What is crude oil (oil pumped from the ground) made of?

I am talking about oil that you pump out of the ground. How was it formed. A basic answer is fine.

3 Responses to “What is crude oil (oil pumped from the ground) made of?”

  1. Elton J Says:

    Contrary to popular culture oils doesn’t come from dead animals and certainly not dinosaurs. It comes from algae. It starts out as kerogen–a waxy hydrocarbon sugar in plant walls. As the algae died, the water insoluble kerogen accumulated on lagoon floors as the algae died and was buried in the normal course of sedimentation.

    Over vast times the pressure from the overlying sediment on the rich organic layers raised the temperature and pressure in the rock strata to a level where "polymerization" of the hydrocarbon chains could take place. This process is essentially is the combining of some of the smaller chains– like methane into heavier chains, linking them together into medium, long, and extra long chains.

    These flow together and seep through pores in the rock they originated in until they reach a cap rock which is too impermeable for the oil and gas to escape. The combined liquids are called crude petroleum.

    When petroleum is refined by "cracking" the very, very, long, tar-like chains are broken into shorter chains by heating and the shorter lengths are drawn off at different temperatures to yield gasoline, diesel, kerosene etc. Generally about 36 gallons of gasoline can be made from every 55 gallons of standardized crude.

  2. Gorkbark Porkduke Gefunken Fubar Says:

    It is the remains of vegetation that died and built up over millions of years and which is heated over millions of years to form complex hydrocarbons. Decaying plants normally give off heat, so when you trap this biomass and expose it to heat for a very long period of time it breaks down into a flammable ooze.

    Refining is the process of heating this ooze (the crude oil) so it evaporates at various rates. This vapor is condensed at different points in the process to yield heating oil, diesel fuel, kerosene, and gasoline, among others.

  3. KTDykes Says:

    It’s generally formed from squidged up oceanic organisms rather than plants; mostly tiny little things that got their juices crushed out of them until they contributed to a goo.