Tc 67/sc 4 n date: 2005-03-9 iso/wd XXXXXX ISO tc 67/sc 4/wg 6 Secretariat: Design of dynamic risers for offshore production systems Élément introductif — Élément central — Élément complémentaire  Warning



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ISO TC 67/SC 4 N 

Date:   2005-03-9

ISO/WD xxxxxx

ISO TC 67/SC 4/WG 6

Secretariat:   

Design of dynamic risers for offshore production systems

Élément introductif — Élément central — Élément complémentaire



Warning

This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an International Standard.

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Contents Page

Foreword ix

Introduction x

1 Scope 1

2 Normative references 2

2.1 ISO Specification, Standards, Recommended Practices, Rules and Guidelines 2

2.2 Other References 3

3 Terms and definitions 6

4 Symbols and abbreviated terms 18

5 General 27

5.1 General functions of risers 27

5.2 Configurations of risers 28

5.3 What is not (fully) covered 28

5.3.1 Risers as mooring elements 28

5.3.2 Control lines or umbilicals 29

5.3.3 Low pressure fluid transfer hoses 29

5.3.4 Bonded flexible pipe 29

5.3.5 Composite (fiber-reinforced) materials 29

5.4 Status of Technology 29

6 Description of Riser Systems and Components 29

6.1 General 29

6.2 Essential system features 29

6.2.1 Riser body 29

6.2.1.1 Metal pipe 30

6.2.1.2 Flexible pipe 30

6.2.1.3 System interfaces 30

6.3 Riser system descriptions 30

6.3.1 Production/injection risers 30

6.3.2 Export risers 31

6.3.3 Drilling risers 31

6.3.4 Completion/workover risers 31

6.3.5 Multi-bore hybrid risers 31

6.3.6 Multi-bore top tensioned metal risers 32

6.4 Riser component descriptions 32

6.4.1 Components for fluid transfer 32

6.4.1.1 Riser segments 32

6.4.1.2 Fluid conduit interfaces 33

6.4.1.3 Fluid control and fluid isolation 34

6.4.2 Components for stability and external load control 34

6.4.2.1 Tensioning and heave motion compensating systems 34

6.4.2.2 Supplemental buoyancy 35

6.4.2.2.1 Distributed buoyancy 35

6.4.2.2.2 Concentrated buoyancy 35

6.4.2.3 Flexure controlling devices 35

6.4.2.3.1 Metal pipe 35

6.4.2.3.2 Flexible Pipe 36

6.4.2.4 Stabilizing structures 36

6.4.2.5 Centralizing devices 36

6.4.2.6 Devices for reduction of hydrodynamic loading effects 36

6.4.3 Monitoring and control systems 37

6.4.4 Fluid purge and containment 37

6.4.4.1 Planned disconnect 37

6.4.4.2 Unplanned disconnect 37

6.4.4.3 Quick disconnect for flexible risers 38

6.4.5 Guidance (re-entry) equipment 38

6.4.6 Anti-fouling equipment 38

6.4.7 Damage limitation measures 39

6.4.7.1 Fire protection 39

6.4.8 Insulation 39

7 General design considerations 39

7.1 General 39

7.2 Safety, risk, and reliability 39

7.2.1 Safety 39

7.2.1.1 Personnel and platform safety 39

7.2.1.2 Pollution safety 40

7.2.2 Risk and reliability 40

7.3 Functional considerations 41

7.3.1 Catenary export risers 41

7.3.2 Catenary import risers 41

7.3.3 Top tensioned production risers 41

7.3.4 Top tensioned injection service risers 41

7.3.5 Drilling risers 41

7.3.6 Top tensioned workover and completion risers 41

7.4 Operational considerations 41

7.4.1 General 41

7.4.2 Operating philosophy 42

7.4.3 Vessel motions & environmental limits 42

7.4.4 Manning 42

7.4.5 Vessel interfaces 42

7.4.6 Riser deployment and retrieval 43

7.4.7 In-Service Operations 43

7.4.7.1 Simultaneous drilling and production 43

7.4.7.1.1 Safety considerations 43

7.4.7.1.2 Limitations and restrictions 44

7.4.7.1.3 Interference considerations 44

7.4.7.2 Well completions and workovers 45

7.4.7.3 Through-riser operations 45

7.4.7.4 Monitoring 46

7.4.7.5 Operational support 46

7.4.7.6 Control 46

7.4.7.7 Manning 47

7.4.7.8 Riser limitations 47

7.4.8 Rig movements and station keeping 47

