OIL & NATURAL GAS
World Energy Consumption, by Source (2013)
[EIA = Energy Information Administration]
Petroleum:
1. What is it?
2. How does it form?
3. Where does it form?
4. How do we find it?
5. How do we remove it?
6. How do we process it?
7. What do we use it for?
8. How much is left?
What do you want in an energy fuel source?
• Easily transportable (liquid or gas)
• Give off energy when participating in a chemical
reaction (“exothermic” not “endothermic”)
• High energy density
How many different kinds of liquids exist
naturally on Earth?
How many different kinds of liquids exist
naturally on Earth?
How many different kinds of gases exist
naturally on Earth?
Water NEEDS energy to be broken down
(endothermic reaction):
Example: Electrolysis of water
2H2O + energy  2H2 + O2
Hydrogen is a good energy source:
Hydrogen is a good energy source:
But you can’t find it naturally on Earth
Water gives off energy if it oxidizes certain materials
Example: Oxidation of sodium
2Na + 2H2O  2NaOH + H2 + Energy
But needs pure sodium (doesn’t exist in nature) and
is quite dangerous
Gasoline:
Natural Gas:
Natural Gas (methane): Combusts in an exothermic
reaction
CH4 + 2 O2 → CO2 + 2 H2O + Energy (heat, light)
Natural Gas (methane): Combusts in an exothermic
reaction
CH4 + 2 O2 → CO2 + 2 H2O + Energy
Why doesn’t it happen immediately? (i.e., why is
there any natural gas in existence?)
 Activation Energy
Can also be: Liquid Natural Gas
How do you do this?
Tar:
Tar: Also occurs naturally
Example: La Brea Pitch Lake (Trinidad)
Petroleum:
Petroleum or crude oil is a naturally occurring,
flammable liquid consisting of a complex
mixture of hydrocarbons (molecules containing
carbon and hydrogen) of various molecular
weights and other liquid organic compounds,
that are found in geologic formations beneath
the Earth's surface.
What pattern do you observe?
A hydrocarbon is an organic compound
consisting entirely of hydrogen and carbon.
Different types of hydrocarbons are
1.Alkanes
2.Cycloalkanes
3.Aromatic hydrocarbons (Arenes)
4.Alkenes
5.Alkynes
Alkanes:(parafi
ns, saturated
hydrocarbons)
Saturated in
hydrogen, all
C-H bonds are
“single bonds”
(share two
electrons)
What pattern
do you
observe about
boiling and
melting points?
Which is most
similar to
water?
Example of Alkanes:
Octane:
Pentane:
Cycloalkanes: How is this different?
Cycloalkane: (naphthenes) are types of alkanes
which have one or more rings of carbon
atoms in the chemical structure of their
molecules.
Ex: cyclobutane
Aromatic hydrocarbons (Arenes) – Have
alternating single and double bonds
between carbons
Ex: Benzene
Alkenes – (olefin, or olefine) is an unsaturated (fewer
hydrogen atoms) chemical compound containing at
least one carbon-to-carbon double bond
Ex: Ethylene - (C2H4) [Compare to Ethane - (C2H6)]
Alkynes – (acetylenes) are hydrocarbons that
have a triple bond between two carbon
atoms, with the formula CnH2n-2
Ex: ethyne - C2H2
Petroleum:
..but varies!
Petroleum:
But I thought
hydrocarbons
were just
carbon and
hydrogen?
Where did the
other stuff
come from?
Petroleum:
…but varies!
Natural gas - primarily methane, with 0-20% higher
hydrocarbons (primarily ethane)
Gasoline (petrol) - refined alkanes from pentane
(C5H12) to octane (C8H18) are refined into petrol
Diesel Fuel and Kerosene (used for jet fuel) - alkanes
from nonane (C9H20) to hexadecane (C16H34)
Fuel oil and lubricating oil - alkanes from
hexadecane upwards
Paraffin wax - an alkane with approximately 25
carbon atoms
Asphalt - made from alkanes with 35 carbon atoms
and up
Hydrocarbons may be mixed with other nonhydrocarbons, to create other end products:
• Alkenes can be manufactured into plastics
• Lubricants (light machine oils, motor oils, and
greases)
• Wax
• Bulk tar
• Asphalt
• Paraffin wax
• Aromatic petrochemicals to be used as precursors
in other chemical production (such as almost all of
our pharmaceuticals and fertilizers)
Fig. 7-8, p. 213
Combustion:
All alkanes react with oxygen in an exothermic
combustion reaction, although they become
increasingly difficult to ignite as the number of carbon
atoms increases. The general equation for complete
combustion is:
CnH2n+2 + (1.5n+0.5)O2 → (n+1)H2O + nCO2 + energy
(What are the end products?)
Combustion:
Normally, for methane:
CH4 + 2O2 → CO2 + 2H2O + Energy
(the end products are water and carbon dioxide)
Combustion:
However, without sufficient oxygen, carbon monoxide
or even soot can be formed:
CnH(2n+2) + nO2 → (n+1)H2O + nCO + Energy
For example, for methane:
2CH4 + 3O2 → 2CO + 4H2O + Energy
(note: the end products are water and carbon
monoxide)
Many steps are needed to go from
this:
to this:
(Octane)
Formation of Petroleum:
1.Ocean organisms (algae, zooplankton) die and sink to the
ocean floor 100-500 million years ago.
2.Burial is rapid (geologically!) and anoxic.
3.Deep burial results in high temperatures that result in the
“cracking” of complex organic molecules (like kerogen) into
lighter hydrocarbons.
4. Most liquid and gas hydrocarbons rise up to the surface and reenter the
carbon cycle.
5. If an appropriate “cap rock” exists (usually shale), then the hydrocarbons
stay underground.
6. Certain geologic events (faults, folds, salt domes) can concentrate the
hydrocarbons, making them economically viable to remove.
Formation of Petroleum:
“Cracking” is an endothermic reaction (you
need to give it energy), but the Earth provides
the energy over long periods of time!
Ex: YOU can make natural gas from glucose in
the following reaction:
C6H12O6 + Energy → 3CH4 + 3CO2
(glucose)
Gas/Ice Giants
Cassini’s voyage to Saturn’s moon Titan.
Titan: only moon with a substantial atmosphere (nitrogen)
Liquid methane on a water-ice surface?
Lakes (liquid methane/ethane) at Titan’s north pole (Cassini)
Lakes (liquid methane/ethane) at Titan’s north pole (Cassini)
New research: Titan could (theoretically) support microbial
life that breathes hydrogen (missing from surface) and
ingests acetylene (missing from atmosphere).
Petroleum that reaches the surface is “eaten”
by certain types of bacteria
(La Brea tar pits)
Certain types
of archaea will
produce
methane
(methanogens)
Certain types of archaea will produce
methane (methanogens)
The energy is released by the
oxidation of hydrogen:
CO2 + 4H2 → CH4 + 2H2O
Methanogens cause marsh gas in
wetlands (two billion tonnes of
methane per year) and in off-shore
ocean sediments, and gas from
animals (cattle, termites, etc.)