El-Reedy Marine Structural Design Calculations

1. Auflage 2014
ISBN: 978-0-08-100002-1
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 456 Seiten

The perfect guide for veteran structural engineers or for engineers just entering the field of offshore design and construction, Marine Structural Design Calculations offers structural and geotechnical engineers a multitude of worked-out marine structural construction and design calculations. Each calculation is discussed in a concise, easy-to-understand manner that provides an authoritative guide for selecting the right formula and solving even the most difficult design calculation. Calculation methods for all areas of marine structural design and construction are presented and practical solutions are provided. Theories, principles, and practices are summarized. The concentration focuses on formula selection and problem solving. A 'quick look up guide, Marine Structural Design Calculations includes both fps and SI units and is divided into categories such as Project Management for Marine Structures; Marine Structures Loads and Strength; Marine Structure Platform Design; and Geotechnical Data and Pile Design. The calculations are based on industry code and standards like American Society of Civil Engineers and American Society of Mechanical Engineers, as well as institutions like the American Petroleum Institute and the US Coast Guard. Case studies and worked examples are included throughout the book. - Calculations are based on industry code and standards such as American Society of Civil Engineers and American Society of Mechanical Engineers - Complete chapter on modeling using SACS software and PDMS software - Includes over 300 marine structural construction and design calculations - Worked-out examples and case studies are provided throughout the book - Includes a number of checklists, design schematics and data tables

Mohamed A. El-Reedy's background is in structural engineering. His main area of research is reliability of concrete and steel structures. He has provided consulting to different engineering companies, the oil and gas industries in Egypt, and international oil companies such as the International Egyptian Oil Company (IEOC) and British Petroleum (BP). Moreover, he provides different concrete and steel structure design packages for residential buildings, warehouses, and telecommunication towers, and for electrical projects with a major oil and gas construction company in Egypt. He has participated in Liquified Natural Gas (LNG) and Natural Gas Liquid (NGL) projects with international engineering firms. Currently, Dr. El-Reedy is responsible for reliability, inspection, and maintenance strategy for onshore concrete structures and offshore steel structure platforms. He has performed these tasks for a hundred structures in the Gulf of Suez and the Red Sea. Mohamed earned a PhD in structural engineering, a M.Sc degree in materials and concrete technology, and a B.Sc. in civil engineering, all from Cairo University.

Autoren/Hrsg.

El-Reedy, Mohamed A.

Inhaltsverzeichnis

1;Front Cover;1
2;Marine Structural Design Calculations;4
3;Copyright Page;5
4;Dedication;6
5;Contents;8
6;About the Author;14
7;Preface;16
8;1 Introduction to Offshore Structures;18
8.1;1.1 Introduction;18
8.2;1.2 History of offshore structures;18
8.3;1.3 Overview of field development;19
8.4;1.4 Types of offshore platforms;21
8.4.1;1.4.1 Drilling/well protected platforms;22