7.4.8.1 Stationkeeping considerations 47

7.4.8.2 Strategy for vessel offset control 48

7.4.9 Storm and Contingency Operations 48

7.4.9.1 Riser operating limitations 48

7.4.9.1.1 Latched operations 48

7.4.9.1.2 Riser hangoff mode 48

7.4.9.1.3 Riser deployment and retrieval 49

7.4.9.2 Disconnect considerations 49

7.5 Structural Considerations 49

7.5.1 Load Combinations for Design Cases 50

7.5.2 Design Criteria 50

7.5.2.1 Allowables 50

7.5.2.2 Interference 50

7.5.2.3 Fatigue and Service Life 51

7.5.2.4 Degradation of syntactic foam buoyancy 51

7.6 Material Considerations 52

7.7 Installation, retrieval, and reinstallation of metal risers 52

7.7.1 Preparations, testing and required support equipment 53

7.7.2 Transportation and handling 53

7.7.3 Installation considerations 54

7.7.3.1 FPS deployed 54

7.7.3.2 Other riser deployment methods 54

7.7.4 Disconnect and Retrieval 55

7.7.5 Reinstallation Considerations 56

7.7.6 Hydrostatic testing 56

7.8 Installation, retrieval and reinstallation of flexible risers 56

7.8.1 Preparations and required support equipment 56

7.8.2 Transportation and Handling 56

7.8.3 Installation Considerations 57

7.8.4 Disconnection and retrieval 58

7.8.5 Reinstallation 58

7.8.6 Hydrostatic Testing 58

7.9 Installation, Retrieval and Reinstallation of Other Risers 58

7.10 Maintenance and Inspections 58

7.10.1 Maintenance and inspection philosophy 58

7.10.2 General Considerations 59

7.10.3 Tensioner System Maintenance 59

7.10.4 Riser Inspections 59

7.10.5 Miscellaneous Inspections 59

7.10.6 Marine Growth 59

7.11 Training 59

7.11.1 Training program 60

7.11.2 Training manuals 60

7.11.3 Operational and safety procedures 60

7.11.4 Offshore commissioning phase 60

7.11.5 Training maintenance 60

8 Loads 60

9 Design Criteria for Riser Pipe 60

10 Connectors and riser components 61

11 Raw materials 61

12 Welding procedure qualification 61

13 Fatigue testing for welds 61

14 Fatigue testing for base metals 61

15 Production welding 61

16 NDT 61

17 Corrosion protection 61

18 Fabrication and Installation 61

19 Riser Integrity Management 61

19.1 Introduction 61

19.2 Risk Management 62

19.3 Quality Assurance 62

19.3.1 General 62

19.3.2 Documentation 62

19.3.2.1 Basis of Design 62

19.3.2.2 Premises of Design 62

19.3.2.3 Methodology and Procedure for Design 62

19.3.2.4 Operation Manual 62

19.3.2.5 Service Records 62

19.3.2.6 Equipment traceability 62

19.3.3 Verification 62

19.4 Operation, Maintenance and Reassessment 63

19.4.1 Operation Procedures 63

19.4.2 In-service Inspection, Maintenance, Replacement and Monitoring 63

19.4.3 Reassessment 63

19.4.3.1 Corrosion 63

19.4.3.2 Leaks and Cracks 63

19.4.3.3 Materials 63

19.4.3.4 Strength 63

19.4.3.5 Fatigue Life 63

Annex A (informative) Analytical Considerations 64

A.1 General 64

A.2 Analytical Considerations by Riser Type 64

A.2.1 Top tensioned risers 64

A.2.1.1 Start-up phase 65

A.2.1.2 Preliminary design and analysis phase 65

A.2.1.2.1 Preliminary riser sizing 65

A.2.1.2.2 Preliminary global riser analysis 65

A.2.1.2.3 Preliminary global riser response assessment 66

A.2.1.2.4 Tensioner design 66

A.2.1.2.5 Preliminary analysis of the individual tubes 66

A.2.1.2.6 Riser component design/analyses 66

A.2.1.2.7 Assess data and mission 66

A.2.1.3 Detailed design and analysis phase 66

A.2.1.3.1 Global riser analysis 67

A.2.1.3.2 Global riser response assessment 67

A.2.1.3.3 Verification of the tensioner design 67

A.2.1.3.4 Analysis of the individual riser tubulars 67

A.2.1.3.5 Riser component design check 67

A.2.1.3.6 Design iteration 68

A.2.1.4 Special analytical considerations 68

A.2.1.4.1 External drilling riser lines 68

A.2.1.4.2 Multiple tubes for production, workover / completion and import / export risers 68

