If there is oil somewhere, does it mean there's coal, too?

Question

If you drilled and found oil somewhere, would there be a good chance that there will also be coal, too.

Answer 1

You're very likely to find coals in areas that are prone to oil and gas...  But not always.  You'll typically find coal where the source rock is for the oil and gas.  If the oil/gas has migrated (as is the case most of the time) from the source rock to the trap, then you may not find any coal.

Answer 2

NOT NECESSARILY BUT THEY ARE OFTEN FOUND IN COMBINATION.

Answer 3

Absolutly not. Believe my experience of exploration geologist.

Coal and oil have two different origins.

Coal is continental, it is made by remains of plants falling inside shallow swampy area. They are buried and usually 'cooked' in the ground for 10s of millions years. Coal is associated to gas very rich in methan. Coal is actually a kind of source rock very rich in kerogen which is a cooked organic matter. There are 4 main types of kerogen :

Type I : Alginite coming from algae mainly

Type II : different type all coming from plants remains : exinite (the pollen of plants), cutinite (the waxy cover of some plants leaves, grains etc...), resinite (the resin of plant) and lipinite (the oil of some plants)

Type III : coming from the cellulose of mainly trees. This one will give coal.

Type IV : decomposed organic matter very rich in aromatic hydrocarbons.

Oil is coming from marine life, mainly planctonic tiny animals and algae. The dead animals fell in the sea bottom, usually a sea which is quite deep and without oxygen in the bottom and they are also very quickly buried inside usually shaly sediments. If there was oxygen, the remains will decay and give carbon dioxyde. This mixture of shales and organic matter is going to give what it is called a source rock rich in kerogen of type I and II. Under proper temperature and pressure condition, the source rock is cooked and will kind of distillate the oil and the gas to near by more porous rocks like sandstone or some limestone. The gas associated with oil is usually more 'wet' i.e. less rich in methan but more in ethan, propane and butane. This is inside the porous rocks that petroleum is found and exploited.

In summary, the origin of coal and petroleum is different. They are both coming from living things but not at all the same. Coal is usually older than oil, for example, in Europe, coal is from carboniferous period while most oil deposits are usually much younger. Finally the formation of coal and oil is not following the same path. The only common thing between the two is the presence of methan.