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A Compilation of Data on Fluids from Geothermal Resources in the United States

Description: This report is part of the Lawrence Berkeley Laboratory work to compile data of characteristics of the main U.S. geothermal source areas. The purpose of this compilation is to provide information on the chemistry of geothermal fluids to scientists and engineers involved with the development of liquid dominated geothermal energy resources. The compilation is a comprehensive tabulation of available geothermal fluid data from the most important geothermal resources in the United States. [Abstracter's note: This was part of a large but short-lived effort at LBNL to collect lots of geothermal data. There may be other reports that are worth searching for to add to the Geothermal Legacy collection at OSTI. DJE-2005]
Date: May 1, 1978
Creator: Cosner, S.R. & Apps, J.A.
Partner: UNT Libraries Government Documents Department

Sampling Geopressured Fluids: Some Contributions from the Properties of the H{sub2}O-CH{sub4} System

Description: This paper is devoted t o predicting and quantitatively estimating geopressured fluid behavior during sampling of reservoirs in their natural, unperturbed conditions. Both the fluid in the sampler and the wellbore fluid are considered. To that end, I have developed a simple model ( an ''equation of state") t o estimate thermophysical properties of geopressured fluids. This model is briefly described. The "equation of state" is applied to compute and discuss fluid properties associated with the different stages of the sampling process. Questions explored include: the probable range of CH4 content of the samples; pressure, phase transitions, fraction of total volume corresponding to each phase, and composition of each phase present in the sample, over the expected range of temperatures; whether and under what conditions the fluid collected at wellhead in a flowing w e l l provides a representative sample of the bottomhole fluid composition; the expected range of fluid pressures in the lubricator; and the expected range of differential stresses on the sampler. Bottomhole temperatures and pressures generally increase with depth in the geopressured formations of the Gulf Coast (e.g., Dorfman and Fisher, 1979). Thus, two well depths, representing approximatley the top and the bottom of the geopressured zone, were considered in detail to assess effects associated with depth. Finally, r e s u l t s and recommendations are summarized in Section I V .
Date: August 18, 1980
Creator: Iglesias, Eduardo R.
Partner: UNT Libraries Government Documents Department

Effect of Measured Wellhead Parameters and Well Scaling on the Computed Downhole Conditions in Cerro Prieto Wells

Description: This paper is devoted to the discussion of the wellbore model and its describing equations, comparison between the computed and measured pressures and the effect of measured wellhead parameters on the downhole pressures in the well. Finally a wellbore model with multiple inside diameters is discussed and the effect of well scaling on the bottom hole pressures is studied.
Date: December 16, 1980
Creator: Goyal, K.P.; Miller, C.W. & Lippmann, M.J.
Partner: UNT Libraries Government Documents Department

Eliminating the Wellbore Response in Transient Well Test Analysis

Description: The main purpose of this work is to show that it is possible to calculate the sandface flowrate given wellhead conditions and the downhole pressure transients. It is not necessary t o know anything about the reservoir itself. First, it is of interest to look at the nonuniform pressure changes in the well, and to illustrate nonisothermal effects on pressure transient data.
Date: December 16, 1980
Creator: Miller, Constance W.
Partner: UNT Libraries Government Documents Department

Numerical Studies of the Energy Sweep in Five-Spot Geothermal Production/Injection Systems

Description: Most recent interest in the injection of cold water into a geothermal reservoir has been related to the disposal of geothermal brines. Injection also offers the potential benefit of prolonging the useful life of a vapor-dominated system by providing additional water to extract energy out of the rock matrix. In a liquid-dominated reservoir injection may help to maintain pressures near the production wells by pushing the hot water toward them and preventing too much local boiling. Pressure maintenance can also be achieved for superheated steam zones, because injection will cause pressures to increase towards the saturation pressure (Schroeder et a l . (1980)). The general physical principles governing these processes are understood but no quantitative information is available. The present work is aimed at helping to improve the qualitative and quantitative understanding of injection into a geothermal reservoir by considering a few idealized problems. First a vapor-dominated, single layer reservoir is considered, next a vapor-dominated, four layer reservoir, and finally a liquid-dominated, single layer reservoir. In each case varying injection rates are considered and in some cases the injectionis changed at different times.
Date: December 16, 1980
Creator: O'Sullivan, M.J. & Pruess, K.
Partner: UNT Libraries Government Documents Department

