Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site

Soler, Josep M.; Landa, Jiří; Havlová, Václava; Tachi, Yukio; Ebina, Takanori; Sardini, Paul; Siitari-Kauppi, Marja; Eikenberg, J.; Martin, Andrew J.

doi:10.1016/j.jconhyd.2015.06.002

Cited by 44 publications

(27 citation statements)

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“…However, such idealizations do not capture hydraulic properties of fractured aquifers at HRFS for many applications (e.g., in situ remediation). Detailed investigations at fractured‐rock research sites (e.g., Grimsel, Aspö) have provided exceptional access to 3D rock exposures supplemented by coreholes and extensive hydrologic, tracer, and geophysical tests (e.g., Martinez‐Landa and Carrera , ; Mettier et al ; Gustafson et al and papers cited within; Soler et al ). Yet, this information has not led to generally accepted methods for estimating fracture distributions to predict hydraulic and transport behavior.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone

Tiedeman¹,

Barrash

2019

Groundwater

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We present the first demonstration of hydraulic tomography (HT) to estimate the three‐dimensional (3D) hydraulic conductivity (K) distribution of a fractured aquifer at high‐resolution field scale (HRFS), including the fracture network and connectivity through it. We invert drawdown data collected from packer‐isolated borehole intervals during 42 pumping tests in a wellfield at the former Naval Air Warfare Center, West Trenton, New Jersey, in the Newark Basin. Five additional tests were reserved for a quality check of HT results. We used an equivalent porous medium forward model and geostatistical inversion to estimate 3D K at high resolution (K blocks <1 m3), using no strict assumptions about K variability or fracture statistics. The resulting 3D K estimate ranges from approximately 0.1 (highest‐K fractures) to approximately 10−13 m/s (unfractured mudstone). Important estimated features include: (1) a highly fractured zone (HFZ) consisting of a sequence of high‐K bedding‐plane fractures; (2) a low‐K zone that disrupts the HFZ; (3) several secondary fractures of limited extent; and (4) regions of very low‐K rock matrix. The 3D K estimate explains complex drawdown behavior observed in the field. Drawdown tracing and particle tracking simulations reveal a 3D fracture network within the estimated K distribution, and connectivity routes through the network. Model fit is best in the shallower part of the wellfield, with high density of observations and tests. The capabilities of HT demonstrated for 3D fractured aquifer characterization at HRFS may support improved in situ remediation for contaminant source zones, and applications in mining, repository assessment, or geotechnical engineering.

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Section: Introductionmentioning

confidence: 99%

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone

Tiedeman¹,

Barrash

2019

Groundwater

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“…It can be seen that the fit fails to explain the late part of the in‐diffusion profile which extends further than the fit to the early part predicts. Similar challenges were faced when analyzing the in‐diffusion profiles from the LTD experiment and the analysis could not be performed using homogeneous models (Jokelainen et al, ; Soler et al, ; Tachi et al, ). The overall shape of the profiles is similar but modeled ones do not extend as far as the ones from the LTD experiment.…”

Section: Resultsmentioning

confidence: 99%

“…In the in situ test of the LTD experiment at the GTS, the initial activity concentration of 134 Cs was 540 Bq/g (Soler et al, ) which is equal to a molar concentration of

8.4 \times 10^{- 11}

M . As the concentration of stable cesium in Grimsel ground water is

5.3 \times 10^{- 9}

M (Aksoyoglu et al, ), the increase in concentration of cesium due to injected 134 Cs can be neglected and simulations could be performed in a constant concentration of

5.3 \times 10^{- 9}

M , and thus constant values for K d were chosen accordingly (see Table when simulating the in‐diffusion profiles in in situ conditions).…”

