Energy - Fossil Fuels -
Oil & Natural Gas

EVPP 111 Lecture

Dr. Largen

Fossil Fuels - Oil & Natural Gas

• Description
• Formation
• Reserves
• Extraction
• Use patterns
• Use issues

Fossil Fuels - Oil

• Description
• oil (actually petroleum or crude oil)
• liquid composed of
• hundreds of combustible hydrocarbon compounds
• hydrocarbons = molecules that contain C and H
• small amounts of S, O, N, other impurities
• components are separated into various products based on boiling points
• gases
• gasoline
• heating oil
• diesel oil
• asphalt
• can be used to produce petrochemicals
• compounds used in production of diverse products such as
• fertilizers
• plastics
• paints
• pesticides
• medicines
• synthetic fibers
• Description
• natural gas
• gas
• contains only a few different hydrocarbons
• methane
• smaller amounts of ethane, propane, butane

• methane
• used to
• heat residential, commercial buildings
• generate electricity in power plants
• variety of purposes in organic chemistry industry
• distributed via
• pressurized pipelines
• refrigerated tankers
• propane and butane
• separated from natural gas
• stored in pressurized tanks as liquid called liquefied petroleum gas
• used primarily as fuel for heating and cooking in rural areas

Fossil Fuels - Oil

• Formation
• oil & natural gas probably originated from microscopic aquatic organisms
• accumulated after death on ocean or lake floors in areas called depositional basins
• became buried by sediments
• over time, sediments became rock called source material or source rock
• source rock
• subjected to increased heat and pressure over great periods of time
• initiated chemical transformation of organic material in sediment into oil and natural gas
• elevated pressure facilitates upward migration of oil and gas, which are relatively light, into a lower-pressure environment, known as reservoir rock
• reservoir rock
• coarser grained (than source rock) and relatively porous
• has relatively high proportion of empty space (~30%) in which to store oil and gas
• sandstone and porous limestone are common reservoir rocks
• since oil and gas are light, they will continue to migrate upward until they are released into atmosphere
• unless their upward mobility is blocked
• for this reason, oil and gas are not generally found in geologically old rocks
• oil and gas fields
• are formed where natural upward migration of gas and oil toward surface
• is interrupted or blocked by a trap
• the rock that helps form the trap is called cap rock
• trap
• cap rock
• usually a fine-grained sedimentary rock composed of silt and clay sized particles
• such as shale
• requires favorable rock structure such as
• anticline
• arch-shaped fold
• fault
• fracture in rock along which displacement has occurred
• presence of rock cap and trap
• allows oil and natural gas to accumulate in the geologic environment
• where they are then discovered and extracted
• oil pools
• might form when shale is covered by
• layer of sandstone, which is covered by
• layer of impermeable rock
• trapped oil usually doesn’t exist as a liquid mass
• but rather as a concentration of oil within sandstone pores
• where it accumulates because water & gas pressure force it out of the shale
• Oil reserves
• ~26% in Saudia Arabia
• ~38% in Iraq, Kuwait, Iran, United Arab Emirates (each have ~9%-10%)
• ~14% in Latin America
• ~7% in Africa
• ~6% in former Soviet Union
• ~4% in Asia
• ~3% in US
• ~2% in Europe

• ~67% of world’s oil reserves are located in 11 countries that make up OPEC(Organization of Petroleum Exporting Countries)
• in 2000, OPEC produced 40% of world’s oil

• known, identified world oil reserves should last
• ~ 53 years at current rate of usage
• ~42 years if usage increases as projected by ~2% per year
• unknown, unidentified world oil reserves should last
• ~20-40 additional years
• identified and unidentified world oil reserves are projected to be ~80% depleted within
• 42-93 years depending on annual rate of use
• known, identified US oil reserves should last
• ~15-24 years at current rate of usage
• ~10-15 years if usage increases as projected by ~2% per year
• unknown, unidentified US oil reserves should last
• ~24 additional years
• identified and unidentified US oil reserves are projected to be ~80% depleted within
• 10-48 years depending on annual rate of use
• assuming we continue to use oil at current rate
• Saudi Arabia (with largest known reserves)
• could supply all the world’s oil needs for only ~10 years
• estimated reserves under Alaska’s North Slope (largest ever found in America)
• would meet current
• world demand for 6 months
• US demand for 3 years
• estimated reserves in Alaska’s Arctic National Wildlife Refuge
• would meet global demands for only ~1-5 months
• would meet US demands for ~7-24 months

• Extraction
• production wells in an oil field recover oil through two methods
• primary production
• enhanced recovery
• primary production
• involves simply pumping oil from wells
• can only recover about 25% of petroleum
• enhanced recovery
• involves injecting substances into the oil reservoir to push the oil toward the wells
• substances include steam, water, carbon dioxide, nitrogen gas
• can increase amount of oil recovered to about 60%
• Use Patterns
• by 1870, oil production in US was supplying 1% of nation’s energy needs
• for first 60 years of production
• principle use of oil was to make kerosene (as a fuel for lamps)
• the gasoline was discarded as a waste product
• during 20th century, percentage of world energy derived from oil increased from 2% to 32%
• US uses ~30%of crude oil extracted each year
• 68% of that is used for transportation
• oil has remained dominant energy source for past 40 years

