How are origins of coal, crude oil, and natural gas similar? how are they different?

Question

How are origins of coal, crude oil, and natural gas similar? how are they different?

Answer 1

They all have a similar origin in that they all mostly come from the long term, high pressure decomposition of plant and animal matter that has taken place from a few hundred million years ago until today.  The dead organic matter piled up over the years and was eventually buried by sediments, then compressed and heated.  It gradually decomposed into hydrocarbon solids, liquids and gases.

I think differences in the amount of heat and pressure and length of time is what gives the different products.

Also, the oil and gas have to form in rock layers that do not allow them to leak out.  The coal does not need this type of rock formation.

Answer 2

they are derived from organic material buried long ago and "cooked" by the increased temperature and pressure of being buried.

they differ in the amount of cooking that has taken place and the type of organic material which formed them.  For example, coal has not cooked as long and so you can still often see the plant remains which make up coal.  Oil is from organics which have been cooked longer and gas has been cooked even longer so that the oil has been naturally "cracked' into other components.