The Use of Risk Analysis in Design
The Use of Risk Analysis in Design
The Use of Risk Analysis in Design
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SPE-121065<br />
<strong>The</strong> <strong>Use</strong> <strong>of</strong> <strong>Risk</strong> <strong>Analysis</strong> <strong>in</strong><br />
<strong>Design</strong><br />
Safety Aspects Related to the<br />
<strong>Design</strong> and Operation <strong>of</strong> a FPSO<br />
Lars Tronstad, StatoilHydro
Contents<br />
• Introduction<br />
• Challenges with FPSOs<br />
• <strong>Risk</strong> analysis <strong>in</strong> design<br />
• Safety Aspects<br />
• Asgard FPSO experience
Challenges with FPSOs<br />
Position<strong>in</strong>g<br />
Safety - Technical<br />
Telemetry<br />
Green l<strong>in</strong>e<br />
Tank atmosphere<br />
Safety - Operation<br />
Stability<br />
Area surveilance<br />
Stern <strong>of</strong>ftake<br />
Swivel<br />
Pitch/roll<br />
Green sea<br />
Cargo operation<br />
Sea chests<br />
Cargo system<br />
Pumps<br />
Pump room<br />
Hull design<br />
Ballast system<br />
Valves<br />
L<strong>in</strong>es<br />
Turret<br />
Cargo system<br />
Flexible risers<br />
Anchor<strong>in</strong>g
Asgard FPSO data<br />
•Length: 278 m<br />
•Breadth: 45 m<br />
•Displacement: 184.300<br />
tonnes<br />
•Storage cap.: 910.000 bbl<br />
•Process cap.: 200.000 bbl/d<br />
•On stream: May 1999<br />
•Estimated produc<strong>in</strong>g life: 20<br />
yrs
Barents sea<br />
Norwegian Sea<br />
Tromsøflaket<br />
Harstad<br />
• Outside Mid-<br />
Norway<br />
Asgard field<br />
• Location <strong>of</strong> Asgard<br />
Stjørdal<br />
Bergen<br />
Stavanger<br />
North Sea
Asgard - Schematic Field Layout<br />
S3<br />
MORVIN<br />
Morv<strong>in</strong> 10.5”<br />
20.1 km w/DEH<br />
Morv<strong>in</strong> 5” -15<br />
km Gas <strong>in</strong>jection<br />
FLOWLINE<br />
BUNDLE AS03 :<br />
G-101, I-101, I-102<br />
F-103<br />
F<br />
E<br />
F-201<br />
TEMPLATE LEGEND:<br />
Oil Production<br />
Gas Production<br />
K-102<br />
STIFS<br />
G<br />
I<br />
G-201<br />
I-201<br />
E-201<br />
E-102<br />
AS03<br />
AS02<br />
12" Condensate<br />
l<strong>in</strong>e from Krist<strong>in</strong><br />
(P-211)<br />
FLOWLINE<br />
BUNDLE:<br />
E-101,F-101,<br />
F-102<br />
Gas Injection<br />
H<br />
HEATING<br />
MEDIUM<br />
MANIFOLD<br />
Umbilical Junction<br />
K<br />
H-201<br />
H-101<br />
H-102<br />
L-102<br />
L-101<br />
L-201<br />
J<br />
K-201<br />
K-101<br />
L<br />
A<br />
B<br />
O-201<br />
J-201<br />
J-102<br />
J-101<br />
AB-103<br />
AB-102<br />
AB-101<br />
42" GAS EXPORT<br />
LINE TO KÅRSTØ.<br />
O<br />
M<br />
N-201<br />
M-101<br />
M-201<br />
P-101<br />
BC-101<br />
EXPORT<br />
RISER<br />
BASE<br />
Åsgard T<br />
P-102<br />
N<br />
Norne Gas<br />
Export -<br />
16"<br />
~126 km<br />
N-101<br />
N-102<br />
C<br />
Norne & Heidrun<br />
Gas Export Pipel<strong>in</strong>es<br />
P<br />
Mikkel 3,5" MEG l<strong>in</strong>e<br />
+<br />
Mikkel Umbilical<br />
