handbook of offshore engineering volume-1

HANDBOOK OF OFFSHORE ENGINEERING SUBRATA K. CHAKRABARTI Offshore Structure Analysis, Inc. Plainfield, Illinois, USA Volume I 2005 ELSEVIER Amsterdam - Boston - Heidelberg - London - New York - Oxford Paris - San Diego - San Francisco - Singapore - Sydney - Tokyo Elsevier The Boulevard, Langford Lane, Kidlington, Oxford OX5 IGB, UK Radarweg 29, PO Box 2 1 1, 1000 AE Amsterdam, The Netherlands First edition 2005 Reprinted 2005, 2006 (twice) Copyright Q 2005 Elsevier Ltd. All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone (+44) (0) 1865 843830; fax (+44) (0) 1865 853333; email: permissions@elsevier.com. Alternatively you can submit your request online by visiting the Elsevier web site at http:/lelsevier.comllocate/permissions, and selecting Obtainingpermission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury andor damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN-13: 978-0-08-044568-7 (v01 1) ISBN-IO: 0-08-044568-3 (VO~ 1) ISBN-13: 978-0-08-044569-4 (v01 2) ISBN-IO: 0-08-044569-1 (v01 2) ISBN-13: 978-0-08-044381-2 (set) ISBN-10: 0-08-044381-8 (set) For information on all Elsevier publications I visit our website at books.elsevier.com Printed and bound in Great Britain 06 07 08 09 10 10 9 8 7 6 5 4 Working together to grow libraries in developing countries www.elsevier.com 1 www.bookaid.org 1 www.sabre.org PREFACE Due to the rapid growth of the offshore field, particularly in the exploration and develop- ment of offshore oil and gas fields in deep waters of the oceans, the science and engineering in this area is seeing a phenomenal advancement. This advanced knowledge is not readily available for use by the practitioners in the field in a single reference. Tremendous strides have been made in the last decades in the advancement of offshore exploration and production of minerals. This has given rise to developments of new concepts and structures and material for application in the deep oceans. This has generated an obvious need of a reference book providing the state-of-the art in offshore engineering. This handbook is an attempt to fill this gap. It covers the important aspects of offshore structure design, installation and operation. The book covers the basic background material and its application in offshore engineering. Particular emphasis is placed in the application of the theory to practical problems. It includes the practical aspects of the offshore structures with handy design guides. simple description of the various components of the offshore engineering and their functions. One of the unique strengths of the book is the impressive and encompassing presentation of current functional and operational offshore development for all those involved with offshore structures. It is tailored as a reference book for the practicing engineers, and should serve as a handy reference book for the design engineers and consultant involved with offshore engineering and the design of offshore structures. This book emphasizes the practical aspects rather than the theoretical treatments needed in the research in the field of offshore engineering. In particular, it describes the dos and don’ts of all aspects of offshore structures. Much hands-on experience has been incorporated in the write up and contents of the book. Simple formulas and guidelines are provided throughout the book. Detailed design calculations, discussion of software development, and the background mathematics has been purposely left out. The book is not intended to provide detailed design methods, which should be used in conjunction with the knowledge and guidelines included in the book. This does not mean that they are not necessary for the design of offshore structures. Typically, the advanced formulations are handled by specialized software. The primary purpose of the book is to provide the important practical aspects of offshore engineering without going into the nitty gritty of the actual detailed design. Long derivations or mathematical treatments are avoided. Where necessary, formulas are stated in simple terms for easy calculations. Illustrations are provided in these cases. Information is provided in handy reference tables and design charts. Examples are provided to show how the theory outlined in the book is applied in the design of structures. Many examples are borrowed from the deep-water offshore structures of interest today including their components, and material that completes the system. vi Contents of the handbook include the following chapters: Historical Development of Offshore Structures Novel and Marginal Field Offshore Structures Ocean Environment Loads and Responses Probabilistic Design of Offshore Structure Fixed Offshore Platform Design Floating Offshore Platform Design Mooring Systems Drilling and Production Risers Topside Facilities Layout