Section: Methodsmentioning

confidence: 99%

“…A few similar in situ experiments with an aim to determine these properties in crystalline rock have been performed in Switzerland, Canada, Sweden, and Finland (Cvetkovic et al, ; Hadermann & Heer, ; Vilks et al, ; Voutilainen et al, ; Widestrand et al, ). In the LTD experiment, a cocktail of radionuclides ( 3 H as HTO, 22 Na, 134 Cs, and 131 I) was circulated in a 0.7 m long packed‐off test‐interval of a borehole (Soler et al, ). During the experiment, the concentration decrease of radionuclides was measured.…”

Section: Introductionmentioning

confidence: 99%

“…During the experiment, the concentration decrease of radionuclides was measured. After the experiment, the test‐interval section was removed by overcoring with a wide diameter drill‐bit and the in‐diffusion profiles of radionuclides in the rock core were determined in the laboratory using a variety of techniques (Ikonen et al, ; Jokelainen et al, ; Soler et al, ). From these measurements, porosity of the rock and effective diffusion coefficients and distribution coefficients of the radionuclides in the Grimsel granodiorite were determined and the results were compared to ones from laboratory experiments (Ikonen et al, ; Tachi et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Modeling Transport of Cesium in Grimsel Granodiorite With Micrometer Scale Heterogeneities and Dynamic Update of K_d

Voutilainen

Kekäläinen

Siitari-Kauppi

et al. 2017

Water Resources Research

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Transport and retardation of cesium in Grimsel granodiorite taking into account heterogeneity of mineral and pore structure was studied using rock samples overcored from an in situ diffusion test at the Grimsel Test Site. The field test was part of the Long‐Term Diffusion (LTD) project designed to characterize retardation properties (diffusion and distribution coefficients) under in situ conditions. Results of the LTD experiment for cesium showed that in‐diffusion profiles and spatial concentration distributions were strongly influenced by the heterogeneous pore structure and mineral distribution. In order to study the effect of heterogeneity on the in‐diffusion profile and spatial concentration distribution, a Time Domain Random Walk (TDRW) method was applied along with a feature for modeling chemical sorption in geological materials. A heterogeneous mineral structure of Grimsel granodiorite was constructed using X‐ray microcomputed tomography (X‐μCT) and the map was linked to previous results for mineral specific porosities and distribution coefficients (Kd) that were determined using C‐14‐PMMA autoradiography and batch sorption experiments, respectively. After this the heterogeneous structure contains information on local porosity and Kd in 3‐D. It was found that the heterogeneity of the mineral structure on the micrometer scale affects significantly the diffusion and sorption of cesium in Grimsel granodiorite at the centimeter scale. Furthermore, the modeled in‐diffusion profiles and spatial concentration distributions show similar shape and pattern to those from the LTD experiment. It was concluded that the use of detailed structure characterization and quantitative data on heterogeneity can significantly improve the interpretation and evaluation of transport experiments.

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In situ migration of tritiated water and iodine in Grimsel granodiorite, part II: assessment of the diffusion coefficients by TDD modelling

Ikonen

Sardini

Siitari-Kauppi

et al. 2016

J Radioanal Nucl Chem

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Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site

Cited by 44 publications

References 50 publications

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone

Modeling Transport of Cesium in Grimsel Granodiorite With Micrometer Scale Heterogeneities and Dynamic Update of K_d

In situ migration of tritiated water and iodine in Grimsel granodiorite, part II: assessment of the diffusion coefficients by TDD modelling

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Comparative modeling of an in situ diffusion experiment in granite at the Grimsel Test Site

Cited by 44 publications

References 50 publications

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone

Hydraulic Tomography: 3D Hydraulic Conductivity, Fracture Network, and Connectivity in Mudstone

Modeling Transport of Cesium in Grimsel Granodiorite With Micrometer Scale Heterogeneities and Dynamic Update of Kd

In situ migration of tritiated water and iodine in Grimsel granodiorite, part II: assessment of the diffusion coefficients by TDD modelling

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Modeling Transport of Cesium in Grimsel Granodiorite With Micrometer Scale Heterogeneities and Dynamic Update of K_d