oil-gas-coal-fuels from
Nature: oil (petroleum) natural gas (CH4) = hydrocarbons (HC)
Formation: 1: large accumulation of organic
matter
2: quick burial
3: P&T = chemical change: large organic (______) hydrocarbon molecules
broken into_______ (lighter) molecules. T range 50o -
100oC
4: Repetition of 3: brings maturation of hydrocarbon: asphalt
oil-gasoline gas
Crude oil: __________ of different type HC compounds
Refining: _____________of different HCs
Cracking: ____________________________ to obtain lighter ones (gasoline)
Oil and gas Migration
From _________rock
to
_________ Rock
Fine grained
porous & permeable
Low permeability
oil displaces water
& floats on top
needs to be trapped by impermeable rock
suitable structure (trap)
Time factor: no oil/gas younger than 1-2 my
Type of resource? _______________
Supply & Demand World Reserves 1 trillion barrels; 400 b.barrels
used in the last two decades.
Remaining US resources: 80 b.barrels ; Reserves:
22.5 b. barrels (1995)
Supplies 40% energy used in U.S.
U.S. oil: More than half of U.S. reserves have been consumed
80's: new reserves of domestic oil found, but total consumption
increased; today ~ 49% oil used in U.S. is imported; represents
25% of world's use
New!! "large" Alaska's North slope deposits will provide
for 2 years U.S. consumption (some say 6 months!!!).
Would you risk developing Alaska for 2 years consumption?
U.S. Natural Gas: reserves: 200
trillion cubic ft
20 trillion cubic ft consumed yearly
=> depletion of U.S. reserves in decades -
supplies 25% U.S. energy
Future prospects:
Enhanced Recovery:
primary +
secondary recovery => extract one third oil in trap.
little pumping
pump water
enhanced by
increase perm. => __________________________
can extract
pressurized CO2 =>__________________________
40% init. oil
hot water - steam => __________________viscosity
detergents Add cost
Something good!! = ______________________________ => no time delay
Something bad =________________________ -______________________
pollution
Geopressurized Natural Gas:
Thousands of m below surface => gas dissolved in ____________
P-To - Drilling problems - Potential unknown
Methane gas hydrates:
abundant, but how to exploit them is still unclear.
Concern about the greenhouse effect
Prospect: Enhanced gas recovery from "tight" rocks in the Rocky Mtns.
Conservation: buy time to develop new renewable sources
demand will not decrease
Oil Spills: natural
seeps
large catastrophic ones
Hope: development of "oil hungry" organisms
COAL
Formation: from land plants, swampy (anaerobic) conditions
1. peat
2. lignite
3. bituminous coal
4. anthracite
harder
C rich
Energy
moisture
yield
Metamorphism: graphite
Reserves &Resources: not in Igneous or Met. Rocks
Non Renewable
not older than 400 m.y.
U.S.= 30 % world reserves - (unused and unmined)
25 % of
total energy today in U.S.
Time to depletion: 200 y. if exclusively coal is used; more
otherwise.
Drawback = Not versatile, not clean
Gasification:
Coal + gas = less heating power than nat. gas
steam
underground gasif. less disturbance
mine thin beds
Liquefaction: _________________________________, feasible, still
not competitive with petroleum. Yield: 70% original coal. Promising.
Environmental Impact:
CO2 from coal burning ??? > CO2 from
oil or gas
=> risk?___________________ _____________
Sulfur in coal > 3%; desirable 1%
pyrite
low grade coal
bound in organic compounds
need burn more
When burned => SO2 (gas) SO2 + H2O => SO4H2
___________________ aquatic life
acid rain
affects ________________ growth
dissolves _______________________ (rocks)
Removal of S from coal - expensive
air pollution - waste disposal
Ash Problems volume
leachable
health = breathe dust => __________(Radon)
Mining Hazards: explosions: gas pockets
fire
Underground mines
strip mines: expose sulfur => sulfuric acid (acid mine
drainage)
Oil Shale: not shale - not oil = Kerogen: waxy
solid from plants, algae, bacteria.
Rock needs to be crushed and distilled
Tar sands
inmature petroleum deposits = heavy semisolid petroleum
orogin
deposits where light hydrocarbons migrated
Technology and environmental concerns similar to oil shale's
Canada has large Tar Sand Deposits - US does not.
CHAPTER 13 - FOSSIL FUELS
REVIEW QUESTIONS AND TOPICS
1) Fossil fuels: definition. Types of fossil fuels.
2) How do oil and gas deposits form? What does the maturation process
of an oil deposit involve?
3) Define: crude oil, cracking and refining. Examples of heavy and
light hydrocarbons.
4) Compare the characteristics of the source rock and the reservoir
rock of an oil deposit. Why is a trap necessary to have an economic
oil deposit?
5) What percentage of U.S. energy comes from fossil fuels?. What percentage
of the oil used in the U.S. is imported?. How many years will the U.S.
oil and gas reserves last at current consumption rates?.
6) How many years of U.S. oil and gas consumption do the "large" oil
deposits of the Alaska North Slope represent? Is it really worthwhile to
develop these deposits considering the environmental cost?
7) Future prospects for oil.
8) Primary, secondary and enhanced recovery methods. Discussion of
advantages and disadvantages.
9) Sources of oil spills. Methods of cleanup.
10) Geopressurized natural gas deposits: What are they? Advantages
and disadvantages. Potential for the future.
11) Discuss the environmental impact of oil/gas exploration, exploitation
and processing.
12) How does coal form? Characteristics of the different types of coal.
13) (Time and spatial) Limitations to coal distribution.
14) Coal in the U.S. Abundance, use, potential.
15) Coal gasification and liquefaction: process involved. Characteristics
of the products. Advantages and disadvantages.
16) Analyze the different environmental impacts and mining hazards
related to coal use and extraction.
17) What relationship exists among fossil fuels and acid rain? How
does acid rain form? What is the environmental impact of acid rain? Is
the effect of acid rain on different types of bedrock equal? Yes, No, Why?
18) Differences and similarities among oil shales and tar sands. Oil
shale and tar sands distribution in North America. U.S. abundance.