Field investigation into unsaturated flow and transport in a fault: model analyses

Liu, Hui‐Hai; Salve, Rohit; Wang, J.S.; Bodvarsson, G.S.; Hudson, David

doi:10.1016/j.jconhyd.2004.02.004

Cited by 25 publications

(25 citation statements)

References 38 publications

(57 reference statements)

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“…Laboratory experiments on rock-matrix cores and field tracer tests at a larger scale have been often employed to estimate this coefficient [e.g., Skagius and Neretnieks, 1986;Ohlsson and Neretnieks, 1995;Ohlsson et al, 2001;Reimus et al, 2003bl. It has been found that the lab-scale matrix diffusion coefficient may be orders of magnitude smaller than a field-scale value for the same geologic site, indicating that matrix diffusion in the field is enhanced in some way [e.g., Hodgkinson and Lever, 1983;Maloszewski and Zuber, 1993;Shapiro, 2001;Neretnieks, 2002;Liu et al, 2003Liu et al, , 2004aAndersson et al, 20041. The enhancement may also be related to the significant inconsistency between rock properties (e.g., fracture aperture and matrix porosity) estimated from field tracer tests and those measured directly or estimated from hydraulic tests [e.g., Novakowski et al, 19851.…”

Section: Introductionmentioning

confidence: 99%

Field-scale effective matrix diffusion coefficient for fractured rock: Results from literature survey

Zhou

Liu

Molz

et al. 2007

Journal of Contaminant Hydrology

103

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Matrix diffusion is an important mechanism for solute transport in fractured rock.We recently conducted a literature survey on the effective matrix diffusion coefficient, D i , a key parameter for describing matrix diffusion processes at the field scale. Forty field tracer tests at 15 fractured geologic sites were surveyed and selected for the study, based on data availability and quality. Field-scale D: values were calculated, either directly using data reported in the literature or by reanalyzing the corresponding field tracer tests. Surveyed data indicate that the effective-matrix-diffusion-coefficient factor FD (defined as the ratio of D i to the lab-scale matrix diffusion coefficient [ Dm 3 of the same tracer) is generally larger than one, indicating that the effective matrix diffusion coefficient in the field is comparatively larger than the matrix diffusion coefficient at the rock-core scale. This larger value can be attributed to the many mass-transfer processes at different scales in naturally heterogeneous, fractured rock systems. Furthermore, we observed a moderate trend toward systematic increase in the FD value with observation scale, indicating that the effective matrix diffusion coefficient is likely to be statistically scale dependent. The FD value ranges from 1 to 10,000 for observation scales from 5 to 2,000 m. At a given scale, the F ' value varies by two orders of magnitude, reflecting the influence of differing degrees of fractured rock heterogeneity at different sites. In addition, the surveyed data indicate that field-scale longitudinal dispersivity generally increases with observation scale, which is consistent with previous studies. The scaledependent field-scale matrix diffusion coefficient (and dispersivity) may have significant 1 implications for assessing long-term, large-scale radionuclide and contaminant transport events in fractured rock, both for nuclear waste disposal and contaminant remediation.

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Section: Introductionmentioning

confidence: 99%

Field-scale effective matrix diffusion coefficient for fractured rock: Results from literature survey

Zhou

Liu

Molz

et al. 2007

Journal of Contaminant Hydrology

103

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“…In addition, site-specific process models and smallscale infiltration experiments were performed at Yucca Mountain to investigate the movement of water and solutes through faults and fracture systems Liu et al, 2004) and seepage into underground openings (Figure 4-, Trautz and Wang, 2002;Cook et al, 2003;Finsterle et al, 2003;Ghezzehei et al, 2004). Flint et al (2000) provide a brief overview of the approaches used to estimate regional recharge in the Death Valley Region of the Mojave Desert, an arid area of the United States, encompassing Yucca Mountain.…”

