19_oil_coal_ore_10_post - 19: Earth’s Resources 2–...

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Unformatted text preview: 19: Earth’s Resources 2– Photo: Chevron Corp. Oil, Coal, Ores Copper-bearing mineral Coal, Ore: 1 Coal bed Energy resources M ost common source Most of energy 150 years ago was wood ago Fig. 14.1 Q1. Which of the following Q1. supplied the most energy to the U.S. in 2000? the A. coal B. natural gas C. nuclear energy D. oil E. wind/running water Coal, Ore: 2 Hydrocarbons Fossil fuels: oil, gas, and coal that oil, are derived from organisms that l ived long ago and thus store solar energy that reached Earth long ago energy Hydrocarbons: molecules consisting molecules of complex arrangements of carbon and hydrogen atoms and Fig. 14.3 Crude oil : lliquid oil pumped out of iquid the ground; it is refined (heated to r efined separate hydrocarbons by density) to produce gasoline, kerosene, heating oil, lubricating oil; residue of refining process is used to make plastics and “ tar” Coal, Ore: 3 Recipe for oil & gas 1. Creation of source rocks: high organic productivity of 1. Creation microscopic organisms (e.g., plankton, algae) plus high preservation microscopic (low 02, rapid burial ) Fig. 14.4 Coal, Ore: 4 Recipe for oil & gas 2. Formation of oil & gas: organic chemicals transformed to 2. Formation hydrocarbons due to heat resulting from burial hydrocarbons Fig. 14.4 Coal, Ore: 5 Recipe for oil & gas 2. Formation of 2. oil & gas: organic oil chemicals transformed to hydrocarbons due to heat resulting f rom burial burial Fig. 14.5 Oil & gas window: typical range of temperature & depth at which hydrocarbons form Coal, Ore: 6 Depths based on geothermal Depths gradient of 25°C/km gradient Recipe for oil & gas 3. Migration: l ow-density oil & gas rise (eventually reaching the 3. Migration: surface unless trapped) surface Fig. 14.4 Coal, Ore: 7 Recipe 4. Trapping: oil & gas 4. Trapping: accumulate in reservoir rock below seal rock within a trap Reservoir rock: rock with high rock porosity and permeability; oil can f low easily into it and can be pumped easily out of it (typically sandstone, l imestone, and highly f ractured rock layers). Seal rock: rock with l ow porosity rock and/or permeability that prevents oil and gas from rising to surface (typically shale, salt, or unfractured crystalline rock units) Trap: geometry of reservoir and seal geometry that allows significant volume of oil and gas to accumulate and Coal, Ore: 8 Fig. 14.8 Recipe for oil & gas Trap: geometry of reservoir and seal that allows significant volume of geometry oil and gas to accumulate; a trap is typically associated with the high region of a reservoir bed or part of a reservoir bed between faults region Photo: Skinner & Porter Coal, Ore: 9 Types of traps High 1. Anticline (upfold) or DOME (upside-down bowl) 2. Salt structure (salt is i mpermeable) High High Fig. 14.9 Coal, Ore: 10 10 Types of traps Dome: upside-down bowl; I DEAL TRAP High Fig. 11.23 High High Sinclair dome, Wyoming. Photo: J. Shelton Coal, Ore: 11 11 Types of traps 3. Fault: j uxtaposes reservoir against seal; f ault rock may act as seal High Fig. 14.9 4. Stratigraphic (angular unconformity) Unconformity-- High Coal, Ore: 12 12 Exercises Cross section (side view) I n this set of exercises, you will determine aspects of the In hydrocarbon system. You will assume that a source rock is present, and that oil can migrate into all of the units except for the seals. You will also assume that salt is a seal but that faults by themselves are not. themselves Coal, Ore: 13 13 Exercises Cross section (side view) Q2. How many reservoir layers are present? A. 2 B. 3 C. 6 D. 7 Q3. How many seal layers (excluding salt) are present? A. 2 B. 3 C. 6 D. 9 Coal, Ore: 14 14 Exercises Q4. At which location would you most likely Q4. find hydrocarbons? find A. 2 only B. 1 & 4 C. 3 only D. none of the above Coal, Ore: 15 15 Exercises Q5. At which of the following locations would you most Q5. likely find hydrocarbons? l ikely A. 5 only B. 5, 7, and 9 C. 6 and 8 D. none of the above Coal, Ore: 16 16 Exercises Q6. At which of the following locations would you most Q6. likely find hydrocarbons? l ikely A . 