02 Oil Spill Basics - Fate of Oil_AAAA.ppt

Safety

1. Oil Spill Basics
2 - Fate of Oil

2. Fate of Oil
•Spreading and Advection (spread out and move)
•Evaporation (lighter ends vaporize)
•Dissolution (dissolve in water)
•Natural Dispersion (forms oil droplets)
•Emulsification (water droplets form in oil)
•Photo-oxidation (sunlight oxidizes oil)
•Sedimentation & Adhesion (oil sticks to solids)
•Biodegradation (microbes eat the oil)

3. Weathering Processes

4. Weathering
•Spreading and Advection (average 0.1 mm thick)
•Evaporation (20 – 40% of crude oil)
•Dissolution (<1% of crude oil)
•Natural Dispersion (1 – 5%, major exceptions)
•Emulsification (up to 80% water)
•Photo-oxidation (<1%, makes more soluble)
•Sedimentation & Adhesion (oil/fines interaction)
•Biodegradation (need nutrients and oxygen)

5. Timing of Weathering Processes

6. Oil Slick Thickness
Near source of large spill 10 mm
Thick dark brown or black slick seen from air1 mm
Light brown or black slick easily seen from air0.1 mm
Yellowish brown slick barely seen from air0.01 mm
Dull colors on calm water 1 m
Bright bands of rainbow color 0.5 m
Silvery sheen on calm water 0.1 m
Barely visible under optimum conditions0.05 m

7. Thickness/Volume Chart

8. Rainbow Sheen

9. Approximate Evaporation for
Various Classes of Oil
Oil Type 12-Hour
Evaporation
48-Hour
Evaporation
Total
Fraction
Evaporated
Group 1 (Gasoline) 50 – 100% 100% 100%
Group 2 (Diesel) 10 – 40% 25 – 80% 95%
Group 3 (Medium
Crude)
5 – 15% 10 – 25% 35%
Group 4 (Heavy Oils)1 – 3% 5 – 10% 15%
Group 5 (Low API) 0 – 2% 1 – 5% 10%

10. Weathering Example

11. Emulsification
•Increases “oil” volume 3-4 times because
stable emulsions can be 70-80% water
•Related to oil’s asphaltene, wax, and resin
content
•Weathering rates much slower (especially
evaporation)
•Oil is much more viscous and sticky
(mechanical cleanup hindered)
•Does not occur with gasoline, kerosene, or
most diesel spills

12. Emulsified Oil

13. Mousse

14. Tar Balls

15. Oil-Fines Interaction

16. Oil-Fines Interaction

17. Oil-Fines Interaction

18. Oil-Fines Interaction