Carbon Preference Index

The Carbon Preference Index (CPI) ( English to German carbon preference index ) is a quantity that the maturity of that help oil is characterized. The ratios of even-numbered to odd-numbered n- alkanes are expressed in a numerical value using the following formula:

${\displaystyle CPI_{25-33}=0{,}5\cdot \left({\frac {(C_{25}+C_{27}+C_{29}+C_{31}+C_{33})}{(C_{24}+C_{26}+C_{28}+C_{30}+C_{32})}}+{\frac {(C_{25}+C_{27}+C_{29}+C_{31}+C_{33})}{(C_{26}+C_{28}+C_{30}+C_{32}+C_{34})}}\right)}$

It is z. B. an alkane with 25 carbon atoms. ${\displaystyle C_{25}}$

The values ​​for immature kerogen will be > 1 (> 3), since biologically odd-numbered n-alkanes are preferred. In the course of diagenesis and catagenesis , even n-alkanes are produced through conversion processes, so that the value approaches 1 with increasing maturity.

Web links

• Methods (PDF file)
• Speciation of Organics (PDF file; 1.44 MB)