Molecular and Isotopic Analyses of the Hydrocarbon Gases within Gas Hydrate-Bearing Rock Units of the Prudhoe Bay-Kuparuk River Area in Northern Alaska

Information about and data from the USGS Open-File Report 92-299 (Molecular
and isotopic analyses of the hydrocarbon gases within gas hydrate-bearing rock
units of the Prudhoe Bay-Kuparuk River area in northern Alaska) are available
On-line via the World Wide Web:

"http://pubs.usgs.gov/of/of92-299//"

or "http://pubs.usgs.gov/of/1992/of92-299/"

The following information about the data set was provided by the data center
contact:

The objective of this study was to document the molecular and isotopic
composition of the gas trapped within the gas hydrate-bearing stratigraphic
intervals overlying the Prudhoe Bay and Kuparuk River oil fields. To reach
this objective, we have analyzed cuttings gas and free gas samples collected
from 10 drilling-production wells in the Prudhoe Bay and Kuparuk River fields.

The dataset includes a report documenting the materials, the procedures used
to analyze them, and the results. Results are given in tabular form as
spreadsheets showing headspace, headspace/free gas, and blended headspace
analyses. Gas characteristics analyzed include nitrogen, carbon dioxide,
methane, ethane, ethene, propane, propene, isobutane, n-butane, isopentane,
n-pentane, stable carbon isotope composition of the methane, ethane, and carbon
dioxide fractions, and deuterium isotope composition of the methane fraction.

Methane is the most abundant hydrocarbon gas within the gas hydrate- bearing
rock units of the Prudhoe Bay-Kuparuk River area in the North Slope of Alaska.
Isotopic analysis indicates that both microbial and thermogenic processes have
contributed to the formation of this methane. The thermogenic component
probably migrated into the rock units from greater depths, since vitrinite
reflectance measurements show that the units never endured temperatures within
the thermogenic range. Approximately 50 to 70 percent of the methane within
the gas hydrate units is thermogenic in origin.

This is U.S. Geological Survey Open-File Report 92-299

This report is preliminary and has not been reviewed for conformity with U.S.
Geological Survey editorial standards or with the North American Stratigraphic
Code. Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the U.S. Government.