Development Design and Construction of Offshore Pipelines Design for Reliability: Human and Organisational Factors Physical Modelling of Offshore Structures Offshore Installation Materials for Offshore Applications Geophysical and Geotechnical Design The book is a collective effort of many technical specialists. Each chapter is written by one or more invited world-renowned experts on the basis of their long-time practical experience in the offshore field. The sixteen chapters, contributed by internationally recognized offshore experts provide invaluable insights on the recent advances and present state-of-knowledge on offshore developments. Attempts were made to choose the people, who have been in the trenches, to write these chapters. They know what it takes to get a structure from the drawing board to the site doing its job for which it is designed. They work everyday on these structures with the design engineers, operations engineers and construction people and make sure that the job is done right. Chapter 1 introduces the historical development of offshore structures in the exploration and production of petroleum reservoirs below the seafloor. It covers both the earlier offshore structures that have been installed in shallow and intermediate water depths as well as those for deep-water development and proposed as ultra-deep water structures. A short description of these structures and their applications are discussed. Chapter 2 describes novel structures and their process of development to meet certain requirements of an offshore field. Several examples given for these structures are operating in offshore fields today. A few others are concepts in various stages of their developments. The main purpose of this chapter is to lay down a logical step that one should follow in developing a structural concept for a particular need and a set of prescribed requirements. The ocean environment is the subject of chapter 3. It describes the environment that may be expected in various parts of the world and their properties. Formulas in describing their magnitudes are provided where appropriate so that the effect of these environments on the structure may be evaluated. The magnitudes of environment in various parts of the world are discussed. They should help the designer in choosing the appropriate metocean conditions that should be used for the structure development. vii Chapter 4 provides a generic description of how to compute loads on an offshore struc- ture and how the structure responds to these loads. Basic formulas have been stated for easy references whenever specific needs arise throughout this handbook. Therefore, this chapter may be consulted during the review of specific structures covered in the handbook. References are made regarding the design guidelines of various certifying agencies. Chapter 5 deals with a statistical design approach incorporating the random nature of environment. Three design approaches are described that include the design wave, design storm and long-term design. Several examples have been given to explain these approaches. The design of fixed offshore structures is described in Chapter 6. The procedure follows a design cycle for the fixed structure and include different types of structure design including tubular joints and fatigue design. Chapter 7 discusses the design of floating structures. in particular those used in offshore oil drilling and production. Both permanent and mobile platforms have been discussed. The design areas of floaters include weight control and stability and dynamic loads on as well as fatigue for equipment, risers, mooring and the hull itself. The effect of large currents in the deepwater Gulf of Mexico, high seas and strong currents in the North Atlantic, and long period swells in West Africa are considered in the design development. Installation of the platforms. mooring and decks in deep water present new challenges. Floating offshore vessels have fit-for-purpose mooring systems. The mooring system selection, and design are the subject of Chapter 8. The mooring system consists of freely hanging lines connecting the surface platform to anchors. or piles, on the seabed, positioned some distance from the platform. Chapter 9 provides a description of the analysis procedures used to support the operation of drilling and production risers in floating vessels. The offshore industry depends on these procedures to assure the integrity of drilling and production risers. The description; selection and design of these risers are described in the chapter. The specific considerations that should be given in the design of a deck structure is described in Chapter 10. The areas and equipment required for deck and the spacing are discussed. The effect of the environment on the deck design is addressed. The control and safety requirements, including