the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Vertical hydraulic conductivity of a clayey-silt aquitard: accelerated fluid flow in a centrifuge permeameter compared with in situ conditions
Abstract. Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, extraction of fuels from strata such as coal beds, and confinement of waste within the earth. Characterizing low or negligible flow rates and transport of solutes can require impractically long periods of field or laboratory testing, but is necessary for evaluations over regional areas and over multi-decadal timescales. The current work reports a custom designed centrifuge permeameter (CP) system, which can provide relatively rapid and reliable hydraulic conductivity (K) measurement compared to column permeameter tests at standard gravity (1g). Linear fluid velocity through a low K porous sample is linearly related to g-level during a CP flight unless consolidation or geochemical reactions occur. The CP module is designed to fit within a standard 2 m diameter, geotechnical centrifuge with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length. At maximum RPM the resultant centrifugal force is equivalent to 550g at base of sample or a total stress of ~2 MPa. K is calculated by measuring influent and effluent volumes. A custom designed mounting system allows minimal disturbance of drill core samples and a centrifugal force that represents realistic in situ stress conditions is applied. Formation fluids were used as influent to limit any shrink-swell phenomena which may alter the resultant K value. Vertical hydraulic conductivity (Kv) results from CP testing of core from the sites in the same clayey silt formation varied (10−7 to 10−9 m s−1, n = 14) but higher than 1g column permeameter tests of adjacent core using deionized water (10−9 to 10−11 m s−1, n = 7). Results at one site were similar to in situ Kv values (3 × 10−9 m s−1) from pore pressure responses within a 30 m clayey sequence in a homogenous area of the formation. Kv sensitivity to sample heterogeneity was observed, and anomalous flow via preferential pathways could be readily identified. Results demonstrate the utility of centrifuge testing for measuring minimum K values that can contribute to assessments of geological formations at large scale. The importance of using realistic stress conditions and influent geochemistry during hydraulic testing is also demonstrated.
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- RC C1844: 'Review Comments', Anonymous Referee #1, 14 Jun 2014
- RC C1923: 'Review', Anonymous Referee #2, 19 Jun 2014
- EC C1927: 'Request for a reply to the reviews', Gerrit H. de Rooij, 19 Jun 2014
- AC C2436: 'Author's reply to reviewers', Wendy Timms, 14 Jul 2014
- RC C1844: 'Review Comments', Anonymous Referee #1, 14 Jun 2014
- RC C1923: 'Review', Anonymous Referee #2, 19 Jun 2014
- EC C1927: 'Request for a reply to the reviews', Gerrit H. de Rooij, 19 Jun 2014
- AC C2436: 'Author's reply to reviewers', Wendy Timms, 14 Jul 2014
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Cited
6 citations as recorded by crossref.
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- Development of a Soil Water Movement Model for the Superabsorbent Polymer Application R. Liao et al. 10.2136/sssaj2017.05.0164
- Inferring Aquitard Hydraulic Conductivity Using Transient Temperature‐Depth Profiles Impacted by Ground Surface Warming V. Bense et al. 10.1029/2021WR030586
- Mapping the hydraulic connection between a coalbed and adjacent aquifer: example of the coal-seam gas resource area, north Galilee Basin, Australia Z. Jiang et al. 10.1007/s10040-016-1447-2
- Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media R. Crane et al. 10.5194/hess-19-3991-2015
- Comparison of hydraulic and chemical methods for determining hydraulic conductivity and leakage rates in argillaceous aquitards J. Batlle-Aguilar et al. 10.1016/j.jhydrol.2015.11.035