In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

Marine and Petroleum Geology
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Abstract

In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.

Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified – an upper ∼43 ft zone with an average gas hydrate saturation of 54% and a lower ∼53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation.

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Publication type Article
Publication Subtype Journal Article
Title In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope
Series title Marine and Petroleum Geology
DOI 10.1016/j.marpetgeo.2009.06.007
Volume 28
Issue 2
Year Published 2011
Language English
Contributing office(s) Central Energy Resources Science Center
Description 11 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Marine and Petroleum Geology
First page 439
Last page 449
Country United States
State Alaska
Other Geospatial Mount Elbert Gas Hydrate Stratigraphic Test Well
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