Geology Chapter 14
What are the main grades of coal and how are they defined? What is the estimated reserve supply of coal in the US?
0. Peat: formed at the earth's surface, combustible. With burial and more heat, pressure, and time, peat gradually dehydrates and forms... 1. Lignite (soft, low carbon content, high moisture content, low heat content - i.e., does not release so much heat when burned relative to higher grades of coal) 2. Subbituminous 3. Bituminous 4. Anthracite (hard, high carbon content, low moisture content, high heat content) Estimated coal reserves are ~ 1 trillion tons; total resources ~ 10 trillion tons. The US possesses about 27% of the world's reserves and, unlike oil, has reserves to supply the nation's energy needs for at least the next 200 years. Unfortunately, there are drawbacks to relying on coal.
What are some of the challenges involved in land reclamation once the mining operation is completed? (p. 330) 26. What are oil shales? Where is the major US resource located and what type of petroleum deposit is formed there?
1977 Surface Mining Control and Reclamation Act that states the mined be restored to its "approximate original contour". Surface mining operations in the West Virginia Appalachians (and elsewhere) sometimes require the removal of an entire mountaintop, a procedure done with explosives and earth-moving equipment. The valleys are then filled with the removed, unused product. To what extent is the original mountaintop expected to be restored, and at what cost? Neither an oil or always found in a shale The hydrocarbon found in these sedimentary rocks is called kerogen, derived from plant remains. The US possesses about 75% of the world's known oil shale resources, and most of it (70%) lies in the Eocene Green River Formation, a 40-million-year old rock layer that runs through Colorado, Wyoming, and Utah. The formation represents an ancient lake deposit and is well-known for its abundant and exceptionally preserved fish fossils.
Why is sulfur content significant with regard to coal?
Coal also carries an additional pollutant: sulfur, > 3% of which can be bound to the.coal as pyrite (FeS). When sulfur is burned along with coal, a poisonous sulfur gas is produced called sulfur dioxide (SO). This gas reacts with water to form sulfuric acid, and mixes with rainwater to form acid rain, which over time can kill aquatic and land-based ecosystems.
What is coal and how does it form? How does the chemical composition of coal differ from that of oil and gas; and how does the origin of coal differ from that of oil and gas?
Coal forms from the remains of land plants that died in swampy environments, often hundreds of millions of years ago, under anaerobic conditions (lacking oxygen; the presence of oxygen would completely destroy the organic matter in the leaves, resulting in no coal forming whatsoever).
What are some of the environmental impacts of coal mining? What is done with the waste product, ash?
Coal mining is also extremely dangerous! Not only for the miners, who risk various respiratory illnesses (e.g. "miner's lung"), radiation exposure (radon), cave-ins, and natural gas explosions; but also for the environment: underground fires in coal seams can run for decades . While safer for the miners, sulfur (in the form of pyrite) is left behind in waste rock in spoil banks. The sulfur reacts with water to form sulfuric acid: This reaction is responsible for most of the acid mine drainage discussed in Ch. 13. The acid runoff can kill vegetation and pollute ground and surface waters. Surface coal mines are refilled with soil when they are reclaimed, but the issue of water availability to support plant re-growth becomes an issue with drier areas out west. After coal is burned, coal leaves behind a solid waste, called ash, that needs to be disposed safely, since it, too, can contain trace amounts of toxic materials such as arsenic, lead, selenium and uranium. Presently, it goes into landfills or containment ponds
What is coal-bed methane?
Coal-bed methane: methane gas occurs naturally in coal seams and previously was released during mining as a waste-product (it is both toxic and explosive). Now it can extracted for economic use, adding to the US gas reserves.
What is cap rock and how does it influence oil production
Commercially, the most valuable oil deposits are those in which a large quantity of oil / gas has been trapped by and concentrated in a layer of impermeable rocks that cap it from above: the impermeable layer is called cap rock.
