Fossil FuelsFossil Fuels

Formation and Distribution

Fossil FuelsFossil Fuels

Coal Oil (Petroleum) Natural Gas

Formation of Fossil Fuels – common conditionsFormation of Fossil Fuels – common conditions

High Organic Production Burial of organic material Reducing conditions – little or no free oxygen Reducing conditions preserve organic matter Coal and Petroleum diverge from here

Formation of CoalFormation of Coal

Accumulation of land plant material Reducing conditions – coastal and inland

swamps

Formation of CoalFormation of Coal

Organic accumulation is greater than destruction (because of reducing conditions)

Organic matter builds up to form peat

Formation of CoalFormation of Coal Peat is compressed to form

lignite – brown coal Lignite is compressed and

volatile compounds are lost to form bituminous coal – soft coal

Bituminous coal is further compressed and heated to form anthracite – hard coal

Formation of Petroleum and Natural GasFormation of Petroleum and Natural Gas

Accumulation of organic material – typically marine mud

Burial and preservation of organic material – reducing conditions

Reducing conditions in deep sea or on continental shelves during times of unusual oceanic circulation

Formation of Petroleum and Natural GasFormation of Petroleum and Natural Gas

Black, organic-rich mud is buried deeper and converted to rock – shale

With burial, the organic matter is heated When heat is sufficient (but not too great) – in

the range of 100-300 degrees C – the organic matter is “cooked” and oil forms

Process is called thermal maturation

Formation of Petroleum and Natural GasFormation of Petroleum and Natural Gas

If heat is greater than 300 degrees C, the liquid petroleum is further broken down to form natural gas

If heat is too great, even the natural gas is broken down to form carbon dioxide, which has no value as a fuel

Migration and ConcentrationMigration and Concentration

Petroleum must leave source rock Process is called migration Migration is essential because most source

rocks are too fine-grained to enable easy extraction of the oil

To be economically concentrated, petroleum must migrate to a reservoir rock with a trap

Examples of Petroleum TrapsExamples of Petroleum Traps

Petroleum ResourcesPetroleum Resources Conditions for source rock

are rare Conditions for maturation

must be just right Migration must not let

petroleum escape to surface

Reservoir rock must be present

Trap must exist before migration occurs

Where did the U.S. Petroleum Industry begin?Where did the U.S. Petroleum Industry begin?

Right here in New York! First gas well –

Fredonia, New York

Distribution of PetroleumDistribution of Petroleum

Economic accumulations of petroleum only occur when all of these conditions are met

These conditions and the sequence of occurrence do not occur everywhere

Conditions are most likely where there are thick accumulations of sedimentary rock – in sedimentary basins

Some of the world’s most productive sedimentary basins

Some of the world’s most productive sedimentary basins

Saudi Arabia Kuwait Alaska – north slope Texas – Louisiana Gulf Coast Iraq and Iran Mexico Venezuela

Refining of PetroleumRefining of Petroleum

Heat and/or chemical treatment to produce: Gasoline Diesel Fuel Kerosene Liquified Propane (LPG) Petroleum bases for plastics