Crude Oil

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  • Crude Oil
    • Formation
      • Dead marine organisms buried and gradually became increasingly pure carbon as other materials were squeezed out.
        • The hydrocarbons that form crude oil were gradually broken down into smaller molecules so solids became liquids with lower and lower viscosity, with gases like methane being formed.
      • Older deposits are generally more useful. older crude oil is less viscous, flows more easily and a greater proportion can be extracted
    • Features that make exploitation difficult
      • Young oils are too viscous to flow
      • The processes are very slow
      • Deep burial makes extraction even more difficult
      • Many deposits are very thin and widely dispersed
    • Extraction
      • Crude oil is found in geological structures where the liquid can flow through permeable rock and collect in the pores between the particles of a porous rock
      • The natural pressure of gas above oil or water beneath oil will force the oil to the surface when a pipe is drilled down to the oil reservoir
      • The recovery rate of oil may be very low, especially if it is young or relatively cool or if the natural pressure is low.
    • Uses
      • Liquid fuels; petrol, diesel, aircraft fuel
      • Gas fuels for heating; propane, butane
      • Making plastics
    • Available resources
      • A lot of oil is inaccessible because it is too deep, found in small amounts or is in inaccessible places
      • Oil shales are solid hydrocarbons that cannot flow to the surface like crude oil.
        • To extract them they must be quarried or heated underground so they will melt and flow to the surface.
        • The amount that could be exploited is much greater than our total reserves of crude oil, but is more expensive to extract.
    • Level of technological development
      • Primary recovery involves the use of natural pressure to force oil to the surface and has a 20% recovery rate
        • Secondary recovery involves pumping down natural gas or water to maintain pressure and has a 40% recovery rate
          • Tertiary recovery involves the use of solvents, steam or detergents to make the oil less viscous and increases the recovery rate to 60%.
    • Environmental Impacts
      • Oil extraction and transportation causes oil pollution.
        • Oil-based drilling mud used to lubricate the drill pipes can cause pollution in groundwater, rivers and the sea.
      • Burning fossil fuels causes acid rain, global climate change, carbon monoxide, photochemical smogs, smoke and ash.
        • Surplus gas on oil rigs may be burnt to reduce the risk of explosions. This causes atmospheric pollution.
      • The construction of oil and gas pipelines can cause habitat damage over a large total area, although careful soil replacement and replanting can reduce this.
    • Economic Issues
      • Fossil fuel use causes economic costs that are not paid by the energy industry. Costs such as pollution damage are paid for by other sectors of society.
    • Political and Trade Problems
      • Crude oil provides most of the worlds energy but the reserves are not evenly distributed. The MEDCs use over half the worlds oil production but only a small proportion is home-produced


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