short course: fate & weathering of oil · weathering of oil jessica miller deputy general...
TRANSCRIPT
Short Course: Fate &
Weathering of Oil
Jessica MillerDeputy General Manager, Preparedness
Australian Marine Oil Spill Centre (AMOSC)
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Fate & Weathering of Oil
Spill Assessment
1. What is it?
2. Where is it?
3. How big is it?(Area/Volume)
4. What is happening to it? (Weathering)
5. Is the source contained?
6. Where is it going?
7. What is in the way?
8. How long until it gets there?
9. What is the Worst Credible Scenario?
10.What can we do?
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Spill Assessment
1. What is it?
2. Where is it?
3. How big is it?(Area/Volume)
4. What is happening to it? (Weathering)
5. Is the source contained?
6. Where is it going?
7. What is in the way?
8. How long until it gets there?
9. What is the Worst Credible Scenario?
10.What can we do?
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Key Properties of Oil
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Specific
Gravity
Density in relation to water (less than 1.03 = likely to
float in sea water). Also expressed as API (> 45 to <
16)
Flash PointTemperature above which the oil may ignite if
exposed to an ignition source
Viscosity Resistance to flow (HIGH flows less easily than
LOW)
Pour Point Temperature below which an oil no longer flows
Asphaltenes &
Wax Content
Dissolved solids components in crude oils (affects
viscosity as % increases)
Content greater than 0.5% will mean a propensity to
form a stable emulsion.
Source: ITOPF Handbook
Classification of oils
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GroupSpecific Gravity
APIViscosity cST
@ 10 - 20oC
1 < 0.8 > 45 < 3
2 0.8 - 0.85 35 - 45 4 – Solid
3 0.85 - 0.95 17.5 - 35 8 – Solid
4 > 0.95 < 17.5 1500 – Solid
Source: ITOPF Handbook
Behaviour of oil – Diesel
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Oil type:
1 = Marine Diesel
2 = Diesel (Weathered ͂ 20%)
Considerations for response;
- Highly volatile,
- Will evaporate quickly,
- Small volumes will spread across
large areas,
- Will not persist very long,
- Clean-up dependent on residual.
Source: ChemCentre, WA
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Source: ITOPF Film – Introduction to Oil Spills
Behaviour of oil – Crude
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Oil type:
6 = North West Shelf Crude Oil
Considerations for response;
• ͂ 1/3 will evaporate within 24 hours,
• Relatively persistent - contamination
can be severe and long-term,
• Oil impacts on wildlife can be severe,
• Clean-up most effective if conducted
quickly.
Source: ChemCentre, WA
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Source: ITOPF Film – Introduction to Oil Spills
Behaviour of oil – Bunker Fuel (IFO 380)
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Oil type:
7 = Bunker Fuel IFO 380
Considerations for response;• Minimal evaporation or dissolution,
• Long-term contamination of sediments
possible,
• Shoreline clean-up difficult under all
conditions - primarily manual,
• Semi-solid (lighter fractions removed) –
increased waste recovery.
Source: ChemCentre, WA
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Source: ITOPF Film – Introduction to Oil Spills
Fate of spilled oil at sea
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Main weathering processes.
Properties & Weathering (so what?)
• What is the relationship?
• Specific Gravity = 0.9 (less than 1.03)
▫ Float or not??
• Viscosity = 6 @ 15deg
▫ High or Low, therefore will it spread?
• Asphaltenes + Wax Content = 0.45%
▫ What about emulsification?
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Example – Gas/Condensate/Crude
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Source: AMOSC
Example – HFO 380
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Source: AMOSC/AMSA
Where is this information?
• Safety Data Sheets (SDS)
• Cargo Handling Sheet (or similar)
• Crudes – Oil Assay Sheet
Planners will gather this
information in the ICC
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Table Activity • Characteristics of Oil
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