Hydrogen and carbon isotopes of C/sub 1/ to C/sub 5/ alkanes in natural gases
Conference
·
· Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5846028
A technique has been developed to determine C/sup 12//C/sup 13/ and D/H isotopic ratios on small quantities of methane through pentane hydrocarbons and has been applied to natural gases from various genetic sources (i.e., early-diagenetic, oil-associated, late-catagenic and mixed-gas sources). Carbon isotopes measured from 27 natural gases have delta/sup 13/C range of 23, 15, and 20 per thousand for the C/sub 1/ to C/sub 3/ alkanes and maximum delta/sup 13/C values of -35.1, -26.8, and -20.8 per thousand respectively. With a smaller sample base, butane and pentane vary within 16 and 4 per thousand, respectively, for those samples with the most positive delta/sup 13/C = -26.5 and -26.9 per thousand. Deuterium isotopes exhibit greater isotopic variation than the corresponding carbon values. D/H variations clearly decrease toward the higher homologues with deltaD ranges of 182, 110, 75, 43 and 29 per thousand for C/sub 1/ through C/sub 5/. Most negative D/H measurements also decrease with carbon number from deltaD = -311 per thousand for methane to -128 per thousand for pentane. These relative changes in carbon and hydrogen isotopic contents for the higher homologues are useful in the classification of natural gases, particularly those of mixed origin.
- Research Organization:
- Bundesanstalt fuer Geowissenschafrten und Rohstoffe, Hannover, West Germany
- OSTI ID:
- 5846028
- Report Number(s):
- CONF-850322-
- Conference Information:
- Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 69:2
- Country of Publication:
- United States
- Language:
- English
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