About Oil and Gas DepositsPublished on 01.07.2015
15 min read
© THINKSTOCK - Hydrocarbons formed over millions of years, at the heart of major geological formations.
It takes millions of years for oil or gas to form. During this time, the molecules migrate slowly to the surface and are "trapped" in natural reservoirs.
How Oil and Gas Deposits Are Formed
Deep in the Earth, oil and natural gas are formed from organic matter from dead plants and animals. These hydrocarbons take millions of years to form under very specific pressure and temperature conditions.
How Oil and Gas Migrate
Starting out from the source rock where they are formed, hydrocarbon molecules, which are light, set off on an upward journey to the surface. They accumulate in porous rock and are blocked by impermeable rock, thereby creating oil and gas deposits.
The Slow Formation of Oil and Natural Gas Deposits
It takes millions of years for decaying organic matter to be transformed into hydrocarbons within source rock. As sedimentation occurs, chemical reactions create the carbon and hydrogen molecules that make up liquid or gaseous hydrocarbons. The hydrocarbons then slowly travel upwards until they are trapped by impermeable rock and form a deposit in a reservoir.