Post on 28-Mar-2020
ICNAME'2015_29th-30th June, 2015, Harbin_China
Offshore Oil and Gas Platforms for
Deep Waters
Atilla Incecik
Department of Naval Architecture, Ocean
and Marine Engineering
University of Strathclyde, Glasgow, UK
(atilla.incecik@strath.ac.uk)
ICNAME'2015_29th-30th June, 2015, Harbin_China
Summary of World Energy Demand
ICNAME'2015_29th-30th June, 2015, Harbin_China
Energy Supply
ICNAME'2015_29th-30th June, 2015, Harbin_China
Global Deep Water Discoveries
ICNAME'2015_29th-30th June, 2015, Harbin_China
Global Deep Water Discoveries
ICNAME'2015_29th-30th June, 2015, Harbin_China
Global Deep Water Discoveries
ICNAME'2015_29th-30th June, 2015, Harbin_China
Deep Water Oil and Gas Platforms
Main Factors to be considered in Concept
Selection:
• Production Volume
• Environment
• Water Depth
• Distance to shore or infrastructure
• The number of drilling centres required to drain
the reservoir
• The well intervention frequency
• Cost
• Strategic reasons
Well Configuration and location options:
• Surface well completion
• Seabed Well Completion tied back to
o adjacent surface facility
o remote surface facility
Development Concept Options:
• TLP
• FPSO
• SPAR
• Semisubmersibles
• Subsea Tieback
Main Platforms Features
TLPs
• Custom designed for site application
• Single drilling centre
• Surface completed wells
• Integral Drilling / Workover Facilities
• No oil storage
• Tensioned rigid risers for production
• Flexible or steel catenary for import or export
• Sensitive to top side loads
• Relatively long development schedule
FPSOs
• New-build or tanker conversation
• Remote wells, normally completed subsea
• Drilling / workover requires specialist vessel
• Integral oil storage and offloading
• Flexible risers
• Insensitive to topside load
• Short development schedule
SPARs• Custom designed for site specific application
• Single drilling centre/surface completed
wells/integral workover, or
• Remote wells completed subsea/workover by
specialist vessel
• Integral oil storage or
• No oil storage
• Tensioned risers, flexibles or steel catenary
risers
• Medium development schedule
Semisubmersibles:
• New-build or conversion
• Remote subsea wells with workover by
specialist vessel
• Wells below with integral
drilling/workover facilities
• No oil storage
• Sensitive to topside load
• Flexible risers
• Short to medium development schedule
Subsea Tie back to Shallow Water• Custom designed for site specific applications
• Multiple drilling centres
• Remote subsea wells
• Well workover by specialist vessel
• No oil storage, oil is exported from host
platform
• Short development schedule
• Hydraulic performance of long flowlines is key
design issue
Floating offshore platforms
Page 118 Global Marine Trends 2030 | Offshore energy sector
Total platformsin 2010270
Fig. 100 Number of floating platformsSource: University of Strathclyde
2010
2
42
3
48
16
58
2
2
27
51
19
ICNAME'2015_29th-30th June, 2015, Harbin_China
ICNAME'2015_29th-30th June, 2015, Harbin_China
ICNAME'2015_29th-30th June, 2015, Harbin_China
Challenges
Medusa Spar
Thunderhorse
Mars TLP
Typhoon TLP
Petronius tower
ICNAME'2015_29th-30th June, 2015, Harbin_China
Hydrodynamic Design Challenges
Short crestedness Extreme waves/spatial wave characteristics Vortex Induced Vibrations/Vortex Induced Motions Multiple body interactions Coupled systems (offloading) Wave impacts Green water Non-linear wave effects Shallow water waves Dynamic Positioning CFD applications Model testing of Deep Water Offshore Platforms
ICNAME'2015_29th-30th June, 2015, Harbin_China
Development of simulation tools for coupled systems
ICNAME'2015_29th-30th June, 2015, Harbin_China
Development of simulation tools
for coupled systems
ICNAME'2015_29th-30th June, 2015, Harbin_China
ICNAME'2015_29th-30th June, 2015, Harbin_China
Development of simulation tools
for coupled systems
ICNAME'2015_29th-30th June, 2015, Harbin_China
ICNAME'2015_29th-30th June, 2015, Harbin_China
Development of analysis tools to predict the
occurrence and impact of ‘green seas’ on
FPSO’s and FPUs
ICNAME'2015_29th-30th June, 2015, Harbin_China
Wave Impact Loading
Wave1
2
3
4
5
6
7
8 9
10
11
Wave Probe
Load Cell
Lower Deck Plan
LC CL
ICNAME'2015_29th-30th June, 2015, Harbin_China
Prediction of Loading and
Response due to Non-linear Waves
ICNAME'2015_29th-30th June, 2015, Harbin_China
Prediction of Loading and
Response due to Non-linear Waves
ICNAME'2015_29th-30th June, 2015, Harbin_China
Experimental investigation into motion
control of Truss Spars
ICNAME'2015_29th-30th June, 2015, Harbin_China
Numerical and experimental studies to
simulate loads and motions during installation
of SPARs
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
ICNAME'2015_29th-30th June, 2015, Harbin_China
Excitation on Floating
Platforms
Waves
• 1st order forces at wave frequency (WF)
• 2nd order forces
mean wave drift forces
forces at sum frequencies (HF)
forces at difference frequencies
ICNAME'2015_29th-30th June, 2015, Harbin_China
