Effect of Mooring Lines on the Responses of Spar Platforms
by
Nur Azimah Mohd Zin
Dissertation submitted in partial fulfilment of the requirements for the
Bachelor of Engineering (Hons) (Civil Engineering)
JULY2008
Universiti Teknologi PETRONAS Bandar Seri Iskandar
31750 Tronoh
Perak Darul Ridzuan
CERTIFICATION OF APPROVAL
Effect Of Mooring Lines On The Responses Of Spar Platform
by
Nur Azimah Mohd Zin
A project dissertation submitted to the Civil Engineering Programme Universiti Teknologi PETRONAS in partial fulfilment of the requirement for the
BACHELOR OF ENGINEERING (Hons) (CIVIL ENGINEERING)
Approved by,
(Assoc. Prof. Dr. Kurian V. John)
Dr Kurian V. John Associate P'rQfesaor Civn fil9lnMring ~-•ln!l.,..onot
UnivOISl!l T8llnolotl PETRl:!HAi -So<! ... 3t1~ T"""'h Perrrlt Darul A~wan, M,'~L-§\Y51A
UNIVERSITI TEKNOLOGI PETRONAS TRONOH, PERAK
July 2008
CERTIFICATION OF ORIGINALITY
This is to certify that I am responsible for the work submitted in this project, that the original work is my own except as specified in the references and acknowledgement, and that the original work contained herein have not been undertaken or done by unspecified sources or persons
(NUR AZIMAH BINTI MOHD ZIN)
ii
ABSTRACT
Spar platform, a competitive alternative structure for deepwater oil field development is modelled as a rigid body with six degree -of-freedom, connected to the sea floor by multi-component catenary mooring lines, which are attached to the spar platform at the fairleads. Since this spar platform is quite new in deepwater exploration, a lot of studies and researches still need to be done. Therefore in this project, the different type of spar platforms as well as the dynamic responses of spar platform such as surge, heave and pitch are being analyzed and compared by using comparison method based on its different mooring lines configurations. The mathematical results by using Linear Airy Wave Theory, Pierson-Moskowitz Spectrum, Morison Equation and Motion Response Spectrum have been conducted. The frequency domain analysis and time domain analysis have been performed by choosing frequency within 0.05 - 0.3Hz and time series within 0 - 100 seconds. For Neptnne Spar Platform, the maximum profile obtained were 1.9 - 2m for surge, 0.78m for heave and 0.065radian for pitch. These values are within the permissible limits for offshore operations. Also, parametric studies have been made by using different number of mooring lines. It is shows that there is no significant effect on the surge and heave responses even though the stiffness increases as the number of mooring lines increases.
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ACKNOWLEDGEMENT
In the name of ALLAH S.W.T. The Most Gracious and The Most Merciful for the blessings and strength to complete this project.
First and foremost, I would like to acknowledge my deepest gratitude to my inspired supervisor, Assoc. Prof. Dr. Kurian V. John for his extent guidance, constant attention, valuable suggestion and enthusiastic support as well as personal concern during one year oftime completing this Final Year Project.
An enormous appreciation to Assoc. Prof. Ir Dr Hj Muhd Fadhil Nuruddin, the Programme Head of Civil Engineering Department for facilities and equipment provided in order to complete my project. Special thanks once again to Final Year Project Coordinators, Mr. Kalaikumar all Vallyutham and Ms. Niraku Rosmawati Ahmad for their excellent guidance to the Final Year students. Not to forget, an infinite gratitude to my internship supervisor, Ir. Abd Khalid Jaafar for his support and motivation that inspired me to complete this project.
Last but not least, special thanks to both of my beloved parents; Hj Mohd Zin Ismail and Hjh Samiah Hj Hasan and supportive brother, Khairul Anwar Hj Mohd Zin for being there all the time, giving continuous aspiration, encouragement and support for me to proceed with my Final Year Project.
