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Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data

Description: We present a three-dimensional modeling study of gas flow inthe unsaturated fractured rock of Yucca Mountain. Our objective is toestimate large-scale fracture permeability, using the changes insubsurface pneumatic pressure in response to barometric pressure changesat the land surface. We incorporate the field-measured pneumatic datainto a multiphase flow model for describing the coupled processes ofliquid and gas flow under ambient geothermal conditions. Comparison offield-measured pneumatic da… more
Date: May 17, 2005
Creator: Wu, Yu-Shu; Zhang, Keni & Liu, Hui-Hai
Partner: UNT Libraries Government Documents Department
open access

Modeling Hydraulic Responses to Meteorological Forcing: fromCanopy to Aquifer

Description: An understanding of the hydrologic interactions amongatmosphere, land surface, and subsurface is one of the keys tounderstanding the water cycling system that supports our life system onearth. Properly modeling such interactionsis a difficult task because oftheinherent coupled processes and complex feedback structures amongsubsystems. In this paper, we present a model that simulates thelandsurface and subsurface hydrologic response to meteorological forcing.This model combines a state of the ar… more
Date: February 8, 2007
Creator: Pan, Lehua; Jin, Jiming; Miller, Norman; Wu, Yu-Shu & Bodvarsson,Gudmundur
Partner: UNT Libraries Government Documents Department
open access

Analyzing flow patterns in unsaturated fractured rock of YuccaMountain using an integrated modeling approach

Description: This paper presents a series of modeling investigations to characterize percolation patterns in the unsaturated zone of Yucca Mountain, Nevada, a proposed underground repository site for storing high-level radioactive waste. The investigations are conducted using a modeling approach that integrates a wide variety of moisture, pneumatic, thermal, and isotopic geochemical field data into a comprehensive three-dimensional numerical model through model calibration. This integrated modeling approach… more
Date: November 3, 2003
Creator: Wu, Yu-Shu; Lu, Guoping; Zhang, Keni; Pan, Lehua & Bodvarsson,Gudmundur S.
Partner: UNT Libraries Government Documents Department
open access

An Integrated Modeling Analysis of Unsaturated Flow Patterns inFractured Rock

Description: Characterizing percolation patterns in unsaturated zones hasposed a greater challenge to numerical modeling investigations thancomparable saturated zone studies, because of the heterogeneous nature ofunsaturated media as well as the great number of variables impactingunsaturated zone flow. This paper presents an integrated modelingmethodology for quantitatively characterizing percolation patterns in theunsaturated zone of Yucca Mountain, Nevada, a proposed undergroundrepository site for storing… more
Date: March 21, 2005
Creator: Wu, Yu-Shu; Lu, Guoping; Zhang, Keni; Pan, Lehua & Bodvarsson,Gudmundur S.
Partner: UNT Libraries Government Documents Department
open access

Analysis of stress sensitivity and its influence on oil productionfrom tight reservoirs

Description: This paper presents a study of the relationship betweenpermeability and effective stress in tight petroleum reservoirformations. Specifically, a quantitative method is developed to describethe correlation between permeability and effective stress, a method basedon the original in situ reservoir effective stress rather than ondecreased effective stress during development. The experimental resultsshow that the relationship between intrinsic permeability and effectivestress in reservoirs in genera… more
Date: August 28, 2007
Creator: Lei, Qun; Xiong, Wei; Yuan, Cui & Wu, Yu-Shu
Partner: UNT Libraries Government Documents Department
open access

Efficient parallel simulation of CO2 geologic sequestration insaline aquifers

Description: An efficient parallel simulator for large-scale, long-termCO2 geologic sequestration in saline aquifers has been developed. Theparallel simulator is a three-dimensional, fully implicit model thatsolves large, sparse linear systems arising from discretization of thepartial differential equations for mass and energy balance in porous andfractured media. The simulator is based on the ECO2N module of the TOUGH2code and inherits all the process capabilities of the single-CPU TOUGH2code, including a … more
Date: January 1, 2007
Creator: Zhang, Keni; Doughty, Christine; Wu, Yu-Shu & Pruess, Karsten
Partner: UNT Libraries Government Documents Department
open access