The Sensitivity of Geothermal Reservoir Behavior to Relative Permeability Parameters

Description: In the present work three problems are considered; (1) the sensitivity of {nu}{sub t} and h{sub f} to variations in the relative permeability functions; (2) the determination of {nu}{sub t} and h{sub f} from well-test data, following which a method of is suggested to use these results together with theoretical plots of k{sub rl} and k{sub rv} versus h{sub f} to deduce the general shape of the relative permeability functions is suggested; and ( 3 ) the effect of the relative permeability functions on the pressure decline and flowing enthalpy build-up during a constant rate production test. It is shown that the characteristic rise in the flowing enthalpy from its initial value to a stable value after a moderate time is strongly influenced by the dependence of h{sub f} on S{sub 1} (and hence k{sub rl} and k{sub rv} on S{sub 1}) .
Date: December 16, 1980
Creator: Bodvarsson, Gudmundur S.; O'Sullivan, Michael J. & Tsang, Chin Fu
Partner: UNT Libraries Government Documents Department

Enhancement of Steam Phase Relative Permeability Due to Phase Transformation Effects in Porous Media

Description: An experimental study of two-phase concurrent flow of steam and water conducted (Verma et al., 1985) and a set of relative permeability curves was obtained. These curves were compared with semi-empirical results (Brooks and Corey, 1964) and experimental results obtained by other investigators (Johnson et al., 1959, and Osoba et al., 1951) for two-phase, two-component flow (oil/gas; gas/water; gas/oil). It was found that while the wetting phase relative permeabilities were in good agreement, the relative permeability for the steam phase was considerably higher than the relative permeabilities of the non-wetting phase (oil in oil/water and non-condensing gas in gas/oil or gas/water) in two-component systems (Figs. 1 and 2). This enhancement of steam relative permeability is attributed to phase transformation effects at the pore level in flow channels. There are two separate mechanisms by which phase transformation affected relative permeability CUTVBS (1) phase transformation in converging-diverging flow channels with hydrophilic walls can cause an enhancement of steam phase relative permeability; and (2) phase transformation along the interface of a stagnant phase and the phase flowing around it controls the irreducible phase saturation of the stagnant phase (Verma, 1986). A pore level model was considered to study the first mechanism. In this model a pore space, shown in Figure 3, is idealized as a toroidal flow channel (Fig. 4) with a throat radius r, and pore body radius rb. Flow of steam and water through the throat portion of a pore was modeled using the MULKOM simulator (Pruess, 1983). The results indicate that when steam encounters a pore throat of a highly constricted flow channel in high conductivity solid, a fraction of the flowing steam condenses upstream from the constriction, depositing its latent heat of condensation. This heat is conducted through the solid grains around the pore throat, and evaporation takes place ...
Date: January 21, 1986
Creator: Verma, A. & Pruess, K.
Partner: UNT Libraries Government Documents Department

Natural State Model of the Nesjavellir Geothermal Field, Iceland

Description: The Nesjavellir geothermal system in southern Iceland is very complex from both a thermal and hydrologic point of view. There are large pressure and temperature gradients in the wellfield and zones with drastically different pressure potentials. Thus, natural fluid flow is substantial in the system and flow patterns are complex. We have developed a two-dimensional natural state model for the Nesjavellir system that matches reasonably well the observed pressure and temperature distributions. The match with field data has allowed determination of the energy recharge to the system and the permeability distribution. Fluids recharge the system at rate of 0.02 kg/s/m with an enthalpy of 1460 kJ/kg. The permeability in the main reservoir is estimated to be in the range of 1.5 to 2.0 md, which agrees well with injection test results from individual wells. Permeabilities in shallower reservoirs are about an order of magnitude higher. Most of the main reservoir is under twephase conditions, as are shallow aquifers in the southern part of the field. The model results also suggest that the low temperatures in the shallow part of the northern region of the field may be due to the young age of the system; i.e., the system is gradually heating up. If this is the case the estimated age of the system near the wellfield is on the order of a few thousand years.
Date: January 21, 1986
Creator: Bodvarsson, G. S.; Pruess, K.; Stefansson, V.; Steingrimsson, B.; Bjornsson, S.; Gunnarsson, A. et al.
Partner: UNT Libraries Government Documents Department