• Use Issues
• two sets of environmental problems resulting from
• combustion
• production and transport
• combustion issues
• CO₂ emissions
• ~20lbs (9kg) of CO₂ released for every gallon of gasoline burned in an automobile
• acid deposition
• oil combustion produces very small amounts of sulfur oxides
• oil combustion does produce nitrogen oxides
• mainly through gasoline combustion in automobiles
• responsible for ~1/2 of nitrogen oxides in atmosphere
• production and transport issues
• land
• use of land
• to construct well pads, pipelines, storage tanks, production facilities, associated roads
• subsidence of land
• as oil is withdrawn
• ecosystems
• loss, disruption or damage to ecosystems
• this is a concern regarding development of petroleum resources in ANWR
• pollution of surface and ground water
• leaks from pipes of tanks containing oil or oil-field chemicals
• salty water that is brought to surface in large volumes with oil and must be disposed of
• in potentially leaky evaporation pits or disposal wells
• marine environment
• oil seepage into sea
• from normal operations of leaks, spills, pipe ruptures
• release of drilling muds into sea
• can contain toxic heavy metals
• aesthetic degradation from presence of offshore drilling platforms

Fossil Fuels - Natural Gas

• Natural gas
• description
• in its underground gaseous state, it’s a mixture of
• ~50-90% by volume methane (CH₄)
• simplest hydrocarbon
• smaller amounts of heavier gaseous hydrocarbons
• ethane, propane, butane
• small amounts of hydrogen sulfide (H₂S)
• highly toxic by-product of naturally occurring sulfur in the earth

• conventional natural gas
• occurs about most reservoirs of crude oil
• unconventional natural gas
• found by itself in other underground sources
• an example is methane hydrate
• composed of small bubbles of natural gas trapped in ice crystals deep under arctic permafrost and beneath ocean sediments
• current technologies do not provide economical means of extracting such sources
• formation
• natural gas (& oil) probably originated from microscopic aquatic organisms
• accumulated after death on ocean or lake floors in areas called depositional basins
• became buried by sediments
• over time, sediments became rock called source material or source rock

• reserves
• world reserves
• ~42% are located in Russia and Kazakhstan
• ~37% are located in7 countries
• Iran (15%)
• Qatar (~5%)
• Saudi Arabia (~4%)
• Algeria (~4%)
• United States (~3%)
• Venezuela (~3%)
• world reserves, known and unknown, estimated to last
• conventional natural gas
• ~125 years at current consumption rates
• ~50 years if usage rates rise 2% per year
• unconventional natural gas
• ~200 years at current consumption rates
• ~80 years is usage rates rise 2% per year
• world reserves, known and unknown, estimated to last
• conventional and unconventional natural gas
• ~205-325 years at current consumption rates
• ~50-130 years if usage rates rise 2% per year
• US reserves
• ~3% of world reserves located in US
• in roughly same areas as US crude oil reserves
• estimated to last ~30 years at current consumption rates
• extraction
• drilling wells on land or beneath the sea floor
• when a natural gas field is tapped
• propane and butane are liquefied and removed as liquefied petroleum gas (LPG)
• stored in pressurized tanks, mostly for use in areas not served by natural gas pipelines
• when a natural gas field is tapped
• propane and butane are liquefied and removed
• remainder of gas (mostly methane) is
• dried to remove water vapor
• cleaned of poisonous hydrogen sulfide and other impurities
• pumped into pressurized pipelines for distribution
• at very low temperatures (-184°C) natural gas can be converted to liquefied natural gas (LNG)
• can then be shipped to other countries in refrigerated tanker ships
• but its highly explosive
• its not uncommon for natural gas found with oil to be burned off as waste
• due to low price of natural gas
• use patterns
• world wide and US
• ~23% of world’s commercial energy supplied by natural gas
• use increased from ~1% to ~23% during 20th century
• most rapidly growing energy source because its
• clean burning , convenient, cheap
• uses
• primarily for heat energy
• in manufacture of petrochemicals and fertilizer
• use increasing in three main areas
• generation of electricity
• transportation
• commercial cooling
• generation of electricity via co-generation
• uses natural gas to produce both electricity and steam
• heat of the exhaust gases provides energy to make steam for water and space heating
• transportation
• natural gas can be used as a fuel for
• trucks, buses, automobiles
• emitting ~90% fewer hydrocarbons, carbon monoxide, toxic emissions
• in 1999, there were ~80,000 natural gas powered vehicles in US
• most of which are fleet vehicles
• LA has largest fleet of natural gas powered transit buses in North America
• commercial cooling
• can be used efficiently for residential and commercial air cooling systems
• such as desiccant-based (air-drying) cooling systems

• use issues
• is least disruptive of the 3 fossil fuels to the environment
• clean burning
• products of combustion are carbon dioxide and water
• even though carbon dioxide is a greenhouse gas, combustion of natural gas produces less CO₂ emissions than other fossil fuels
• contains almost no sulfur
• difficult to ship or store in large quantities
• some gas fields are too far from consumers to make pipelines practical
• costs roughly 4 times as much to transport through pipelines than crude oil
• environmental damage is associated with the construction of pipelines necessary for transport
• production and transport issues
• land
• use of land
• to construct well pads, pipelines, storage tanks, production facilities, associated roads
• subsidence of land
• as gas (oil) is withdrawn
• ecosystems
• loss, disruption or damage to ecosystems
• this is a concern regarding development of petroleum resources in ANWR
• pollution of surface and ground water
• as discussed for oil
• marine environment
• as discussed for oil

The End