Sensitivity Analysis Of Hydrological Parameters In Modeling FlowAnd Transport In The Unsaturated Zone Of Yucca Mountain

Description: The unsaturated fractured volcanic deposits at Yucca Mountain in Nevada, USA, have been intensively investigated as a possible repository site for storing high-level radioactive waste. Field studies at the site have revealed that there exist large variabilities in hydrological parameters over the spatial domain of the mountain. Systematic analyses of hydrological parameters using a site-scale three-dimensional unsaturated zone (UZ) flow model have been undertaken. The main objective of the sens… more
Date: February 1, 2006
Creator: Zhang, Keni; Wu, Yu-Shu & Houseworth, James E.
Partner: UNT Libraries Government Documents Department
open access

A triple-continuum approach for modeling flow and transportprocesses in fractured rock

Description: This paper presents a triple-continuum conceptual model forsimulating flow and transport processes in fractured rock. Field datacollected from the unsaturated zone of Yucca Mountain, a repository siteof high-level nuclear waste, show a large number of small-scalefractures. The effect of these small fractures has not been considered inprevious modeling investigations within the context of a continuumapproach. A new triple-continuum model (consisting of matrix,small-fracture, and large-fracture c… more
Date: August 31, 2001
Creator: Wu, Yu-Shu; Liu, H. H.; Bodvarsson, G. S. & Zellmer, K. E.
Partner: UNT Libraries Government Documents Department
open access

An integrated methodology for characterizing flow and transport processes in fractured rock

Description: To investigate the coupled processes involved in fluid andheat flow and chemical transport in the highly heterogeneous,unsaturated-zone (UZ) fractured rock of Yucca Mountain, we present anintegrated modeling methodology. This approach integrates a wide varietyof moisture, pneumatic, thermal, and geochemical isotopic field data intoa comprehensive three-dimensional numerical model for modeling analyses.The results of field applications of the methodology show that moisturedata, such as water pot… more
Date: August 31, 2007
Creator: Wu, Yu-Shu
Partner: UNT Libraries Government Documents Department
open access

Enhancing Scalability and Efficiency of the TOUGH2_MP for LinuxClusters

Description: TOUGH2{_}MP, the parallel version TOUGH2 code, has been enhanced by implementing more efficient communication schemes. This enhancement is achieved through reducing the amount of small-size messages and the volume of large messages. The message exchange speed is further improved by using non-blocking communications for both linear and nonlinear iterations. In addition, we have modified the AZTEC parallel linear-equation solver to nonblocking communication. Through the improvement of code struct… more
Date: April 17, 2006
Creator: Zhang, Keni & Wu, Yu-Shu
Partner: UNT Libraries Government Documents Department
open access

Efficient Schemes for Reducing Numerical Dispersion in ModelingMultiphase Transport through Porous and Fractured Media

Description: Numerical issues with modeling transport of chemicals or solute in realistic large-scale subsurface systems have been a serious concern, even with the continual progress made in both simulation algorithms and computer hardware in the past few decades. The problem remains and becomes even more difficult when dealing with chemical transport in a multiphase flow system using coarse, multidimensional regular or irregular grids, because of the known effects of numerical dispersion associated with mo… more
Date: April 13, 2006
Creator: Wu, Yu-Shu & Forsyth, Peter A.
Partner: UNT Libraries Government Documents Department
open access

A Mountain-Scale Thermal Hydrologic Model for Simulating FluidFlow and Heat Transfer in Unsaturated Fractured Rock

Description: A multidimensional, mountain-scale, thermal-hydrologic (TH) numerical model is presented for investigating unsaturated flow behavior in response to decay heat from the radioactive waste repository in the Yucca Mountain unsaturated zone (UZ), Nevada. The model, consisting of both two-dimensional (2-D) and three-dimensional (3-D) representations of the UZ repository system, is based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climate … more
Date: May 25, 2005
Creator: Wu, Yu-Shu; Mukhopadhyay, Sumit; Zhang, Keni & Bodvarsson,Gudmundur S.
Partner: UNT Libraries Government Documents Department
open access