8.4.2;1.4.2 Tender platforms;22
8.4.3;1.4.3 Self-contained platforms;22
8.4.4;1.4.4 Production platforms;22
8.4.5;1.4.5 Quarters platforms;23
8.4.6;1.4.6 Flare jackets and flare towers;23
8.4.7;1.4.7 Auxiliary platforms;23
8.4.8;1.4.8 Bridges;23
8.4.9;1.4.9 Helidecks;23
8.5;1.5 Types of offshore structures;23
8.6;Further reading;29
9;2 Engineering Management for Marine Structures;30
9.1;2.1 Overview of field development;30
9.1.1;2.1.1 Project cost and the life cycle;30
9.1.2;2.1.2 Concept and screening selection;32
9.2;2.2 FEED engineering phase;33
9.3;2.3 Detail engineering phase;34
9.4;2.4 Engineering design management;35
9.4.1;2.4.1 Engineering stage time and cost control;36
9.4.1.1;2.4.1.1 Time schedule control;36
9.4.1.2;2.4.1.2 Engineering cost control;39
9.4.2;2.4.2 Engineering interfaces;39
9.4.3;2.4.3 Structural engineering quality control;40
9.5;Further reading;49
10;3 Offshore Structures’ Loads and Strength;50
10.1;3.1 Introduction;50
10.2;3.2 Gravity load;50
10.2.1;3.2.1 Dead load;50
10.2.2;3.2.2 Live load;52
10.2.3;3.2.3 Impact load;55
10.2.4;3.2.4 Design for serviceability limit state;55
10.2.5;3.2.5 Crane support structures;56
10.3;3.3 Wind load;58
10.3.1;3.3.1.1.1 Example 3.1;62
10.3.1.1;Gravity loads;62
10.3.2;3.3.1.1.2 Wind loads;62
10.4;3.4 Offshore loads;63
10.4.1;3.4.1 Wave load;64
10.4.1.1;3.4.1.1 Drag force;68
10.4.1.2;3.4.1.2 Inertia force;69
10.4.1.3;3.4.1.3 Wave load calculation;69
10.4.1.4;3.4.1.4 Comparison between wind and wave calculation;70
10.4.1.4.1;3.4.1.4.1 Example 3.2;70
10.4.1.4.2;3.4.1.4.2 Example 3.3;70
10.4.1.5;3.4.1.5 Conductor shielding factor;73
10.4.1.5.1;3.4.1.5.1 Example 3.4;73
10.4.1.5.1.1;Solution;74
10.4.2;3.4.2 Current load;74
10.4.2.1;3.4.2.1 Design current profiles;75
10.5;3.5 Earthquake load;76
10.5.1;3.5.1 Extreme level earthquake requirements;81
10.5.2;3.5.2 Abnormal level earthquake requirements;82
10.5.3;3.5.3 ALE structural and foundation modeling;82
10.5.3.1;3.5.3.1 Topside appurtenances and equipment;84
10.6;3.6 Ice loads;85
10.7;3.7 Other loads;85
10.7.1;3.7.1 Marine growth;86
10.7.2;3.7.2 Scour;86
10.8;3.8 Design for ultimate limit state;86
10.8.1;3.8.1 Load factors;87
10.8.1.1;3.8.1.1 In-place analysis by ISO19902;88
10.8.1.2;3.8.1.2 Extreme environmental situation for fixed offshore platforms;89
10.8.1.2.1;3.8.1.2.1 Example 3.6;89
10.8.1.2.2;3.8.1.2.2 Example 3.7;90
10.8.1.3;3.8.1.3 Operating environmental situations for fixed platforms;90
10.8.2;3.8.2 Partial action factors;91
10.9;3.9 Collision events;93
10.10;3.10 Material strength;95
10.11;3.11 Cement grout;96
10.12;Further reading;100
11;4 Offshore structures design;102
11.1;4.1 Introduction;102
11.2;4.2 Guide for preliminary design;102
11.2.1;4.2.1 Approximate dimensions;106
11.2.2;4.2.2 Bracing system;109
11.2.3;4.2.3 Jacket design;111
11.3;4.3 Structure analysis;112
11.3.1;4.3.1 Global structure analysis;113
11.3.2;4.3.2 The loads on the piles;116
11.3.2.1;Example 4.1;116
11.3.2.1.1;Solution;117
11.3.3;4.3.3 Modeling techniques;119
11.3.3.1;4.3.3.1 Joint coordinates;119
11.3.3.2;4.3.3.2 Local member axes;122
11.3.3.3;4.3.3.3 Member effective lengths;122
11.3.3.4;4.3.3.4 Joint eccentricities;122
11.4;4.4 Dynamic structure analysis;123
11.4.1;4.4.1 Natural frequency;124
11.4.1.1;Example 4.2;128
11.5;4.5 Cylinder member strength;129
11.5.1;4.5.1 Cylinder member strength calculation by ISO19902;130
11.5.1.1;4.5.1.1 Axial tension;130
11.5.1.2;4.5.1.2 Axial compression;130
11.5.1.3;4.5.1.3 Column buckling;131