Excitation on Floating
Platforms
Wind
• Mean wind forces
• Fluctuating wind forces due gusts in the wind field
• Vortex induced vibrations/motions (VIV/VIM)
ICNAME'2015_29th-30th June, 2015, Harbin_China
Excitation on Floating
Platforms
Current
• Mean current forces
• Fluctuating current forces
• Vortex induced vibrations/motions (VIV/VIM)
ICNAME'2015_29th-30th June, 2015, Harbin_China
Excitation on Floating
Platforms
Current
• Mean current forces
• Fluctuating current forces
• Vortex induced vibrations/motions (VIV/VIM)
ICNAME'2015_29th-30th June, 2015, Harbin_China
Dynamic Responses
Motions
• Mean offset, WF, and LF
Mooring Forces
• Mean, WF, LF and HF (for TLPs)
ICNAME'2015_29th-30th June, 2015, Harbin_China
Dynamic Responses
Vessel Natural periods (s)
Surge Sway Heave Roll Pitch Yaw
FPSO >100 >100 5-12 5-30 5-12 >100
SemiSub >100 >100 20-50 30-60 30-60 >100
Spar >100 >100 20-50 50-100 50-100 >100
TLP >100 >100 <5 <5 <5 >100
ICNAME'2015_29th-30th June, 2015, Harbin_China
Dynamic Responses
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 10 20 30 40 50 60 70 80
Period (s)
He
av
e A
mp
litu
de
/Wa
ve
Am
plitu
de
(m
/m)
Spectrum
FPSO
SEMISUB
SPAR
ICNAME'2015_29th-30th June, 2015, Harbin_China
Dynamic Responses
Horizontal Motion
WF
LF
WF
LF
M
W WF
M LF M M
Water Depth (m)
70 330 2000
Horizontal motions
are obtained from the
solutions of coupled
equations
ICNAME'2015_29th-30th June, 2015, Harbin_China
Sources of Low Frequency
Damping
Wind Damping
Wave Drift Damping
Wave radiation
Viscous Hull Damping
Viscous mooring line and riser damping
Friction between the mooring lines and sea bed
ICNAME'2015_29th-30th June, 2015, Harbin_China
Low Frequency Damping for an FPSO
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6
Item
% o
f T
ota
l D
am
pin
g
Series1
Series2
Series3
ITEM:
1. Wind Damping 2. Wave Drift damping in 2.0 m/s current
3. Hull Damping in 2.0 m/s current 4. Mooring and riser damping in still water
5. Mooring and riser damping in 2.0 m current 6. Mooring and riser damping in 2.0 m/s current and
8 m regular waves
Series 1: 70 m water, mooring only
Series 2 : 860 m, mooring only
Series 3 : 860 m water, mooring and riser
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
Properly scaled system
• Prerequisites : All mooring lines to be included, correctly scaled with respect to mass, elastic and geometric properties.
• Results: Hull forces, motions, and mooring system loads can be obtained, including mooring line tension
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
Simplified catenary modelling i.e. simplified or omitted lines • Prerequisites : Careful documentation of
modelling approximation by means of verified theoretical models or special calibration tests must be provided to demonstrate adequate damping and stiffness properties
• Results: Hull forces and motions can be obtained
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
Catenary mooring lines replaced by horizontal lines • Prerequisites : Correct restoring force
characteristics needs to be documented
• Results: Since the mooring line damping is not modelled the motions will be too large. Wave drift forces on the hull can be obtained
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
Dynamically controlled mooring lines • Prerequisites : Documentation of the winches
ability to simulate the dynamic mooring characteristics.
• Results: In principle it should be feasible but it will be very difficult to represent the instantaneous dynamic effect of wave frequency motions on line tensions. Hull forces and first order motions can be obtained but low frequency motions and mooring line tension cannot be obtained easily.
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
Passive Hybrid SystemsTruncated parts of the mooring lines and risers are represented by a system of springs, masses and dampers.
In a passive hybrid system the horizontal mooring stiffness can be modelled correctly whereas damping due to mooring lines and mooring line dynamics cannot be obtained accurately.
ICNAME'2015_29th-30th June, 2015, Harbin_China
Model Testing of Deep Water Offshore
Platforms
Active Hybrid SystemsTruncated parts of the mooring lines and risers are represented by computer controlled actuators that can work in model scale and in real time.
In an active hybrid system the dynamic mooring line behaviour can be simulated, including the damping and mooring line sea-bed friction characteristics
ICNAME'2015_29th-30th June, 2015, Harbin_China
Concluding Remarks
For the offshore oil and gas industry, the challenge is to continue to provide for the future energy needs of the world’s consumers from resources in difficult locations in ways which are environmentally responsible, safe and economically viable.
This lecture presented the factors in the selection of a concept design for deep water offshore oil and gas field developments, and the recent research and development activities and challenges in hydrodynamics analysis of deep water platform designs.