ca. 63 km<br />
Q-101<br />
Q-102<br />
R-201<br />
R-102<br />
R-101<br />
Q-201<br />
P-201<br />
R<br />
S-101<br />
S-102<br />
Preferred<br />
Rig Head<strong>in</strong>g<br />
B-401<br />
Heidrun Gas<br />
Export - 16"<br />
~ 40 km<br />
Q<br />
S-201<br />
S<br />
HALTENPIPE, 16"<br />
HEIDRUN FIBRE CABLE<br />
Y-103<br />
X-101<br />
Mikkel A located<br />
28930 m south and<br />
2165 m east <strong>of</strong> the<br />
Midgard Z template.<br />
Q-202<br />
ÅSGARD<br />
Fibre Cable<br />
B-401, Field<br />
Jo<strong>in</strong>t with<br />
Heidrun Fibre<br />
Cable.<br />
Y-102<br />
Y-101<br />
10" Gas <strong>in</strong>jection<br />
to Tyrihans.<br />
X-201<br />
MIKKEL<br />
225 o<br />
Mikkel A<br />
S2<br />
FSM<br />
X<br />
10" ROV<br />
valves<br />
Y-102<br />
Template<br />
slot<br />
position<br />
S1<br />
Yttergryta<br />
20" ROV<br />
valve<br />
Y-201<br />
Y-103<br />
Y<br />
Y-101<br />
S4<br />
10" ROV<br />
valves<br />
18" Mikkel<br />
LINE TO<br />
"Z"<br />
Mikkel 36891 Bmeter<br />
Z<br />
Z-201
Heidrun<br />
Asgard<br />
Midgard<br />
Draugen<br />
42”<br />
Tjeldbergodden<br />
Statfjord<br />
Frigg<br />
Gullfaks<br />
Troll<br />
Kollsnes<br />
Norway<br />
Heimdal<br />
Kårstø<br />
Sleipner<br />
Draupner<br />
St. Fergus<br />
Ek<strong>of</strong>isk<br />
UK<br />
Eur<br />
opipe<br />
Norpipe<br />
Zeepipe Norfra<br />
Zeebrügge<br />
Dunkerque<br />
Emden<br />
Etzel<br />
Germany
Asgard Field
Layout - Mar<strong>in</strong>e loads
FPSO - Turret loads<br />
Jumper<br />
• Load overview:<br />
– Turret weight<br />
– Moor<strong>in</strong>g loads<br />
EV<br />
Stigerør oppheng<br />
Ankerv<strong>in</strong>sj<br />
Swivel<br />
– Riser loads<br />
– Boyancy load<br />
Ship<br />
Turret<br />
Bear<strong>in</strong>gs<br />
– Dynamic loads<br />
– “Added mass” with<br />
Bunn<br />
vessel motion<br />
Anchorl<strong>in</strong>e<br />
Riser<br />
Fairleads
Flexible Risers - Critical<br />
Areas<br />
End connection<br />
area (C<strong>of</strong>lon)<br />
Crack growth<br />
Fatigue<br />
Bend stiffener<br />
area (armour)<br />
Boyancy elements<br />
Hydrolysis<br />
Riser base<br />
Sag bend<br />
area (Rilsan)
FPSO - Load Calculator<br />
Input: Updated light ship condition, loads from anchor l<strong>in</strong>es, risers, variable weights, tank levels,<br />
draught for and aft, w<strong>in</strong>d loads<br />
Output: Stability data, stability marg<strong>in</strong>s, hull bend<strong>in</strong>g moment and shear loads with limit curves
Wave impacts - Lessons<br />
•High forecastle<br />
•Strong w<strong>in</strong>dows<br />
•Solid design fwd
“Green sea” protection<br />
Panels<br />
Cargo deck (tank top)
"Green sea"<br />
panels<br />
Protection panels design:<br />
• prevent green sea damages<br />
• ma<strong>in</strong>ta<strong>in</strong> good ventilation<br />
• m<strong>in</strong>imize explosion risk<br />
• CFD analyses
Gas dispersion and Explosion<br />
modell<strong>in</strong>g<br />
- All areas modelled for optimized layout!
