Fossil Fuels

Petroleum & Natural Gas

U.S. Energy Consumption The U.S. is the number one consumer of energy in the world and that consumption is rising

BTU In the United States, the term BTU or Btu (British thermal unit) is used to describe the energy content of fuels

A BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit

143 BTU is required to melt a pound of ice

BTU One quadrillion BTU is:

1,000,000,000,000,000 BTU

That is a 1 followed by 15 zeros

It would take over 31 million years to count to a quadrillion at the rate of one number per second

But we are talking about 100 quadrillion

U.S. Energy Consumption The U.S. produces a staggering amount of energy per year, and over 80% of that energy comes from the fossil fuels: coal, natural gas and oil

Oil and Natural GasPetroleum or crude oil, is not a single chemical compound

Liquid petroleum, or oil, comprises a variety of liquid hydrocarbon compounds, which are made up of long molecular strings of carbon and hydrogen

There are also a variety of gaseous hydrocarbons, collectively called natural gas, of which the compound methane (CH4) is the most common

How is Petroleum Created? Most geologists believe that crude oil and natural gas are the product of compression and heating of ancient organic materials over long geological time

According to this theory, oil is formed from the preserved remains of prehistoric zooplankton and algae which have settled to the ocean bottom in large quantities under anoxic conditions (no oxygen)

How is Petroleum Created?

Over geological time this organic matter, mixed with mud, is buried under heavy layers of sediment

As burial continues, the pressure and the temperature both increase, and chemical changes begin to occur

The large, complex organic molecules are slowly broken down into long chains of hydrocarbon molecules, which have the consistency of asphalt

How is Petroleum Created?

Specifically, the organic molecules change into a waxy material known as kerogen, which is found in various oil shales around the world

Such as below:

How is Petroleum Created?

With time and if the kerogen is subjected to more heat, it is further changed into liquid and gaseous hydrocarbons in a process known as catagenesis

An oil geologist would say, the petroleum “matures”, successively changing from “heavy” long hydrocarbon molecules into “light” simple gas and oil molecules

The thick liquids become progressively thinner and more valuable

How is Petroleum Created? Most of the maturation process occurs between 50o to 100o C (120o to 210o F)

At higher temperatures the hydrocarbon converts to methane gas

Oil and Gas Migration

We want to extract the oil

But the majority of the petroleum source rocks are fine-grained sedimentary rocks of low permeability

The petroleum is spread throughout the rock and it is hard and uneconomical to extract large quantities of oil or gas quickly

Oil and Gas Migration

To become economical, two things need to happen:

The gas and/or oil must migrate out of the source rocks into more permeable rocks, which is called the reservoir rock

And eventually, a large quantity must become concentrated and confined into a petroleum trap beneath an impermeable layer called a cap rock

Types of Petroleum Traps (A) A simple fold trap (B) fossilized coral reef (C) fault trap (D) salt dome

Hydrocarbon UsesA given oil field may contain a variety of hydrocarbon compounds and these different compounds have different uses

Oil, gas and methane can all be found together

The Time FactorThe amount of time it takes to create petroleum is not precisely known

However, petroleum is not found in rock that is younger than 1 or 2 million years old

So, this is a slow process which takes million of years

This means that we are using up oil much much faster than it can be replaced by nature

We have essentially a finite supply of oil, then it will be gone

Supply and Demand

Oil is commonly discussed in quantities of barrels, where one barrel equal 42 gallons

Worldwide, over 500 billion barrels of oil has been consumed

Unfortunately, half of that consumption occurred over the past 25 years

The estimated proven oil reserves are about 1 trillion barrels

Or 50 years at the current rate of use

Proven World ReservesCrude oil and natural gas reserves as of 2002

Proven World ReservesLike other resources, petroleum sources are very unevenly spread around the world

For example, high-tech, densely-populated Japan has no oil, and must import 100% of the oil it needs

U.S. Oil Supplies

The U.S. originally had about 10% of all the world’s oil supply

The U.S. has consumed over 200 billion barrels of oil

We currently consume about 7 billion barrels a year

For the past three decades we have been discovering new oil in the U.S. as fast as we were consuming

Proven U.S. Reserves

Declining Yields

For land or offshore, the average yield from producing wells in the U.S. is declining, from a peak of 18.6 barrels per well per day in 1972 to 10.9 barrels in 2000

Imported oilMore than half of the oil consumed by the U.S. has been imported

Principle sources were Saudi Arabia, Venezuela, Canada and Mexico

U.S. Natural Gas UseThe supply and demand picture for natural gas is similar to that for oil

Natural gas provides about 25% of the energy used in the U.S.