11.5.1.4;4.5.1.4 Local buckling;131
11.5.1.5;4.5.1.5 Bending;132
11.5.1.6;4.5.1.6 Shear;133
11.5.1.7;4.5.1.7 Torsional shear;134
11.5.1.8;4.5.1.8 Hydrostatic pressure;134
11.5.1.9;4.5.1.9 Hoop buckling;135
11.5.1.10;4.5.1.10 Tubular members subjected to combined forces without hydrostatic pressure;136
11.5.1.10.1;4.5.1.10.1 Axial tension and bending;137
11.5.1.10.2;4.5.1.10.2 Axial compression and bending;137
11.5.1.11;4.5.1.11 Tubular members subjected to combined forces with hydrostatic pressure;138
11.5.1.11.1;4.5.1.11.1 Axial tension, bending, and hydrostatic pressure;138
11.5.1.11.2;4.5.1.11.2 Axial compression, bending, and hydrostatic pressure;139
11.5.1.12;4.5.1.12 Effective lengths and moment reduction factors;140
11.5.2;4.5.2 Cylinder member strength calculation by API RP2A;142
11.5.2.1;4.5.2.1 Axial tension;142
11.5.2.2;4.5.2.2 Axial compression;142
11.5.2.3;4.5.2.3 Local buckling;142
11.5.2.4;4.5.2.4 Bending;143
11.5.2.5;4.5.2.5 Shear;143
11.5.2.6;4.5.2.6 Torsional shear;144
11.5.2.7;4.5.2.7 Pressure (stiffened and unstiffened cylinders);144
11.5.2.8;4.5.2.8 Design hydrostatic head;144
11.5.2.9;4.5.2.9 Hoop buckling stress;145
11.5.2.10;4.5.2.10 Combined stresses for cylindrical members;145
11.5.2.10.1;4.5.2.10.1 Combined axial compression and bending;146
11.5.2.10.2;4.5.2.10.2 Member slenderness;146
11.5.2.11;4.5.2.11 Combined axial tension and bending;146
11.5.2.12;4.5.2.12 Axial tension and hydrostatic pressure;147
11.5.2.13;4.5.2.13 Axial compression and hydrostatic pressure;149
11.5.2.14;4.5.2.14 Safety factors;149
11.5.2.14.1;Example 4.3;149
11.5.2.14.1.1;Calculation Results;150
11.5.2.14.2;Example 4.4;150
11.5.2.14.2.1;Calculations;150
11.5.2.14.3;Example 4.5;151
11.5.2.14.3.1;Hydrostatic data;151
11.5.2.14.3.2;Section properties;151
11.5.2.14.3.3;Hydrostatic properties;152
11.5.2.14.3.4;Acting stress;152
11.5.2.14.3.5;Allowable stress;152
11.5.2.14.3.6;Code check;152
11.5.2.14.3.7;Ring design;152
11.6;4.6 Tubular joint design;152
11.6.1;4.6.1 Simple joint calculation from API RP2A (2007);153
11.6.1.1;4.6.1.1 Joint classification and detailing;153
11.6.1.2;4.6.1.2 Simple tubular joint calculation;156
11.6.1.2.1;4.6.1.2.1 Strength factor Qu;157
11.6.1.2.2;4.6.1.2.2 Chord load factor Qf;158
11.6.1.2.3;4.6.1.2.3 Joints with thickened cans;159
11.6.1.2.4;4.6.1.2.4 Strength check;160
11.6.1.2.5;4.6.1.2.5 Overlapping joints;160
11.6.1.2.6;4.6.1.2.6 Grouted joints;160
11.6.2;4.6.2 Joint calculation from API RP2A (2000);162
11.6.2.1;4.6.2.1 Punching shear;162
11.6.2.2;4.6.2.2 Allowable joint capacity;163
11.6.2.2.1;Example 4.6;163
11.6.2.3;4.6.2.3 Tubularjoint punching failure;165
11.7;4.7 Fatigue analysis;167
11.7.1;4.7.1 Stress concentration factors;168
11.7.1.1;4.7.1.1 SCFs in grouted joints;171
11.7.1.2;4.7.1.2 SCFs in cast nodes;171
11.7.2;4.7.2 S-N curves for all members and connections, except tubular connections;171
11.7.3;4.7.3 S-N curves for tubular connections;172
11.7.3.1;4.7.3.1 Thickness effect;173
11.7.3.1.1;4.7.3.1.1 Axial load, chord ends fixed;174
11.7.3.1.2;4.7.3.1.2 Axial load, general fixity conditions;175
11.7.3.1.3;4.7.3.1.3 In-plane bending;176
11.7.3.1.4;4.7.3.1.4 Out-of-plane bending;176
11.7.3.1.5;4.7.3.1.5 Axial load, balanced;176
11.7.3.1.6;4.7.3.1.6 In-plane bending;178
11.7.3.1.7;4.7.3.1.7 Out-of-plane bending, balanced;178
11.7.3.1.8;4.7.3.1.8 Balanced axial load;179
11.7.3.1.9;4.7.3.1.9 Unbalanced in-plane bending;179