fuel and ignition sources, firewall and fire equipment are given. The objective of chapter 11 is to guide the offshore pipeline engineer during the design process. The aspects of offshore pipeline design that are discussed include a design basis, route selection. sizing the pipe diameter, and wall thickness. on-bottom pipeline stability, bottom roughness analysis, external corrosion protection, crossing design and construction feasibility. Chapter 12 is focused on people and their organizations and how to design offshore structures to achieve desirable reliability in these aspects. The objective of this chapter is to provide engineers design-oriented guidelines to help develop success in design of offshore structures. Application of these guidelines are illustrated with a couple of practical examples. The scale model testing is the subject of Chapter 13. This chapter describes the need. the modeling background and the method of physical testing of offshore structures in a viii small-scale model. The physical modeling involves design and construction of scale model. generation of environment in an appropriate facility, measuring responses of the model subjected to the scaled environment and scaling up of the measured responses to the design values. These aspects are discussed here. Installation, foundation, load-out and transportation are covered in Chapter 14. Installa- tion methods of the following substructures are covered: Jackets; Jack-ups; Compliant towers and Gravity base structures. Different types of foundations and their unique methods of installation are discussed. The phase of transferring the completed structure onto the deck of a cargo vessel and its journey to the site, referred to as the load-out and transportation operation, and their types are described. Chapter 15 reviews the important materials for offshore application and their corrosion issues. It discusses the key factors that affect materials selection and design. The chapter includes performance data and specifications for materials commonly used for offshore developments. These materials include carbon steel, corrosion resistant alloys, elastomers and composites. In addition the chapter discusses key design issues such as fracture, fatigue: corrosion control and welding. Chapter 16 provides an overview of the geophysical and geotechnical techniques and solutions available for investigating the soils and rocks that lay beneath the seabed. A project’s successful outcome depends on securing the services of highly competent contractors and technical advisors. What is achievable is governed by a combination of factors, such as geology, water depth; environment and vessel capabilities. The discussions are transcribed without recourse to complex science, mathematics or lengthy descriptions of complicated procedures. Because of the practical nature of the examples used in the handbook, many of which came from past experiences in different offshore locations of the world, it was not possible to use a consistent set of engineering units. Therefore, the English and metric units are interchangeably used throughout the book. Dual units are included as far as practical, especially in the beginning chapters. A conversion table is included in the handbook for those who are more familiar with and prefer to use one or the other unit system. This handbook should have wide applications in offshore engineering. People in the follow- ing disciplines will be benefited from this book: Offshore Structure designers and fabricators; Offshore Field Engineers; Operators of rigs and offshore structures; Consulting Engineers; Undergraduate & Graduate Students; Faculty Members in OceaniOffshore Eng. & Naval Architectural Depts.; University libraries; Offshore industry personnel; Design firm personnel. Subrata Cliakrabarti Tech ical Editor X\ TABLE OF CONTENTS Preface v Abbreviations ix Conversion Factors xi List of Contributors xiii Chapter 1 . Historical Development of Offshore Structures 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Introduction 1.1.1 Definition of Offshore Structures 1.1.2 Historical Development 1.1.3 Selection of Deepwater Production Concepts I. 1.4 Offshore Disasters Deepwater Challenges Functions of Offshore Structures 1.3.1 Exploratory Drilling Structures I . 3.2 Production Structures . 