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Title: Molecular nitrogen in natural gas accumulations: Generation from sedimentary organic matter at high temperatures

Abstract

The occurrence of natural gas accumulations with high percentages (up to 100%) of molecular nitrogen in various hydrocarbon provinces represents a largely unresolved problem and a serious exploration risk. In this context, a geochemical and basin modeling study was performed to evaluate the potential of sedimentary organic matter to generate molecular nitrogen. The masses of nitrogen present in coals - if converted into molecular nitrogen - are sufficient to fill commercial gas reservoirs. A calculation for gas accumulations in northern Germany, where percentages of molecular nitrogen range from less than 5 to greater than 90%, reveals that the molecular nitrogen generated in underlying coal-bearing strata is sufficient to account for the nitrogen gas even in the largest fields. In addition, much of the total nitrogen in clay-rich rock types, such as shales and mudstones, is fixed in sedimentary organic matter and may add to the nitrogen generation capacity of the coals.

Authors:
; ;  [1];  [2]
  1. Institut fuer Erdoel und Organische Geochemie, Juelich (Germany)
  2. BEB Erdgas und Erdoel GmbH, Hannover (Germany)
Publication Date:
OSTI Identifier:
35518
Resource Type:
Journal Article
Resource Relation:
Journal Name: AAPG Bulletin; Journal Volume: 79; Journal Issue: 3; Other Information: PBD: Mar 1995
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 01 COAL, LIGNITE, AND PEAT; 58 GEOSCIENCES; NATURAL GAS FIELDS; HAZARDS; NATURAL GAS DEPOSITS; GEOCHEMISTRY; ORIGIN; NITROGEN; ECOLOGICAL CONCENTRATION; COAL DEPOSITS; CARBONIFEROUS PERIOD; FEDERAL REPUBLIC OF GERMANY; RESERVOIR ROCK

