6.11-structural-design-philosophy.pdf

KCP-GNS-SRD-DPR-0001 Rev.: 05

Project Title: Kingsnorth Carbon Capture & Storage Project Page 1 of 11

Document Title: Structural Design Philosophy

Kingsnorth CCS Demonstration Project The information contained in this document (the Information) is provided in good faith. E.ON UK plc, its subcontractors, subsidiaries, affiliates, employees, advisers, and the Department of Energy and Climate Change (DECC) make no representation or warranty as to the accuracy, reliability or completeness of the Information and neither E.ON UK plc nor any of its subcontractors, subsidiaries, affiliates, employees, advisers or DECC shall have any liability whatsoever for any direct or indirect loss howsoever arising from the use of the Information by any party.

Structural Design Philosophy Table of Contents

1 SCOPE AND FUNCTIONAL REQUIREMENTS ................................................. 3

1.1 SCOPE OF DOCUMENT ..................................................................................... 3 1.2 DEFINITIONS .................................................................................................... 3 1.3 ABBREVIATIONS ............................................................................................... 3 1.4 SYSTEM OF UNITS AND CONSTANTS ................................................................. 4 1.5 FUNCTIONAL REQUIREMENT ............................................................................. 4

2 CODES AND STANDARDS ............................................................................... 5

2.1 GENERAL ........................................................................................................ 5

3 DESIGN REQUIREMENTS ................................................................................. 6

3.1 DESCRIPTION OF THE OFFSHORE INSTALLATION ............................................... 6 3.2 DESIGN LIFE .................................................................................................... 6 3.3 STRUCTURAL EFFICIENCY ................................................................................ 6 3.4 DECK ELEVATIONS (AIR GAP) .......................................................................... 6 3.5 DESIGN LOAD CONDITIONS .............................................................................. 6 3.6 ABANDONMENT ............................................................................................... 6 3.7 ENVIRONMENTAL DATA .................................................................................... 7 3.8 MARINE GROWTH ............................................................................................ 7 3.9 SOIL CONDITIONS ............................................................................................ 7 3.10 MATERIAL .................................................................................................... 7 3.11 CORROSION PROTECTION ............................................................................ 8

3.11.1 Jacket Substructure ............................................................................... 8 3.11.2 Topsides Structures ............................................................................... 8

3.12 PLATFORM SUB-STRUCTURE CONFIGURATION .............................................. 8 3.13 TOPSIDES CONFIGURATION .......................................................................... 8

4 MANDATORY REFERENCES ......................................................................... 10

4.1 REGULATIONS AND STATUTES ........................................................................ 10 4.2 DESIGN CODES ............................................................................................. 10

5 SUPPORTING REFERENCES ......................................................................... 11

5.1 PROJECT DOCUMENTATION ........................................................................... 11 5.2 GENERAL REFERENCES ................................................................................. 11





Table of Holds HOLD No. Description Section

1 Environmental Data 3.7 2 Soil Conditions 3.9 3 Conductor size 3.12 4 Riser size 3.12 5 Number and size of Caissons 3.12





1 SCOPE AND FUNCTIONAL REQUIREMENTS

1.1 Scope of Document

This document outlines the structural design philosophy for the offshore installation at the Hewett gas reservoir and collates all of the design data to be used and the assumptions to be made in undertaking the design activities.

The offshore installation for this document is assumed to include the following:

Platform foundations; Platform substructure; Platform topsides structure. This document will be reviewed and updated as necessary during the course of the design to reflect changes necessary to meet E-ON requirements.

1.2 Definitions

COMPANY E.ON UK or its nominated representative.

CONTRACTOR The companies designated on the purchase order form as being the selected Contractor of materials and services.

WORK The task, process or operation being conducted by the CONTRACTOR on any tier on behalf of COMPANY.

Shall Indicates mandatory requirement

Should Indicates preferred course of action

May Indicates optional course of action

1.3 Abbreviations

API American Petroleum Institute BS British Standard CO2 Carbon Dioxide CP Cathodic Protection DTI Department of Trade and Industry ESD Emergency Shut Down FEED Front End Engineering Design HAT Highest Astronomical Tide HSE Health and Safety Executive IMO International Maritime Organisation ISO International Standardisation Organisation LAT Lowest Astronomical Tide MSL Mean Sea Level N/A Not Applicable NPS Nominal Pipe Size NUI Normally Unattended Installation OD Outside Diameter PFP Passive Fire Protection SI System International SMYS Specified Minimum Yield Strength





SMTS Specified Minimum Tensile Strength SWL Static Water Level UPS Uninterruptible Power Supply WHP Wellhead Platform WT Wall Thickness

1.4 System of Units and Constants

Systme International d'units (SI) units shall be used throughout the FEED design. The following consistent set of units will be used to describe the offshore installation:

Mass metric tonne, te (kg x 103); Force kilonewton, kN (N x 103) Length metre, m The following constants will be adopted for the offshore infrastructure FEED designs:

Youngs Modulus for steel, E 2.1 x 108 kN/m2; Poissons ratio, 0.3; Density of steel, steel 7.85 te/m3; Density of seawater, sea 1.025 te/m3; Coefficient of Thermal Expansion for steel, 12 x 10-6/C.

