In
petroleum geology
Petroleum geology is the study of origin, occurrence, movement, accumulation, and exploration of hydrocarbon fuels. It refers to the specific set of geological disciplines that are applied to the search for hydrocarbons (oil exploration).
Sedime ...
, the maturity of a
rock is a measure of its state in terms of
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
generation. Maturity is established using a combination of
geochemical
Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the ...
and
basin modelling techniques.
Rocks with high
total organic carbon
Total organic carbon (TOC) is the amount of carbon found in an organic compound and is often used as a non-specific indicator of water quality or cleanliness of pharmaceutical manufacturing equipment. TOC may also refer to the amount of organic c ...
, (termed
source rocks), will alter under increasing
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied on ...
such that the organic
molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bio ...
s slowly mature into
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
s (see
diagenesis
Diagenesis () is the process that describes physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play ...
). Source rocks are therefore broadly categorised as ''immature'' (no hydrocarbon generation), ''sub-mature'' (limited hydrocarbon generation), ''mature'' (extensive hydrocarbon generation) and ''overmature'' (most hydrocarbons have been generated).
The maturity of a source rock can also be used as an indicator of its hydrocarbon ''potential''. That is, if a rock is sub-mature, then it has a much higher potential to generate further hydrocarbons than one that is overmature.
See also
*
Van Krevelen diagram
References
* van Krevelen, D.W. (1950). "Graphical-statistical method for the study of structure and reaction processes of coal", ''Fuel'', 29, 269–84.
* van Krevelen, D.W. and Schuyer, J. (1957) ''Coal science''. Elsevier publishing company.
The chemistry and technology of petroleum
Publications
Maturity (Maturation) Publications
Geochemistry
Petroleum geology
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