Jackup Moving (Oilfield Seamanship Series, Volume 2) - 2nd Edition

This second edition reflects significant changes to the ways in which jackups are managed when afloat, such as those concerning design rules, regulations, guidelines and codes of practice. It includes changes to jackup moving operations, which are now conducted under a detailed and agreed Rig Move Procedure (RMP). This document clearly sets out the duties and responsibilities of the principal parties involved, the criteria to be used when making decisions regarding starting and stopping operations and the details of any sea passage to be undertaken. The book is appended with pre-move checklists and verified tow Master calculations.

This edition has been updated to include intricate technical illustrations, which have been annotated to reflect the steps involved in complex positioning operations. Factors such as weather criteria, seabed analysis and Certificate of Approval acquisition have also been included, making this a both a comprehensive and practical reference tool.

This volume of the Oilfield Seamanship Series illustrates how jackup rigs are safely moved from one location to another in an offshore environment. The purpose of the book is to support tow Masters, personnel responsible for moving jackup rigs, tug and anchoring handling vessel crews, and those ashore involved in planning rig move operations.

Tow Masters moving jackup rigs should have relevant experience of working on tugs or as barge engineers. Barge engineers are familiar with jacking gear, preloading requirements, maintenance of jacking equipment and issues associated with rack phase differences (RPDs). Tow Masters with experience on vessels have a good understanding of towing wires and ropes, tow angles, bollard pull (BP) requirements and weather criteria. The subjects covered in this publication will complement the existing knowledge of tow Masters who want to expand their understanding of particular jacking or vessel operations.

Jackup rig crews are familiar with their own operations, ie drilling, but if not experienced in moving rigs, they must be well briefed in afloat operations by the tow Master on board. This ensures that all personnel are aware of the risks associated with the marine environment and potential poor weather.

In 2022 there are over 500 jackup rigs in worldwide operation, compared to 205 semi-submersibles1. Despite advances in technology such as remote RPD measurements, more stringent Class build requirements and warranty requirements on towing, there continue to be incidents where jackup rigs are damaged, or indeed lost, such as the ‘Naga 7’ in 2021. A better understanding of the operational aspects of jackup rig moving will assist in all parties’ appreciation of potential hazards when moving from one location to the next, and what can be done to safely mitigate those hazards.

The work contained within this publication was carried out with the assistance of the original author Captain Michael Hancox and Captains Hans Villadsen, Rob Breure and Josh Develing.