1.5 Functional Requirement

The aim of the offshore platform structural design is to produce an efficient and robust structure that is cost effective and simple to fabricate locally. The structures must provide adequate space and support for the proposed topside facilities, over the design life, and must accommodate well operations from an adjacent jack-up rig. The structures must be capable of being installed using readily available crane barges and offshore marine construction vessels.

The platform will operate as a Normally Unattended Installation (NUI) and will support four injection wells, an import riser, a J-tube for power and control cables, and topsides injection and support facilities.

The Base Case structural concept comprises the following:

Four leg welded tubular steel jacket substructure; Jacket foundations constructed using driven tubular steel piles; Four leg welded steel integrated deck stabbed into the top of the jacket. Note that if fired heaters are selected over electric heaters, then a fuel gas riser or diesel storage would also be required.





2 CODES AND STANDARDS

2.1 General The following codes and specifications will be used as the primary design codes, except that parameters and design methods specified in this document will take precedence where they are in conflict with these codes.

API RP 2A - WSD Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms Working Stress Design, 21st ed, Dec 2000 including Supplement 1, Dec 2002, Supplement 2, Sept 2005 and Supplement 3, Oct 2007, Ref. [M6]

ANS.AISC 360-05 Specification for Structural Steel Buildings, March 9, 2005, Ref. [M7]

DnV RP B401 Cathodic Protection Design, Ref [M13].

API Spec 2C Specification for Offshore Pedestal Mounted Cranes, 6th Ed, Sep 2004, Ref. [M14]

AWS D1.1 Structural Welding Code Steel, 2004, Ref [M15].

CAP 437 Offshore Helicopter Landing Areas Guidance on Standards, Ref. [M17]





3 DESIGN REQUIREMENTS

3.1 Description of the Offshore Installation

The base-case offshore facility design selected is a new build fixed steel jacket structure supporting a normally unattended integrated deck topsides and appurtenances; the geographical co-ordinates of the offshore injection facilities will be confirmed during the FEED 2 study.

3.2 Design Life

It is assumed that the offshore facilities will have a minimum service life of 40 years.

3.3 Structural Efficiency

The structural arrangement and details shall be optimised with regard to minimising the installed weight and simplifying fabrication whilst maximising robustness and redundancy.

The jacket top plan dimensions will be optimised to suit the topsides layout requirements. Jacket base dimensions will be selected with due consideration to the foundation design and jack-up access requirements.

The jacket will be fabricated at a yard, transported to site on a barge and lift-installed using a suitable and readily available crane barge.

The plan dimensions of the topsides structure and the number of deck levels will be governed by the layout requirements.

Preliminary deck design assumptions are as follows:

Completed and commissioned onshore before transportation on a barge; Lift installed in one piece by a heavy lift vessel after installation and piling of jacket; Stabbed into top of jacket legs / leg piles and welded out. 3.4 Deck Elevations (Air Gap)

The minimum air gap will be 1.5 m based on the extreme crest elevation of the 100 year wave and the extreme 100 year maximum design water depth. The air gap provision will also be checked to ensure that the 10,000 year wave does not strike the topsides deck structure. The water depth for the 10,000 year wave analysis will be taken as MSL.

3.5 Design Load Conditions

For the in-place condition, the platform facilities will be designed to support the functional dead loads and live loads, the operating and extreme storm environmental loads, including seismic loads, and credible accidental load conditions, e.g. boat impact and helicopter crash landing loads

In addition the platform structures will be designed to withstand forces associated with the construction, transportation, installation and decommissioning load conditions.

3.6 Abandonment

In the UK, decommissioning of offshore installations, including pipelines is controlled through the Petroleum Act 1998, as amended by the Energy Act 2008. Administration of the decommissioning process is through the Department of Energy and Climate Change (DECC 2010).

The International Maritime Organisation Guidelines and Standards for the Removal of Offshore Installations and Structures on the Continental Shelf and in the Exclusive Economic Zone (IMO 1989), set out the minimum global standards to be applied to the removal of offshore installations and structures. The Guidelines and Standards were designed essentially to ensure the safety of navigation and are not intended to preclude a coastal state from imposing more stringent removal requirements.





