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2dev>Jmdonev at 17:30, 17 December 2018

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[[File:Anticline Reservoir.jpg|400px|thumb|right|Figure 1. An anticline oil and gas reservoir. The source rock would be the bottom-most layer or set off to either side.<ref>Source unknown. Please contact us if you know this image's source.</ref>]]
<onlyinclude>Source rocks are [[rock]]s that contain sufficient organic material to create [[hydrocarbon]]s when subjected to [[heat]] and [[pressure]] over time.</onlyinclude><ref name= Hyne>Hyne, N., 2012. "Nontechnical Guide to Petroleum Geology, Exploration, Drilling, and Production", Tulsa: PennWell Corporation.</ref> Source rocks are usually shales or limestones (sedimentary rocks). To be a productive source rock, the rock needs time to mature (time to form the oil and/or gas) and the hydrocarbons need to be able to migrate to a [[reservoir]] or seep. Source rocks are usually a separate layer from the reservoir rock layers but occasionally they can be both source and reservoir. Source rocks are often offset from the reservoir, meaning that they are not directly below the reservoir but off to the side.<ref name= Hyne/>

As the source rock becomes more deeply buried under layers of [[sediment]], the [[temperature]] begins to increase triggering geochemical reactions that convert the organic materials into hydrocarbons. [[Crude oil]] forms from 65 to 150 degrees Celsius. If the temperature goes over 150 degrees Celsius, [[natural gas]] can be formed (see Figure 2). This usually occurs at greater depths than oil formation. Marine rocks tend to form oil while terrestrial, or land, rocks tend to form gas.<ref name= Hyne/>

[[File:Migration-of-oil-and-gas.png|820px|thumb|centre|Figure 2. Diagram showing the windows for oil and gas formation at different depths/temperatures.<ref name= Open>Steven Earle, 2012. "20.3 Fossil Fuels", Accessed Dec.8, 2018. [Online] Available from:https://opentextbc.ca/geology/chapter/20-3-fossil-fuels/</ref> Note that natural gas forms deeper than oil because the source rock will be at a higher temperature and pressure. After formation, these can move quite some distance before being trapped.]]

Once the hydrocarbons have formed, they migrate from the source rock. They are then either trapped in a reservoir or are "lost" during migration. "Lost" hydrocarbons escape from the Earth through seeping (essentially they leak out of the ground) or disperse throughout the Earth's surface instead of collecting in one spot. It is estimated that only 10% of the oil and gas that has formed has been trapped. Oil and gas reservoirs typically form in traps. There are a few types of traps: anticlinal, fault, stratigraphic, and reef and/or salt traps. While the exact mechanics of each trap type differs, they all trap oil and gas in a reservoir by having an impermeable [[cap rock]] layer and by sealing the bottom of the reservoir with water (oil and gas are less dense than water) or another impermeable rock layer.<ref name= Hyne/>

==For Further Reading==
*[[Cap rock]]
*[[Oil and gas reservoir]]
*[[Hydrocarbon]]
*[[Sedimentary rock]]
*[[Temperature]]
*Or explore a [[Special:Random|random page]]

==References==
{{reflist}}
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Source rock - Revision history

Jmdonev: 1 revision imported

2dev>Jmdonev at 17:30, 17 December 2018