Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

M. E. Torres, T. S. Collett, K. K. Rose, James C Sample, W. F. Agena, E. J. Rosenbaum

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled and cored from 606.5 to 760.1. m on the North Slope of Alaska, to evaluate the occurrence, distribution and formation of gas hydrate in sediments below the base of the ice-bearing permafrost. Both the dissolved chloride and the isotopic composition of the water co-vary in the gas hydrate-bearing zones, consistent with gas hydrate dissociation during core recovery, and they provide independent indicators to constrain the zone of gas hydrate occurrence. Analyses of chloride and water isotope data indicate that an observed increase in salinity towards the top of the cored section reflects the presence of residual fluids from ion exclusion during ice formation at the base of the permafrost layer. These salinity changes are the main factor controlling major and minor ion distributions in the Mount Elbert Well. The resulting background chloride can be simulated with a one-dimensional diffusion model, and the results suggest that the ion exclusion at the top of the cored section reflects deepening of the permafrost layer following the last glaciation (∼100 kyr), consistent with published thermal models. Gas hydrate saturation values estimated from dissolved chloride agree with estimates based on logging data when the gas hydrate occupies more than 20% of the pore space; the correlation is less robust at lower saturation values. The highest gas hydrate concentrations at the Mount Elbert Well are clearly associated with coarse-grained sedimentary sections, as expected from theoretical calculations and field observations in marine and other arctic sediment cores.

Original languageEnglish (US)
Pages (from-to)332-342
Number of pages11
JournalMarine and Petroleum Geology
Volume28
Issue number2
DOIs
StatePublished - Feb 2011

Fingerprint

gas hydrate
geochemistry
hydrates
slopes
porosity
well
fluid
fluids
permafrost
gases
chlorides
chloride
salinity
exclusion
ion
sediments
occurrences
saturation
ice
ice formation

Keywords

  • Gas hydrate
  • Mt Elbert Well
  • Permafrost
  • Pore water
  • Water isotopes

ASJC Scopus subject areas

  • Economic Geology
  • Geology
  • Geophysics
  • Stratigraphy
  • Oceanography

Cite this

Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope. / Torres, M. E.; Collett, T. S.; Rose, K. K.; Sample, James C; Agena, W. F.; Rosenbaum, E. J.

In: Marine and Petroleum Geology, Vol. 28, No. 2, 02.2011, p. 332-342.

Research output: Contribution to journalArticle

Torres, M. E. ; Collett, T. S. ; Rose, K. K. ; Sample, James C ; Agena, W. F. ; Rosenbaum, E. J. / Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope. In: Marine and Petroleum Geology. 2011 ; Vol. 28, No. 2. pp. 332-342.
@article{858d61d24301467eb9f10b9f77116b04,
title = "Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope",
abstract = "The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled and cored from 606.5 to 760.1. m on the North Slope of Alaska, to evaluate the occurrence, distribution and formation of gas hydrate in sediments below the base of the ice-bearing permafrost. Both the dissolved chloride and the isotopic composition of the water co-vary in the gas hydrate-bearing zones, consistent with gas hydrate dissociation during core recovery, and they provide independent indicators to constrain the zone of gas hydrate occurrence. Analyses of chloride and water isotope data indicate that an observed increase in salinity towards the top of the cored section reflects the presence of residual fluids from ion exclusion during ice formation at the base of the permafrost layer. These salinity changes are the main factor controlling major and minor ion distributions in the Mount Elbert Well. The resulting background chloride can be simulated with a one-dimensional diffusion model, and the results suggest that the ion exclusion at the top of the cored section reflects deepening of the permafrost layer following the last glaciation (∼100 kyr), consistent with published thermal models. Gas hydrate saturation values estimated from dissolved chloride agree with estimates based on logging data when the gas hydrate occupies more than 20{\%} of the pore space; the correlation is less robust at lower saturation values. The highest gas hydrate concentrations at the Mount Elbert Well are clearly associated with coarse-grained sedimentary sections, as expected from theoretical calculations and field observations in marine and other arctic sediment cores.",
keywords = "Gas hydrate, Mt Elbert Well, Permafrost, Pore water, Water isotopes",
author = "Torres, {M. E.} and Collett, {T. S.} and Rose, {K. K.} and Sample, {James C} and Agena, {W. F.} and Rosenbaum, {E. J.}",
year = "2011",
month = "2",
doi = "10.1016/j.marpetgeo.2009.10.001",
language = "English (US)",
volume = "28",
pages = "332--342",
journal = "Marine and Petroleum Geology",
issn = "0264-8172",
publisher = "Elsevier BV",
number = "2",

