Prof. J.K. Paika) and Dr. J. Czujkob)a) President of The Ship and Offshore Research Institute, PNU, Korea

b) CEO of NOWATEC E&C, Korea

Engineering and Design Disciplines Associated withManagement of Hydrocarbon Explosion and Fire Risks

in Offshore Oil and Gas Facilities

SIMS 2012 International Conference15-16 November 2012, Busan, Korea

Accidents in Offshore Oil and Gas Facilities

Piper Alpha Accident occurred on July 6, 1988 in the North Sea

(167 killed with 1.4 billion USD insurance claims)

Deepwater Horizon Accident occurred on April 20, 2010 in the Gulf of Mexico

(11 killed and 17 injured with 30 billion USD environmental damage)

Presentation OverviewBackground and ObjectivesExplosion and Fire MechanismCurrent Industry Practices versus Advanced Method (EFEF JIP Procedure)Engineering and DesignParadigm Change in Safety Design

Background and Objectives

Top 10 Problems for Next 50 Years

Source: www.kostic.niu.edu and US CIA

1 Energy2 Water3 Food4 Environment5 Poverty6 Terrorism and War7 Disease8 Education9 Democracy10 Population

Population in 2012: 7.2 Billion

Population in 2050: 9.3 Billion

Population in 2100: 10 Billion

Energy Sources

Coal Oil NaturalGasMethaneHydrate

Current Tide

Nuclear Solar Wind

Wave

Hydro

Hydrogen Bio-Fuels Source: Shell

Resources in Subsea

Oil NaturalGas Methane MineralsHydrate

Deepwater Reservoirs under Development

Accident Statistics in Offshore Facilities

0

5

10

15

20

25

30

35

40

45

World Statistics 1990-2007

Explosion/Fire StructuralFailure

Collision

Risk-Based Disciplines in HFE Principles FrameworkHazard

identification (Step1)Risk

assessment (Step2)Decision making

recommendations (Step5)

Risk control options (Step3)

Cost benefit assessment (Step4)

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Project phase

Relationship between cost related to risk reduction and project phase

Mechanism of Hydrocarbon Explosions and Fires

Causes and Consequences of Explosions and Fires

Release of flammable gas and/or liquid

Release of flammable gas and/or liquid

No ignitionNo ignition

Immediateignition

Immediateignition

Formationof

flammablefuel-aircloud

(pre-mixed)

Formationof

flammablefuel-aircloud

(pre-mixed)

FireFire

Ignition(delayed)Ignition

(delayed)Gas

explosionGas

explosionNo

damageNo

damage

Damageto

personneland

material

Damageto

personneland

material

Fireand/orBLEVE

Fireand/orBLEVE

BLEVE = Boiling liquid expanding vapour explosions

Norwegian Continental Shelf

Hydrocarbon Explosion Mechanism depending on Topology and Geometry

Gas burns

Volume increases

Gas flow increases

Turbulence

Gas expands

Larger volume pushes unburntgas ahead

Unburnt gas pushed around obstacles

Flame front wrinkled, burning surface greater, increased mixing, faster burning

BLAST

CONGESTION? CONFINEMENT?

Factors Affecting Explosions and Fires

Wind direction Wind speed Leak rate Leak direction Leak duration Leak position (x) Leak position (y) Leak position (z) Type of oil or gas (molecules) Concentration ratio Temperature of oil or gas

(LNG Cryogenic -163 degrees C)

High Temp. Blast Pressure

Current Industry Practicesversus

EFEF JIP Procedure

Joint Industry Projects

EFEF JIP Explosion and Fire Engineering of FPSOs

27th JIP during 2009 to 2011

Coordinators:- Prof. J.K. Paik: Pusan National University, Korea- Dr. J. Czujko: Nowatec AS, Norway

Partners:- DSME, SHI, HHI, ABS, KR, LR- Gexcon, CompuIT, USFOS, UK HSE, NTUA

Current Industry Practices vs. EFEF JIP ProcedureCurrent Industry Practices EFEF JIP Procedure

