Constraining the genetic relationships of 25-norhopanes, hopanoic and 25-norhopanoic acids in onshore Niger Delta oils using a temperature-dependent material balance

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Abstract

Analysis of oil samples from the Niger Delta (Nigeria) revealed a range of structurally related hopanes, including 25-norhopanes, and hopanoic and 25-norhopanoic acids. 25-Norhopanes were detected in all medium and heavily biodegraded oils and were most abundant in the heavily degraded oils. Hopanoic acids (C30-C33) and 25-norhopanoic acids (C30-C31) were most abundant in moderately degraded oils and occurred in reduced concentration in heavily degraded oils but were absent from, or in trace concentration in, slightly degraded oils. Consideration of the structures suggests that 25-norhopanoic acids form via carboxylation of 25-norhopanes or demethylation of hopanoic acids. Mass balance for the onshore Niger Delta oils suggests that formation of 25-norhopanes operates independently of 25-norhopanoic acid formation and that 25-norhopanoic acids are likely transient intermediates for only a small proportion of the 25-norhopanes.
Original languageEnglish
Pages (from-to)31-43
Number of pages13
JournalOrganic Geochemistry
Volume79
Early online date13 Dec 2014
DOIs
Publication statusPublished - Feb 2015

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Oils
Acids
oil
acid
temperature
Temperature
Carboxylation
material
mass balance

Keywords

  • biodegradation
  • crude oil
  • hopanes
  • 25-Norhopanes
  • hopanoic acids
  • 25-norhopanoic acids
  • mass balance
  • Niger Delta

Cite this

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title = "Constraining the genetic relationships of 25-norhopanes, hopanoic and 25-norhopanoic acids in onshore Niger Delta oils using a temperature-dependent material balance",
abstract = "Analysis of oil samples from the Niger Delta (Nigeria) revealed a range of structurally related hopanes, including 25-norhopanes, and hopanoic and 25-norhopanoic acids. 25-Norhopanes were detected in all medium and heavily biodegraded oils and were most abundant in the heavily degraded oils. Hopanoic acids (C30-C33) and 25-norhopanoic acids (C30-C31) were most abundant in moderately degraded oils and occurred in reduced concentration in heavily degraded oils but were absent from, or in trace concentration in, slightly degraded oils. Consideration of the structures suggests that 25-norhopanoic acids form via carboxylation of 25-norhopanes or demethylation of hopanoic acids. Mass balance for the onshore Niger Delta oils suggests that formation of 25-norhopanes operates independently of 25-norhopanoic acid formation and that 25-norhopanoic acids are likely transient intermediates for only a small proportion of the 25-norhopanes.",
keywords = "biodegradation, crude oil, hopanes, 25-Norhopanes, hopanoic acids, 25-norhopanoic acids, mass balance, Niger Delta",
author = "Lamorde, {Umar A.} and John Parnell and Bowden, {Stephen A.}",
note = "Acknowledgements U.L. acknowledges the Department of Petroleum Resources of Nigeria for permission to release crude oil samples and the management of Shell Nigeria for provision of samples. The Petroleum Technology Development Fund (PTDF) provided the funds for this research through the award of scholarship to U.L. Sadat Kolonic (SPDC, Nigeria) provided the corrected BHT. The manuscript and work greatly benefitted from the critical and insightful reviews provided by K. Peters and an anonymous reviewer.",
year = "2015",
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doi = "10.1016/j.orggeochem.2014.12.004",
language = "English",
volume = "79",
pages = "31--43",
journal = "Organic Geochemistry",
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TY - JOUR

T1 - Constraining the genetic relationships of 25-norhopanes, hopanoic and 25-norhopanoic acids in onshore Niger Delta oils using a temperature-dependent material balance

AU - Lamorde, Umar A.

AU - Parnell, John

AU - Bowden, Stephen A.

N1 - Acknowledgements U.L. acknowledges the Department of Petroleum Resources of Nigeria for permission to release crude oil samples and the management of Shell Nigeria for provision of samples. The Petroleum Technology Development Fund (PTDF) provided the funds for this research through the award of scholarship to U.L. Sadat Kolonic (SPDC, Nigeria) provided the corrected BHT. The manuscript and work greatly benefitted from the critical and insightful reviews provided by K. Peters and an anonymous reviewer.

PY - 2015/2

Y1 - 2015/2

N2 - Analysis of oil samples from the Niger Delta (Nigeria) revealed a range of structurally related hopanes, including 25-norhopanes, and hopanoic and 25-norhopanoic acids. 25-Norhopanes were detected in all medium and heavily biodegraded oils and were most abundant in the heavily degraded oils. Hopanoic acids (C30-C33) and 25-norhopanoic acids (C30-C31) were most abundant in moderately degraded oils and occurred in reduced concentration in heavily degraded oils but were absent from, or in trace concentration in, slightly degraded oils. Consideration of the structures suggests that 25-norhopanoic acids form via carboxylation of 25-norhopanes or demethylation of hopanoic acids. Mass balance for the onshore Niger Delta oils suggests that formation of 25-norhopanes operates independently of 25-norhopanoic acid formation and that 25-norhopanoic acids are likely transient intermediates for only a small proportion of the 25-norhopanes.

AB - Analysis of oil samples from the Niger Delta (Nigeria) revealed a range of structurally related hopanes, including 25-norhopanes, and hopanoic and 25-norhopanoic acids. 25-Norhopanes were detected in all medium and heavily biodegraded oils and were most abundant in the heavily degraded oils. Hopanoic acids (C30-C33) and 25-norhopanoic acids (C30-C31) were most abundant in moderately degraded oils and occurred in reduced concentration in heavily degraded oils but were absent from, or in trace concentration in, slightly degraded oils. Consideration of the structures suggests that 25-norhopanoic acids form via carboxylation of 25-norhopanes or demethylation of hopanoic acids. Mass balance for the onshore Niger Delta oils suggests that formation of 25-norhopanes operates independently of 25-norhopanoic acid formation and that 25-norhopanoic acids are likely transient intermediates for only a small proportion of the 25-norhopanes.

KW - biodegradation

KW - crude oil

KW - hopanes

KW - 25-Norhopanes

KW - hopanoic acids

KW - 25-norhopanoic acids

KW - mass balance

KW - Niger Delta

U2 - 10.1016/j.orggeochem.2014.12.004

DO - 10.1016/j.orggeochem.2014.12.004

M3 - Article

VL - 79

SP - 31

EP - 43

JO - Organic Geochemistry

JF - Organic Geochemistry

SN - 0146-6380

ER -