11.7.3.1.10;4.7.3.1.10 Unbalanced out-of plane bending OPB;180
11.7.3.1.11;4.7.3.1.11 Balanced axial load for three braces;181
11.7.3.1.12;4.7.3.1.12 In-plane bending for three braces;181
11.7.3.1.13;4.7.3.1.13 Unbalanced out-of-plane bending for three braces;181
11.7.3.2;4.7.3.2 Effect of weld toe position;182
11.7.3.2.1;Example 4.7;184
11.7.3.2.2;Example 4.8;185
11.7.3.2.3;Example 4.9;185
11.7.3.2.4;Example 4.10;185
11.7.4;4.7.4 Jacket fatigue design;185
11.8;4.8 Topside design;189
11.8.1;4.8.1 Topside structure analysis;189
11.8.2;4.8.2 Deck design to support vibrating machines;190
11.8.2.1;Example 4.11;190
11.8.2.1.1;Solution;191
11.8.3;4.8.3 Grating design;191
11.8.3.1;Example 4.12;192
11.8.3.1.1;Solution;192
11.8.4;4.8.4 Handrails, walkways, stairways, and ladders;192
11.9;4.9 Bridges;195
11.10;4.10 Vortex-induced vibration;196
11.10.1;Example 4.13;199
11.10.2;Example 4.14;201
11.10.3;Example 4.15;202
11.10.4;Example 4.16;203
11.10.4.1;Solution;203
11.10.5;Example 4.17;203
11.10.5.1;Solution;203
11.11;Further reading;204
12;5 Helidecks and boat landing design;206
12.1;5.1 Introduction;206
12.2;5.2 Helideck design;206
12.2.1;5.2.1 Helicopter landing loads;206
12.2.1.1;5.2.1.1 Loads for helicopter landings;207
12.2.1.2;5.2.1.2 Loads for helicopters at rest;209
12.2.1.3;5.2.1.3 Helicopter static loads;209
12.2.1.4;5.2.1.4 Area load;209
12.2.1.5;5.2.1.5 Helicopter tie-down loads;209
12.2.1.6;5.2.1.6 Wind loading;209
12.2.1.7;5.2.1.7 Installation motion;210
12.2.2;5.2.2 Safety net arms and framing;210
12.3;5.3 Design load conditions;215
12.3.1;5.3.1 Helideck layout design steps;218
12.3.2;5.3.2 Plate thickness calculation;221
12.3.2.1;Example 5.2;221
12.3.3;5.3.3 Aluminum helideck;222
12.4;5.4 Boat landing design;222
12.4.1;5.4.1 Boat landing calculation;223
12.4.1.1;Example 5.3;225
12.4.1.2;5.4.1.1 Cases of impact load;226
12.4.2;5.4.2 Boat landing design using a nonlinear analysis method;226
12.4.3;5.4.3 Boat impact methods;227
12.4.4;5.4.4 Tubular member denting analysis;228
12.4.4.1;5.4.4.1 Simplified method for denting limit calculation;229
12.5;5.5 Riser guard;231
12.5.1;5.5.1 Riser guard design calculation;231
12.5.1.1;Example 5.4;232
12.5.1.2;5.5.1.1 Cases of impact load;233
12.6;Further reading;233
13;6 Geotechnical data and piles design;234
13.1;6.1 Introduction;234
13.2;6.2 Geotechnical investigation;234
13.2.1;6.2.1 Performing an offshore investigation;235
13.3;6.3 Soil tests;235
13.4;6.4 In-situ testing;237
13.4.1;6.4.1 Cone penetration test;237
13.4.1.1;6.4.1.1 Equipment requirements;239
13.4.1.2;6.4.1.2 CPT results;240
13.4.2;6.4.2 Field vane test;242
13.5;6.5 Soil properties;243
13.5.1;6.5.1 Strength;244
13.5.2;6.5.2 Soil characterization;247
13.6;6.6 Pile foundations;248
13.6.1;6.6.1 Pile capacity for axial loads;249
13.6.1.1;6.6.1.1 Skin friction and end bearing in cohesive soils;251
13.6.1.1.1;Example 6.1;252
13.6.1.1.1.1;Solution;252
13.6.1.1.2;Example 6.2;252
13.6.1.1.2.1;Solution;252
13.6.1.1.3;Example 6.3;253
13.6.1.1.3.1;Solution;253
13.6.1.2;6.6.1.2 Shaft friction and end bearing in cohesionless soils;253
13.6.2;6.6.2 Foundation size;256
13.6.2.1;6.6.2.1 Pile penetration;257
13.6.3;6.6.3 Axial pile performance;257
13.6.3.1;6.6.3.1 Static load-deflection behavior;257
13.6.3.2;6.6.3.2 Cyclic response;257
13.6.3.3;6.6.3.3 Axial load-deflection (t-z and Q-z) data;258
13.6.3.4;6.6.3.4 Axial pile capacity;261
13.6.3.5;6.6.3.5 Laterally loaded piles reaction;263
13.6.3.6;6.6.3.6 Lateral bearing capacity for soft clay;264
