19_oil_coal_ore_10_post

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. Copper-bearing mineral Coal, Ore: 1 Oil, Coal, Ores Coal bed Energy resources M ost common source of energy 150 years ago was wood ago 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 Fig. 14.1 Hydrocarbons Fossil fuels: oil, gas, and coal that oil, are derived from organisms that lived long ago and thus store solar energy that reached Earth long energy ago ago Hydrocarbons: molecules molecules consisting of complex arrangements of carbon and hydrogen atoms hydrogen Crude oil: liquid oil pumped out liquid of the ground; it is refined (heated refined to 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 Fig. 14.3 Fig. Recipe for oil & gas 1. Creation of source rocks: high organic productivity of 1. Creation microscopic organisms (e.g., plankton, algae) plus high preservation (________________) preservation Fig. 14.4 Coal, Ore: 4 Recipe for oil & gas 2. Formation of oil & gas: organic chemicals transformed to 2. F ormation hydrocarbons due to heat resulting from _____ _____ Fig. 14.4 Coal, Ore: 5 Recipe for oil & gas 2. F ormation of 2. oil & gas: oil organic chemicals transformed to hydrocarbons due to heat r esulting from _____ _____ Oil & gas window: typical range of temperature & depth at which hydrocarbons form Coal, Ore: 6 Fig. 14.5 Depths based on geothermal Depths gradient of 25°C/km gradient Recipe for oil & gas 3. Migration: low-density oil & gas rise (eventually reaching 3. M igration: the surface unless trapped) the Fig. 14.4 Coal, Ore: 7 Recipe 4. Trapping: oil & gas 4. Trapping: accumulate in r eservoir rock below seal rock within a trap Reservoir rock: r ock with high rock porosity and permeability; oil can flow easily into it and can be pumped easily out of it (typically sandstone, limestone, and highly fractured rock layers). Seal rock: r ock with low 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 geometry seal that allows significant volume of oil and gas to accumulate of Coal, Ore: 8 Fig. 14.8 Recipe for oil & gas Trap: geometry of reservoir and seal that allows significant geometry volume of 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 between Photo: Skinner & Porter Coal, Ore: 9 Types of traps High 1. Anticline (upfold) or DOME (upsidedown bowl) 2. Salt structure (salt is impermeable) High Fig. 14.9 Coal, Ore: 10 10 High Types of traps Dome: upside-down bowl; I DEAL TRAP Fig. 11.23 High High High Sinclair dome, Wyoming. Photo: J. Shelton Coal, Ore: 11 11 Types of traps 3. F ault: j uxtaposes r eservoir against seal; fault rock may act as seal High Fig. 14.9 4. Stratigraphic (angular unconformity) Coal, Ore: 12 12 Unconformity-- High Exercises Cross section (side view) Coal, Ore: 13 13 I n this set of exercises, you will determine aspects of the 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. by Exercises Cross section (side view) Coal, Ore: 14 14 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 Exercises Coal, Ore: 15 15 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 Exercises Coal, Ore: 16 16 Q5. At which of the following locations would you Q5. most likely find hydrocarbons? most A. 5 only B. 5, 7, and 9 C. 6 and 8 D. none of the above Exercises Coal, Ore: 17 17 Q6. At which of the following locations would you Q6. most likely find hydrocarbons? most A. 10, 11, 12, 13, 14 A. B. 10, 12, 14 B. C. 11 & 13 D. none of the above Exercises Coal, Ore: 18 18 Q7. At which of the following locations would you Q7. most likely find hydrocarbons? most A. 15, 16, 17, 18, 19 B. 15, 17, 19 C. 16 & 18 D. none of the above Why does (did) does oil cost so much? Fears over supply shortages; political tensions; strong demand Fears (China, I ndia), weakening demand (recession), weakening weakening weakening dollar / economic recovery dollar Coal, Ore: 19 19 Are we running out of oil? Non-renewable resource: r esource that cannot be r eplenished on the time scale of a few years (all fossil fuels, most mineral resources, some aquifers) aquifers) Renewable resource: r esource 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 likely 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 W ell Coal, Ore: 21 21 - Deepwater Horizon - M acondo BP Oil Disaster Water depth at well location: ~5000 ft. Total depth of M acondo well: ~18,000 ft. M inimum pressure in reservoir: P=ρ wghw+ρ r ghr 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 For official report on For causes of disaster and other information r elated to offshore hydrocarbon exploration, visit: http://www. oilspillcommission.go v Coal, Ore: 22 22 Unofficial and unconfirmed Gulf of M exico • Normal faults and salt structures structures • M ississippi River delta • M ost wells located on the continental shelf and onshore onshore 1000? m 2000? m Coal, Ore: 23 23 Gulf of M exico • M ost wells located on the continental shelf and onshore continental • I ncreasing numbers of wells in deep-water and ultra-deep-water Coal, Ore: 24 24 Gulf of M exico • Continental rifting during breakup of Pangea (subsalt normal faults; thinned crust) Continental • Deposition of widespread salt during initiation of seafloor spreading (oceanic crust) Deposition • M assive input of sediment sourced from M ississippi River •“L andsliding” and salt flow down-slope (normal faults upslope; thrust (reverse) faults Landsliding” downslope) downslope) • H ydrocarbons sourced from massive amounts of organic-rich shales; sandstone provides reservoirs; shales provide seals; salt structures, faults, and related folds provide traps r eservoirs; 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 Site accumulation: _______ _______ Fig. 14.18 Coal, Ore: 27 27 Coal: progressive transformation • Original plant material is compacted and partially decays to form peat. • Peat is transformed first into lignite (brown coal) and then bituminous coal as a result of burial. Coal, Ore: 28 28 Fig. 14.19 Coal: progressive transformation M etamorphism of coal produces anthracite. Fig. 14.19 I ncreasing rank (energy content): Peat --> Lignite --> Bituminous --> Anthracite Coal, Ore: 29 29 Conditions favoring coal formation M ost extensive coal deposits in Late CarboniferousPermian (320-245 M a) North America located on equator: _________ _________ Fig. 13.22 Coal, Ore: 30 30 South Pole Fig. 14.16 M ineral Resources Ore minerals: minerals that contain metal in high concentrations and in 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 M agmatic: early-formed, dense, metalbearing minerals accumulate at the bottom of a magma chamber Coal, Ore: 33 33 Fig. 15.7 Ore-forming processes Hydrothermal: metals precipitated from hot-water solutions circulating through magma or through the r ocks or fractures in rock surrounding an igneous intrusion Fig. 15.8 Coal, Ore: 34 34 Ore-forming processes Hydrothermal deposits Black smokers along seafloorspreading 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 less oxygen-rich water below the water table, forming 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 r ocks containing metals erode and create a mixture of clasts and metal fragments; the moving water carries away the less-dense grains, leaving behind the higher-density metals (like gold, with a density of 19 g/cm3). Fig. 15.14 Fig. 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. I n order to produce a commercially viable oil deposit, there must be a source rock, a reservoir 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 r eservoir 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 rocks 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. I n 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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