The U.S. has 200 trillion cubic feet of proven reserves

But U.S. reserves are now steadily declining

And we import 15% of our natural gas

Burning Gas at the Well HeadNote the bright lights in the Gulf

Strategic Petroleum Reserve

The Strategic Petroleum Reserve was established in 1977 to store about 550 million barrels of oil

Strategic Petroleum Reserve

It was to hold a 115 day supply

But daily use has steadily increased and the current supply will only last 60 days

Hubbard’s PeakM. King Hubbard was an oil man, who predicted 30 years ago that oil production would follow a bell curve

Future ProspectsMany people think that as oil prices soar, there will be increased exploration and discovery of new reserves

There is a finite amount of petroleum in the ground and we have found most of it

Two-thirds of new exploratory wells come up dry

The days of the gushers are over

Future ProspectsIt is very expensive to drill an exploratory oil well on land

$2 to $20 million dollars per well

Future ProspectsThe costs for drilling offshore are substantially higher, easily over $100 million

Deep water wells are currently too expensive

Enhanced Oil Recovery

Some of the first oils wells were gushers, where the oil behaved like water in an artesian well

Extracting oil using no techniques beyond pumping is called primary recovery

This will only remove part of the oil deposit, usually a third or much less

However, on the average, two-thirds of the oil is left in the ground

Secondary Recovery

There are many secondary recovery techniques that allow addition oil to be extracted

When flow falls off, water can be pumped into the reservoir rock, filling empty pore space and buoying up more oil

Or you can pump in steam

Or explosives can be set off in the oil zone, fracturing the rock and increasing permeability

Or carbon dioxide gas can be pumped in

Secondary RecoveryMany oil experts feel that secondary recovery may allow an additional 40% of the known oil reserves to be extracted

All of these secondary recovery methods add to the cost of oil extraction

Very Deep Natural Gas

Deep exploratory wells have provided evidence that additional natural gas reserves may exist at depth of several thousand meters

At those depths, any petroleum molecules would have been broken down into natural gas

The gas is under tremendously high pressure and is typically dissolved into fluids such as saline brines

Estimation of reserves range from 150 trillion to 2 quadrillion cubic feet

Very Deep Natural GasSpecial technologies will have be developed to extract this deep gas

It is difficult and very expensive to drill down into this high-pressure environment

Plus the saline brine represents a serious environmental problem

The gas is under such pressure that it will gush out of the wells

Oil Spills on land

In general, oil spills on land are small and confined

Pipe line ruptures, train wreaks, tanker truck accidents and illegal waste dumping are the most common sources of spill

This spill in Siberia was burned off, but that creates airborne oil-smoke pollution

Oil and Water Don’t Mix

It is estimated that 600,000 tons of oil per year naturally escapes from permeable rocks into the oceans

The news concentrates on major spills, but most oil spills are small, but in the course of a year, they can add up

The U.S. Coast Guard reports that there are about 10,000 oil spills in U.S. waters each year, totaling 15 to 25 million gallons

Oil and Water Don’t MixWhen an oil spill occurs at sea, the oil, being less dense than water, floats

The lightest, most volatile hydrocarbons start to evaporate immediately, causing air pollution

Over several months, sunlight and bacteria action, can destroy up to 85% the oil, leaving thick asphalt lumps that can persist for many months

Oil and Water Don’t Mix

If a spill is small, it can be contained by floating barriers, and the oil skimmed off of the surface

Chalk, wood shavings and peat moss have been used to soak up oil

In big spills, detergent is added to the oil to speed up decomposition, but detergent is toxic to fish and birds

Oil and Animals Don’t MixOil is toxic to marine life, causes water-birds to drown when their feathers become coated and decimates fish and shell fish populations

Oil and Animals Don’t MixFeathers can be cleaned of oil using soap and water, but it is very traumatic to the bird

The survival rate is low

IXTOC 1 Oil Well

Ixtoc I was an exploratory oil well platform in the Gulf of Mexico, about 600 miles south of Texas

On June 3, 1979, the well suffered a blowout and became the largest unintentional oil well spill in history

IXTOC 1 Oil Well

The oil caught on fire and the drilling platform collapsed

140 million gallons of oil spilled out into the Gulf

The well was finally capped on March 23, 1980

La Brea Tar PitsThe Rancho La Brea Tar pits are a famous series of natural tar (asphalt) pits in Los Angeles

La Brea Tar PitsPools of water covers the sticky tar, and for thousands of years, animals who tried to drink the water became trapped in the tar, creating a treasure trove of fossils

The predators who fed on the trapped prey, also became trapped

La Brea Tar PitsSince 1901, over one million bones of Pleistocene animals have been removed by paleontologists, including saber-toothed cat and giant sloth