13.6.3.7;6.6.3.7 Lateral bearing capacity for stiff clay;265
13.6.3.8;6.6.3.8 Lateral bearing capacity for sand;266
13.6.3.9;6.6.3.9 Changes in axial capacity in clay with time;267
13.6.4;6.6.4 Pile capacity calculation methods;269
13.6.4.1;6.6.4.1 Application of CPT;271
13.7;6.7 Pile wall thickness;271
13.7.1;6.7.1 Design pile stresses;272
13.7.2;6.7.2 Stresses due to the weight of the hammer during hammer placement;272
13.7.3;6.7.3 Minimum wall thickness;275
13.7.4;6.7.4 Driving shoe and head;277
13.7.5;6.7.5 Pile section lengths;277
13.8;6.8 Pile drivability analysis;278
13.8.1;6.8.1 Evaluation of soil resistance drive;278
13.8.2;6.8.2 Unit shaft resistance and unit end bearing for uncemented materials;278
13.8.3;6.8.3 Upper- and lower-bound SRD;279
13.8.3.1;Example 6.4;279
13.8.3.1.1;Solution;279
13.8.4;6.8.4 Results of wave equation analysis;280
13.8.5;6.8.5 Results of drivability calculations;282
13.8.6;6.8.6 Recommendations for pile installation;283
13.9;6.9 Soil investigation report;284
13.9.1;Example 6.5;285
13.9.1.1;Solution;285
13.9.2;Example 6.6;286
13.9.2.1;Solution;286
13.10;6.10 Composite pile;286
13.10.1;6.10.1.1 Computation of allowable axial force;288
13.10.1.1;Example 6.7;290
13.11;6.11 Mud mat design;291
13.11.1;Example 6.8;292
13.11.1.1;Solution;294
13.11.2;Example 6.9;294
13.11.2.1;Solution;294
13.11.3;Example 6.10;294
13.11.3.1;Solution;294
13.12;Further reading;295
14;7 Construction and installation lifting analysis;298
14.1;7.1 Introduction;298
14.2;7.2 Construction procedure;298
14.3;7.3 Engineering the execution;299
14.4;7.4 Construction process;299
14.4.1;7.4.1 Fabrication tolerances;300
14.4.1.1;7.4.1.1 Leg spacing tolerances;301
14.4.1.2;7.4.1.2 Vertical level tolerances;302
14.4.1.3;7.4.1.3 Tubular member tolerances;302
14.4.1.4;7.4.1.4 Tolerances of leg alignment and straightness;303
14.4.1.5;7.4.1.5 Tubular joint tolerances;304
14.4.2;7.4.2 Stiffener tolerances;305
14.4.3;7.4.3 Conductor guides and piles tolerances;307
14.4.4;7.4.4 Dimensional control;308
14.4.5;7.4.5 Jacket assembly and erection;308
14.5;7.5 Installation process;311
14.5.1;7.5.1 Loadout process;312
14.5.2;7.5.2 Transportation process;312
14.5.2.1;Example 7.1;317
14.5.3;7.5.3 Barges;318
14.5.4;7.5.4 Launching and upending forces;320
14.6;7.6 Lifting analysis;323
14.6.1;7.6.1 Weight control;323
14.6.2;7.6.2 Weight calculation;324
14.6.3;7.6.3 Classification of weight accuracy;325
14.6.3.1;7.6.3.1 Allowances and contingencies;326
14.6.3.2;7.6.3.2 Weight engineering procedures;327
14.6.4;7.6.4 Loads from transportation, launch, and lifting operations;328
14.6.5;7.6.5 Lifting procedure and calculation;328
14.6.5.1;7.6.5.1 Calculated weight;330
14.6.5.2;7.6.5.2 Hook load;334
14.6.5.3;7.6.5.3 Skew load factor;335
14.6.5.4;7.6.5.4 Resolved padeye load;335
14.6.5.4.1;Example 7.2;336
14.6.5.4.2;Example 7.3;337
14.6.5.4.3;Example 7.4;340
14.6.5.5;7.6.5.5 Sling force;344
14.6.5.6;7.6.5.6 Crane lift factors;345
14.6.5.7;7.6.5.7 Part sling factor;345
14.6.5.8;7.6.5.8 Termination efficiency factor;345
14.6.5.9;7.6.5.9 Bending efficiency factor;345
14.6.5.10;7.6.5.10 Grommets;346
14.6.5.11;7.6.5.11 Shackle safety factors;347
14.6.5.12;7.6.5.12 Consequence factors;347
14.6.6;7.6.6 Structural calculations;347
14.6.7;7.6.7 Lift point design;349
14.6.8;7.6.8 Clearances;350
14.6.8.1;7.6.8.1 Clearances around the lifted object;350
14.6.8.2;7.6.8.2 Clearances around the crane vessel;350
14.6.8.2.1;Example 7.5;352