Quantitative Model of the Cerro Prieto Field

Description: A three-dimensional model of the Cerro Prieto geothermal field, Mexico, is under development. It is based on an updated version of LBL's hydrogeologic model of the field. It takes into account major faults and their effects on fluid and heat flow in the system. First, the field under natural state conditions is modeled. The results of this model match reasonably well observed pressure and temperature distributions. Then, a preliminary simulation of the early exploitation of the field is performed. The results show that the fluid in Cerro Prieto under natural state conditions moves primarily from east to west, rising along a major normal fault (Fault H). Horizontal fluid and heat flow occurs in a shallower region in the western part of the field due to the presence of permeable intergranular layers. Estimates of permeabilities in major aquifers are obtained, and the strength of the heat source feeding the hydrothermal system is determined.
Date: January 21, 1986
Creator: Halfman, S.E.; Lippmann, M.J. & Bodvarsson, G.S.
Partner: UNT Libraries Government Documents Department

Analysis of Thermally Induced Permeability Enhancement in Geothermal Injection Wells

Description: Reinjection of spent geothermal brine is a common means of disposing of geothermal effluents and maintaining reservoir pressures. Contrary to the predictions of two-fluid models (two-viscosity) of nonisothermal injection, an increase of injectivity, with continued injection, is often observed. Injectivity enhancement and thermally-affected pressure transients are particularly apparent in short-term injection tests at the Los Azufres Geothermal Field, Mexico. During an injection test, it is not uncommon to observe that after an initial pressure increase, the pressure decreases with time. As this typically occurs far below the pressure at which hydraulic fracturing is expected, some other mechanism for increasing the near-bore permeability must explain the observed behavior. This paper focuses on calculating the magnitude of the near-bore permeability changes observed in several nonisothermal injection tests conducted at the Los Azufres Geothermal Field. In order to evaluate the pressure transient data and calculate the magnitude of the thermally induced permeability changes, a new analytic solution for calculating pressure transients with time-varying sandface flowrates and temperatures has been developed. The effects of temperature-dependent fluid and rock properties, as well as a moving thermal front, are explicitly included in the calculations. Based on this new solution, a technique is developed for calculating the reservoir permeability, skin factor of the well, and near-bore permeability increases. The results of these calculations indicate that the permeability increases by a factor of 5 in the near-bore region during the 2 to 3 hour injection tests. A good correlation between the permeability increase and the sandface injection temperature indicates that the permeability increase is caused by cooling the formation. 9 figs., 9 refs.
Date: January 20, 1987
Creator: Benson, S. M.; Daggett, J. S.; Iglesias, E.; Arellano, V. & Ortiz-Ramirez, J.
Partner: UNT Libraries Government Documents Department

Conceptual Model of the Klamath Falls, Oregon Geothermal Area

Description: Over the last 50 years significant amounts of data have been obtained from the Klamath Falls geothermal resource. To date, the complexity of the system has stymied researchers, leading to the development of only very generalized hydrogeologic and geothermal models of the area. Recently, the large quantity of available temperature data have been re-evaluated, revealing new information on subsurface heat flow and locations of faults in the system. These inferences are supported by borehole, geochemical, geophysical, and hydrologic data. Based on re-evaluation of all available data, a detailed conceptual model for the Klamath Falls geothermal resource is proposed. 1 tab., 8 figs., 21 refs.
Date: January 20, 1987
Creator: Prucha, R.H.; Benson, S.M. & Witherspoon, P.A.
Partner: UNT Libraries Government Documents Department

Decline Curve Analysis of Production Data from the Geysers Geothermal Field

Description: Production data for over two hundred wells at The Geysers geothermal field were compiled and analysed. Decline curves for groups of wells with 5, 10, and 40 acre spacing are presented and compared to curves published previously by Budd (1972) and Dykstra (1981). Decline curves for several individual wells and leases are discussed to illustrate the effects of well spacing and location, as well as the heterogeneous nature of the reservoir. 6 figs., 1 tab., 10 refs.
Date: January 20, 1987
Creator: Ripperda, M. & Bodvarsson, G.S.
Partner: UNT Libraries Government Documents Department

