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Working together for a safer world
Risk analysis of marine operations involving dynamic positioning
Dr. Haibo Chen
20 May 2014
70 years anniversary seminar and
celebration
for
Professor Odd M. Faltinsen and
Professor Torgeir Moan
©Lloyd’s Register Consulting
Haibo Chen – Who am I ?
• 1999 – 2003, Dr.ing study supervised by
Prof. Torgeir Moan
• 2003, Joined Scandpower AS
• 2005, relocated to Scandpower Inc. in
China in. Live and work in Beijing, China
since then.
• 2006 – present, President of Scandpower
Inc. in China.
• 2010, became part of Lloyd’s Register
since. Managing Director for Lloyd’s
Register Consulting Asia since 2013.
• A risk analysis professional, 15 years on
safety of marine operations involving
dynamic positioning.
©Lloyd’s Register Consulting
Dr.ing: FPSO and shuttle tanker collisions (1999 – 2003)
• "Probabilistic Evaluation of FPSO-Tanker
Collision in Tandem Offloading Operation“, IMT-
Report 2003:1, Dept. of Marine Technology,
NTNU, January 2003. Reprinted in 2010.
• Fortunate to have wide co-operations with
industry, e.g. Statoil, Navion, SMSC, Kongsberg,
SINTEF, HSE(UK), and a few shuttle tanker
captains.
Bedre sikkerhet i Nordsjøen (17.3.03, 12:55)
Et doktorgradsarbeid ved Institutt for marin teknikk bidrar til økt
sikkerhet under lasteoperasjoner i Nordsjøen.
Offshore-industrien var sterkt representert under en doktordisputas på
Tyholt fredag. Haibo Chen forsvarte da sin avhandling "Probabilstic
Evaluation of FPSO-Tanker Collision in Tandem Offloading Operation".
©Lloyd’s Register Consulting
A practical formulation of Risk Model for Marine Operations
• Accident: collisions, loss of well integrity,
rupture of loading hose, etc.
• Position loss: drive-off vs. drift-off,
frequency.
• Recovery: human intervention to
mitigate/avoid accident, or other automatic
safety systems to function.
• Automatic safety system, e.g. Drive-off
Preventer, Auto EDS, SDS system, etc.
P(position
loss)
P(failure of recovery)
P(accident) =
Frequency of position
loss
Failure probability of recovery actions
initiated by DP operator, or automatic safety
systems, given position loss.
©Lloyd’s Register Consulting
How frequent had a position loss happened?
• Rule of thumb: 0.3 per year, 0.2
drift-off and 0.1 drive-off,
averaged for DP class 2+3
vessels.
• DP class 1 vessels?
• Frequencies in the chart have
very different DP operational
hours behind.
©Lloyd’s Register Consulting
Position loss incident and DP time reporting
• Lack of a common DP incident reporting scheme on the NCS/worldwide
• SYNERGI
• WSOG logging
• DP watch checklist
• IMCA (vulnerary basis)
• Ambiguity contents or insufficient information in the reporting, and under reporting, a hidden unknown factor
• Major deficiencies to failure frequency and risk analysis: Missing reported vessel DP time
• Recommendation 1: to improve reporting of
DP incident and DP time.
• This may be linked to Well/location Specific
Operating Guideline.
• Enable better DP failure frequency data
• Recommendation 2: Differentiate types of
DP vessels in causal analysis. The same
applies for DP2 vs. DP3.
Environment
Thruster
DP-Control
Power
Key DP
Personnel
Incident Category Causal Areas
Advisory
Yellow
Red
DP Incidents
Loss of Position
Non Loss of
Position
©Lloyd’s Register Consulting
DP failure frequency: from Generic to Vessel & Operations Specific
• Objective: vessel and/or DP
operational specific position loss
frequency.
• Challenge: Significant variations
among different risk analyses on this
element. Reasoning for adjustment
often not well documented.
• Experience from a DP flotel study
(2011-2013), methodology of
vessel/operations “adjustment
factors”.
• Recommendation 3: Need a systematic and
robust approach to handle “frequency
adjustment” in risk analyses.