Prescriptive selection of scenarios Probabilistic selection of scenarios

Effect of confinement in explosion Effect of confinement in explosion

Effect of congestion in explosion Effect of congestion in explosion

No effect of confinement in fire Effect of confinement in fire

No effect of congestion in fire Effect of congestion in fire

Explosion criteria: overpressure Explosion criteria: overpressure, drag force, impulse

Fire criteria: flame length Fire criteria: temperature, heat dose, heating rate

No structural consequence analysis Structural consequence analysis

EFEF JIP Procedure for Fire Risk Assessment

Selection of credible scenarios involving PDF parameters of leak and environment conditions

CAD modelCFD model

Fire CFD simulationDesign loads with exceedance curve

Nonlinear consequenceanalysis under fire Temperature(K)

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200 400 600 800 1000 1200

0.00001

0.0001

0.001

0.01

0.1

Mean temperature (Point20 and Point31)

Mean temperature (Point41 and Point52)

Latin hypercube sampling technique

EFEF JIP Procedure for Explosion Risk AssessmentSelection of credible scenarios involving PDF parameters of leak and environment conditions

Selection of credible scenarios involving PDF parameters ofgas cloud condition

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Overpressure (MPa)0 0.02 0.04 0.06 0.08 0.1

0.00001

0.0001

0.001

0.01Large cylindrical vessels (Point 171 )

CAD modelCFD model

Gas dispersion analysis

Explosion CFD simulation Design loads with exceedance curve Nonlinear consequenceanalysis under explosion

Latin hypercube sampling technique

Applied Example: VLCC-class FPSO in off West Africa

Selection of Scenarios x1 = wind direction x2 = wind speed x3 = leak rate x4 = leak direction x5 = leak duration x6 = leak position (x) x7 = leak position (y) x8 = leak position (z)

360

05

1015

20

45

90

135

180

225

270

31525

3035

40(%)

Probability of wind direction (windrose)in the ocean of West Africa

Fire CFD Simulations using KFX Code

Time(s)

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(

K

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0 40 80 120 160 200

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1400

Scenario 27

Elevation A(Point 6)

Elevation B(Point 19)

Elevation C(Point 30)

Elevation D(Point 43)

Elevation E(Point 54)

Exceedance Curves for Maximum Gas Temperatures

Temperature(K)

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280 300 320 340 360 380

0.0001

0.001

0.01

0.1

0.00001

Separation train 2(Point 77)

Oil inlet(Point 96)

Gas compressor(Point 75)

Surrounding separation train1

Gas Cloud Volume versus Overpressure

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Equivalent volume (m3)0 2000 4000 6000 8000 10000 12000

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

FPSO AFPSO B

EFEF JIP

Explosion CFD Simulations

Temperature[K] (upper) and radiation heat flux[kW/m2] (lower)

Explosion CFD Simulations using FLACS Code

Exceedance Curves for Maximum Overpressure

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Overpressure (MPa)0 0.02 0.04 0.06 0.08

0.00001

0.0001

0.001

0.01

Boundary forward-El. C(Point 126)

Boundary pipe rack side-El. C(Point 142)

Boundary Aft.-El. E(Point 196)

Blast walls

Exceedance Curves for Maximum Impulse

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Overpressure impulse (MPa*s)0 0.0005 0.001 0.0015 0.002 0.0025

0.00001

0.0001

0.001

0.01Blast walls

Boundary forward-El. C(Point 126)

Boundary pipe rack side-El. C(Point 142)

Boundary Aft.-El. E(Point 196)

Comparison between Current Practices and EFEF JIPLocation

EFEF JIP(Design loads by

10-4 /year)