Section: Infiltration and Recharge Evaluationmentioning

confidence: 99%

Feature Detection, Characterization and Confirmation Methodology: Final Report

Karasaki¹,

Apps²,

Doughty³

et al. 2007

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Executive SummaryThis is the final report of the NUMO-LBNL collaborative project: Feature Detection, Characterization and Confirmation Methodology under NUMO-DOE/LBNL collaboration agreement, the task description of which can be found in the Appendix.We examine site characterization projects from several sites in the world. The list includes Yucca Mountain in the USA, Tono and Horonobe in Japan, AECL in Canada, sites in Sweden, and Olkiluoto in Finland. We identify important geologic features and parameters common to most (or all) sites to provide useful information for future repository siting activity. At first glance, one could question whether there was any commonality among the sites, which are in different rock types at different locations. For example, the planned Yucca Mountain site is a dry repository in unsaturated tuff, whereas the Swedish sites are situated in saturated granite. However, the study concludes that indeed there are a number of important common features and parameters among all the sites-namely, (1) fault properties, (2) fracture-matrix interaction (3) groundwater flux, (4) boundary conditions, and (5) the permeability and porosity of the materials.We list the lessons learned from the Yucca Mountain Project and other site characterization programs. Most programs have by and large been quite successful. Nonetheless, there are definitely "should-haves" and "could-haves," or lessons to be learned, in all these programs. Although each site characterization program has some unique aspects, we believe that these crosscutting lessons can be very useful for future site investigations to be conducted in Japan. One of the most common lessons learned is that a repository program should allow for flexibility, in both schedule and approach.We examine field investigation technologies used to collect site characterization data in the field. An extensive list of existing field technologies is presented, with some discussion on usage and limitations. Many of the technologies on the list were in fact used during the characterization of Yucca Mountain and elsewhere by LBNL personnel. The study also includes emerging technologies and identifies the need to develop better estimation of important parameters for repository siting. Notable emerging technologies include 3-D seismic and satellite-based remote sensing and wireless micro electro mechanical systems (MEMS) sensors. They enable cost-effective and ubiquitous monitoring to be applied for site characterization.We list and classify the types of uncertainties involved in site characterization. Uncertainties can exist in all aspects of site characterization: data, interpretation, conceptualization, and modeling. We use the Swedish program to exemplify such uncertainties. We also devote a chapter on geochemical issues regarding the interaction between groundwater and natural and engineered barrier materials. A recommendation has been made to take advantage of the recent advancement in geochemical modeling capabilities in natural systems. Although it is not o...

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“…In recent years, interest has grown in investigating solute transport through fractured rock, driven by environmental concerns related to radionuclide transport in fractured formations (e.g., Liu et al 2003Liu et al , 2004aHu et al 2004;Reimus and Callahan 2007). Moreover, suitability evaluations for underground geological storage of high-level radioactive waste in fractured rock have generated renewed interest in investigations of tracer and radionuclide transport in a fractured geological system.…”

Section: Introductionmentioning

confidence: 99%

“…Since the 1970s, while understanding fracture-matrix interaction has been the focus of investigation into flow and transport processes in fractured rock, matrix diffusion has been gradually recognized as one of the most important mechanisms that control radionuclide transport processes in fractured rock (e.g., Neretnieks 1980;Neretnieks et al 1982;Maloszewski and Zuber 1993;Liu et al 2004a). Even in the laboratory, fracture-matrix diffusion is also found to be dominant Sudicky et al 1985;Wu and Pruess 2000).…”

Section: Introductionmentioning

confidence: 99%

Fracture-Flow-Enhanced Matrix Diffusion in Solute Transport Through Fractured Porous Media

Ye²,

Sudicky

2009

Transp Porous Med

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Over the past few decades, significant progress of assessing chemical transport in fractured rocks has been made in laboratory and field investigations as well as in mathematic modeling. In most of these studies, however, matrix diffusion on fracture-matrix surfaces is considered as a process of molecular diffusion only. Mathematical modeling based on this traditional concept often had problems in explaining or predicting tracer transport in fractured rock. In this article, we propose a new conceptual model of fracture-flow-enhanced matrix diffusion, which correlates with fracture-flow velocity. The proposed model incorporates an additional matrix-diffusion process, induced by rapid fluid flow along fractures. According to the boundary-layer theory, fracture-flow-enhanced matrix diffusion may dominate masstransfer processes at fracture-matrix interfaces, where rapid flow occurs through fractures. The new conceptual model can be easily integrated with analytical solutions, as demonstrated in this article, and numerical models, as we foresee. The new conceptual model is preliminarily validated using laboratory experimental results from a series of tracer breakthrough tests with different velocities in a simple fracture system. Validating of the new model with field experiments in complicated fracture systems and numerical modeling will be explored in future research. 123 22 Y.-S. Wu et al. List of Symbols b Half aperture of fractures (m) c Concentration (kg/m 3 ) c, c i Simulated concentration (kg/m 3 ) c * Measured concentration (kg/m 3 ) c f (Averaged) solute concentration across fractures (kg/m 3 ) c m Solute concentration of the matrix on the matrix block surface (kg/m 3 ) c o Constant fracture source solute concentration (kg/m 3 ) D Hydrodynamic dispersion coefficient along fractures (m 2 /s) D E Effective enhanced matrix-diffusion coefficient (m 2 /s) D m Free-solution molecular diffusion coefficient (m 2 /s) D * Effective molecular diffusion coefficient (m 2 /s) h c Mass-transfer coefficient at the fracture-matrix interface (m/s)

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Field investigation into unsaturated flow and transport in a fault: model analyses

Cited by 25 publications

References 38 publications

Field-scale effective matrix diffusion coefficient for fractured rock: Results from literature survey

Field-scale effective matrix diffusion coefficient for fractured rock: Results from literature survey

Feature Detection, Characterization and Confirmation Methodology: Final Report

Fracture-Flow-Enhanced Matrix Diffusion in Solute Transport Through Fractured Porous Media

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