The competitive threat to fixed steel platforms
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The competitive threat to fixed steel platforms

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ISSN 1018-5593 EU RO PEAN COMMISSION SCIENCE RESEARCH DEVELOPMENT technical steel research operties and in-service performance The competitive threat to fixed steel platforms Phase 2 Report hi EUR 18011 EN STEEL RESEARCH EUROPEAN COMMISSION Edith CRESSON, Member of the Commission responsible for research, innovation, education, training and youth DG XII/C.2 — RTD actions: industrial and materials technologies — Materials and steel Contact: MrJ.-L Martin Address: European Commission, rue de la Loi 200 (MO 75 1/10), B-1049 Brussels — Tel. (32-2) 29-53453; fax (32-2) 29-65987 European Commission technical steel research Properties and in-service performance The competitive threat to fixed steel platforms Phase 2 A. M. Cuthill British Steel pic 9 Albert Embankment London SE1 7SN United Kingdom Contract No 7210-MC/804 1 July 1992 to 30 June 1994 Final report Directorate-General Science, Research and Development 1998 EUR 18011 EN LEGAL NOTICE Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of the following information. A great deal of additional information on the European Union is available on the Internet. It can be accessed through the Europa server (http://europa.eu.int). Cataloguing data can be found at the end of this publication.

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ISSN 1018-5593
EU RO PEAN
COMMISSION
SCIENCE
RESEARCH
DEVELOPMENT
technical steel research
operties and in-service performance
The competitive
threat to fixed steel
platforms
Phase 2
Report hi
EUR 18011 EN
STEEL RESEARCH EUROPEAN COMMISSION
Edith CRESSON, Member of the Commission
responsible for research, innovation, education, training and youth
DG XII/C.2 — RTD actions: industrial and materials technologies —
Materials and steel
Contact: MrJ.-L Martin
Address: European Commission, rue de la Loi 200 (MO 75 1/10),
B-1049 Brussels — Tel. (32-2) 29-53453; fax (32-2) 29-65987 European Commission
technical steel research
Properties and in-service performance
The competitive threat to fixed steel platforms
Phase 2
A. M. Cuthill
British Steel pic
9 Albert Embankment
London SE1 7SN
United Kingdom
Contract No 7210-MC/804
1 July 1992 to 30 June 1994
Final report
Directorate-General
Science, Research and Development
1998 EUR 18011 EN LEGAL NOTICE
Neither the European Commission nor any person acting on behalf of the Commission
is responsible for the use which might be made of the following information.
A great deal of additional information on the European Union is available on the Internet.
It can be accessed through the Europa server (http://europa.eu.int).
Cataloguing data can be found at the end of this publication.
Luxembourg: Office for Official Publications of the European Communities, 1998
ISBN 92-828-3528-6
© European Communities, 1998
Reproduction is authorised provided the source is acknowledged.
Printed in Luxembourg
PRINTED ON WHITE CHLORINE-FREE PAPER CONTENTS PAGE
1. INTRODUCTION 7
2. PROJECT SCOPE OF WORK 8
3. MARKET SURVEY 9
4. DESIGN PREMISE 14
5. CONCEPTUAL DESIGN AND ANALYSIS 22
6. WEIGHT TRENDS AND COST ESTIMATES7
7. RECENT ADVANCES IN THE TECHNOLOGY OF FIXED STEEL 31
PLATFORMS
8. FABRICATION YARD SURVEY 4
9. CONCLUSIONS3
REFERENCES4
TABLES7
FIGURES 5
APPENDIX 1 CONCEPTUAL DESIGN OF 85 m/50001 BATTERED JACKET 75
APPENDIX 2L DESIGN OF 85 m/10 000 tD JACKET 83
APPENDIX 3 CONCEPTUAL DESIGN OF 85 m/10 0001 VERTICAL JACKET 91
APPENDIX 4L DESIGN OF 85 m/16 0001L JACKET9
APPENDIX 5 CONCEPTUAL DESIGN OF 120 m/50001 BATTERED JACKET 107
APPENDIX 6L DESIGN OF 120 m/10 0001D JACKET 115
APPENDIX 7 CONCEPTUAL DESIGN OF 120 m/16 000 t BATTERED JACKET 123
