Crude oil is a heterogeneous mixture of hydrocarbons which stays liquid after extraction. Depending on density oil can be light — 650–870 kg/m3, middle — 871–910 kg/m3 and heavy — 920–1050 kg/m3. Crude oil is formed when large quantities of dead organisms are buried underneath sedimentary rock and subjected to both intense heat and pressure up to 70–110°C. Intense heat destroys long carbonic chains and forms low grade hydrocarbons.
Condensate is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields.
Natural gas liquids, combination gas refer to non-methane fraction of natural gas from ethane to pentane.
Extra heavy oil has the density of more than 1000 kg/m3. It is mostly produced in Orinoco (Venezuela). Due to high viscosity its extraction and delivery are very complicated and require dissolvent.
Oil sands are located not far from the rock surface which contains sand, clay, water and bitum –less heavy than extra heavy oil. Bitum is formed as a result of degradation of surface deposits of oil which lost is light fraction due to vaporization, ground waters washing or bacterial decomposition. Bitum is processed into synthetic crude oil for pipeline delivery. The main deposit is located in Albert State, Canada.
Shale oil is an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution. Main locations are Bakken formation (Montana, North Dakota) and Eagle Ford (South Taxes).
Kerogenic oil is formed from kerogen – organic substance in disperse sedimentaries. Kerogen is produced by shaft method. It is detached from the ground; heated and the vaporized substance is formed into oil. There is an idea to heat underground but it did not find commercial application due to high costs. One of such large deposits is located in Israel.
Gas synthetic fuel is methane transformation into high molecular hydrocarbons by using Fischer – Tropsch method. This method provides quality liquid fuel without contaminants as sulphur.
Synthetic fuel from coal is made by pyrolysis of coal.
Biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion. Second generation biofuel should not compete for cultivated areas with food products and can be extracted from weeds and timber. There is also possibility of butanol extraction from timber.