10, 11, 12, 13, 14 A. B. 10, 12, 14 B. C. 11 & 13 D. none of the above Coal, Ore: 17 17 Exercises Q7. At which of the following locations would you most Q7. likely find hydrocarbons? l ikely A. 15, 16, 17, 18, 19 B. 15, 17, 19 C. 16 & 18 D. none of the above Coal, Ore: 18 18 Why does (did) does oil cost so much? Fears over supply shortages; political tensions; strong demand Fears (China, India), weakening demand (recession), weakening dollar / weakening weakening economic recovery economic Coal, Ore: 19 19 Are we running out of oil? Non-renewable resource: resource that cannot be replenished on the time scale of a f ew years (all fossil fuels, most mineral resources, some aquifers) mineral Renewable resource: resource resource that can be replenished on the time scale of a few years (solar, wind, geothermal, tidal, hydropower) hydropower) Q8. The world’ s supply of oil is l ikely to be depleted in about _______ years. A. 10 B. 100 C. 1000 D. 1 million Coal, Ore: 20 20 Fig. 14.31 BP Oil Disaster - Deepwater Horizon - Macondo Well Coal, Ore: 21 21 BP Oil Disaster Water depth at well location: ~5000 ft. Total depth of Macondo well: ~18,000 ft. Minimum pressure in reservoir: P=ρ wghw+ρ rghr P=(1000 kg/m3)(9.8 m/s2)(1520 m) + (2400 kg/m3(9.8 m/s2)(3960 m) P=(1.49x107 + 9.32x107) kg/ms2 = 1.08x108 Pa = 1070 atm = 15,700 psi 35 psi (pounds/in2) in tires Unofficial and unconfirmed For official report on For causes of disaster and other information related to offshore hydrocarbon exploration, visit: http://www. oilspillcommission.gov Coal, Ore: 22 22 Gulf of Mexico • Normal faults and salt structures structures • Mississippi River delta M ississippi • M ost wells located on the continental shelf and onshore onshore 1000? m 2000? m Coal, Ore: 23 23 Gulf of Mexico • M ost wells located on the continental shelf and onshore shelf • Increasing numbers of wells in deepI ncreasing water and ultra-deep-water settings Coal, Ore: 24 24 Gulf of Mexico • Continental rifting during breakup of Pangea (subsalt normal faults; thinned crust) Continental • Deposition of widespread salt during initiation of seafloor spreading (oceanic crust) Deposition • Massive input of sediment sourced from Mississippi River M assive •“ L andsliding” and salt flow down-slope (normal faults upslope; thrust (reverse) faults Landsliding” downslope) downslope) • Hydrocarbons sourced from massive amounts of organic-rich shales; sandstone provides reservoirs; shales provide seals; salt structures, faults, and related folds provide traps reservoirs; Coal, Ore: 25 25 Energy resources: coal Coal : black, brittle sedimentary rock that burns; it consists mostly of carbon derived from terrestrial (land) plants Fig. 14.14 Coal, Ore: 26 26 Energy resources: coal Fig. 14.16 Conditions for Conditions preservation: preservation: --__________ --__________ Site of accumulation: Site _______ _______ Fig. 14.18 Coal, Ore: 27 27 Coal: progressive transformation • Original plant material is compacted and partially decays to f orm peat. • Peat is transformed f irst into l ignite (brown coal) and then bituminous coal as a result of burial. Fig. 14.19 Coal, Ore: 28 28 Coal: progressive transformation Metamorphism of coal produces anthracite. Fig. 14.19 Increasing rank (energy content): Peat --> Lignite --> Bituminous --> Anthracite Coal, Ore: 29 29 Conditions favoring coal formation Most extensive coal deposits in L ate Carboniferous-Permian (320-245 Ma) Fig. 14.16 North A merica l ocated on equator: _________ _________ Fig. 13.22 Coal, Ore: 30 30 South Pole M ineral Resources Ore minerals: minerals that contain metal in high concentrations and i n a form that can be easily extracted. Photo: C. Clark Coal, Ore: 31 31 M ineral Resources Ores (rocks containing ore minerals) are produced when geologic processes concentrate metal-bearing minerals in abundances higher than normal. Fig. 15.5b Coal, Ore: 32 32 Ore-forming processes Magmatic: earlyformed, dense, metal-bearing minerals accumulate at the bottom of a magma chamber Fig. 15.7 Coal, Ore: 33 33 Ore-forming processes Hydrothermal : metals precipitated from hot-water solutions circulating through magma or through the rocks or fractures i n rock surrounding an i gneous intrusion Fig. 15.8 Coal, Ore: 34 34 Ore-forming processes Hydrothermal deposits Black smokers along seafloor-spreading centers Photo: D.B. Foster Coal, Ore: 35 35 Fig. 15.10 Ore-forming processes Fig. 15.11 Secondary enrichment: oxygen-rich water dissolves minerals out of an low-grade ore body and precipitates them in l ess oxygen-rich water below the water table, f orming a high-grade ore body Coal, Ore: 36 36 