A.2.1.4.3 Special riser joints 68

A.2.1.4.4 Riser clearance 69

A.2.1.4.5 Fatigue 69

A.2.1.4.6 BOP installation 69

A.2.1.4.7 Production riser installation 69

A.2.1.4.8 Completion/workover riser installation 69

A.2.1.4.9 Well completions 69

A.2.1.4.10 Tubing hanger installation operations 69

A.2.2 Flexible pipe risers 69

A.2.3 Hybrid risers 70

A.2.3.1 Analysis approach 70

A.2.3.2 Design Approach 71

A.2.3.2.1 Sizing 72

A.2.3.2.2 Preliminary Analysis 72

A.2.3.2.3 Extreme Load Response 73

A.2.3.2.4 Fatigue and Fracture Analysis 73

A.2.3.3 Installation 74

A.2.3.3.1 Tow-out option 74

A.2.3.3.2 Running option 75

A.2.4 Multibore top tensioned metal risers 75

A.2.5 Steel catenary risers (SCRs) 76

A.2.5.1 Initial sizing and static design 76

A.2.5.2 VIV analysis and VIV suppression requirements 77

A.2.5.3 Extreme response and strength analysis 77

A.2.5.3.1 SCR model 77

A.2.5.3.2 Analysis considerations 78

A.2.5.4 Fatigue analysis 78

A.2.5.4.1 Stress responses for fatigue analysis 79

A.2.5.4.2 Damage computation 79

A.2.5.5 Installation analysis 79

A.3 Hydrodynamic Considerations 79

A.3.1 Waves 79

A.3.1.1 Sea State 79

A.3.1.2 Wave spreading 80

A.3.1.3 Wave profile and kinematics 81

A.3.1.4 Wave spectrum discretization 81

A.3.1.5 Wave directionality 82

A.3.1.6 Regular waves 82

A.3.2 Current 82

A.3.3 Loading types and flow conditions 82

A.3.3.1 Oscillatory flow due to waves and vessel motions 82

A.3.3.1.1 Condition 1. Stationary vertical riser in waves 83

A.3.3.1.2 Condition 2. Riser oscillating in calm water 83

A.3.3.1.3 Condition 3. Riser oscillating in waves 84

A.3.3.2 Non‑oscillatory incident flow 85

A.3.3.2.1 Static load 85

A.3.3.2.2 Equivalent static load 85

A.3.3.2.3 Vortex induced fluctuating loads 86

A.3.3.2.3.1 Spanwise correlation 86

A.3.3.2.3.2 Effect of riser oscillation 87

A.3.3.2.4 Vortex induced loads on flexible risers 87

A.3.3.3 Superposition of waves and currents 87

A.3.3.4 Hydrodynamic interaction of dual or multiple risers 87

A.3.3.4.1 Dual risers 87

A.3.3.4.2 Multiple risers 88

A.3.4 Load model 88

A.3.4.1 Equivalent linearization 89

A.3.4.2 Calculate the Static Deflection of the Riser 89

A.3.4.3 Calculate the Hydrodynamic Forces Outside the Lock‑on Region of the Riser 90

A.3.4.4 Calculate the Vortex Induced Forces in the Lock‑on Region of the Riser 90