What are some examples of fossil fuels? Why are they called fossil fuels? What two elements are fossil fuels predominantly made up of? What percentage (%) of our nation's energy supply comes from fossil fuels versus, say, hydropower / nuclear power? Are fossil fuels renewable
Fossil fuels: All are nonrenewable energy sources that formed from the remains of once-living organisms. Fossil fuels include: 1. Oil: 37% 2. Natural gas: 25% 3. Coal: 21% 4. Fuels derived from oil shale and tar sand The US relies on fossil fuels for about 83% of its energy. Fossil fuels are predominantly made up of Carbon and Hydrogen
What is the difference between primary / secondary and enhanced recovery of oil and gas?
Historically, roughly 2/3 of the oil in each deposit has been left in the ground: there isn't an easy way to get it out (the first 1⁄2 comes out either on its own pressure as a gusher [primary recovery] or is pumped out with water [secondary recovery]). Enhanced recovery involves extracting the remaining oil, and these techniques, though costly, could recover an additional 40% of the oil initially in a reservoir, helping to increase reserves. Techniques include fracking, or applications of high pressure CO2gas or steam. Again, such techniques drive up the cost of extraction, and concerns over pollution remain
What are some of the benefits / drawbacks to using coal? How does the CO2 emission output of coal compare to that of oil and gas?
Limitations on Coal Use 1. Not as versatile as oil / gas. You don't fill up a car or plane with coal! 2. It's dirty. Coal was once used to power steamboats and steam train engines but diesel engines became more popular in part due to being a cleaner fuel. Also, coal is not the most convenient fuel for home heating (most US residents rely on oil or gas), though many countries certainly use coal to warm up a room. Fossil fuels, coal included produce CO2 when burned. Coal produces far more CO2 per unit energy than either oil or natural gas
What are oil sands (tar sands)? What is the name of the petroleum product that they produce? What country possesses most of the world's oil sand reserves?
Oil sands are sedimentary rocks that contain a thick, semisolid, tar-like petroleum called bitumen. These sands represent very immature petroleum deposits. Like with oil shales, the sand must be mined, crushed, or heated to extract the petroleum, and then refined into various fuels. Oil sands that are near-surface deposits are commonly strip-mined. Canada has ~70% of the world's oil sand reserves, mostly located in the province of Alberta in a region called the Athabasca oil sand.
What is the difference between petroleum, oil, and natural gas? (pp. 309-310) What is the chemical makeup of most natural gas?
Petroleum-a hydrocarbon, organic compound of hydrogen and carbon Oil: liquid petroleum, made up of a variety of liquid hydrocarbon compounds (molecules that consist primarily or entirely of the elements hydrogen and carbon). Natural gas: petroleum in the gaseous phase, including the compound methane CH4.
What is shale gas, and how is it typically mined? What are some of its environmental impacts? (pp. 316-317) 15. How do the future prospects look for oil and gas
Shale gas: extracted through a technique known as hydraulic fracturing, or fracking. This is an extraction technique that involves drilling first vertically (straight down), and then turning horizontally between beds to extract natural gas. Shale-gas reserves continue to rise as extraction is on-going. Some states, however, have noticed a rise in seismicity associated with fracking, and have slowed production pending further study.
Where is the biggest oil field in the US? What is the significance of the NPRA and the ANWR (and what do they stand for?), and what are some of the issues regarding to drill or not to drill in these areas? About how long does it take to develop a new oil field? How is oil transported from the Alaskan North Slope to the southern part of the state?
The largest oil field in the US is the Prudhoe Bay field on the North Slope of Alaska. It is operated and owned by British Petroleum (BP), ExxonMobil, and Conoco Phillips. Drilling began in 1969, led to the building of the 800-mile Trans-Alaska Pipeline (at a cost of $8 billion), and continues today. As its reserves decline, the pressure to develop oil field in offshore and wilderness areas increases, such as 1. the neighboring Arctic National Wildlife Refuge (ANWR), established in 1980 during the Carter administration. The ANWR is just east of Prudhoe Bay, making up the northeast corner of the state, and is thought to contain several billion gallons of oil. 2. the neighboring National Petroleum Reserve-Alaska (NPRA), established in 1923 during the Harding administration. The NPRA is just west of Prudhoe Bay and exploratory drilling has confirmed the presence of both oil and natural gas.