}

TY - JOUR

T1 - Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

AU - Torres, M. E.

AU - Collett, T. S.

AU - Rose, K. K.

AU - Sample, James C

AU - Agena, W. F.

AU - Rosenbaum, E. J.

PY - 2011/2

Y1 - 2011/2

N2 - The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled and cored from 606.5 to 760.1. m on the North Slope of Alaska, to evaluate the occurrence, distribution and formation of gas hydrate in sediments below the base of the ice-bearing permafrost. Both the dissolved chloride and the isotopic composition of the water co-vary in the gas hydrate-bearing zones, consistent with gas hydrate dissociation during core recovery, and they provide independent indicators to constrain the zone of gas hydrate occurrence. Analyses of chloride and water isotope data indicate that an observed increase in salinity towards the top of the cored section reflects the presence of residual fluids from ion exclusion during ice formation at the base of the permafrost layer. These salinity changes are the main factor controlling major and minor ion distributions in the Mount Elbert Well. The resulting background chloride can be simulated with a one-dimensional diffusion model, and the results suggest that the ion exclusion at the top of the cored section reflects deepening of the permafrost layer following the last glaciation (∼100 kyr), consistent with published thermal models. Gas hydrate saturation values estimated from dissolved chloride agree with estimates based on logging data when the gas hydrate occupies more than 20% of the pore space; the correlation is less robust at lower saturation values. The highest gas hydrate concentrations at the Mount Elbert Well are clearly associated with coarse-grained sedimentary sections, as expected from theoretical calculations and field observations in marine and other arctic sediment cores.

AB - The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled and cored from 606.5 to 760.1. m on the North Slope of Alaska, to evaluate the occurrence, distribution and formation of gas hydrate in sediments below the base of the ice-bearing permafrost. Both the dissolved chloride and the isotopic composition of the water co-vary in the gas hydrate-bearing zones, consistent with gas hydrate dissociation during core recovery, and they provide independent indicators to constrain the zone of gas hydrate occurrence. Analyses of chloride and water isotope data indicate that an observed increase in salinity towards the top of the cored section reflects the presence of residual fluids from ion exclusion during ice formation at the base of the permafrost layer. These salinity changes are the main factor controlling major and minor ion distributions in the Mount Elbert Well. The resulting background chloride can be simulated with a one-dimensional diffusion model, and the results suggest that the ion exclusion at the top of the cored section reflects deepening of the permafrost layer following the last glaciation (∼100 kyr), consistent with published thermal models. Gas hydrate saturation values estimated from dissolved chloride agree with estimates based on logging data when the gas hydrate occupies more than 20% of the pore space; the correlation is less robust at lower saturation values. The highest gas hydrate concentrations at the Mount Elbert Well are clearly associated with coarse-grained sedimentary sections, as expected from theoretical calculations and field observations in marine and other arctic sediment cores.

KW - Gas hydrate

KW - Mt Elbert Well

KW - Permafrost

KW - Pore water

KW - Water isotopes

UR - http://www.scopus.com/inward/record.url?scp=78651416486&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78651416486&partnerID=8YFLogxK

U2 - 10.1016/j.marpetgeo.2009.10.001

DO - 10.1016/j.marpetgeo.2009.10.001

M3 - Article

AN - SCOPUS:78651416486

VL - 28

SP - 332

EP - 342

JO - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

SN - 0264-8172

IS - 2

ER -