Coupling TOUGH2 with CLM3: Developing a Coupled Land Surface andSubsurface Model

Description: An understanding of the hydrologic interactions among atmosphere, land surface, and subsurface is one of the keys to understanding the water cycling system that supports life on earth. The inherent coupled processes and complex feedback structures among subsystems make such interactions difficult to simulate. In this paper, we present a model that simulates the land surface and subsurface hydrologic response to meteorological forcing. This model combines a state-of-the-art land-surface model, t… more
Date: May 19, 2006
Creator: Pan, Lehua; Jin, Jiming; Miller, Norman; Wu, Yu-Shu & Bodvarsson,Gudmundur
Partner: UNT Libraries Government Documents Department
open access

Temporal Damping Effect of the Yucca Mountain FracturedUnsaturated Rock on Transient Infiltration Pulses

Description: Performance assessment of the Yucca Mountain unsaturated zone (UZ) as the site for an underground repository of high-level radioactive waste relies on the crucial assumption that water percolation processes in the unsaturated zone can be approximated as a steady-state condition. Justification of such an assumption is based on temporal damping effects of several geological units within the unsaturated tuff formation. In particular, the nonwelded tuff of the Painbrush Group (PTn unit) at Yucca Mo… more
Date: May 2, 2005
Creator: Zhang, Keni; Wu, Yu-Shu & Pan, Lehua
Partner: UNT Libraries Government Documents Department
open access

Modeling Unsaturated Flow and Transport Processes in Fractured Tuffs of Yucca Mountain

Description: This paper presents a field modeling study characterizing fluid flow and tracer transport in the unsaturated zone of Yucca Mountain, Nevada, a proposed underground repository for storing high-level radioactive waste. The 500 to 700 meter thick unsaturated zone of Yucca Mountain consists of highly heterogeneous layers of anisotropic, fractured ash flow and air fall tuffs. Characterization of fluid flow and heat transfer through such a system has been a challenge due to the heterogeneities preval… more
Date: July 15, 2003
Creator: Wu, Yu-Shu; Lu, Guoping; Zhang, Keni & Bodvarsson, G.S.
Partner: UNT Libraries Government Documents Department
open access

A mountain-scale model for characterizing unsaturated flow and transport in fractured tuffs of Yucca Mountain

Description: This paper presents a large-scale modeling study characterizing fluid flow and tracer transport in the unsaturated zone of Yucca Mountain, Nevada, the proposed underground repository site for storing high-level radioactive waste. The modeling study is conducted using a three-dimensional numerical model, which incorporates a wide variety of field data and takes into account the coupled processes of flow and transport in Yucca Mountain's highly heterogeneous, unsaturated, fractured porous rock. T… more
Date: July 18, 2003
Creator: Wu, Yu-Shu; Lu, Guoping; Zhang, Keni & Bodvarsson, G.S.
Partner: UNT Libraries Government Documents Department
open access

Development of discrete flow paths in unsaturated fractures at Yucca Mountain

Description: We have carried out numerical modeling studies to investigate the development of discrete fracture flow paths and flow-focusing phenomena in the unsaturated rock of the potential repository horizon at Yucca Mountain, Nevada. These studies are based on two- and three dimensional (2-D and 3-D) numerical models using site-specific parameters. The 2-D and 3-D models use high-resolution spatial discretization to explicitly include effects of discrete fractures with stochastically developed fracture … more
Date: September 1, 2002
Creator: Bodvarsson, G.S.; Wu, Yu-Shu & Zhang, Keni
Partner: UNT Libraries Government Documents Department
open access

Modeling thermal-hydrological response of the unsaturated zone at Yucca Mountain, Nevada, to thermal load at a potential repository

Description: This paper presents a numerical study on the response of the unsaturated zone (UZ) system of Yucca Mountain to heat generated from decaying radioactive wastes emplaced at the proposed repository. The modeling study is based on the current thermal-hydrological (TH) mountain-scale model, which uses a locally refined 2D north-south cross section and dual-permeability numerical approach. The model provides a prediction of the mountain-scale TH response under the thermal-load scenario of 1.45 kW/m, … more
Date: September 1, 2002
Creator: Haukwa, C. B.; Wu, Yu-Shu & Bodvarsson, G. S.
Partner: UNT Libraries Government Documents Department
open access

