Cargando…

Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia

The hydraulic integrity of aquitards is generally assumed and relies on a few core‐scale permeability measurements, drill‐stem tests, or textbook values. This approach is because hydraulic data across the full aquitard thickness is generally lacking. Proper assessment of aquitard integrity should be...

Descripción completa

Detalles Bibliográficos
Autores principales: Smith, Stanley D., Mathouchanh, Emeline, Mallants, Dirk
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Blackwell Publishing Ltd 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379531/
https://www.ncbi.nlm.nih.gov/pubmed/29573410
http://dx.doi.org/10.1111/gwat.12665
_version_ 1783562661656526848
author Smith, Stanley D.
Mathouchanh, Emeline
Mallants, Dirk
author_facet Smith, Stanley D.
Mathouchanh, Emeline
Mallants, Dirk
author_sort Smith, Stanley D.
collection PubMed
description The hydraulic integrity of aquitards is generally assumed and relies on a few core‐scale permeability measurements, drill‐stem tests, or textbook values. This approach is because hydraulic data across the full aquitard thickness is generally lacking. Proper assessment of aquitard integrity should be studied at the formation (spanning its entire thickness at a single point) or regional (formation properties at multiple locations throughout the basin) scale. One formation‐scale approach uses environmental tracers and advection‐dispersion modeling to constrain fluid flow rates. This study demonstrates the use of helium concentrations in quartz as a method of constraining the rate of fluid flow in a 520‐m thick aquitard in the Gunnedah Basin, NSW, Australia. Quartz was separated from existing core samples in the Watermark and Porcupine Formations at depths from 750 to 1200 m. The helium was released from these samples by heating and select samples were impregnated with helium to determine the rate of helium diffusion through the quartz. One‐dimensional advection‐dispersion modeling of the helium profile accounting for diffusive helium exchange between quartz and pore water revealed, that (1) vertical fluid velocity has been on the order of 0.02 mm/year or less for tens to thousands of years, (2) helium is in equilibrium between quartz and pore water, and (3) the helium profile is transient indicating that helium concentrations in the underlying Maules Creek Formation has varied over geological time. Further modeling identified aquitard conditions (thickness and temperature) for which equilibrium exists, a precondition for deriving formation‐scale permeability.
format Online
Article
Text
id pubmed-7379531
institution National Center for Biotechnology Information
language English
publishDate 2018
publisher Blackwell Publishing Ltd
record_format MEDLINE/PubMed
spelling pubmed-73795312020-07-24 Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia Smith, Stanley D. Mathouchanh, Emeline Mallants, Dirk Ground Water Research Papers/ The hydraulic integrity of aquitards is generally assumed and relies on a few core‐scale permeability measurements, drill‐stem tests, or textbook values. This approach is because hydraulic data across the full aquitard thickness is generally lacking. Proper assessment of aquitard integrity should be studied at the formation (spanning its entire thickness at a single point) or regional (formation properties at multiple locations throughout the basin) scale. One formation‐scale approach uses environmental tracers and advection‐dispersion modeling to constrain fluid flow rates. This study demonstrates the use of helium concentrations in quartz as a method of constraining the rate of fluid flow in a 520‐m thick aquitard in the Gunnedah Basin, NSW, Australia. Quartz was separated from existing core samples in the Watermark and Porcupine Formations at depths from 750 to 1200 m. The helium was released from these samples by heating and select samples were impregnated with helium to determine the rate of helium diffusion through the quartz. One‐dimensional advection‐dispersion modeling of the helium profile accounting for diffusive helium exchange between quartz and pore water revealed, that (1) vertical fluid velocity has been on the order of 0.02 mm/year or less for tens to thousands of years, (2) helium is in equilibrium between quartz and pore water, and (3) the helium profile is transient indicating that helium concentrations in the underlying Maules Creek Formation has varied over geological time. Further modeling identified aquitard conditions (thickness and temperature) for which equilibrium exists, a precondition for deriving formation‐scale permeability. Blackwell Publishing Ltd 2018-04-10 2019 /pmc/articles/PMC7379531/ /pubmed/29573410 http://dx.doi.org/10.1111/gwat.12665 Text en © 2018 The Authors. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association. This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
spellingShingle Research Papers/
Smith, Stanley D.
Mathouchanh, Emeline
Mallants, Dirk
Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia
title Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia
title_full Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia
title_fullStr Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia
title_full_unstemmed Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia
title_short Quartz‐Helium Method to Estimate Fluid Flow in Thick Aquitards, Gunnedah Basin, Australia
title_sort quartz‐helium method to estimate fluid flow in thick aquitards, gunnedah basin, australia
topic Research Papers/
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379531/
https://www.ncbi.nlm.nih.gov/pubmed/29573410
http://dx.doi.org/10.1111/gwat.12665
work_keys_str_mv AT smithstanleyd quartzheliummethodtoestimatefluidflowinthickaquitardsgunnedahbasinaustralia
AT mathouchanhemeline quartzheliummethodtoestimatefluidflowinthickaquitardsgunnedahbasinaustralia
AT mallantsdirk quartzheliummethodtoestimatefluidflowinthickaquitardsgunnedahbasinaustralia