In large part, the UKs approach to decommissioning is governed under the 1992 Convention for the Protection of the Marine Environment of the North East Atlantic (OSPAR Convention). Agreement on the regime to be applied to the decommissioning of offshore installations in the Convention area was reached at a meeting of the OSPAR Commission in July 1998 (OSPAR 98/3). The UKs acceptance of OSPAR Decision 98/3 means that the UK will apply the provisions of that instrument when considering the decommissioning of offshore installations rather than the standards and guidelines laid down by the IMO. However, certain aspects of the IMO Guidelines and Standards are still relevant. These are:

Any disused installation or structure, or part thereof, which projects above the surface of the sea should be adequately maintained.

An unobstructed water column of at least 55 metres must be provided above the remains of any partially removed installation to ensure safety of navigation.

The position, surveyed depth and dimensions of any installation not entirely removed should be indicated on nautical charts and any remains, where necessary, properly marked with aids to navigation.

The person responsible for maintaining any aids to navigation and for monitoring the condition of any remaining material should be identified.

The liability for meeting any claims for damages which may arise in the future should be clear. On or after 1 January 1998, no installation or structure should be placed on any continental

shelf or in any exclusive economic zone unless the design and construction of the installation or structure is such that entire removal upon abandonment or permanent disuse would be feasible.

The Strategy with regards to abandonment is discussed further in Ref [S8].

No technical difficulties are anticipated in conforming to abandonment legislation. At a practical level, the main recommendation is to ensure that all lifting points are left in place and remain accessible following installation.

3.7 Environmental Data

Environmental data for the structural design is as presented in the Basis of Design for Studies document, Ref. [S7] HOLD 1.

3.8 Marine Growth

Marine Growth profiles to be adopted for the design will be in accordance with Ref [S7] HOLD 1.

3.9 Soil Conditions

A site-specific geotechnical survey will be conducted as part of the FEED 2 work. HOLD 2.

3.10 Material

Primary, special primary and secondary steel materials (Grades S275, S355, and S450) shall comply with BS EN 10225: 2001 - Specification for Weldable Structural Steels for Fixed Offshore Structures, Ref. [M8].

Tertiary steel (Grades S275, S355) shall comply with the following:

BS EN 10025: 1993 - Specification for Hot Rolled Products of Non-Alloy Structural Steels and their Technical Delivery Conditions , Ref [M9];

BS EN 10210: Parts 1 and 2 - Specification for Hot-Finished Structural Hollow Sections, Ref. [M11].





Consideration should be given to the use of corrosion resistant materials (e.g. aluminium, GRP and FRP) for the construction of topsides secondary and tertiary structures such as, helideck structures, walkways and landings, lighting and cable tray supports, etc. This will reduce the long-term inspection and maintenance burden for the topside structures and their corrosion protection systems.

3.11 Corrosion Protection

3.11.1 Jacket Substructure A preliminary corrosion allowance (i.e. additional steel thickness to compensate for the effect of metal loss by corrosion on structural members), shall be applied to the jacket substructure members in the splash and atmospheric zones. Elsewhere on the substructure, corrosion protection will be provided by cathodic protection suitable for the 40 year target design life.

3.11.2 Topsides Structures All permanent topsides steelwork shall be protected against corrosion as specified in the project specification for protective coatings. Hand-railing, stair treads and open grill floor grating shall be hot dip galvanised. In addition, handrailing shall be painted after galvanizing.

No corrosion allowances shall be applied to the thickness of topsides steel sections. Suitable isolation shall be provided at interfaces between mild steel and aluminium or stainless steel to prevent bi-metallic corrosion (for example helideck and wall cladding systems).

3.12 Platform Sub-structure Configuration

The substructure will be a jacket with skirt piles or piles through the legs.

The primary aspects of the substructure configuration are as follows:

Well slots: 4 no (Note that the four well slots are required for injection of the planned initial volumes of CO2 the Base Case. Up to eight additional well slots would be required to enable the platform to be used to inject the full Kingsnorth and potential Thames Cluster CCS volumes in the future. This will be considered as an Optional Case);

Well slot spacing: 2.50 m; Conductors: Platform drilled, 30 OD HOLD 3; Import riser: 36 NPS HOLD 4 The riser will be routed within the jacket framing envelope such

that it is protected from potential ship impacts.;

Sea water lift utility caisson HOLD 5; J-Tube for power and control cables. The substructure will support boat landings and/or barge bumpers, and will be designed to

withstand accidental impact loads from attendant vessels.

3.13 Topsides Configuration

The topsides will be an integrated deck which can be pre-commissioned onshore and lift-installed onto the substructure using a marine heavy lift crane vessel.

Personnel access to the platform will be by helicopter transfer. Drilling will be by jack-up rig working in cantilever mode. Well intervention work will be carried out using a separate work over barge.