A.3.5 Conditions that affect hydrodynamic loads 90

A.3.5.1 Free stream turbulence 90

A.3.5.2 Surface roughness 91

A.3.5.3 Marine growth 91

A.3.5.4 Effect of appendages 92

A.3.5.4.1 Satellite lines 92

A.3.5.4.2 Local irregularities 92

A.3.5.5 Wave kinematics 92

A.3.5.6 Wave amplification 93

A.3.5.7 Vortex suppression devices 93

A.3.5.7.1 Wake fairing 93

A.3.5.7.2 Helical strake 93

A.3.5.7.3 Alternate Buoyancy Joints 94

A.3.6 Model testing 94

A.4 Global Analysis 94

A.4.1 Equation of motion 94

A.4.1.1 Discretized equation of motion 96

A.4.1.2 Mass modeling 96

A.4.1.3 Buoyancy and pressure forces 97

A.4.2 Riser boundary conditions 97

A.4.2.1 Top end 97

A.4.2.1.1 Vessel motions 97

A.4.2.1.1.1 Wave frequency motion response 98

A.4.2.1.1.2 Low frequency motion response 98

19.4.3.5.1.1 Combination of motion components 98

A.4.2.1.2 Tensioner modeling 98

A.4.2.2 Bottom end 99

A.4.2.2.1 Flex joints 99

A.4.2.2.2 Stress joints 99

A.4.3 Solution methods 99

A.4.3.1 Discretization 100

A.4.3.2 Small versus large angle formulation 100

A.4.3.3 Planar versus three-dimensional analysis 100

A.4.3.4 Tension coupling 101

A.4.3.5 Stroke and tensioner stiffness 101

A.4.3.6 Stability 101

A.4.3.7 Nominal forces and stresses 101

A.4.3.8 Frequency domain analysis 102

A.4.3.9 Time-domain analysis 103

A.4.3.9.1 Integration approach 103

A.4.4 Special modeling considerations 104

A.4.4.1 Equivalent pipe model 104

A.4.4.2 Coupled vessel/riser analysis 104

A.4.4.3 Design statistics and transfer functions 104

A.4.4.3.1 Frequency domain 104

A.4.4.3.1.1 Extreme values 104

A.4.4.3.1.2 Transfer functions 105

A.4.4.3.2 Time-domain 105

A.4.4.3.2.1 Extreme values 105

A.4.4.3.2.2 Transfer functions 106

A.5 Component Analysis 106

A.5.1 Individual riser tubulars 106

A.5.2 Connectors and stress joints 107

A.5.3 Flex joints 108

A.5.4 Effect of appendages on local stress 108

A.5.5 Tensioning system 109

A.6 Special Purpose Analysis 109

A.6.1 Clearance 109

A.6.1.1 Waves 109

A.6.1.2 Currents 110

A.6.1.2.1 Basic wake formulae 110

A.6.1.2.2 Flexible risers of arbitrary geometry 112

A.6.2 Hydrostatic collapse 112

A.6.2.1 Collapse of metal pipe 113

A.6.2.2 Collapse propagation 114

A.6.2.3 Commentary 114

A.6.3 Vortex-induced vibrations 114

A.7 Service Life 115

A.7.1 Fitness-for-service 115

A.7.1.1 Fracture mechanics assessment procedures 116

A.7.1.2 Fatigue design 116

A.7.1.2.1 S-N curve approach 117

A.7.1.2.1.1 Parent material S-N curves 117

A.7.1.2.1.2 Welded joint S-N curves 117

A.7.1.2.2 Fatigue crack growth assessment procedures 117

A.7.1.2.3 Stresses for fatigue assessment 118

A.7.1.3 Environmental cracking 119

A.7.1.3.1 Prevention of further cracking 119

A.7.1.3.2 Predict remaining life using crack growth law and determine inspection intervals 120

A.7.2 Wear 120

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO xxxxxx was prepared by Technical Committee ISO/TC 67, Materials, Equipment and Offshore Structures for Petroleum and Natural Gas Industries: Drilling, Production, Refining and Transport by Pipelines, Subcommittee SC 4, Drilling and Production Equipment.

This second/third/... edition cancels and replaces the first/second/... edition (), [clause(s) / subclause(s) / table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.

Introduction

Since the first edition of API-RP-2RD “Recommended Practice for Design of Risers for Floating Production Systems (FPSs) and Tensioned-Leg Platforms (TLPs)” was issued in June 1998, and the first edition of DnV OS-201 “Dynamic Risers” was issued in 2001, hydrocarbon exploration in deep water environments has increased significantly. As a consequence of this, the need has been identified to update and reconcile those codes of practice to address the issues of deepwater dynamic risers in sufficient detail in water depths up to 10,000 feet.

ISO Technical Committee 67 (Materials, equipment and offshore structures for petroleum and natural gas industries), Subcommittee 4 (Drilling and production equipment) and API Committee 2 (Offshore/Subsea Standards), Subcommittee 2 (Offshore Structures), Resource Group 10 (Risers), formed a task group in 2004 to draft an ISO standard for production riser systems. Volunteers were distributed among six sub-working groups, with each group responsible for one or two sections of the standard. A leader was appointed for each of the groups. The scope of work and the proposed outline of the standard were discussed on the first workshop held on February 10, 2004. The scope of the standard and the frame of each sub-working group were debated on the second workshop held on March 23, 2004. The workshops were attended by 18~20 specialists and included five attendees from Europe. (This first draft was published in October 2005. A second draft was published in …, and a final draft was published in …)

This standard was developed on the basis of API RP 2RD:1998, Design of Risers for Floating Production Systems (FPSs) and Tension-Leg Platforms (TLPs), and other relevant documents on dynamic riser systems. Others documents includes DNV Offshore Standard DNV-OS-F201 (2001) “Dynamic Risers”, ISO/FIDS:2003 13628-7 “Petroleum and natural gas industries – Design and operation of subsea production systems – Part 7: Completion/work-over riser systems”, and API RP 1111 (1999) “Design, Construction, Operation and Maintenance of Offshore Hydrocrabon Pipelines”.

This standard is the result of reviews by ISO/IEC TC 67/SC4 of the proposed standard issued by a Joint Task Group of ISO/TC 67/SC4 and API C2/SC2, and managed by Technip Offshore, Inc.

Design of dynamic risers for offshore production systems




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