14.6.9;7.6.9 Lifting calculation report;354
14.6.9.1;7.6.9.1 The crane vessel;356
14.7;Further reading;356
15;8 SACS Software;358
15.1;8.1 Introduction;358
15.2;8.2 In-place analysis;358
15.3;8.3 Defining member properties;363
15.4;8.4 Input the load data;365
15.4.1;8.4.1 Joint can;372
15.4.2;8.4.2 The foundation model;377
15.5;8.5 Output data;383
15.6;8.6 Dynamic analysis;388
15.6.1;8.6.1 Eigenvalue analysis;390
15.7;8.7 Seismic analysis;393
15.7.1;8.7.1 Combination of seismic and gravity loads;395
15.8;8.8 Collapse analysis;397
15.9;8.9 Loadout;402
15.10;8.10 Sea fastening;403
15.10.1;8.10.1 Load combinations;405
15.11;8.11 Fatigue analysis;411
15.11.1;8.11.1 Center of damage;412
15.11.2;8.11.2 Generation of the foundation superelement;415
15.11.3;8.11.3 Dynamic wave response analysis;417
15.11.4;8.11.4 Fatigue input data;426
15.12;8.12 Lifting analysis;427
15.13;8.13 Flotation and upbending;432
15.14;8.14 On-bottom stability;434
15.15;8.15 Launch analysis;437
15.16;8.16 Summary;437
15.16.1;8.16.1 Static analysis;437
15.16.2;8.16.2 Dynamic analysis;438
15.16.3;8.16.3 Seismic analysis;438
15.17;8.17 Fatigue analysis;438
15.17.1;8.17.1 Collapse analysis;438
15.17.2;8.17.2 Lifting analysis;438
15.17.3;8.17.3 On-bottom stability;439
15.17.4;8.17.4 Tow analysis;439
16;Appendix: Assignment;440
17;Index;446

Leseproben

1 Introduction to Offshore Structures
Chapter one is covering an over view of the offshore structure and different types and how to choose the best option between them Keywords
Offshore structure; tension leg; concrete gravity; TLP; FPSO 1.1 Introduction
Marine structures and specifically offshore structures have special characteristics from the economic and technical points of view. Oil and gas production depend on offshore structure platforms, which relates directly to global investment, as it has a direct effect on the oil price. From a practical point of view, because of increasing oil prices, as happened in 2008, many offshore structure projects were begun. From technical point of view, offshore structure platform design and construction is a merger between steel structure design and harbor design, and a limited number of engineering faculties focus on offshore structural engineering as the design of fixed offshore platforms, floating and other types. On the other hand, the number of offshore structural projects is limited relative to conventional steel structure projects, such as residences, factories, and other buildings, which depend on the continuous research and worldwide studies over a long time period. Also, no available textbook covers the calculations for these types of offshore structures, so that is the aim of this book. All the major multinational companies working in the oil and gas industry provide a wealth of information from research and studies in offshore structures. All major oil and gas companies continuously support research and development to enhance the capability of the engineering offices and construction contractors they deal with to support their business needs. 1.2 History of offshore structures