1.3.3 Storage Structures 1.3.4 Export Systems Offshore Structure Configurations 1.4.1 Bottom-Supported Structures 1.4.2 Floating Offshore Structures 1.4.3 Floating vs . Fixed Offshore Structures Bottom-Supported Fixed Structures 1.5.1 Minimal Platforms 1.5.2 Jacket Structures 1.5.3 Gravity Base Stru 1.5.4 Jack-ups 1.5.5 Subsea Templates 1.5.6 Subsea Pipelines Compliant Structures 1.6.1 Articulated Platforms 1.6.2 Compliant Tower 1.6.3 Guyed Tower Floating Structures 1.7.1 Floating Platform Types 1.7.2 Drilling Units 1.7.3 Production Uni s 1.7.4 Drilling and Production Units 1.7.5 Platform Configurations 1 2 2 5 8 9 11 11 12 13 14 15 16 16 17 19 19 20 21 21 22 22 24 24 24 25 26 26 26 27 28 28 1.8 Classification Societies and Industry Standard Groups 34 Chapter 2. Novel and Small Field Offshore Structures 39 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Introduction 39 Overview of Oil and Gas Field Developments 40 2.2.1 Field Development Par 2.2.2 Structure Types 2.2.3 Selection of Field Deve Technical Basis for Developing Novel Offshore Structures 44 2.3.1 Overview of Historical Innovations 44 2.3.2 Basic Technical Principles Other Considerations for Developing Novel Offshore Structures 2.4.1 Financially-Driven Developments 52 2.4.2 Regulatory-Driven Developments 53 2.5.1 Bottom-Supported Systems . 53 Novel Field Development Systems 53 2.5.2 Neutrally-Buoyant Floating 56 2.5.3 Positively-Buoyant Floating Systems 60 Discussion of Selected Innovative Field Development Concept 63 2.6.1 Overview 63 2.6.2 Field Development Concept Discussion of Selected Innovative Structures 2.7.1 Structures Selected for In-Depth Discussion 66 2.7.2 Construction and Construction Schedule 66 2.7.3 Transportation and Installation 68 2.7.4 In-Service Response and Utilisation 69 2.7.6 Capital and Operating Expenditures 71 2.7.5 Post-service Utilisation 70 2.7.7 2.7.8 Summary Discussion Future Field Development Options Residual Value and Risk Factors 2.8.1 Technological Innovations and their Impact 73 2.8.2 Innovations Affecting Cost Efficiencies 75 2.8.3 Most Likely Field Development Inn Chapter 3. Ocean Environment 3.1 Introduction 3.2 Ocean Water Properties. 3.2.1 Density, Viscosity d Temperature 3.3.1 Linear Wave Theory 3.3.2 Second-Order Stokes Wave Theory 3.3.3 3.3.4 Stream Function Theory 3.3 Wave Theory Fifth-Order Stokes Wave Theory 79 79 80 80 80 83 91 93 94 xvii 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.3.5 Stretching Formulas for Waves at SWL 98 3.3.7 Wave Group 103 3.3.8 Series Representation of Long-Crested Wave 103 Breaking Waves 104 Internal Waves 105 106 3.6.1 Spectrum Model 106 3.6.2 Applicability of Spectrum Model 110 3.6.3 Simulation of Two-dimensional Sea 113 3.6.4 Directional Spectrum 114 3.6.5 Simulation of Directional Sea 116 Sea States 117 Wave-driven Current 118 3.8.1 Steady Uniform Current 118 3.8.2 Steady Shear Current 119 3.8.3 Combined Current and Waves 119 Loop Current Wind and Wind Spectrum 123 3.10.1 Wind Speed 123 Offshore Environment by Location 125 3.3.6 Applicability of Wave Theory 101 3.10.2 Wind Spectrum 123 Chapter 4 . Loads and Responses 133 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Introduction 133 Gravity Loads 135 Hydrostatic Loads 136 Resistance Loads 136 Current Loads on Structures 137 4.5.1 Current Drag and Lift Force 137 4.5.2 Blockage Factor in Current 141 Steady and Dynamic Wind Loads on Structures 143 Wave Loads on Structures . 143 4.7.1 Morison Equation 144 4.7.2 Forces on Oscillating Structures 145 4.7.3 Wave Plus Current Loads 150 4.7.4 Design Values for Hydrodynamic Coefficients 152 4.7.5 FroudeXrylov Force on Structure 158 4.7.6 Wave Diffraction Force on Structure 160 4.7.7 Added Mass and Damping Coefficien 161 4.7.8 Haskind Relationship for Accuracy C 162 4.7.9 Linear Diffraction Radiation Theory Software 162 Applicability of Morison Force vs . Diffraction Force 164 Steady Wave Drift Force 166 4.9.1 Steady Drift Potential Force 167 4.9.2 Viscous Drift Force 170 xviii 4.10 Slow-Drift Wave Forces 172 4.1 1 Varying Wind Load 174 4.12 Impulse Loads 175 4.12.1 Wave Slamming Load 176 4.12.2 Breaking Wave Load 177 4.12.3 Wave Run-U 177 4.13 Response of Structure 178 4.13.1 Structure Mo 178 4.13.2 Transient Response of Structure 180 4.13.3 Forced Linearly Damped System 183 4.13.4 Non-linearly Damped Structure Response 186 4.13.5 Motions of Floating Structure 4.13.6 Interaction of Two Floating Structures 4.13.8 4.13.9 High-Frequency Respons 4.13.10 Hydrodynamic Damping Applicability of Response Formula 194 4.14.1 Key Responses for Offshore Structures 194 4.13.7 Slowly-Varying Response 189 Simplified Computation of Slow-Drift Oscillation 189 4.14 Chapter 5. Probabilistic Design of Offshore Structures 197 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 Application of Statistics in Offshore Engineering Wave Statistics 197 5.2.1 The Gaussian Distribution 201 5.2.2 The Rayleigh Distribution 202 Design Approaches 210 5.4.1 Design Wave 210 5.4.3 Long-Term Design 216 Combination of Multiple Sto 5.5.1 Combination of First Probabilistic Design of Offsh 5.6.1 Introduction 5.6.2 Response Statistics 207 5.4.2 Short-Term Design 21 1 Limit States and Failure Criteria 227 Uncertainty Measures. 232 5.7.1 General Description 232 5.7.2 Representation 235 5.7.3 Probabilistic Description of Response in Complex Structures 237 Structural Reliability Analysis 240 5.8.1 Elementary Case 240 5.8.2 Generalisation of Reliability Analysis. 