New technologies for fossil fuel extraction

coal liquefaction

conversion of coal to liquid hydrocarbons using solvents which can then be used as vehicle fuels; allows exploitation of previously inaccessible coal deposits but solvent chemicals may cause ground and water pollution

coal gasification

inaccessible coal deposits can be burnt underground to produce fuel gases like hydrogen and methane; can produce harmful pollutant and greenhouses gases

primary oil recovery

using the natural pressure of water below the oil to force it upwards, causes limited surface habitat destruction, limited pumping equipment needed however only 20% of available oil is extracted

secondary oil recovery

pumping of water/natural gas to maintain pressure to increase oil recovery; increases oil recovery up to 40% and reduces the need for new we;;s to be drilled but can manage local water supplies

tertiary oil recovery or Enhanced Oil Recovery (EOR)

these are techniques used to reduce viscosity e.g:

• steam can be used to heat the oil

• controlled combustion

• detergents and solvents used to decrease surface tension

• bacteria can be used to partially digest heavy oils into lighter ones, producing carbon dioxide to maintain pressure

increases oil recovery to more than 60% but can harm ecosystems due to chemical and gas leaks

directional drilling

allows the drilling of wells that aren’t vertical and therefore allows many wells to be drilled from one platform; can be used to target smaller reservoirs and prevent surface habitat damage, can be expensive and sand influx is unreliable and high effort

subsea production wells

wells located in the sea bed with no surface production platform, allows operations up to 2000m deep but any issues can cause huge habitat damage

ROV and AOVs

used to survey the seabed, inspect equipment; enables maintenance of deepwater equipment but cannot fix all problems identified

fracking

water, sands and solvents are pumped into cracks in rocks to fracture them and release oil; increases oil recovery rate but is incredibly water intensive and causes toxic metals to be released into water sources

tar sands

heavy oil and sands are separated using hot water and steam injection to produce lighter oils; increases oil recovery rate to 75% and waste sand backfilled into mines, creating waste heaps

oil shales

can be extracted and heated to drain off fluid hydrocarbons; there are high potential reservoirs but is expensive and requires high energy inputs

enhanced gas recovery

injection of carbon dioxide and nitrogen gas around the edge of the gas field to maintain pressure; has a high recovery rate but natural gas may enter aquifers and polluting water

methane hydrate

ice-like solids found in polar regions and sea beds and can be extracted by the heating of water, depressurisation and carbon dioxide injection; increasing energy density but may have unknown ecological impacts on ocean floor biodiversity