On Fluid and Heat Transfer in Deep Zones of Vapor-Dominated Geothermal Reservoirs

Description: We have presented a preliminary analysis of permeability structure and fluid and heat flow conditions in the deeper horizons of the Larderello geothermal system. Our main observations and findings are: (1) Measurements in deep Larderello wells have indicated formation temperatures near 300 ยบ C at 3000 m depth, and even higher temperatures at greater depth. (2) From an analysis of heat transfer mechanisms we suggest that a transition from vapor-dominated to liquid-dominated conditions must have been present in the natural state of the Larderello geothermal system. No reliable determination of the depth at which this transition occurred has yet been made, but a depth of approximately 2000 m or more appears most likely. (3) From temperature-depth data in two-phase reservoirs it is in principle possible to estimate vertical permeability. (4) For exploited reservoirs such as Larderello, reconstruction of permeability and temperature trends with depth can be made indirectly, using numerical simulation. Our preliminary results indicate that production of high-enthalpy fluids can be explained from two-phase flow effects in a fractured-porous medium. 18 refs., 2 tabs., 7 figs.
Date: January 20, 1987
Creator: Pruess, K.; Celati, R.; Calore, C. & Cappetti, G.
Partner: UNT Libraries Government Documents Department

Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior

Description: The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant part of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Fall in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with the development and exploitation of geothermal resources.
Date: March 21, 1989
Creator: Lippmann, Marcelo J.
Partner: UNT Libraries Government Documents Department

Automatic History Matching of Geothermal Field Performance

Description: We have developed inverse modeling capabilities for the multiphase multicomponent numerical simulator TOUGH2 to facilitate automatic history matching and parameter estimation based on data obtained during exploitation of geothermal fields. The ITOUGH2 code allows one to estimate TOUGH2 input parameters based on any type of observation for which a corresponding TOUGH2 output can be calculated. Furthermore, a detailed residual and error analysis is performed, and the uncertainty of model predictions can be evaluated. This paper focuses on the solution of the inverse problem, i.e. the determination of model-related parameters by automatically calibrating a conceptual model of the geothermal system against data obtained during field operation. We first describe the modeling approach used to simulate fluid and heat flow in fractured-porous media. The inverse problem is then formulated, followed by a brief discussion of the optimization algorithm. A sample problem is given to demonstrate the application of the method to geothermal reservoir data.
Date: January 1, 1995
Creator: Finsterle, S. & Pruess, K.
Partner: UNT Libraries Government Documents Department

ITOUGH2 sample problems

Description: This report contains a collection of ITOUGH2 sample problems. It complements the ITOUGH2 User`s Guide [Finsterle, 1997a], and the ITOUGH2 Command Reference [Finsterle, 1997b]. ITOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media [Preuss, 1987, 1991a]. The report ITOUGH2 User`s Guide [Finsterle, 1997a] describes the inverse modeling framework and provides the theoretical background. The report ITOUGH2 Command Reference [Finsterle, 1997b] contains the syntax of all ITOUGH2 commands. This report describes a variety of sample problems solved by ITOUGH2. Table 1.1 contains a short description of the seven sample problems discussed in this report. The TOUGH2 equation-of-state (EOS) module that needs to be linked to ITOUGH2 is also indicated. Each sample problem focuses on a few selected issues shown in Table 1.2. ITOUGH2 input features and the usage of program options are described. Furthermore, interpretations of selected inverse modeling results are given. Problem 1 is a multipart tutorial, describing basic ITOUGH2 input files for the main ITOUGH2 application modes; no interpretation of results is given. Problem 2 focuses on non-uniqueness, residual analysis, and correlation structure. Problem 3 illustrates a variety of parameter and observation types, and describes parameter selection strategies. Problem 4 compares the performance of minimization algorithms and discusses model identification. Problem 5 explains how to set up a combined inversion of steady-state and transient data. Problem 6 provides a detailed residual and error analysis. Finally, Problem 7 illustrates how the estimation of model-related parameters may help compensate for errors in that model.
Date: November 1, 1997
Creator: Finsterle, S.
Partner: UNT Libraries Government Documents Department