The primary aspects of the topsides configuration can be summarised as follows:

Cellar Deck; Mezzanine Deck;





Weather Deck; Emergency Shelter, Tool Store, Control System, UPS Battery and Switch Rooms; Helideck; CO2 Vent to sea; Pedestal Crane. It is not intended to provide Passive Fire Protection (PFP) to the topsides structure. Thermal protection to critical members adjacent to the Riser ESDV, as well as the underside of the topsides structure, may be required to protect them from the cold effects from potential CO2 loss of containment,





4 MANDATORY REFERENCES

4.1 Regulations and Statutes

The following acts and regulations shall be complied with:

[M1] Construction (Design & Management) Regulations 2007;

[M2] Environmental Protection Act 1990;

[M3] Health and Safety at Work Act 1974;

[M4] Offshore Installations (Safety Case) Regulations 2005;

[M5] Offshore Installations and Wells (Design and Construction, etc.) Regulations 1996.

4.2 Design Codes

[M6] American Petroleum Institute, Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms Working Stress Design,API RP2A - WSD, 21st Edition, Dec 2000 including Supplement 1, Dec 2002, , Supplement 2, Sept 2005 and Supplement 3, Oct 2007;

[M7] American Institute of Steel Construction, Specification for Structural Steel Buildings, ANS.AISC 360-05, March 9, 2005;

[M8] British Standards Institution, BS EN 10225: 2001 - Specification for Weldable Structural Steels for Fixed Offshore Structures

[M9] British Standards Institution, BS EN 10025 1-6: 2004 - Hot Rolled Products of Structural Steels

[M10] British Standards Institution, BS4: Part 1: 1993, Structural Steel Sections: Hot-rolled Sections

[M11] British Standards Institution, BS EN 10210-1:2006, Specification for Hot-Finished Structural Hollow Sections of Non-alloy and Fine Grain Steels Part 1: Technical Delivery Requirements

[M12] British Standards Institution, BS EN 10056-1: 1999, Specification for Structural Steel Equal and Unequal Angles.

[M13] DnV RP B401, Cathodic Protection Design, 1993

[M14] API Spec 2C, Specification for Offshore Pedestal Mounted Cranes, 6th ed, Sep 2004

[M15] AWS D1.1, Structural Welding Code Steel, 2004

[M16] Norsok M-501, Surface Preparation and Protective Coating, 2004

[M17] CAP 437 Offshore Helicopter Landing Areas Guidance on Standards. - 5th ed. UK CAA 2005





5 SUPPORTING REFERENCES 5.1 Project Documentation

[S1] Submission D159, Description of the Offshore Installation facilities;

[S2] Submission D161, Offshore Installation Equipment to be used ;

[S3] Submission D168, Basis of Design for the Offshore Installation;

[S4] Submission D170, Access and accommodation on the platform;

[S5] Submission D171, Configuration of proposed offshore infrastructure ;

[S6] Submission D176, Offshore Installation construction methodology;

[S7] Basis of Design for Studies, Document No KCP-GNS-PCD-STU-0001, Rev.: 03

[S8] Decommissioning Strategy, Document No KCP-GNS-DCM-REP-0001, Rev.: 03

5.2 General References

[S8] Clean Coal 2010 Clean coal: an industrial strategy for the development of carbon capture and storage across the UK (March 2010).

http://www.decc.gov.uk/Media/viewfile.ashx?FilePath=What%20we%20do\UK%20energy%20supply\Energy%20mix\Carbon%20capture%20and%20storage\1_20100317090007_e_@@_CleanCoalIndustrialStrategy.pdf&filetype=4

[S9] DECC 2010 Decommissioning of Offshore Oil and Gas Installations and Pipelines under the Petroleum Act 1998, January 2010.

[S10] IMO 1989. International Maritime Organisation October 1989, (Resolution A.672 (16)).

[S11] OSPAR 98/3 OSPAR Decision 98/3 on the Disposal of Disused Offshore Installations, Sintra, 1998 (http://www.ospar.org/documents/DBASE/DECRECS/Decisions/od98-03e.doc).

1.1 Scope of Document1.2 Definitions1.3 Abbreviations1.4 System of Units and Constants1.5 Functional Requirement2.1 General3.1 Description of the Offshore Installation3.2 Design Life3.3 Structural Efficiency3.4 Deck Elevations (Air Gap)3.5 Design Load Conditions3.6 Abandonment3.7 Environmental Data3.8 Marine Growth3.9 Soil Conditions3.10 Material3.11 Corrosion Protection3.11.1 Jacket Substructure3.11.2 Topsides Structures

3.12 Platform Sub-structure Configuration3.13 Topsides Configuration4 MANDATORY REFERENCES4.1 Regulations and Statutes4.2 Design Codes

5 SUPPORTING REFERENCES5.1 Project Documentation5.2 General References

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