As early as 1909 or 1910, wells were being drilled in Louisiana. Wooden derricks were erected on hastily built wooden platforms constructed on top of wood piles. Over the past 50 years, two majors categories of fixed platforms have been developed, the steel template type, which was pioneered in the Gulf of Mexico (GoM), and the concrete gravity type, which was first developed in the North Sea. Recently, a third type, the tension leg platform, was used due to the need to drill wells and develop gas projects in deep water. In 1976, Exxon installed a platform in the Santa Barbara Channel to water depth of 259 m (850 ft). There are three basic requirements in designing fixed offshore platforms: 1. Withstand all loads expected during fabrication, transportation, and installation. 2. Withstand loads resulting from severe storms and earthquakes. 3. Provide functional safety as a combined drilling, production, and housing facility. Around 1950, while the developments were taking place in the GoM and the Santa Barbara Channel, the BP company engaged in similar exploration on the coast of Abu Dhabi in the Persian Gulf. The water depth is less than 30 m (100 ft), and the operation has grown steadily over the years. In the 1960s, hurricanes in the GoM caused serious damage to offshore platforms, so reevaluation of platform design criteria was strongly needed. The hurricane history of the GoM follows: • In 1964, Hurricane Hilda, had wave heights of 13 m and wind gusts up to 89 m/s. This 100-year storm destroyed 13 platforms. • The next year, another 100-year storm, Hurricane Betsy, destroyed three platforms and damaged many others. • For that, designers abandoned the 25-and 50-year conditions and began to design for a storm recurrence interval of 100 years. 1.3 Overview of field development
Estimating future oil reserves in different areas of the world is based on geological and geophysical studies and oil and gas discoveries. As of January 1996, about 53% of these reserves were in the Middle East, which could be a reason for the political troubles in that area. Noting that, 60% of all reserves were controlled by the Organization of Petroleum Exporting Countries (OPEC). This explains why OPEC and the Middle East are so important for the world’s current energy needs In reality, all the companies or countries have a good assessment of the undiscovered reserves in the Middle East and the former Soviet republics. Most researchers believe that the major land-based hydrocarbon reserves are already discovered and most significant future discoveries are expected to be in offshore, arctic, and other difficult-to-reach and -produce areas of the world Geological research found that North America, northwest Europe, the coastal areas of West Africa, and eastern South America appear to have similar potential for deepwater production. During an early stage in geological history, the sediments were deposited in basins with restricted circulation, which were later converted to the super source rocks found in the coastal regions of these areas. The presence of these geological formations gives us the initial indication for the discovery of hydrocarbons. Before feasible alternatives for producing oil and gas from an onshore field are identified and the most desirable production scheme is selected, exploratory work defining the reservoir characteristics have to be completed. First, a decision has to be made whether an offshore location has the potential for hydrocarbon reserves. This assessment is usually performed through a study of geological formations by geologists and geophysicists The geologists and geophysicists must decide that this field could be economically viable and further exploratory activities are warranted. This decision involves preparing cost, schedule, and financial return estimates for selected