Thomas Feakins, 2022

Foreword vii

Introduction ix

Notes on Units of Measurement xi

1. Jackup Rigs

1.1 Moving Jackups

1.2 Rig Types in Operation

1.3 Structure of Rigs

1.4 Towing Arrangements On Board

1.5 Anchors

1.6 Positioning System Equipment

1.7 Survey Equipment

1.8 Correction and Misalignment – Elevated Operations

1.9 Location onto Subsea Templates/Wellheads – Wire Method

1.10 Marine Operations Manual

2. Tugs and Equipment

2.1 Overview of Tugs

2.2 Tugs

2.3 Anchor Handling Tugs

2.4 Small Seagoing Tugs/Multipurpose Tugs

2.5 Harbour Tugs

2.6 Towing Wires, Ropes, Pennants and Other Equipment

2.7 Tow Master’s Equipment

2.8 Towing Power Calculations

3. Jackup Move Plan and Process

3.1 Initial Stages

3.2 Outline of Jackup Rig Move Procedure (RMP)

3.3 Shoreside Hazard Identification and Risk Assessment (HIRA)

3.4 Pre-move Operations

3.5 Criteria for Towing

4. Emergency and Contingency Plans

4.1 Overview

4.2 Class Requirements

4.3 Emergency Plans

4.4 Contingency Plans

5. Jacking Down, Freeing Legs and Getting Afloat

5.1 Hazards Associated with Jacking Down and Getting Afloat

5.2 Jacking Down

5.3 Freeing Legs

5.4 Freeing Deeply Penetrated Legs

5.5 Connection of Tugs

5.6 Working in Areas of High Tidal Range

6. Towage

6.1 Hazards Associated with Towing Off Location

6.2 Manoeuvring with Tugs

6.3 Towage During Sea Passages

6.4 Passage Considerations

6.5 Passage Interfield – Short Distances

6.6 Port Towage

7. Float On/Off Heavy Lift Vessels (HLVs)

7.1 Hazards Associated with Floating On and Off an HLV

7.2 Use of Tugs

7.3 Use of HLV Lines

7.4 Responsibilities

7.5 Stability and Ballasting Operations

7.6 HLV Sea Fastenings

7.7 Securing Rigs for Barge or HLV Tows

8. Approach to Standoff Location

8.1 Hazards When Approaching Standoff Location

8.2 Picking up Towlines

8.3 Lowering Legs

8.4 Calculations for Standoff Location

8.5 Wavelength and Jacking

9. Jacking Gear and Jacking Operations

9.1 Overview of Jacking Gear

9.2 Precautions with Jacking Gear

9.3 Common Issues with Jacking Gear

9.4 Sequence of Jacking Operations

9.5 Decision Making Process – Jacking Criteria

9.6 Example for Checking Torque on Jacking Motors

10. Running Anchors

10.1 Hazards Associated with Running Anchors

10.2 Mooring Arrangements

10.3 Midline Buoy Procedures

10.4 Anchors

10.5 Winches and Mooring Wires

10.6 AHTS Setup for Working Anchors

11. Positioning at Location

11.1 Hazards Associated with Positioning

11.2 Open Location – Tug Deployment

11.3 Use of Stern Bridle

11.4 Tug Operations

11.5 Transit Between Standoff and Final Position

11.6 Positioning onto a Platform – Basic Method

11.7 Positioning onto a Platform – Complex Method

11.8 Walking onto a Final Position

11.9 Winch Operations

12. Preloading Operations

12.1 Hazards Associated with Preloading Operations

12.2 Procedures for Preloading

12.3 Monitoring of the Rig During Preloading Operations

12.4 Preloading – One Leg at a Time

12.5 Punch Throughs and Rapid Penetrations

12.6 Preloading Four-legged Jackups

12.7 Hydraulic Preloading

12.8 Preloading in Areas of High Tidal Range

12.9 Leg Footing Strength – Hard Seabeds

13. Rack Phase Differences (RPDs)

13.1 Overview 16913.2 Causes of RPDs

13.3 Existing Spudcan Holes

13.4 Repositioning a Jackup to Avoid RPDs

13.5 Measuring RPDs

13.6 Preventing RPDs from Causing Damage

13.7 Practical Solutions to RPDs

13.8 Leg Foundation Stability

13.9 Scour Considerations

14. Marine Warranty Surveyor

14.1 Overview

14.2 Certificate of Approval (CofA)

14.3 Weather Criteria

14.4 Site Investigation Hazards and Evaluation

15. Stability

15.1 Jackup Rig Stability

15.2 Calculating Leg Reactions

15.3 Motion Limits – Diagrams and their Use

15.4 Critical Motion Curves

15.5 Tug Stability

Appendices

Appendix 1: Calculating Leg Reactions

Appendix 2: Tow Master’s Approximate Calculations

Appendix 3: Selecting Tugs for Jackup Operations

Appendix 4: Pre-move Checklist

Appendix 4A: Tow Master (in conjunction with the OIM/barge Master)

Appendix 4B: OIM/barge Master (in conjunction with tow Master and rig Superintendent/Senior Toolpusher)

Appendix 4C: Barge engineer

Appendix 5: Daily Afloat Operations Checklist

Appendix 6: Rig Move Checklist

Appendix 7: Tow Master Checklist

Appendix 8: Soil Classification Table

Glossary of Terms

References

Practical Exercises

Witherby Publishing Group

Witherbys titles are developed using scripts developed by technical experts that are peer reviewed within work groups. Typically, they seek to improve understanding of the regulations, recommendations and guidelines issued by Industry.

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