Subsea gas plume –<br />
Buoyancy?<br />
355 kg/s subsea riser rupture (5 m/s w<strong>in</strong>d 15 deg. on port side)
Layout - Segregation
Fire walls/deck<br />
Fire wall/deck
Escape tunnel<br />
Escape tunnel
Escape tunnel
Turret / Swivel area<br />
•Risers<br />
<strong>in</strong>side guide<br />
tubes<br />
• Riser ESV<br />
fireprotecti<br />
on<br />
– 2 hrs jet fire<br />
• Open layout<br />
ESV
Material handl<strong>in</strong>g<br />
• Laydown areas<br />
• Storage areas<br />
• Crane operations<br />
• Crash barriers<br />
• Lift<strong>in</strong>g restrictions
Vessel motions<br />
20m high waves – Large difference <strong>in</strong> heave; semi/fpso
Weather limitations<br />
Helideck:<br />
• Heave<br />
•Pitch<br />
•Roll<br />
• Night flights
Sea fasten<strong>in</strong>g
Offload<strong>in</strong>g
Offload<strong>in</strong>g arrangement<br />
• 20” hose<br />
• 8000 m 3 /h
Offload<strong>in</strong>g arrangement
Offload<strong>in</strong>g arrangement<br />
Challenges:<br />
• Work<strong>in</strong>g<br />
env. issues<br />
• Simpler<br />
handl<strong>in</strong>g<br />
needed
Preferred system
Shuttle tanker – Collision<br />
• Flare stack location<br />
• Aft arrangement<br />
• Tandem operation<br />
risk
Shuttle Tanker Collision aft
Collision aft – Flare stack
• Alarm zones<br />
• Longer <strong>of</strong>fload<strong>in</strong>g hose<br />
• Strict requirements to the shuttle<br />
tankers<br />
Collision avoidance<br />
FPSO<br />
Shuttle tanker<br />
ESD I<br />
ESD II
Collision avoidance<br />
• Strict technical and operative<br />
requirements to the shuttle tankers:<br />
– All shuttle tankers DP2-class<br />
– Several DP reference systems<br />
– Early warn<strong>in</strong>g systems - manual takeover<br />
– At least two DP operators at all times<br />
– DP operator competence<br />
requirements<br />
– Simulator tra<strong>in</strong><strong>in</strong>g for tandem load<strong>in</strong>g
…Long list <strong>of</strong> risk/safety<br />
analyses:<br />
–Concept <strong>Risk</strong> & Emergency Preparedness <strong>Analysis</strong><br />
–<strong>Design</strong> Accidental Load Specification<br />
–Leaks <strong>in</strong>side guide tubes<br />
–FMECA <strong>of</strong> riser system<br />
–Gas dispersion study<br />
–Explosion evaluation report<br />
–Fire risk assessment<br />
–<strong>Risk</strong> related to material handl<strong>in</strong>g<br />
–Qualitative assessment <strong>of</strong> escape and evac.<br />
–Safety eval. <strong>of</strong> essential diesel eng<strong>in</strong>es<br />
–Safety eval. <strong>of</strong> compass thrusters<br />
–Safety review <strong>of</strong> emergency power system<br />
–<strong>Risk</strong> analysis <strong>of</strong> pedestal cranes<br />
–Qualitative analysis <strong>of</strong> ballast system<br />
–Tank explosion frequency assessment<br />
–Quantitative fire and explosion study <strong>of</strong> oil storage systems<br />
–Reliability analysis <strong>of</strong> <strong>in</strong>strumented overpressure protection for cargo tanks<br />
–Passive fire protection optimization<br />
–DP-operations <strong>of</strong> tankers <strong>of</strong>fload<strong>in</strong>g Asgard<br />
–Technical and operational requirements to shuttle tankers serv<strong>in</strong>g Asgard<br />
–Environmental Impact Assessment<br />
–Emergency Preparedness <strong>Analysis</strong><br />
–Quantitative <strong>Risk</strong> Assessment, QRA<br />
–Total <strong>Risk</strong> Assessment, TRA
Safe <strong>Design</strong> - Summary<br />
•Good segregation between HC areas and safe areas<br />
•LQ, evacuation means and HVAC <strong>in</strong>take upw<strong>in</strong>d<br />
•Escape tunnel along the whole ship<br />
•Process area segregated from cargo deck by plated<br />
H-0 deck<br />
•No high pressure HC equipment on cargo deck
Safe <strong>Design</strong> - Summary (contd.)<br />
•Water ballast tanks around the cargo tanks, double<br />
barrier (double hull)<br />
•Open layout <strong>in</strong> modules; reduced explosion risk<br />
•<strong>Design</strong> the aft for shuttle tanker collision<br />
•Include measures for collision avoidance<br />
•Large helideck
Safe <strong>Design</strong> – Summary<br />
(contd.)<br />
•Ship movements must be considered for all material<br />
handl<strong>in</strong>g and storage<br />
•Dropped/ sw<strong>in</strong>g<strong>in</strong>g load barriers<br />
•Lift<strong>in</strong>g above pressurized equipment prohibited<br />
•One must expect green sea <strong>in</strong> bad weather condition;<br />
Personnel should not be present at cargo deck <strong>in</strong><br />
such conditions
FPSO - Experience<br />
transfer<br />
• Workgroup between the FPSO<br />
operators <strong>in</strong> Norwegian and UK:<br />
– Improve FPSO operation and design for<br />
future projects<br />
– Web-site: http://fpso.olf.no/lesson<br />
• OGP: “Guidel<strong>in</strong>e for Manag<strong>in</strong>g<br />
Mar<strong>in</strong>e <strong>Risk</strong>s Associated with<br />
FPSOs”
Conclusions<br />
• Assess risk and safety<br />
– Early<br />
– In all phases<br />
• Gather experience<br />
• Identify all hazards<br />
• Def<strong>in</strong>e safety strategies and<br />
standards<br />
• Follow up with control and<br />
documentation
Conclusions<br />
• <strong>The</strong>re are challenges with<br />
FPSOs, but if properly<br />
designed and operated,<br />
a FPSO is a very safe<br />
concept!
Thank You<br />
for listen<strong>in</strong>g!<br />
Questions?
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