Chapter 20 Flashcards
Formation of petroleum
A source rock rich in organic material is deposited without being oxidized. The organic material experiences elevated temperatures when buried by overlying sedimentary rocks and allows oil and gas to be formed.
Oil window
75 -150°C at a depth of 2–4 km.
Gas window
+100°C at a depth of up to 3 km.
Structural traps
Formed by folds and faults.
Stratigraphic traps
Formed by the sequence of deposition that placed an impermeable cap rock above a porous reservoir layer.
Movement of oil and gas
Low density of oil and gas causes them to move upwards. This can be blocked by an impermeable layer that overlies a porous reservoir causing the oil and gas accumulate in a trap.
Where is Petroleum in Canada distributed?
Sedimentary basins formed in the Paleozoic and Mesozoic when sea levels were high. Trapped in overlying carbonates (reefs) and sandstones.
Formation of coal
Fibrous and woody remains of land plants that accumulate in oxygen poor environments are cooked and compressed.
Density of coal (3)
Density goes up with pressure/temperature in sequence:
1. Lignite
2. Bituminous coal
3. Anthracite
Distribution of coal in Canada
Coastal environments around shallow seas where oil and gas formed. 98% in the Mesozoic (BC, AB, SK) and the Paleozoic (Maritimes)
Oil sands
Mixture of sediment, water and bitumen, with oil that migrated upwards to the surface where the lighter components were lost.
Oil shale
When the source rock is not subject to high temperatures and still contains kerogen. It is usually fine grained limestone that can be heated to crack the kerogen and form petroleum.
Athabasca oil sands
50% of Canada’s oil production. Surface mining and underground extraction with steam assisted gravity drainage (SAGD).
Coal Bed Methane
Gas trapped in coal seams that is extracted with water.
Shale gas
Gas trapped in impermeable shale that is extracted with hydraulic fracturing and direction drilling.
Methane hydrate
Solid mixture of methane and water that needs high pressure and low temperature to be stable. It is
found 200-500 m beneath seafloor on the continental shelf and formed by the reduction of carbon dioxide by bacteria.
Primary pollutants
Pollutants emitted from identifiable sources
Secondary pollutants
Pollutants formed from chemical reactions involving primary pollutants.
Capacity factor
(energy generated)/(energy generated if operated all year) = ~0.5
Electrical energy generated in Canada in 1 year
641.1 TWh = 2,308,000 TJ
Averaged over the year this is a power of 73 GW and an installed capacity of 145 GW.
Hydroelectricity
60% of Canadian electricity. Large dams are efficient but eventually fill with sediment.
Pumped storage allows the grid to work with other sources. Installed capacity is ~80 GW, with BC Hydro at 12 GW.
Geothermal advantages (4)
- Low CO2 emissions
- High capacity factor (24/7)
- Small surface footprint
- Scalable
Geothermal disadvantages (5)
- Location specific
- Uncertainty of resource size from exploration
- High initial costs
- Needs water supply
- Induces earthquakes
Solar
Heat water directly or use
Photovoltaic (PV) panels to produce electricity.
