Geology 1010 lecture outline - Energy Resources

Introduction: definition of energy, units, first law of thermodynamics, cost of and economic importance.

Where do we obtain energy from?

What are the relative contributions of different energy sources to the energy 'picture'?

• source rock:
  • need to preserve organics in the rocks.
  • euxinic environments favorable to presrvation found in restricted marine bodies or lakes. Where found today?
  • sulfur compounds also common to euxinic environments.
  • basin subsidence (to bury and isolate).
  • black shales or limestones common source rocks.
  • some 50% of source rock formed in the Cretaceous Period.
• thermal window (thermogenic component):
  • kerogen: waxy and complex organics in source rock.
  • need to be cooked into oil (low simmer) or gas (hotter).
  • too high and change organics into useless forms.
• reservoir or trap:
  • need reservoir rock and seal.
  • stratigraphic traps (e.g. reef, channel or offshore sand bodies within finer grained sediment).
  • structural traps: the classic anticline.
• time element? Not such that it is renewable.

• reserves: estimate of size of discovered deposits.
• resources: reserves plus estimate of yet-to-be discovered deposits.
• conventional: those deposits economic given present technology and price.
• unconventional: those deposits economic given reasonable advances in technology or at higher prices.

What are factors determining economics of geologic resource exploitation?

How much oil is left (oil reserves and resources, future projections, and energy policy)?

Cradle to grave approach from an environmental perspective.

What are exploration techniques for hydrocarbons?

Extraction and secondary recovery techniques.

• drilling depths of several 1000' common, 20,000' done regularly, and up to 30,000' have been done by industry. 1982 average cost per foot was $52.56. One 18,000' hole in Gulf of Alaska in 1983 cost $44 million.

  ---

  Figure of offshore drilling/production platform being refitted in Galveston Harbor, Texas.

  ---

• overpressurized reservoirs a major concern.
• drilling mud density such that weight of column in drill stem yields bottom pressure greater than reservoir pressure. Increase density by adding barium chloride.
• Campeche 1979-1980 history: exploratory well in Gulf of Mexico had a blowout on June 3rd, 1979. Caught fire. March 23rd 1980 intercepted and under control. More than 3 million barrels of oil lost, oil slick 120-160 km long that fouled Texas beaches.
• Recovery rates and secondary recovery techniques:

Concerns associated with transportation, refinement?

What are concerns associated with fossil fuel use?

Alternate hydrocarbon energy resources: oil shales, tar sands, methane hydrates.

Biogenic methane.

What will likely replace oil?

Coal as an energy source

Geologic formation factors.

Reserves and resources.

Environmental concerns related to extraction.

• strip mining and reclaimation.
• tailings and acid mine drainage.
• underground mine fires, collapse, miner saftey.
  

Return to index page for environmental geology course. Return to homepage of H. D. Maher Jr..