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Title: Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs

Abstract

Accurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, Sh, using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n. Though n = 1.9 has been measured for ice–bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate–bearing sands. In this work, we calibrate n for hydrate–bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L–38, by establishing an independent downhole Sh profile based on compressional–wave velocity log data. Using the independently determined Sh profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n, and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L–38 well, we also apply this method to two marine, coarse–grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313–H and Green Canyon 955–H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Furthermore,more » for the coarse–grained hydrate bearing ( Sh > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. The Ohio State Univ., Columbus, OH (United States)
  2. U.S. Geological Survey, Woods Hole, MA (United States)
Publication Date:
Research Org.:
Univ. of Texas, Austin, TX (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1537315
Alternate Identifier(s):
OSTI ID: 1425505
Grant/Contract Number:  
FE0023919
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Solid Earth
Additional Journal Information:
Journal Volume: 123; Journal Issue: 3; Journal ID: ISSN 2169-9313
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Geochemistry & Geophysics; gas hydrate; resistivity; velocity; hydrate saturation; Mallik; Gulf of Mexico

Citation Formats

Cook, Ann E., and Waite, William F. Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs. United States: N. p., 2018. Web. doi:10.1002/2017jb015138.
Cook, Ann E., & Waite, William F. Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs. United States. doi:10.1002/2017jb015138.
Cook, Ann E., and Waite, William F. Sat . "Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs". United States. doi:10.1002/2017jb015138. https://www.osti.gov/servlets/purl/1537315.
@article{osti_1537315,
title = {Archie's Saturation Exponent for Natural Gas Hydrate in Coarse-Grained Reservoirs},
author = {Cook, Ann E. and Waite, William F.},
abstractNote = {Accurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, Sh, using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n. Though n = 1.9 has been measured for ice–bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate–bearing sands. In this work, we calibrate n for hydrate–bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L–38, by establishing an independent downhole Sh profile based on compressional–wave velocity log data. Using the independently determined Sh profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n, and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L–38 well, we also apply this method to two marine, coarse–grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313–H and Green Canyon 955–H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Furthermore, for the coarse–grained hydrate bearing (Sh > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available.},
doi = {10.1002/2017jb015138},
journal = {Journal of Geophysical Research. Solid Earth},
number = 3,
volume = 123,
place = {United States},
year = {2018},
month = {2}
}

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Cited by: 4 works
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