Analysis of flow behavior in fractured lithophysal reservoirs

Description: This study develops a mathematical model for the analysis of pressure behavior in fractured lithophysal reservoirs. The lithophysal rock is described as a tri-continuum medium, consisting of fractures, rock matrices, and cavities. In the conceptual model, fractures have homogeneous properties throughout and interact with rock matrices and cavities that have different permeabilities and porosities. Global flow occurs through the fracture network only, while rock matrices and cavities contain the… more
Date: September 1, 2002
Creator: Liu, Jianchun; Bodvarsson, G.S. & Wu, Yu-Shu
Partner: UNT Libraries Government Documents Department
open access

A Physically Based Approach for Modeling Multiphase Fracture-Matrix Interaction in Fractured Porous Media

Description: Modeling fracture-matrix interaction within a complex multiple phase flow system is a key issue for fractured reservoir simulation. Commonly used mathematical models for dealing with such interactions employ a dual- or multiple-continuum concept, in which fractures and matrix are represented as overlapping, different, but interconnected continua, described by parallel sets of conservation equations. The conventional single-point upstream weighting scheme, in which the fracture relative permeabi… more
Date: March 15, 2004
Creator: Wu, Yu-Shu; Pan, Lehua & Pruess, Karsten
Partner: UNT Libraries Government Documents Department
open access

Flow focusing in unsaturated fracture networks: A numerical investigation

Description: A numerical modeling study is presented to investigate flow-focusing phenomena in a large-scale fracture network, constructed using field data collected from the unsaturated zone of Yucca Mountain, Nevada, the proposed repository site for high-level nuclear waste. The two-dimensional fracture network for an area of 100 m x 150 m contains more than 20,000 fractures. Steady-state unsaturated flow in the fracture network is investigated for different boundary conditions and rock properties. Simula… more
Date: April 17, 2003
Creator: Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G.S. & Liu, Hui-Hai
Partner: UNT Libraries Government Documents Department
open access

A physically based numerical approach for modeling fracture-matrix interaction in fractured reservoirs

Description: Modeling fracture-matrix interaction within a multiple-phase flow system is a key issue for fractured reservoir simulation. Commonly used mathematical models for dealing with such interactions employ dual- or multiple-continuum concepts, in which fractures and matrix are represented as overlapping, different, but interconnected continua, described by parallel sets of conservation equations. The conventional single-point upstream weighting scheme is most commonly used to estimate flow mobility f… more
Date: May 4, 2004
Creator: Wu, Yu-Shu & Pruess, Karsten
Partner: UNT Libraries Government Documents Department
open access

Massively parallel computing simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada

Description: This paper presents the application of parallel computing techniques to large-scale modeling of fluid flow in the unsaturated zone (UZ) at Yucca Mountain, Nevada. In this study, parallel computing techniques, as implemented into the TOUGH2 code, are applied in large-scale numerical simulations on a distributed-memory parallel computer. The modeling study has been conducted using an over-one-million-cell three-dimensional numerical model, which incorporates a wide variety of field data for the h… more
Date: August 31, 2001
Creator: Zhang, Keni; Wu, Yu-Shu & Bodvarsson, G. S.
Partner: UNT Libraries Government Documents Department
open access

Geothermal Reservoir Dynamics - TOUGHREACT

Description: This project has been active for several years and has focused on developing, enhancing and applying mathematical modeling capabilities for fractured geothermal systems. The emphasis of our work has recently shifted towards enhanced geothermal systems (EGS) and hot dry rock (HDR), and FY05 is the first year that the DOE-AOP actually lists this project under Enhanced Geothermal Systems. Our overall purpose is to develop new engineering tools and a better understanding of the coupling between flu… more
Date: March 15, 2005
Creator: Pruess, Karsten; Xu, Tianfu; Shan, Chao; Zhang, Yingqi; Wu, Yu-Shu; Sonnenthal, Eric et al.
Partner: UNT Libraries Government Documents Department
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