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https://www.ias.ac.in/article/fulltext/boms/036/02/0311-0317

Maturity; methylnaphthalenes; methylphenanthrenes; asphaltenes; pyrolysate; kerogen.

Asphaltenes separated from two different crude oils from upper Assam, India, having different geological origins, viz. DK(eocene) and JN (oligocene–miocene) were pyrolysed at 600 °C and the products were analysed by gas chromatography–mass spectrometry (GC/MS) especially for the generated alkylnaphthalenes and alkylphenanthrenes. Both the asphaltenes produce aliphatic as well as aromatic compound classes. Alkylnaphthalenes and alkylphenanthrenes were identified by using reference chromatograms and literature data and the distributions used to assess thermalmaturity of the asphaltenes. The ratios of 𝛽-substituted to 𝛼-substituted isomers of both alkylnaphthalenes and alkylphenanthrenes revealed higher maturity of the JN asphaltenes than the DK asphaltenes. For both the asphaltenes, the abundance of 1-methylphenanthrene dominates over that of 9-methylphenanthrene showing the terrestrial nature of the organic matter.

Manoj Kumar Sarmah¹ Arun Borthakur² Aradhana Dutta³

1. Oil India Limited, P.O. Duliajan, Dist. Dibrugarh 786 602, India
2. North East Institute of Science and Technology, P.O. Jorhat 786 001, India
3. Dibrugarh University, P.O. Dibrugarh 786 002, India

Published

April 2013

Manuscript received

10 February 2009

Manuscript revised

7 September 2012