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Isotope heterogeneity in ethyltoluenes from Australian condensates, and their stable carbon site-specific isotope analysis

Cesar, Jaime and Eiler, John and Dallas, Brooke and Chimiak, Laura and Grice, Kliti (2019) Isotope heterogeneity in ethyltoluenes from Australian condensates, and their stable carbon site-specific isotope analysis. Organic Geochemistry, 135 . pp. 32-37. ISSN 0146-6380. doi:10.1016/j.orggeochem.2019.06.002. https://resolver.caltech.edu/CaltechAUTHORS:20190613-135632195

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Abstract

Low-molecular-weight (LMW) aromatic compounds from petroleum fluids have not been widely studied for fluid-source correlations due to their volatility and their relatively low abundances in source rocks. However, LMW aromatics are important components in fluids, including condensates which lack biomarkers (molecular fossils typically used for correlation studies). Here, we have investigated the distribution of ethyltoluenes (o-ET, m-ET and p-ET; ortho, meta and para, respectively) in fluvial-deltaic condensates which contain relatively high abundances of the meta- isomer. The meta-selectivity found in these petroleum fluids is consistent with a mineral catalytic effect on the molecular distribution of these compounds, as it occurs during the clay-catalyzed synthesis of ethyltoluenes. Isomers differ up to 6‰ in δ^(13)C values. Condensates from the Northern Carnarvon Basin, North West Shelf of Australia (NWS), have been analyzed by compound specific isotope analysis (CSIA) by GC-ir-MS, and site-specific isotope analysis (SSIA) using a Q-Exactive-GC Orbitrap^(TM)-based mass spectrometer. The SSIA revealed a ^(13)C enrichment at the methyl end of the ethyl branch of m-ET, following a normal kinetic isotope effect during thermal maturation (cleavage). Continuous development of this first SSIA application will make possible high resolution analysis of light aromatics to outline the evolution of the organic matter to hydrocarbons in petroleum systems.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.orggeochem.2019.06.002DOIArticle
ORCID:
AuthorORCID
Dallas, Brooke0000-0002-1313-3270
Additional Information:© 2019 Published by Elsevier. Received 25 March 2019, Revised 31 May 2019, Accepted 10 June 2019, Available online 13 June 2019.
Subject Keywords:petroleum; ethyltoluene; isomer; site-specific; carbon isotopes; mass spectrometry
DOI:10.1016/j.orggeochem.2019.06.002
Record Number:CaltechAUTHORS:20190613-135632195
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190613-135632195
Official Citation:Jaime Cesar, John Eiler, Brooke Dallas, Laura Chimiak, Kliti Grice, Isotope heterogeneity in ethyltoluenes from Australian condensates, and their stable carbon site-specific isotope analysis, Organic Geochemistry, Volume 135, 2019, Pages 32-37, ISSN 0146-6380, https://doi.org/10.1016/j.orggeochem.2019.06.002. (http://www.sciencedirect.com/science/article/pii/S0146638019301032)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96392
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:17 Jun 2019 15:09
Last Modified:16 Nov 2021 17:20

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