Sensitivity study on hydraulic well testing inversion using simulated annealing

Description: For environmental remediation, management of nuclear waste disposal, or geothermal reservoir engineering, it is very important to evaluate the permeabilities, spacing, and sizes of the subsurface fractures which control ground water flow. Cluster variable aperture (CVA) simulated annealing has been used as an inversion technique to construct fluid flow models of fractured formations based on transient pressure data from hydraulic tests. A two-dimensional fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes an aperture of cluster of fracture elements, which are chosen randomly from a list of discrete apertures, to improve the match to observed pressure transients. The size of the clusters is held constant throughout the iterations. Sensitivity studies using simple fracture models with eight wells show that, in general, it is necessary to conduct interference tests using at least three different wells as pumping well in order to reconstruct the fracture network with a transmissivity contrast of one order of magnitude, particularly when the cluster size is not known a priori. Because hydraulic inversion is inherently non-unique, it is important to utilize additional information. The authors investigated the relationship between the scale of heterogeneity and the optimum cluster size (and its shape) to enhance the reliability and convergence of the inversion. It appears that the cluster size corresponding to about 20--40 % of the practical range of the spatial correlation is optimal. Inversion results of the Raymond test site data are also presented and the practical range of spatial correlation is evaluated to be about 5--10 m from the optimal cluster size in the inversion.
Date: November 1, 1997
Creator: Nakao, Shinsuke; Najita, J. & Karasaki, Kenzi
Partner: UNT Libraries Government Documents Department

Modifications and additions to selected TOUGH2 modules

Description: The purpose of this report is to provide all software baseline documents necessary for the software qualification of the revised versions of the selected TOUGH2 modules, which include single-phase gas (EOS1G), effective continuum method (EOS3/ECM), saturated/unsaturated flow (EOS9), and radionuclide transport (T2R3D) modules of the TOUGH2 code. TOUGH2 is a numerical simulation code for multi-dimensional, coupled fluid and heat flow of multiphase, multicomponent fluid mixtures in porous and fractured media. This report augments the document Software Qualification of Selected TOUGH2 modules. This report contains the following sections: (1) requirement specifications and code development and (2) software validation test plan and results. These sections comprise sequential parts of Software Lifecycle, and should be used in conjunction with the TOUGH User`s Guide, TOUGH2 documentation, TOUGH2 Software Qualification, and Software Qualification of Selected TOUGH2 modules. The version of TOUGH2 used with the software being qualified herein is the October 1996 Standard Version 1.2, as qualified in Wu et al. (1996) and housed at the Department of Energy`s Energy Science and Technology Software Center (ESTSC) in Oak Ridge, Tennessee.
Date: January 1, 1998
Creator: Wu, Y.S. & Mishra, A.K.
Partner: UNT Libraries Government Documents Department

Laboratory studies of groundwater degassing in replicas of natural fractured rock for linear flow geometry

Description: Laboratory experiments to simulate two-phase (gas and water) flow in fractured rock evolving from groundwater degassing were conducted in transparent replicas of natural rock fractures. These experiments extend the work by Geller et al. (1995) and Jarsjo and Geller (1996) that tests the hypothesis that groundwater degassing caused observed flow reductions in the Stripa Simulated Drift Experiment (SDE). Understanding degassing effects over a range of gas contents is needed due to the uncertainty in the gas contents of the water at the SDE. The main objectives of this study were to: (1) measure the effect of groundwater degassing on liquid flow rates for lower gas contents than the values used in Geller for linear flow geometry in the same fracture replicas of Geller; (2) provide a data set to develop a predictive model of two-phase flow in fractures for conditions of groundwater degassing; and (3) improve the certainty of experimental gas contents (this effort included modifications to the experimental system used by Geller et al. and separate gas-water equilibration tests). The Stripa site is being considered for a high-level radioactive waste repository.
Date: February 1, 1998
Creator: Geller, J.T.
Partner: UNT Libraries Government Documents Department