©Lloyd’s Register Consulting
Nature of DP operations and human machine dynamics
Monitoring & checking
80 %
Emergency Situation
ca. 1 %
Not Automated Task
19 %
Challenges:
Passive surveillance => Lose Situation Awareness => No early detection
Out-of-the-loop in system dynamics + commercial pressure => Difficult to act in time
• Recommendation 4: systematic human
reliability study to improve operator
performance.
©Lloyd’s Register Consulting
How quick can DP operators react to drive-off?
DP Operator Reaction Time in Drive-off Scenarios
0
50
100
150
200
250
300
3 6 7 8 9 10 11 12 13 14 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 45 46 47 49 50 51 52 53 54 55 56 57 58 59
Simulator Observation Case ID
Tim
e (
s)
Decision & Execution Time
Detection Time
• Incident data, Expert judgment, 2001-2002
• DP captain questionnaire survey 2002
• Logging of DP operator reaction time
during offloading simulator training
(simulated drive-offs) in 2003-2006
Time to prevent collision in drive-off: 60 s
vs.
Mean Reaction time by DPO: 85 s
©Lloyd’s Register Consulting
Risk analysis of direct offloading concept (2007 – 2011)
• Separation distance 200 - 250 m
• Weathervane with inherent safe heading
philosophy
• Heading pivot point
• Min. 150 m no entry zone
• DP shuttle tanker position loss!
• Towards installation = Collision risk
• Away from installation = Hose rupture
and oil spill risk
• Selected offloading concept for, e.g.
Goliat, Aasta Hansteen, etc.
150
m
250 m
Illustration drawing: The size and distance are not to scale.
Heading pivot point
hose
Wind
Fixed / Geostationary Offshore Installations
Zone 1Zone 2
Zone 1
Zone 2
©Lloyd’s Register Consulting
Inherent operational safety barriers in direct offloading concept
• Shuttle tanker positioning
strategy = Not heading towards
installation (less than 1 hour
drive-off collision risk exposure
time vs. 20 hours)
• 250 m distance = Time window
for recovery action by tanker DP
operator is 3 minutes vs. 1
minute (80 m distance).
• Collision frequency can be within
1% of an equivalent tandem
offloading concept.
DP Operator Reaction Time in Drive-off Scenario
(2003-2006, 66 simulator observations)
0.0
0.2
0.4
0.6
0.8
1.0
0 20 40 60 80 100 120 140 160 180 200
Time (s)
Pro
bab
ilit
y o
f R
eact
ion
wit
hin
Tim
e
©Lloyd’s Register Consulting
Safety of DP drilling operations (2003 – 2007)
Objective: Improve safety of DP operations on mobile offshore drilling
units on the Norwegian Continental Shelf.
©Lloyd’s Register Consulting
Barrier methodology to model and analyze DP drilling safety
1. DP incident data collection and analysis: drive-off due to satellite based position reference
system failures.
2. Modeling of barrier functions and barrier element
3. Investigate performance shaping factors for the human barrier (DP operator).
©Lloyd’s Register Consulting
Summary: Questions in the industry ?
• What are risk elements involved in DP operations?
• Can a position loss happen? If so, how frequent? What are main contributors?
• What’s role for DP operators, causes to failure or last safety barrier?
• What are key areas for risk mitigation efforts?
• What should a risk analysis include, and where to further improve?
©Lloyd’s Register Consulting
Answers: Learning in the past 15 years… (1999 – 2014)
1. Risk model for marine operations involving DP.
• P(accident) = P(position loss) x P(failure of recovery)
2. Minimize position loss events and frequency
• Recommendation 1: to improve reporting of DP incident and DP time.
• Recommendation 2: Differentiate types of DP vessels in causal analysis. The same applies for
DP2 vs. DP3
• Recommendation 3: Need a systematic and robust approach to handle “frequency adjustment” in
risk analyses.
3. Improve human intervention given position loss
• Recommendation 4: systematic human reliability study to improve operator performance.
Lloyd’s Register and variants of it are trading names of Lloyd’s Register Group Limited, its subsidiaries and affiliates.
Copyright © Lloyd’s Register Consulting. 2013. A member of the Lloyd’s Register group.
Working together for a safer world
Dr. Haibo Chen Managing Director Asia
T +86 1380-132-0200 E [email protected]
Lloyd’s Register Consulting
www.lr.org/consulting