancy

and weights and hydrodynamic overrides

Inclusion of marine growth for de-commissioning

Properties, forces, and positions plotted vs. step

Upending forces including gravity, sling loads, buoyancy,

and buoyancy tank loads generated for any step of the

upending sequence

Upending phase summary reports including pitch, roll,

and yaw angles, mud line clearance, etc.

Tow:Transportation Inertia Load Generator

Input motion for six degrees of freedom

Output location for selected points

Automatic weight calculation

User input member and joint weights

Generates distributed member and plate loads

Converts user defined loads into inertias

MTO:Material Take-Off, Weight Control,and Cost Estimation

Member lengths including cuts

Steel tonnage and CG location

Material list, cost estimate, and weight

control reports

Weld volume requirements and cost

Required protective anodes and cost

Surface area calculations by elevation

Anode calculation in accordance to NACE SPO176-2007

(formerly RP0176-2003) and DnV-RP-B401

Transportation Analysis Tow Analysis

Combine Multiple Common Solution Files

Static Analysis with Non-linear GAP Elements

Seafastener Design

Documents

Offshore General Introduction Analysis