FPSO C FPSO D

Design load

Nominal load

Design loads by 10-4 /year

Design load

Nominal load

Design loads by 10-4 /year

Under the solid process deck 0.013 - - - - - -

Solid process deck 0.070 0.094 0.100 0.094 0.090 0.100 0.090

Above the solid process deck

around primary structures

0.095 - - - 0.110 0.100 0.110

Above the middle process deck 0.070 - - - - - -

Under the top process deck

around primary structures

0.155 - - - - - -

Top process deck 0.107 - - - - - -

Above the top process deck 0.010 - - - - - -

Blast walls

Boundary forward 0.048

0.054 0.150 0.054 0.090 0.100 0.090 Boundary

aft. 0.043

Boundary pipe rack

side0.027

Large cylindrical vessels 0.070

0.040 ~ 0.087 0.040 0.087

0.050 ~ 0.120 0.100 0.120

Wall of the living quarter 0.001 - - -

0.012 ~ 0.030 0.010 0.015

Equipment and piping

on the solid process deck (drag)

0.012 0.040 0.012 0.034 0.040 0.030 0.030

Concluding Remarks Current Practices vs. EFEF JIP ProcedureNo standard industry practices are available.The current industry practices are based on prescriptive approaches. For minor leaks causing a small amount of gas cloud volume,the current industry practices tend to underestimate overpressure,and vice versa for significant leaks. The current industry practices address design guidelines only forlimited areas, while the EFEF JIP procedure can be applied toassess and manage the risks in greater detail.The EFEF JIP procedures are more refined methods for quantitativeassessment and management of both explosion and fire risks.

Engineering and Design

Engineering and Design of Offshore Oil and Gas Facilities

Process module Utility module Blast walls Fire walls Living quarters Helidecks Flare towers Equipment and piping Risers Pipelines

Engineering and Design for Hydrocarbon Explosion

Engineering and Design for Hydrocarbon Explosion

Explosion CFD AnalysisNonlinear Structural

Consequence Analysis

Time dependent Overpressure

for each structure in FE model

Safety - StructuralInterface

Engineering and Design of Offshore Facilities

Topsides Design

Dynamic Analysis (start from 0.3s to 3.5s)

Static Analysis (start from 0.0s to 0.3s)

Blast Wall Design

Equipment Design

Piping Design

Control Room Design(1/3)

Control Room Design(2/3)

Control Room Design(3/3)

Offshore Helideck Design

Further Works in Engineering and DesignFully quantitative risk-based design procedures combining both probabilistic loads and probabilistic consequence models are required. Full scale or at least large scale model testing in terms of both explosion or fire loads and structural consequences is required to validate mathematical algorithms.

Source: Fire and Blast Information Group, The Steel Construction Institute

Without water sprays With water sprays

Full/Large Scale Test Facilities in Hadong

Norway Fire TestTrondheim UKExplosion/Fire Test

SpadeadamUSA Explosion/Fire TestHouston

KoreaExplosion/Fire, Subsea,

Structural FailureHadong

North Sea

GOM

Paradigm Change in Safety Design

General Trends in Risk-based Disciplines

Qualitative Quantitative

Prescriptive Probabilistic

Past Experience-Based Simulation-Based

Specific Scenarios All Possible Scenarios

Experiment

Paradigm Change in Safety Design(1/3)

In the light of tragic consequences of recent accidents in the offshore industry, public pressure forces a focus shift in the business. Financial measures, important as ever, are even more challenging for industry today due to public pressure on companies to invest in health, safety and environmental performance.

Paradigm Change in Safety Design(2/3)

One of the key findings of the Deepwater Horison Study Group (2010) was:

The Macondo well project failures have demonstrated that the consequences of major offshore oil and gas system failures can be several orders of magnitude greater than associated with previous generations of these activities.

Paradigm Change in Safety Design(3/3)

As companies look to improve the bottom line, there is more and more interest in demonstrating the contributions made with respect to health and safety, such as:

Immediate society response to large offshore accidents National and international investigations Adoption of the industry to lesson-learned new procedures,

requirements and standards Changes in legislation and regulatory agencies Significant rise in insurance premiums following Deepwater Horizon

accident Increased society and governmental focus on safety and environment