Powerpoint Presentation Physical Geology, 10/e

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Geologic ResourcesChapter 21
Oil Field in Wyoming
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Geologic Resources and Earths Systems

• Geologic resources - valuable materials of
  geologic origin that can be extracted from the
  Earth
• Many geologic resources originate in the
  hydrosphere
• Petroleum and coal come from organisms that lived
  and died in water
• Halite (salt) and other evaporite minerals come
  from dry lake beds
• Weathering interactions between geosphere,
  atmosphere and hydrosphere produce metal oxide
  ores
• Humans (biosphere) interact directly with the
  geosphere, hydrosphere, and atmosphere when
  extracting and utilizing geologic resources
• Groundwater (hydrosphere) is a renewable geologic
  resource
• If it cant be grown, it must be mined

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Types of Geologic Resources

• Geologic resources are grouped into three major
  categories
• Energy resources - petroleum (oil and
  natural gas), coal, uranium, geothermal resources
• Metals - iron, copper, aluminum, lead, zinc,
  gold, silver, platinum
• Non-metallic resources - sand and gravel,
  limestone, building stone, salt, sulfur, gems,
  gypsum, phosphates, groundwater, etc.

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Resources and Reserves

• Resources - the total amount of a valuable
  geologic material in all deposits, discovered and
  undiscovered
• Reserves - discovered deposits of geologic
  resources that can be extracted economically and
  legally under present conditions
• The short-term supply of a geologic materials

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Energy Resources - Coal

• Fossil fuels (oil, natural gas, and coal) account
  for nearly 90 of U.S. energy
• Coal is a sedimentary rock that forms from the
  compaction of plant material that has not
  completely decayed
• Forms from shallow burial and compaction of peat

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Energy Resources - Coal

• Four varieties of coal
• Lignite (brown coal) is soft and crumbly
• Sub-bituminous and bituminous coal (soft coal)
• black and dusty
• burn with a smoky flame
• commonly strip-mined
• Anthracite (hard coal)
• shiny and dust-free
• burns with a smokeless flame
• low-level metamorphic rock
• Burning of high-sulfur coal can produce acid
  rain strip mines can scar landscape
• U.S. coal reserves could last for centuries

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Energy Resources -Petroleum

• Petroleum - oil and natural gas - occurs in
  underground pools
• Occurrence of oil pools requires
• A source rock (rich in organic matter)
• A reservoir rock in which it can be stored and
  transmitted (e.g., sandstone)
• An oil trap (set of conditions holding rock in
  reservoir rock and preventing migration)
• Deep enough burial (and sufficient time) to
  cook the oil and gas out of the organic matter

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Structural Traps for Gas and Oil
2300 m 4600 m Oil formation 4600 m
Gas formation
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Energy Resources - Petroleum
Eroded anticline forms trap in Landers oil field
in Wyoming.
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Other Oil Traps in Geological Structures
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Petroleum Recovery

• Oil fields are regions underlain by one or more
  oil pools
• Largest in U.S. are in Texas and Alaska
• Oil and natural gas are removed through wells
  drilled down into an oil trap within a
  reservoir rock
• Negative environmental effects resulting from oil
  recovery and transport include oil spills, brine
  contamination of surface water, and ground
  subsidence

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Oil Peak, Oil Panic ? (Study by Amos Nur -
Stanford)
U.S., Canada, Japan, Germany, France, Italy, UK,
are the biggest consumers of oil reserves
worldwide.
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Oil Peaks 1960's
In the 1850's oil mainly used for kerosene lamps
remaining was burned or disgarded.
Current oil production rates peaked in 1960's but
U.S. consumption rates increase dramatically
above this. Don't panic! -Try to conserve
energy -Seek alternative energy sources
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Petroleum Reserves
At current rate of use, worldwide oil reserves
should last 30-40 years, and natural gas reserves
somewhat longer (estimates from USGS)
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Petroleum Reserves

• As petroleum prices rise, alternate petroleum
  sources, such as heavy crude, oil shale and
  oil sand, will be increasingly exploited
• Heavy crude is dense, viscous petroleum
• Oil shale is black or brown shale with high solid
  organic matter content from which oil can be
  extracted by distillation
• Oil sands (or tar sands) are asphalt-cemented
  sand or sandstone deposits

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Jobs and Salaries in Geology

• Starting salaries for petroleum geologists with
  0-2 yrs experience.
• Mixture of B.S. and M.S. Degrees.

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Jobs and Salaries in Geology

• Geologists in Environmental (e.g. EPA,
  Geotechnical firms) and
• Geologists in Government make 50 K 75 K
• Geology Ph.D. faculty starting salaries in 2007
  (70 K 80 K)\

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Metals and Ores

• Metal ores - naturally occurring materials that
  can be profitably mined
• Whether or not a mineral deposit is an ore
  depends on chemical composition, the percent
  extractable metal, and current market value of
  the metal
• Metallic ore deposits originate from crystal
  settling in igneous intrusions, hydrothermal
  fluids cooling in pores and factures, chemical
  precipitation in water, or sedimentation in
  rivers (placers)

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Mining and Metals

• Mining can be done at Earths surface (strip
  mines, open-pit mines, and placer mines) or
  underground
• Metals mined include iron, copper, aluminum,
  lead, zinc, silver, gold and many others
• With care, negative environmental effects of
  mining, including unsightly tailings piles,
  surface scars, land subsidence, and acid mine
  drainage can be minimized

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Non-metallic Resources

• Non-metallic resources - not mined to extract a
  metal or an energy source
• construction materials
• sand, gravel, limestone, and gypsum
• agriculture
• phosphate, nitrate and potassium compounds)
• industrial uses
• rock salt, sulfur, asbestos)
• gemstones
• diamonds, rubies, etc.
• household and business products
• glass sand, fluorite, diatomite, graphite)