Notes from april 25
Notes from april 25 GEO 100
Popular in Physical Geology
Popular in Geology
This 5 page Class Notes was uploaded by samantha Flavell on Saturday April 30, 2016. The Class Notes belongs to GEO 100 at State University of New York at Oswego taught by Rachel Lee (P) in Fall 2015. Since its upload, it has received 17 views. For similar materials see Physical Geology in Geology at State University of New York at Oswego.
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Date Created: 04/30/16
April 25, 2016 Geo 100800 Prof. Nandini Kar Seismic Reflection Profiling *Crosssectional view of crust *Shows bedding, stratigraphy and structure Oil Exploration *Seismic Reflection profiles layers and discontinuities Sound “bounces off” contrasts between layers Allows geologists to look for subsurface structures Seismic surveys are conducted on land and at sea *Diamondcoated rotary bit grinds rock *Rapid circulation of high density drilling mud: Lifts cuttings to the ground surface Reduces the risk of blow outs Cools the drill a bit *When a reservoir is penetrated, the drilling ceases *Steel casing is used to prevent collapse of weaker rocks in to the hole *After the hole is case, the well is tested and pumped *Primary recovery Uses reservoir fluid pressure and pumping to extract oil Can only recover ~30% of the oil *Standard Recovery Uses fluids (steam, CO2) to heat, “thin” and push oil Hydraulic fracturing artificially increases permeability Can only recover an additional ~20% of the oil *Crude oil must be refined Crude oil is distilled into separate mixtures by weight Lighter molecules rise to the top of distillation columns Heavier molecules remain at the bottom Alternative Hydrocarbons *Natural Gas: Shortchain hydrocarbons *methane, ethane, propane, butane and others *form at temperatures just above the oil window *natural Gas is more abundant than oil; it’s a cleaner fuel *Now being drilled from shale oil, using direction drilling and hydraulic fracturing Hydraulic Fracturing (“Fracking”) *Pumps high pressure water and chemicals into drill hole Creates new fractures, opens preexisting fractures Fracking fluid= oil, acids, detergents, antifreeze, biocides Sand pumped into fractures to keep them open Increases recovery of oil *To frack one segment of a hole uses the same volume of water as an Olympic size swimming pool NonFossil Fuel Energy Sources *Among the renewables, US use is as follows: 1) Bioenergy 2) Hydro 3) Wind 4) Geothermal 5) Solar **Nuclear is way ahead, but nonrenewable** Nuclear Power *Nuclear power= energy from breaking apart atoms *Neutrons strike nuclei of fuel molecules to cause fission *Fission produces neutrons to split other nuclei *Fission produces other elements *Fission produces energy (heat) *Most reactors use fuel rods of uranium oxide pellets **When fission reactions take place, radioactive nuclei are split apart, releasing large amounts of energy. One capsulesize uranium pellet can yield the energy equivalent of one ton of coal Nuclear Power in the World *Currently over 440 reactors are proving energy worldwide. In some countries, nuclear is the #1 power source (i.e. France 75%) *As a demonstration of how large the energy demand of the US is, we are the #1 world nuclear product, even though nuclear power is a distant 5 in the total national consumption *Uranium resources, even at accelerated use, will last well beyond 200 yrs., assuming more efficient reactors become widely used. With efficient reactors, we may have enough Uranium to last ~100 yrs. From Nuclear Fission to Electricity *Nuclear Power generation accounts for <0.3% of the average human’s total lifetime exposure to radiation, natural and artificial. Spent Nuclear Fuel *When the fission productivity of nuclear fuel drops below a certain level it is ‘spent’ *The material is very radioactive containing Uranium plus radioactive byproduct elements *Much of the ~<10kton (>80,000,000lb) of spent nuclear fuel (uranium oxide pellets in steel jackets) sit in pools, on site. *The water acts as a radiation buffer, as well as a cooling environment Getting Rid of Nuclear Waste *At present there is no waste storage facility in the US *A repository has been constructed at Yucca Mtn. NV but is currently unlicensed *It could handle 70kton. At present we have about this much waste. Do you see a problem? Geothermal Energy *Energy from Earths internal heat Geothermal gradient: Earth becomes hotter with depth Geothermal gradients vary from 15 degrees C/Km to 50 degrees C/Km High geothermal gradients: hotter at shallower depths *Geothermal may produce was brines *Geothermal produces no CO2 *Geothermal energy can be utilized in a variety of geological environments *Directuse: geothermal systems are used for home heating. Waters of moderate temperature typify both the normal geothermal areas and large scale sedimentary basins. Seasonal heat pumps can be used virtually anywhere *High temperature: geothermal systems exist in tectonically active areas, where bodies of magma are close to the Earth’s surface Hydroelectric Power *Running water represents kinetic energy (ke) *Dams halt the flow of water, converting PE back to Ke, and flows through turbines to create electricity *Tidal Flux used at some dams *Positive Aspects Reduces flood risks Stores water for drinking irrigation, and recreation provides renewable energy Doesn’t create hazardous waste or produce CO2 Negative Aspects Dams and reservoirs alter landscapes and ecosystems The filling of reservoirs often trigger seismicity Reservoirs halt the downstream movement of sediment Downstream delta and beaches are destabilized The reservoir loses capacity and must be dredged
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