APPENDIX 8L DESIGN OF 155 m/10 0001D JACKET 131
APPENDIX 9 CONCEPTUAL DESIGN OF 155 m/16 0001 BATTERED JACKET 139
APPENDIX 10L DESIGN OF 155 m/25 0001D JACKET 147
APPENDIX 11 CONCEPTUAL DESIGN OF 200 m/16 0001 BATTERED JACKET 155
APPENDIX 12L DESIGN OF 200 m/25 0001D JACKET 165
APPENDIX 13 CONCEPTUAL DESIGN OF 250 m/16 0001 BATTERED JACKET 173
APPENDIX 14 JACKET COST PREDICTION PROGRAM 183 LIST OF TABLES
1. Database of North West European Prospects
2.e of Existing Structures
3. Mechanical Properties for Plates
4. Weight and Cost Comparisons for Battered and Vertical Jackets
5. 120 m Water Depth, 10 0001 Topside Battered Jacket Optimised for Three Different Grades
of Steel
6. Component Fabrication Rates
LIST OF APPENDICES
1. Conceptual Design of 85 m/50001 Battered Jacket
2.l Design of 85 m/10 000 t Battered Jacket
3.l Design of 85 m/10 0001 Vertical Jacket
4. Conceptual Design of 85 m/16 0001 Vertical Jacket
5.l Design of 120 m/5 000 t Battered Jacket
6.l Design of 120 m/10 0001 Battered Jacket
7. Conceptual Design of 120 m/16 000 t Battered Jacket
8.l Design of 155 m/10 000 t Battered Jacket
9.l Design of 155 m/16 0001 Battered Jacket
10. Conceptual Design of 155 m/25 0001 Battered Jacket
11.l Design of 200 m/16 0001 Battered Jacket
12. Conceptual Design of 200 m/25 0001 Battered Jacket
13.l Design of 250 m/16 0001 Battered Jacket
14. The Jacket Cost Prediction Program LIST OF FIGURES
1. Platform Locations Assumed for Determining Environmental Criteria
2. Jacket Weight ν Water Depth - Data Points from Phase II Analyses with Curves Fitted
3.t Fabrication Costs Normalised to a £/tonne Rate
4. Total Jacket Weight ν Water Depth - Data Points from Phase I with Fitted Curves and
Curves from Phase II
5.l Jacket Weight ν Water Depth - Prediction Curves
6. Total Pile Weight ν Water Depth - From Analyses and Pile Design for Grade 355EM Steel
7. Predicted Total Pile Weight ν Actual Total Pile Weight - Good Soil Condition
8.d Total Pile Weight ν Actual Total Pile Weight - Average Soil Condition
9. Predicted Total Pile Weight ν Actual Total Pile Weight - Poor Soil Condition
10. Details of Europipe Foundations
11. Hydra-LokTool
12. Comparison Between Traditional Grouted Pile Sleeves and Hydra-Lok Method
13. Connection 'Finger-Print' Shows Water Pressure Against Volume of Water Pumped to Tool
14. Comparison Between Stokes, NewWave and Measured Base Shear
15. Backing-Strip Fitting Details for Closure Welds
16. Analysis and Experimental Comparison of Frame II Response
17. Frames Project Phase III Tests of a 3D Structure 1. INTRODUCTION
This document reports the work undertaken by Billington Osborne-Moss Engineering Limited to
investigate the competitive threat to fixed steel platforms. This work was carried out on behalf of British
Steel pic and completed with the financial aid of the European Coal and Steel Community.
The work reported herein forms the second phase of a two-part project. Phase one examined shallow water
platforms, covering water depths up to 50 m and was completed in 1990. This second phase examines
deeper water applications.
One of the primary objectives of this project was to produce a cost estimating tool which can be used when
evaluating new field development plans. Whilst a few forecasters of this type are already available, they
mainly rely on existing platforms for their weight and cost data. These data may include significantly
'out-of-date' designs which bear little resemblance to modern platforms. Consequently the existing cost
forecasters can be described as more 'historical' than 'predictive' and are of limited value when trying to
appraise new development plans. On a recent development consisting of three platforms, the total jacket
and pile fabrication cost was forecast by one cost algorithm to be £123 million. The actual cost came out to
be £69 million!
