Short Course: Fate &

Weathering of Oil

Jessica MillerDeputy General Manager, Preparedness

Australian Marine Oil Spill Centre (AMOSC)

2

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?

3

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?

4

Key Properties of Oil

5

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

6

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

7

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

8

Source: ITOPF Film – Introduction to Oil Spills

Behaviour of oil – Crude

9

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

10

Source: ITOPF Film – Introduction to Oil Spills

Behaviour of oil – Bunker Fuel (IFO 380)

11

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

12

Source: ITOPF Film – Introduction to Oil Spills

Fate of spilled oil at sea

13

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?

14

Example – Gas/Condensate/Crude

15

Source: AMOSC

Example – HFO 380

16

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

17

Table Activity • Characteristics of Oil

18

19