PEAK OIL

#4 What is the Difference between Conventional and Unconventional Oil
and how Is it Recovered?
- Conventional oil is oil that is generally easy to recover, in contrast to oil sands, oil
shale, heavy oil, deep-water oil, polar oil and gas condensate. Conventional oil
reserves are extracted using their inherent pressure, pumps, flooding or injection
of water or gas. Approximately 95% of all oil production comes from conventional
oil reserves.
- Unconventional oil is oil that is technically more difficult to extract and more
expensive to recover. The term unconventional refers not only to the geological
formation and characteristics of the deposits but also to the technical realisation of
ecologically acceptable and economical usage.
Oil shale is a sedimentary rock that is saturated with oils and bitumen and has
not transformed into crude oil. The liquefaction process encompasses mining,
crushing and heating the shale. Its net energy yield is rated as low and its ecobalance
as poor.
Oil sands (tar sands) are sandstone containing some viscous heavy and extraheavy
oils that are recovered by surface-mining and liquefied through heating
and separation. The recovery process is very elaborate but more efficient than
that of oil shale.
Heavy crude oil is oil containing less than 17.5º API (API gravity) but more
than 10º API (extra-heavy crude oil). Its production rate is limited by technical
factors rather than by the quantity available of the resource.
Deep-water oil refers to underwater oil reserves from a water depth of 500 m.
Its recovery is technically very complex and expensive.
Polar oil refers to the oil reserves along the polar circle. It is extracted mainly
in Alaska and Siberia and also requires complicated techniques.
Coal-to-liquid or gas-to-liquid products are liquid hydrocarbons that are
synthesised from the conversion of coal or natural gas.
104