Analysis of gases in the earth's crust. Annual report, March 1985-February 1986
In order to investigate the origin and fate of natural gas in the earth's crust, approximately 700 gas samples have been analyzed for chemical composition and stable isotopic ratios of carbon, hydrogen, nitrogen, sulfur and oxygen. During the current reporting period, helium isotope measurements confirmed the presence of mantle volatiles in the Sacramento basin, a dry gas province in northern California (Section 3.1). Methane carbon isotope ratios and N/sub 2/Ar ratios suggest that Sacramento basin commercial gases with up to 88% nitrogen are derived from metasedimentary rocks. Studies of seep gases in Los Angeles indicate that ethane and higher hydrocarbons may be retarded during natural gas migration and that propane is selectively attacked during bacterial alteration. Carbon dioxide reduction and acetate dissimilation, the two main pathways for microbial methane formation, are characterized by different methane hydrogen isotope ratios. Hydrogen isotope ratios of methane and carbon isotope ratios of carbon dioxide and ethane help to distinguish microbial gases, thermogenic gases, and mixed gases (Section 3.2).
- Research Organization:
- Global Geochemistry Corp., Canoga Park, CA (USA)
- OSTI ID:
- 6968165
- Report Number(s):
- PB-87-116257/XAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EARTH CRUST
NATURAL GAS
CHEMICAL ANALYSIS
CALIFORNIA
ENERGY SOURCES
GAS ANALYSIS
GEOCHEMISTRY
HYDROCARBONS
ISOTOPE RATIO
METHANE
RARE GASES
SAMPLING
ALKANES
CHEMISTRY
ELEMENTS
FEDERAL REGION IX
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
NONMETALS
NORTH AMERICA
ORGANIC COMPOUNDS
USA
033000* - Natural Gas- Properties & Composition