Week 9 Geology

Question 1

What are unconventional fuels ?

Answer 1

Fuels that require significant investment and advanced technology for exploration and discovery

Question 2

Give some examples of unconventional fuels

Answer 2

Oil(tar) sand
Heavy oil
Shale Gas
Oil shale
Coal-bed methane
Coal-to-liquids
Methane Hydrate

Question 3

What are Oil Sands

Answer 3

Essentially conventional oils that were biodegraded: a mixture of hydrocarbons, sand, clay and water.
High viscosity, high density, and significant content of asphaltenes. (N,S,O - containing compounds).
Tar sands with heavy oils - API gravity < 22.
Tar sands with extra heavy oils - API gravity < 10.

Question 4

What is API gravity

Answer 4

API stands for the American Petroleum institute.
Represents about 400 corporations in the petroleum industry.
Developed a method of measuring the density of petroleum.
API gravity is determined at 60 degree F.
API gravity = (141.5/specific gravity) - 131.5.

Question 5

Explain degradation of Hydrocarbons

Answer 5

At temperatures lower than 80 degrees celsius, (which is in most cases shallower than a few km), microbial degradation of crude oil kicks in. As a result, the density and viscosity of the oil are greatly increased over time.

Question 6

World reserves

Answer 6

Currently, 90% of production is from conventional oil.
Heavy oil and bitumen are growing rapidly.
Canada and Venezuela together have greater than 35% of the non conventional oil reserves.

Question 7

Give some facts about the Athabasca Oil Sand deposits

Answer 7

Total global resource: 3.3 trillion barrels (529 times 10 to the 9m cubed) of oil.
70% of total global resource in Canada; remainder mostly in Russia and Venezuela.
Compare: Saudi Arabia conventional oil reserves approx 0.3 trillion barrels (45 times 10 to the 9 m cubed)
Oil sands in Canada are found in Cretaceous deposits of sand (stone).

Question 8

How do you get it out

Answer 8

Open pit mining - separation of sand, water, clay and tar in processing facilities.
In-situ techniques aim to free up the tar so it will flow freely through the sand matrix to an abstraction well.
Groups of in-situ techniques.
Heating by which tar viscosity is reduced sufficiently.
Injection of chemicals to mobilise the tar (solvents).

Question 9

What is shale gas

Answer 9

Shale gas in natural gas (methane and other higher alkanes) trapped in shale deposits.

Question 10

Explain shale gas in more detail

Answer 10

Shale gas (mainly methane CH4) is a product of degradation of organic matter in shale.
Permeability of shales usually low to allow significant fluid flow.
Shales with economic quantities of gas are:
Rich organic material (0.5% to 25%).
Usually mature petroleum source rocks in the thermogenic gas window, where high heat and pressure have converted petroleum to natural gas.
Sufficiently brittle and rigid enough to maintain open fractures.

Question 11

How do we get shale gas from the ground ?

Answer 11

Two main techniques, Hydraulic fracturing and horizontal drilling.

Question 12

Explain more about fracking for fuel

Answer 12

Due to low matrix permeability, commercial gas production requires fractures to provide permeability.
This is where “fracking” comes in, the process by which fluids (water + a suite of chemicals + proppant) are injected under very high pressures to create fracture networks in the shale.
Boreholes are often horizontal at the level of the shale for distances of up to about 3km.

Question 13

Talk about shale gas on a global scale.

Answer 13

Shale rocks, potentially containing gas reserves, are found throughout the world.
3.3 trillion m3, is the world gas consumption 2012 (21% of total energy consumption)
207 trillion m cubed is the amount of estimated global shale gas reserves.

Question 14

What are some of the main issues with fracking.

Answer 14

1) Air pollution
The health effects of air pollution from fracking are poorly understand. Any methane leaks would compound global warming.
2) Wast water
In the US, toxic chemicals from waste water have been found in rivers. European regulations should prevent this.
3 Casing Leaks
Chemicals can seep out of the fracking pipes into aquifers, but only iff casings art thick enough or sufficiently monitored.
4 Earthquakes
Fracking may trigger earthquakes, although typically too small to be felt.
5 Underground migration
Fracking could link natural fractures in the rock, opening conduits fro chemicals and gas. This can be avoided with prior geological surveys.

Question 15

Explain some basic facts and principles about coal

Answer 15

Can be a carbon source e.g. fro steel, Coal Mine methane
Coal bed methane, abandoned mine methane
Hydrocarbon source rock, Mine water as heat.
Coal as a problem
C02 Emissions
Spoil heaps
Mine subsidences and earthquakes
Mine water pollution
Heavy metal pollution

Question 16

Explain coal in the history of great Britain

Answer 16

Coal mining has a big role in the industrial history of great Britain. The legacy of coal extraction has implications for society, and the coal strata are important for other reasons to.

Question 17

Explain some more facts about coal in Great Britain

Answer 17

In 1914 there were >2500 deep mines producing coal in the uk.
In march 2023 there were 6 active deep mines and 2 active surface mines.
Active mines in Derbyshire, Gloucestershire, Northumberland and South Wales.
In September 2024, the last remaining coal-fired power station (Ratcliff-on-Soar) was shut down. The UK - the first G7 nation to stop using coal for generating power.

Question 18

British Coal imports statistics

Answer 18

In 2015, UK imported 24 million tonnes of coal. (Russia supplied 38%, Colombia 29% USA 22%). In 2018 it was 10.1 Mt. In 2022 it was 6.4 Mt.

Us Coal production as continued to increase instead of decreasing.

Question 19

What else is in coal ?

Answer 19

Minerals including quartz, clay minerals, carbonate minerals, iron disulphides and many other accessory minerals. These minerals may be:-
Detrial, (transported by wind or water or other ways)
Plant derived or
Authigenic (solid formed in sediment or rock after decomposition).