Clearly such poor forecasting tools work to the detriment of the fixed steel platform industry and can only
serve to confuse those trying to estimate the costs of new field developments. The forecaster created within
this project seeks to avoid such pitfalls by not relying on historical data. This has been achieved by
designing a suite of structures which belong to the current, or even the future generation of jackets.
The ranges of water depths and topside loads considered in the study were decided on after carrying out a
comprehensive survey of possible new field developments. This Market Survey is fully described in
Section 3 of this report.
Having decided upon these basic parameters, it was necessary to establish all other relevant design
information which would be required. This included such topics as environmental loading criteria, which
design codes to use, the number of caissons and other appurtenances to be considered, soil parameters,
steel grades, etc. The Design Premise presented in Section 4 lists and explains the background to these
various items.
Section 5 of the report describes the conceptual jacket designs produced, along with the various analyses
which were undertaken. Thirteen different designs were generated and these covered a variety of jacket
types. The smallest structures were four legged lifted jackets and included both battered leg and vertical
leg arrangements. For the deeper water jackets with heavier topsides lifted structures are not feasible and
resort must be made to launched jacket technology. Relatively conventional eight legged launched jackets
were designed to cope with the heavier topside loads. For more moderate payloads a completely new form
of launched structure has been designed. In an attempt to reduce costs, this novel form of jacket aims to
improve upon previous four legged launched structures by utilising steel in a much more efficient manner.
The conceptual designs were also used to investigate the effect of using higher strength steels, both in the
main jacket structure and in the piles. The weight trends elucidated by the conceptual designs are described in Section 6. Clear trends have
emerged for the various platform types and this information forms the basis of the cost forecaster.
The cost data that have been generated are also described and explained in Section 6. These incorporate
information from numerous recent actual platform constructions. The data is therefore seen as being
robust and capable of accurately predicting jacket fabrication costs.
The weight trends and cost data combine to form the forecaster and this is also described in Section 6. For
simplicity, accuracy and ease of use the forecaster has been created in the form of a PC based program. It
has deliberately been kept simple to operate and relies upon the user specifying the absolute minimum
amount of data. The Lotus 123 spreadsheet program is used for the forecaster, on the grounds that it is
well known and widely available.
Recent advances in the technology of fixed steel platforms have been reviewed and appraised and these are
reported in Section 7. The topics covered include materials, design techniques, fabrication aspects and
installation technology. Several of these new developments are, individually, likely to result in
significantly cheaper jackets in the years to come. In combination, cost savings of 20% to 30% appear to be
quite feasible. Other topics reviewed relate to reliability issues and should lead to both a better
understanding of jacket behaviour and more efficient designs.
A survey of fabrication yards was undertaken as part of the project and this is reported in Section 8. The
appendices at the back of the report present the detailed information of each of the conceptual jacket
designs, including drawings showing the general arrangements and member sizes.
As a whole the project has produced a number of interesting findings and some useful conclusions.
2. PROJECT SCOPE OF WORK
The aims of this second phase of the project were defined at its inception and comprised:
• To address the competitive threat to deeper water fixed steel platforms.
• To prepare a comprehensive weight and cost estimating methodology for such
platforms.
• To enumerate recent advances in materials, design, fabrication and installation
technologies which improve the competitiveness of steel.
• To disseminate the results of both phases of the work.
These aims were expanded to create the following formal scope of work:
• Determine the possible forthcoming deep water developments in Europe.
• Establish design criteria for design analyses.
• Produce conceptual designs for a range of platforms.
• Verify/revise the conceptual designs produced.
• Identify the capabilities of the various European fabrication yards.
• Produce MTO and cost information for the various conceptual designs.
•e a PC based cost forecasting program.
• Prepare a report of the project and a manual to accompany the cost program.
All of the above topics have been successfully addressed and are reported in the relevant sections of this
document.