Citation Formats

Littke, R., Krooss, B., Frielingsdorf, J., and Idiz, E. Molecular nitrogen in natural gas accumulations: Generation from sedimentary organic matter at high temperatures. United States: N. p., 1995. Web.
Littke, R., Krooss, B., Frielingsdorf, J., & Idiz, E. Molecular nitrogen in natural gas accumulations: Generation from sedimentary organic matter at high temperatures. United States.
Littke, R., Krooss, B., Frielingsdorf, J., and Idiz, E. Wed . "Molecular nitrogen in natural gas accumulations: Generation from sedimentary organic matter at high temperatures". United States. doi:.
@article{osti_35518,
title = {Molecular nitrogen in natural gas accumulations: Generation from sedimentary organic matter at high temperatures},
author = {Littke, R. and Krooss, B. and Frielingsdorf, J. and Idiz, E.},
abstractNote = {The occurrence of natural gas accumulations with high percentages (up to 100%) of molecular nitrogen in various hydrocarbon provinces represents a largely unresolved problem and a serious exploration risk. In this context, a geochemical and basin modeling study was performed to evaluate the potential of sedimentary organic matter to generate molecular nitrogen. The masses of nitrogen present in coals - if converted into molecular nitrogen - are sufficient to fill commercial gas reservoirs. A calculation for gas accumulations in northern Germany, where percentages of molecular nitrogen range from less than 5 to greater than 90%, reveals that the molecular nitrogen generated in underlying coal-bearing strata is sufficient to account for the nitrogen gas even in the largest fields. In addition, much of the total nitrogen in clay-rich rock types, such as shales and mudstones, is fixed in sedimentary organic matter and may add to the nitrogen generation capacity of the coals.},
doi = {},
journal = {AAPG Bulletin},
number = 3,
volume = 79,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 1995},
month = {Wed Mar 01 00:00:00 EST 1995}
}
  • This bibliography and the matching subject and author indexes are intended to serve geologists and others studying organic matter in sedimentary rocks and to aid in the prediction of the presence of petroleum in particular sedimentary strata. The articles, books, theses, maps, and preprints included pertain to (1) petrology and petrography of dispersed solid organic matter and coal, (2) diagenesis and catagenesis of organic matter (including coal) in sediments and regional studies of catagenesis and coalification, (3) the relation of hydrocarbon generation and maturation of oil and gas ''deadlines'' to catagenesis of organic matter, (4) geochemistry of dispersed (especially solid)more » organic matter, and (5) temperatures and paleotemperatures in sedimentary basins.« less
  • This bibliography and the matching subject and author indexes are intended to serve geologists and others doing research on organic matter in sedimentary rocks. In the last decade, there has been a great increase in both physical and chemical studies of solid organic matter in sedimentary rocks, and the results of these studies have been valuable, particularly in petroleum exploration. Analyses of amount and type of solid organic matter and of the state of maturation resulting from increased temperature and other factors acting through geologic time permit prediction of whether or not petroleum or natural gas will likely be foundmore » in particular sedimentary strata. (approx. 700 refs.)« less
  • Average {sup 14}C ages of dissolved organic carbon (DOC) in the ocean are 3--6,000 years, and are influenced by old DOC from continental margins. However, sources of DOC from terrestrial, autochthonous, and sedimentary organic carbon seem to be too young to be responsible for the old DOC observed in the ocean. Since colloidal organic carbon (COC, i.e., high molecular weight DOC), which is chemically very similar to that of bulk DOC, can be effectively isolated from seawater using cross-flow ultrafiltration, it can hold clues to sources and pathways of DOC turnover in the ocean. Radiocarbon measurements on COC in themore » water column and benthic nepheloid layer (BNL) from two continental margin areas (the Middle Atlantic Bight and the Gulf of Mexico) and controlled laboratory experiments were carried out to study sources of old DOC in the ocean margin areas. Vertical distributions of suspended particulate matter (SPM), particulate organic carbon (POC), nitrogen (PON), and DOC in the water column and bottom waters near the sediment-water interface all demonstrate a well developed benthic nepheloid layer in both ocean margin areas. COC from the BNL was much older than COC from the overlying water column. These results, together with strong concentration gradients of SPM, POC, PON, and DOC, suggest a sedimentary source for organic carbon species and possibly for old COC as well in BNL waters. This is confirmed by the results from controlled laboratory experiments. The heterogeneity of {Delta}{sup 14}C signatures in bulk SOC thus points to a preferential release of old organic components from sediment resuspension, which can be the transport mechanism of the old benthic COC observed in ocean margin areas. Old COC from continental margin nepheloid layers may thus be a potential source of old DOC to the deep ocean.« less
  • To supplement the relatively sparse set of calorimetric data available for the multitude of high molecular weight organic compounds of biogeochemical interest, group additivity algorithms have been developed to estimate heat capacity power function coefficients and the standard molal thermodynamic properties at 25 C and 1 bar of high molecular weight compounds in hydrocarbon source rocks and reservoirs, including crystalline and liquid isoprenoids, steroids, tricyclic diterpenoids, hopanoids, and polynuclear aromatic hydrocarbons. A total of ninety-six group contributions for each coefficient and property were generated from the thermodynamic properties of lower molecular weight reference species for which calorimetric data are availablemore » in the literature. These group contributions were then used to compute corresponding coefficients and properties for {approximately}360 representative solid and liquid high molecular weight compounds in kerogen, bitumen, and petroleum for which few or no experimental data are available. The coefficients and properties of these high molecular weight compounds are summarized in tables, together with those of the groups and reference species from which they were generated. The tabulated heat capacity power function coefficients and standard molal thermodynamic properties at 25 C and 1 bar include selected crystalline and liquid regular, irregular and highly branched isoprenoids, tricyclic diterpanes, 17{alpha}(H)- and 17{beta}(H)-hopanes, 5{alpha}(H),14{alpha}(H)-, 5{beta}(H),14{alpha}(H)-, 5{alpha}(H),14{beta}(H)-, and 5{beta}(H),14{beta}(H)-steranes, double ether- and ester-bonded n-alkanes, and various polynuclear aromatic hydrocarbons, including methylated biphenyls, naphthalenes, phenanthrenes, anthracenes, pyrenes, and chrysenes. However, corresponding coefficients and properties for many more saturated and unsaturated high molecular weight hydrocarbons can be estimated from the equations of state group additivity algorithms. Calculations of this kind permit comprehensive thermodynamic description of the chemical evolution of organic matter with increasing depth in sedimentary basins.« less
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