exploration and production schemes. After that, they must compare several of these alternatives and identify the most beneficial one. Due to the absence of detailed information with respect to the reservoir characteristics, future market conditions, and field development alternatives, the experts have to make judgments based on their past experience. The total cost and schedule estimates are based on the data available to the company from its previous history regarding this type of project. The power of the oil and gas companies depends on their expertise in these decisions, so most of these companies keep such expertise within the company and compete with each other to steal them. Sometimes, these data do not help enough, so the decision can result from brainstorming sessions attended by experts and management and be greatly affected by the company culture and past experience. The reservoir management plan is affected by the reservoir and produced fluid characteristics, Reservoir uncertainty may regard size and topography, regional as well as national politics, company and partner culture, and the economics of the entire field development scheme. Well system and completion design are affected by the same factors that affect the reservoir management plan, except perhaps political factors. Platforms and facilities for process and production, storage and export are affected by all these factors. The following factors affect the decision on the field development: • Reservoir characteristics. • Production composition (oil, gas, water , H2S, and other). • Reservoir uncertainty. • Environment at the water depth. • Regional development status. • Local technologies available. • Politics. • National politics. • Partners. • Company culture. • Schedule. • Equipment availability. • Construction facilities availability. • Market availability. • Economics. If the preliminary economic studies in this feasibility study are positive, seismic data generation and evaluation by geophysicists follow. These result in reasonable information with respect to the reservoir characteristics, such as its depth, spread, faults, domes, other factors and an approximate estimate for recoverable reserves of hydrocarbons. If the seismic indications are positive and the decision is to explore further, exploratory drilling activities commence. Depending on the water depth, environment, and a suitable exploration scheme is selected. A jack-up exploratory unit is suitable for shallow water depths. In water depths exceeding 120 m (400 ft), ships or semisubmersible drilling units are utilized. In the case of 300 m (1000 ft) depths, floating drilling units require special mooring arrangements or a dynamic positioning system. Noting that, a floating semisubmersible drilling rig capable of operating in 900 to 1200 m (3000 to 4000 ft) water depths is needed. Delineation of the exploratory drilling work follows the discovery well. This generally requires three to six wells drilled at selected points of a reservoir. These activities and production testing of the wells where oil and gas are encountered give reasonably detailed information about the size, depth, extent, and topography of a reservoir, such as the fault lines, impermeable layers and their recoverable reserves, viscosity (API grade), liquid properties (such as oil/water ratio), and other impurities (such as sulfur or other critical components). Reservoir information enables the geologists...