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CARBON PREFERENTIAL INDEX [1 record]

Record 1 2000-12-18

English

Subject field(s)
  • Chemical Elements and Compounds
DEF

The ratio of the amounts of odd-carbon n-alkanes to those of even-carbon n-alkanes.

CONT

Carbon Preference Index (CPI). Generally the ratio of abundance of odd over even carbon number paraffins, specifically calculated over the C24-C34 range. Hydrocarbons derived predominantly from terrestrial sources and/or at low maturity exhibit a predominance of odd-numbered alkanes (resulting in a high CPI); this feature disappears with increasing maturation level (CPI approaches 1.0).

CONT

... case studies show that in ancient detrital sediment the predominance of the original odd n-alkanes of high molecular weight is preserved mainly in relatively shallow shales and silts, where degradation of kerogen has not yet started ... With increasing maturity, and odd-even preference (also known as CPI: carbon preference index) of about 5:1 in shallow detrital material is reduced to around unity in the zone of oil formation, as a result of thermal degradation and the introduction of new alkanes, which dilutes the original odd-even predominance.

French

Domaine(s)
  • Éléments et composés chimiques
DEF

Quotient des alcanes en chaîne droite ayant un nombre impair d'atomes de carbone et des alcanes en chaîne droite ayant un nombre pair d'atomes de carbone.

Spanish

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