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TABLE OF CONTENTS
CERTIFICATION OF APPROVAL ...•...•... i
CERTIFICATION OF ORIGINALITY ... ii
ABSTRACT ..•...•...•...•....•...•... iii
ACKNOWLEDGEMENT ...•.•...•..•...•.•...•...•.•••...• iv
TABLE OF CONTENTS ...•...•...•...•...•....•....•...• v
LIST OF FIGURES ...•...•..•...•... vi
LIST OF TABLE ...•...•.•..•.•....•.•...•....•..•.•.•..•.•...•....•....•.... vii
ABBREVIATIONS & NOMENCLATURES ..•...•...•...•...•.•. viii
CHAPTER 1-INTRODUCTION .•...••....•...•....•... 1
1.1 BACKGROUND OF STUDY ... 1
1.2 PROBLEM STATEMENT ... 7
1.3 OBJECTIVES ... 7
1.4 SCOPE OF STUDY. ... 8
CHAPTER 2 -LITERATURE REVIEW ... 9
2.1 SPAR PLATFORM ... 9
2.2 MOORlNG LINES ... 12
2.3 THEORY ... 14
CHAPTER 3- METHODOLOGY ...•....•...••...•...•...•...••.•.•...•....••...•... 19
3.1 PROCEDURE ... 19
3.2 SOFTWAREREQUIRED ... 21
3.3 HEALTH, SAFETY & ENVIRONMENT (HSE) ANAL YSIS ... 22
CHAPTER 4- RESULTS & DISCUSSIONS .•...•...•.•...•... 23
4.1 RESEARCH & DATA GATHER1NG ... 23
4.2 ANALYSIS ... 26 v
4.3 PARAMETRIC STUDY (MOORING LINES) ... 35
CHAPTER 5- CONCLUSIONS & RECOMMENDATIONS ... 38
5.1 CONCLUSIONS ... 38
5.2 RECOMMENDATIONS ... 39
REFERENCES ... 40
APPENDICES ... 43
vi
LIST OF FIGURES
Figure 1.1 : Floating Production and Subsea Systems ... 2
Figure 1.2: (a) Classic Spar, (b) Truss Spar, (c) Cell Spar ... 3
Figure 1.3 : Typical Spar Components ... 4
Figure 1.4 : List of Spar Platform available in the world (Technip Offshore) ... 5
Figure 1.5 : Kikeh Spar Platfrom (Technip Offshore) ... 6
Figure 2.1 : Sample of Mooring Lines used for Offshore Platform ... 13
Figure 2.2: Sample of Taut Mooring configuration ... 13
Figure 2.3 : Sample of Layout of Mooring Lines and Risers and Environmental Orientation ... 13
Figure 2.4: Wave Theory ... 14
Figure 2.5 : Orbital motion under linear waves ... 15
Figure 2.6 : Motion of a particle in an ocean wave ... 16
Figure 3.1 : Steps of conducting analysis ... 21
Figure 4.1 : Neptune Spar Platform Diagram ... 25
Figure 4.2: Wave-Particle Velocity ... 26
Figure 4.3 : Wave Spectrum ... 27
Figure 4.4 : Wave Profile ... 28
Figure 4.5 : Total Horizontal Forces ... 29
Figure 4.6 : Surge Response Spectrum ... 30
Figure 4. 7 : Surge Profile ... 31
Figure 4.8 : Heave Response Spectrum ... 32
Figure 4.9 : Heave Profile ... 33
Figure 4.10 : Pitch Response Spectrum ... 34
Figure 4.11 : Pitch Profile ... 35
Figure 4.12: Mooring Lines Configuration ... 36 vii
Figure 4.13 : Surge Stiffness ... 36
Figure 4.14 : Heave Stiffness ... 36
Figure 4.15: Surge Response Spectrum ... 36
Figure 4.16: Heave Response Spectrum ... 36
Figure 4.17: Surge Profile ... 37
Figure 4.18: Heave Profile ... 37
viii
LIST OF TABLE
Table 4.1 : Details of Neptune Spar Platform ... 23
Table 4.2 : General Natural Period for spar platform ... 24
Table 4.3 : Wave Height (H(f)) for each frequency ... 28
Table 5.1 : Maximum Responses for Surge, Heave and Pitch ... 38
ix
CB
CG
FPS FPSO FYPl FYP2 GoM HAZID HAZOP HSA HSE HSEM PCSB PPE RAO
SACS TADU TLP
ABBREVIATIONS & NOMENCLATURES
Center of Buoyancy Center of Gravity
Floating Production System
Floating Production, Storage and Offloading Final Year Project 1
F ina! Year Project 2 Gulf of Mexico Hazard Identification
Hazard and Operability Study Health Risk Assessment
Health, Safety and Enviromnent
Health, Safety and Enviromnent Manual PETRONAS Carigali Sdn Bhd
Personal Protective Equipment Response Amplitude Operations Structural Analysis Computer System Tender Assisted Drilling Unit
Tension Leg Platform
X