What were the circumstances behind the Exxon Valdez and Deepwater Horizon incidents? What were some of the options used in the clean-up of the spills?
The largest tanker accident in the US was that of the Exxon Valdez, in 1989, resulting in a clean-up that cost Exxon $2.5 billion. That may sound like a lot but bear in mind, Exxon's annual revenue in 2016 was nearly $200 billion. The Deepwater Horizon incident of 2010 off the Louisiana coast involved an offshore oil rig run by British Petroleum (BP) that drilled an exploratory well that hit a high-pressure pocket resulting in a blowout and subsequent explosion of the rig, killing 11 of the workers. The resulting oil spill was over 10x the size of the Exxon Valdez and was only halted when a cap was successfully applied to plug the well and its erupting oil, 5 months later. BP paid nearly $19 billion in fines in July 2015. Clean-up attempts in both cases were costly and limited in their effectiveness. A combination of skimmer ships, chemical dispersants, and outright burning of the oil slicks were just some of the clean-up methods applied.
What is the difference between source rock and reservoir rock?
The majority of petroleum originates in fine-grained clastic sedimentary rocks called source rocks. From there, the oil gradually and naturally seeps out of its source rock and migrates elsewhere. Eventually, the oil may accumulate either by i) getting trapped in a permeable, porous rock (called reservoir rock) or by ii) moving up on its own to the Earth's surface (creating an oil seep).
What is the minimum estimated burial time needed to produce oil and gas to form
The process of how organic material is converted into oil is not well understood and is thought to take at least 1-2 million years.
How many gallons are in a barrel of oil? Roughly, what is the number of global oil reserves? Roughly, what is the number of US reserves? About how long would they be expected to last if no new reserves were found? (p. 312) 9. How much oil does the US consume per year, and how much overall energy does it supply to our total needs? About how much oil (%) do we import, and what are the primary countries from whom we import oil?
There are 42 gallons in a barrel of oil. 1.26 trillion barrels remain in the global reserves. Current remaining US reserves range about 22 billion barrels. The US consumes 7 billion barrels of oil a year, to supply 37% of its energy needs.. Each year about as much is discovered as is used, but we use slightly more than we find, so reserve levels have been gradually dropping. Without imports (see above), our reserve supply would drop far more quickly. We import about half our oil from Canada, Saudi Arabia, Mexico, Venezuela, Iraq, and over 80 other countries The US consumes over 20% of the oil used worldwide
What are some of the environmental conditions needed to create fossil fuels? Under what temperatures do fossils fuels ideally form?
To create a large deposit of fossil fuel, two requirements need to be met: 1. A large supply of organic matter (this material will be rich in carbon and hydrogen). 2. Rapid burial, to protect it from being broken down by oxygen in the atmosphere.
What does peak oil production refer to? Do we run out of oil at that point? What is expected to happen to the price of oil after this occurs? Globally, around what year is peak production predicted to occur? When did it occur in the US? Who is M. King Hubbert?
US oil production peaked in 1970, at 9.64 million barrels/day, and has declined since (5.5 million barrels/day in 2010). The peak of US oil production was accurately predicted by US geologist M. King Hubbert back in the 1950s: Hubbert developed equations sometimes referred to as "Hubbert Curves" (or peak oil curves) that showed how production of a resource changed over time (see Fig. 14.7, p. 313).
in what type of geological environments does oil get trapped? Which of these reflects the vast oil reserves found in Saudi Arabia?
the impermeable layer is called cap rock. The Saudi Arabian oil fields are an example of such a deposit.