A Mountain-Scale Model for Characterizing Unsaturated Flow and Transport in Fractured Tuffs of Yucca Mountain

Wu, Yu‐Shu; Lu, Guoping; Zhang, Keni; Bodvarsson, G.S.

doi:10.2113/3.3.796

Cited by 16 publications

(17 citation statements)

References 29 publications

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“…The hydrogeological units vary significantly in thickness and sloping over the model domain ( Figure 2). UZ-Flow Conceptual Model: Figure 2 presents a typical geological profile along a vertical east-west transect ( Figure 1), illustrating a conceptual model currently used to analyze UZ flow patterns, as well as explaining the possible effects of faults and perched water on the UZ system 4,5 . As illustrated in Figure 2, the ground surface of the UZ is subject to spatially and temporally varying infiltration pulses from precipitation, which provide the water source for deep percolation into the UZ.…”

Section: Hydrogeology and Conceptual Modelmentioning

confidence: 99%

“…The 18 3-D flow simulations are generated using nine infiltration maps (See Table 1), two sets of fracture-matrix parameters, one base case and one alternative. The classification of base-case and alternative parameters is based on model calibration results from the two different property sets for the PTn unit, because the base-case (or first-set) parameter models provide a better overall match to field data than the alternative properties 5,15 .…”

Section: Model Calibrationmentioning

confidence: 99%

“…Here, we discuss the detailed rationale for using Cl to constrain the percolation fluxes. The results of Cl transport modeling is briefly described; more detailed discussion and results using chloride and other isotopic data are provided in BSC and Wu et al 5,15 .…”

Section: Model Calibrationmentioning

confidence: 99%

“…Several comparisons with borehole data are presented in BSC and Wu et al 5,15 . As shown in Figure 9, modeled chloride distributions in the UZ are very sensitive to both conceptual models of the PTn and net surface infiltration rates.…”

Section: Model Calibrationmentioning

confidence: 99%

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An Integrated Modeling Approach for Characterizing Multiphase Flow, Chemical Transport, and Heat Transfer in Fractured Reservoirs

Zhang

et al. 2007

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Section: Hydrogeology and Conceptual Modelmentioning

confidence: 99%

Section: Model Calibrationmentioning

confidence: 99%

Section: Model Calibrationmentioning

confidence: 99%

Section: Model Calibrationmentioning

confidence: 99%

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An Integrated Modeling Approach for Characterizing Multiphase Flow, Chemical Transport, and Heat Transfer in Fractured Reservoirs

Zhang

et al. 2007

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“…Even with the significant progress has been made towards understanding and modeling of flow and transport processes in fractured rock so far, most studies have focused primarily on naturally fractured reservoirs without taking into consideration of faults explicitly. Recently, characterizing fractured rock of faults or fault zones has received attention, because fault zones are found to be closely associated with and may dominate flow and transport processes in fractured reservoirs (Wu et al 2004;2006a;2007a).…”

Section: Introductionmentioning

confidence: 99%

Conceptualization and Modeling of Flow and Transport Through Fault Zones

Harasaki

2009

Latin American and Caribbean Petroleum Engineering Conference

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A physically based fault conceptual model is presented for modeling multiphase flow and transport processes in fractured rock of fault zones. In particular, we discuss a general mathematical framework model for dealing with fracture-matrix interactions, which is applicable to both continuum and discrete fracture conceptualization in fault zones. In this conceptual model, faults or fault zones of formations are conceptualized as a multiple-continuum medium, consisting of (1) highly permeable, large-scale and well-connected fractures, (2) low-permeability rock matrix, (3) various-sized vugs or large pore volumes, and (4) surrounding fractured or matrix formations on both sides. Flow through fault zones may be different from that through fractured reservoir rock, because of higer permeabilities and larger pore spaces in fault zones. In addition fault flow may be further complicated by non-Darcy's and other nonlinear flow behavior because of large pore space. To account for such complicated flow regime, our model formulation includes non-Darcy flow, using the multiphase extension of the Forchheimer equation as well as descriptions for flow in parallel-wall fractures or tubes, based on solutions of flow through a parallel-wall, uniform fracture and Hagen-Poiseuille tube flow.The proposed fault flow model is discretized using an unstructured grid with regular or irregular meshes, followed by time discretization carried out using a backward, first-order, finite-difference method. The final discrete nonlinear equations are handled fully implicitly, using Newton iteration. The numerical scheme proposed is applicable to simulating multiphase fluid and heat flow as well as solute transport through the fractured fault zones and their interaction with surrounding rocks. The conceptual fault model is implemented into a general-purpose reservoir simulator, applicable to 1-D, 2-D, and 3-D simulation of multiphase flow in fault zones. As a demonstration example, we apply the model to simulate pressure and temperature responses in wells for a flow system controlled by faults.

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Hydrologic issues associated with nuclear waste repositories

2015

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Significant progress in hydrology, especially in subsurface flow and solute transport, has been made over the last 35 years because of sustained interest in underground nuclear waste repositories. The present paper provides an overview of the key hydrologic issues involved, and to highlight advances in their understanding and treatment because of these efforts. The focus is not on the development of radioactive waste repositories and their safety assessment, but instead on the advances in hydrologic science that have emerged from such studies. Work and results associated with three rock types, which are being considered to host the repositories, are reviewed, with a different emphasis for each rock type. The first rock type is fractured crystalline rock, for which the discussion will be mainly on flow and transport in saturated fractured rock. The second rock type is unsaturated tuff, for which the emphasis will be on flow from the shallow subsurface through the unsaturated zone to the repository. The third rock type is clay-rich formations, whose permeability is very low in an undisturbed state. In this case, the emphasis will be on hydrologic issues that arise from mechanical and thermal disturbances; i.e., on the relevant coupled thermo-hydromechanical processes. The extensive research results, especially those from multiyear large-scale underground research laboratory investigations, represent a rich body of information and data that can form the basis for further development in the related areas of hydrologic research. General IntroductionSignificant progress in hydrology, especially in subsurface flow and solute transport, has been made over the last 35 years because of sustained interest in the performance assessment of proposed underground nuclear waste repositories. The present paper attempts to provide an overview of the key hydrologic issues involved and to highlight the advances in their understanding and treatment because of these efforts. This paper is not focused on the development of high-level nuclear waste repositories and their safety assessment; it focuses instead on the advances in hydrologic science which have emerged from such studies. These advances may find applications in other hydrology-related problems of current importance at the national and international levels, such as environmental contamination remediation, carbon dioxide geosequestration, and natural gas production through fracking.In the next section, we present, in a general way, the context for the hydrologic framework related to performance and safety assessment of underground nuclear waste repositories that are proposed to be constructed in three particular rock formations-crystalline rock, unsaturated tuffs, and clays. Then, we discuss some particularly challenging factors concerning the research common to these three formations. This discussion will be followed by three sections devoted to each of these three rock types, respectively, to present a review of hydrologic research in these areas.

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A Mountain-Scale Model for Characterizing Unsaturated Flow and Transport in Fractured Tuffs of Yucca Mountain

Cited by 16 publications

References 29 publications

An Integrated Modeling Approach for Characterizing Multiphase Flow, Chemical Transport, and Heat Transfer in Fractured Reservoirs

An Integrated Modeling Approach for Characterizing Multiphase Flow, Chemical Transport, and Heat Transfer in Fractured Reservoirs

Conceptualization and Modeling of Flow and Transport Through Fault Zones

Hydrologic issues associated with nuclear waste repositories

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