243 5.8.3 Fatigue Reliability 25 1 Design Values and Calibration of Partial Factors 253 5.8.4 [...]... Development The offshore exploration of oil and gas dates back to the nineteenth century The first offshore oil wells were drilled from extended piers into the waters of Pacific Ocean, offshore Summerlands, California in the 1890s (and offshore Baku, Azerbaijan in the Caspian Sea) However, the birth of the offshore industry is commonly considered as in 1947 when Kerr-McGee completed the first successful offshore. .. leased Mobile Offshore Drilling Unit (MODU) will be used Further discussion on concept selection is included in Chapter 7 1.1.4 Offshore Disasters Although most of the offshore structures constructed to date have withstood the test of time, there have been several catastrophic failures of offshore structures as well Weather, Historical Developmenr of Offshove Structures 9 Figure 1.7 Accident of P-36 converted... 652 Handbook of Offshore Engineering S Chakrabarti (Ed.) C 2005 Elsevier Ltd All rights resened 1 Chapter 1 Historical Development of Offshore Structures Subrata Chakrabarti Offshore Structuve Analysis, Inc., Plainfield, IL, USA John Halkyard Technip, Houston, T X , USA Cuneyt Capanoglu I.D.E.A.S., Inc., Sun Fyancisco, CA, USA 1.1 Introduction The offshore industry requires continued development of. .. Triangle” of the Gulf of Mexico, offshore West Africa and Brazil (fig 1.6) As of this writing, 8 Chapter 1 Figure 1.6 Worldwide distribution of floating production platforms [Offshow, 20021 production Spars have only been installed in the Gulf of Mexico TLPs have been installed in the Gulf of Mexico, West Africa, the North Sea and in Indonesia FPSOs have been installed in virtually all of the offshore. .. in Chapter 2 In order to meet the need for offshore exploration and production of oiligas, a new generation of bottomsupported and floating structures is being developed The purpose of this chapter is to introduce the historical development of offshore structures in the exploration of petroleum reservoirs below the seafloor The chapter covers both the earlier offshore structures that have been installed... inaccessible to exploit with the existing technologies Sometimes, the cost of production with the existing know-how makes it unattractive With the depletion of onshore and offshore shallow water reserves, the exploration and production of oil in deep water has become a challenge to the offshore industry Offshore exploration and production of minerals is advancing into deeper waters at a fast pace Many deepwater... installed in 1991 The progression of fixed structures into deeper waters upto 1988 is shown in fig 1.1 Since 1947, more than 10,000 offshore platforms of various types and sizes have been constructed and installed worldwide As of 1995, 30% of the world’s production of crude came from offshore Recently, new discoveries have been made in increasingly deeper waters In 2003, 3 % of the world’s oil and gas supply... Titanium and composite materials are also being developed for top tensioned risers Historicul Development of Offshore Structures 11 1.3 Functions of Offshore Structures Offshore structures may be defined by their two interdependent parameters, namely their function and configuration A Mobile Offshore Drilling Unit (MODU) configuration is largely determined by the variable deck payload and transit... The motions of the platform are coupled with the dynamics of the mooring system The coupling of motions between 17 Historical Development of Offshore Structures the platform, risers and mooring systems becomes increasingly more important as water depth increases The discussion of the dynamic analysis of these platforms subjected to environment is included in Chapter 4 1.4.3 Floating vs Fixed Offshore. .. Installation of subsea pipeline is a common occurrence in moderately deep water u p to a few hundred meters As of April 1998, there were 26,600 miles of pipeline in the Gulf of Mexico Nearly 50% of this is in deepwater ( > 1000 ft or 300 m) and Historicul Deveiopmeni of Offshore Srruciures 23 Figure 1.14 Pipelines in the Gulf of Mexico, 20 in (508 mm) or greater between 300 and 500 miles (480-800 km) of deepwater . and Construction of Offshore Pipelines Design for Reliability: Human and Organisational Factors Physical Modelling of Offshore Structures Offshore Installation Materials for Offshore Applications. Handbook of Offshore Engineering S. Chakrabarti (Ed.) C 2005 Elsevier Ltd. All rights resened 1 Chapter 1 Historical Development of Offshore Structures Subrata Chakrabarti Offshore. of offshore structures. Typically, the advanced formulations are handled by specialized software. The primary purpose of the book is to provide the important practical aspects of offshore engineering