Formation of Petroleum and Natural Gas Energy came to the earth in the form of sunlight hundreds of millions of years ago. Radiant energy was then captured by algae through photosynthesis. Dead algae and plankton accumulated at the bottom of the ancient seas.
Formation Continued… Accumulation continued, increasing the pressure and temperature on the underlying layers. The result was a loss of oxygen and the formation of solid, liquid, and gaseous hydrocarbons i.e. They were gradually buried by layers of rock which stopped them rotting The liquid and gaseous hydrocarbons moved upward through the porous rock until reaching an impermeable layer of rock.
Migration 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
Petroleum 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
Refining of Petroleum Heat and/or chemical treatment to produce: Gasoline Diesel Fuel Kerosene Liquified Propane (LPG) Petroleum bases for plastics
Distribution 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
Some of the world’s most productive sedimentary basins Saudi Arabia Kuwait Alaska – north slope Texas – Louisiana Gulf Coast Iraq and Iran Mexico Venezuela
Oil Reserves Total world production of petroleum in 1996 was 62 million barrels per day. A study performed in 1993 revealed that there is 1.8 trillion barrels of oil that is economically recoverable. At the highest expected production rates, there is an estimated 50 years of oil left.
Coal Formation Unlike oil and natural gas, coal formed from decaying plants in ancient swamps. When the peat is exposed to high temperatures and pressures, it forms coal. There are three main types of coal: anthracite, bituminous, and lignite.
Anthracite It is the oldest and hardest form of coal. Its carbon content is up to 95%, which means it is also the cleanest burning of the coals. Only 1% of minable coal in the U.S. is anthracite. Almost all anthracite is found in Pennsylvania.
Bituminous Coal It is roughly 300 million years old, and comprised of 50% to 80% carbon. Bituminous coal makes up 71% of the minable coal in the U.S. It is located mainly in the Rocky Mountains and the Mississippi River Basin.
Lignite Was formed about 150 million years ago. It is comprised of roughly 50% carbon. Lignite makes up 28% of minable coal in the U.S. Mainly located in the Rocky Mountain region and the southern U.S.
Formation of Fossil Fuels – simplified Burial of organic material millions of years ago Reducing conditions – little or no free oxygen Reducing conditions preserve organic matter Coal and Petroleum diverge from here
Formation of Coal Accumulation of land plant material Reducing conditions – coastal and inland swamps