Notes 20100909.124006 Oil Sands Group Meeting

From SnOwy - Ed's Wiki Notebook

Athabasca Oil Sands

Contents 1 Background - Oil Sands 2 Oil Sand Composition 3 Mining 4 Bitumen Extraction 5 Waste Water 6 Naphthenic acids 7 Phytoremediation

Background - Oil Sands

• 2010 august news item: Syncrude had an open pond of oil
• ducks arrived from migration early, landed in oil and drowned
• a lot of public relations issues with oil extraction etc.
  • Alberta -- sands, bird deaths
• 3 major oil sand deposits in Alberta
  1. Athabasca
  2. Peace River
  3. Cold Lake
• covers 141,000 km²
• Athabasca -- the only one that can be mined at the surface
• oil sands originally discovered by natives: water proofing water vessels

Oil Sand Composition

• Sand hydrated with a layer of water, enclosed with bitumen film (bitumen is the oily interesting part)

Mining

• 2 main categories
  1. surface mining
  2. in situ methods:
     1. steam assisted gravity drainage (SAGD)
     2. cyclic steam stimulation (CSS)
• CSS: steam causes bitumen to heat up and be drained off in a parallel tube.
• SAGD: steam is pumped in and remains underground for a day-- bitumen is pulled on top of sand and water
• most frequent methods today are surface mining techniques
• surface mining looks a bit like strip mining...
• area is reclaimed and regenerated as open strip geometry shifts

Bitumen Extraction

• Clark hot water extraction method
• oil mixed with hot water and sodium hydroxide.
• bitumen floats
• siphoned
• upgraded to crude
• water and sand remains in tank
• 3m² water per 1m² oil sand
• accumulates toxic materials and other contaminants
• silt sands, clay etc.,
  • most dangerous class of compounds: Naphthenic acids
• waste water is settled in old mine pits

Waste Water

• toxic to aquatic life -- not toxic to algae and plants
• roughly one trillion litres of waste water on surface of Alberta

Naphthenic acids

• mixture of cyclic and acyclic compounds
• resistant to natural degradation
• attempted to use wet landscape and dry landscape techniques -- letting the NAs set in the tailings water
  • able to break down, but is too slow (compared to current rate of production)
• ozonation?
• phytoremediation -- promising approach

Phytoremediation

• algal culture exposed to NA -- searching for resistant species / species that can degrade NAs
• different concentrations used
• species (23)
  • Cyanobacteria
  • Chlorophytes
  • one Diatom
• variable reactions -- even for species within the same class
• estimate the EC% values for each species
• EC50 used -- similar to LD50, except the range is in cessation of growth, not cessation of life
• values based on logistic regression
• only two species could be curve fit
• basically, there's not enough resolution in the interesting domain of NA concentration
  • the logistic curve phase transition occurs right where there isn't enough data
• three species chosen for toxicity and uptake