Ore-forming processes Banded-iron formations: iron-oxide-rich deposits that formed between 2 and 2.5 billion years ago, when rising oxygen levels (produced by photosynthesis) in the atmosphere and oceans caused previously dissolved iron to precipitate (come out of solution) Fig. 15.12 Coal, Ore: 37 37 Ore-forming processes Placer: concentration of metal grains in stream sediment that develop when rocks containing metals erode and create a mixture of clasts and metal f ragments; the moving water carries away the l ess-dense grains, l eaving behind the higher-density metals (like gold, with a density of 19 g/cm3). Fig. 15.14 Coal, Ore: 38 38 Review Questions 19-1. What type of rock is most likely to contain oil, natural gas, and coal? A. igneous B. sedimentary C. metamorphic 19-2. Chemically, oil and gas are both ____________. A. pure forms of carbon B. carbohydrates C. hydrocarbons D. carbonate minerals 19-3. Most of the hydrocarbons within oil and natural gas are derived from the breakdown of organic matter from once-living ____________. A. dinosaurs B. plankton & algae C. terrestrial (land) plants D. mammals 19-4. In order to produce a commercially viable oil deposit, there must be a source rock, a r eservoir rock, a seal rock, and a ____________. A. large fracture connecting the reservoir rock to the surface of the Earth, so the oil can move freely toward the surface B. filter rock—a rock of intermediate permeability located between the source and reservoir rocks to remove impurities C. heater rock—an intrusive igneous rock beneath the source rock to heat the oil and give it buoyancy D. trap—a geologic configuration that forces oil to pool up and denies it passage to the surface Coal, Ore: 39 39 Review Questions 19-5. A black, organic-rich shale could likely serve as either of which two necessary types of r ocks within oil fields? A. source rock or seal rock B. reservoir rock or seal rock C. source rock or reservoir rock 19-6. Which of the following is a good reservoir rock for hydrocarbons? A. rock salt B. sandstone C. shale 19-7. A permeable and porous rock, regardless of lithology, is a good candidate to serve as a _______ in an oil producing scenario. A. reservoir rock B. seal rock C. source rock 19-8. Shale, salt, and unfractured crystalline rocks are all good candidates to serve as _______ within an oil field. A. a reservoir rock B. a seal rock C. a source rock D. either a source or a reservoir rock 19-9. The best type of structure for trapping hydrocarbons is a(n) ___. A. anticline B. basin C. dome D. syncline 19-10. Which of the following is NOT an important type of oil trap? A. salt dome B. syncline C. stratigraphic D. anticline Coal, Ore: 40 40 Review Questions 19-11. A. True / B. False: For hydrocarbons and coal deposits to form, organic matter must accumulate in a high-oxygen environment. 19-12. Coal is the altered remains of ancient _______. A. dinosaurs B. plankton & algae C. terrestrial plants D. mammals 19-13. Most of the world’ s coal was deposited in swamps during the _______. A. Cretaceous B. Ordovician C. Carboniferous D. Jurassic 19-14. Which sequence of coal types is ordered from lowest to highest rank? A. anthracite, bituminous, lignite B. lignite, bituminous, anthracite C. bituminous, lignite, anthracite D. bituminous, anthracite, lignite 19-15. A. True / B. False: Anthracite is associated with igneous rocks. 19-16. A. True / B. False: During the Carboniferous period, North America was located near the equator. Coal, Ore: 41 41 Review Questions 19-17. In magma chambers, ore minerals typically ______. A. rise to the top B. sink to the bottom C. mix well with the rest of the magma D. solidify and reside in the middle of the magma 19-18. A. True / B. False: Magmatic ore deposits are the last minerals to crystallize in a magma chamber. 19-19. Hydrothermal ore deposits are common at ___ plate boundaries. [ Hint: Which plate boundary is associated with black smokers and other hydrothermal vents?] A . conservative B. convergent C. divergent 19-20. Which ore metals are commonly present in ancient sedimentary deposits that are 2 billion years old? A. copper B. aluminum C. iron D. copper Coal, Ore: 42 42 ...
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This note was uploaded on 02/08/2011 for the course ENVSCI 100 taught by Professor A during the Fall '10 term at Rutgers.

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