Abstract
Bulk sedimentary nitrogen isotope profiles are often used as proxies for depositional redox conditions, nitrogen cycling, and nutrient uptake in modern and ancient marine systems. The general preference in terms of analysis is that the sediments measured have undergone minimal thermal alteration, as post-depositional processes might have altered the initial δ15N signal, thus complicating the interpretation of these records. Although not a traditional proxy for petroleum evaluation purposes, recently the use of nitrogen isotopes in petroleum systems has been investigated as potential proxies to reconstruct paleoenvironmental conditions such as redox, and for organic matter evaluation. In this paper we review the use of nitrogen isotope data in petroleum systems, their interpretations, and factors that may complicate their use as proxies. We review the evidence for nitrogen isotopic fractionation during diagenesis, catagenesis, and fluid migration as determined by lab experiments, and how these might impact interpretation of δ15N data in petroleum systems. We also analyze the use and interpretation of δ15N data from petroleum-producing reservoir units, including unconventional reservoirs and lacustrine basins. Lastly, we discuss potential applications for nitrogen isotopes in petroleum systems with regards to their use as both geochemical proxies and as tools to evaluate petroleum reservoirs.
Highlights
Nitrogen isotopes are being used in an increasing number of recent sedimentary system studies as paleoenvironmental proxies
Nitrogen isotope (δ15N) measurements of sediments have been shown to record processes occurring in the water column, allowing them to serve as proxies for paleoredox conditions and nitrogen cycling (Altabet and Francois, 1994)
The details have been discussed in several papers (e.g., Delwiche and Steyn, 1970; Wada et al, 1980; Altabet and Francois, 1994; Talbot, 2001; Robinson et al, 2012), but in brief, the sedimentary δ15N values reflect the δ15N of sinking organic matter, which is in turn influenced by the nitrogen reactions and environmental conditions occurring in the water column
Summary
Nitrogen isotopes are being used in an increasing number of recent sedimentary system studies as paleoenvironmental proxies. The details have been discussed in several papers (e.g., Delwiche and Steyn, 1970; Wada et al, 1980; Altabet and Francois, 1994; Talbot, 2001; Robinson et al, 2012), but in brief, the sedimentary δ15N values reflect the δ15N of sinking organic matter, which is in turn influenced by the nitrogen reactions and environmental conditions occurring in the water column. Suboxic water column conditions, because these conditions favor strongly fractionating denitrification and anammox reactions that result in organic matter enriched in 15N, which is recorded in the sediments as higher δ15N values (Altabet and Francois, 1994; Robinson et al, 2012 and references within). We review the recent research on nitrogen isotopes in petroleum systems, including fractionation due to diagenesis and catagensis, and the influence of kerogen type, and highlight applications of δ15N data as paleoenvironmental proxies in petroleum systems
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