Multiphase inverse modeling: An Overview

Description: Inverse modeling is a technique to derive model-related parameters from a variety of observations made on hydrogeologic systems, from small-scale laboratory experiments to field tests to long-term geothermal reservoir responses. If properly chosen, these observations contain information about the system behavior that is relevant to the performance of a geothermal field. Estimating model-related parameters and reducing their uncertainty is an important step in model development, because errors in the parameters constitute a major source of prediction errors. This paper contains an overview of inverse modeling applications using the ITOUGH2 code, demonstrating the possibilities and limitations of a formalized approach to the parameter estimation problem.
Date: March 1, 1998
Creator: Finsterle, S.
Partner: UNT Libraries Government Documents Department

Theoretical and experimental investigations of ferrofluids for guiding and detecting liquids in the subsurface. FY 1997 annual report

Description: Ferrofluids are stable colloidal suspensions of magnetic particles in various carrier liquids with high saturation magnetizations, which can be manipulated in virtually any fashion, defying gravitational or viscous forces in response to external magnetic fields. In this report, the authors review the results of their investigation of the potential of ferrofluids (1) to accurately and effectively guide reactants (for in-situ treatment) or barrier liquids (low-viscosity permeation grouts) to contaminated target zones in the subsurface using electromagnetic forces, and (2) to trace the movement and position of liquids injected in the subsurface using geophysical methods. They investigate the use of ferrofluids to enhance the efficiency of in-situ treatment and waste containment through (a) accurate guidance and delivery of reagent liquids to the desired subsurface contamination targets and/or (b) effective sweeping of the contaminated zone as ferrofluids move from the application point to an attracting magnet/collection point. They also investigate exploiting the strong magnetic signature of ferrofluids to develop a method for monitoring of liquid movement and position during injection using electromagnetic methods. The authors demonstrated the ability to induce ferrofluid movement in response to a magnetic field, and measured the corresponding magnetopressure. They demonstrated the feasibility of using conventional magnetometry for detecting subsurface zones of various shapes containing ferrofluids for tracing liquids injected for remediation or barrier formation. Experiments involving spherical, cylindrical and horizontal slabs showed a very good agreement between predictions and measurements.
Date: March 1, 1998
Creator: Moridis, G.J.; Borglin, S.E.; Oldenburg, C.M. & Becker, A.
Partner: UNT Libraries Government Documents Department

EOS9nT: A TOUGH2 module for the simulation of flow and solute/colloid transport

Description: EOS9nT is a new TOUGH2 module for the simulation of flow and transport of an arbitrary number n of tracers (solutes and/or colloids) in the subsurface. The module first solves the flow-related equations, which are comprised of (a) the Richards equation and, depending on conditions, may also include (b) the flow equation of a dense brine or aqueous suspension and/or (c) the heat equation. A second set of transport equations, corresponding to the n tracers, are then solved sequentially. The low concentrations of the n tracers are considered to have no effect on the liquid phase, thus making possible the decoupling of their equations. The first set of equations in EOS9nT provides the flow regime and account for fluid density variations due to thermal and/or solute concentration effects. The n tracer transport equations account for sorption, radioactive decay, advection, hydrodynamic dispersion, molecular diffusion, as well as filtration (for colloids only). EOS9nT can handle gridblocks or irregular geometry in three-dimensional domains. Preliminary results from four 1-D verification problems show an excellent agreement between the numerical predictions and the known analytical solutions.
Date: April 1, 1998
Creator: Moridis, G.J.; Wu, Y.S. & Pruess, K.
Partner: UNT Libraries Government Documents Department

TOUGH90: A FORTRAN90 implementation of TOUGH2

Description: TOUGH90 is a FORTRAN90 implementation of TOUGH2, and represents a major change in syntax and architecture over TOUGH2, while maintaining full backward compatibility with existing input data files. The main features of TOUGH90 include dynamic memory management, the use of modules, derived types, array operations, matrix manipulation, and new and very powerful intrinsic procedures. These result in a faster, more efficient and compact code, which is conceptually simpler, and significantly easier to modify and upgrade.
Date: April 1, 1998
Creator: Moridis, G.J.
Partner: UNT Libraries Government Documents Department

Numerical modeling of field tests in unsaturated fractured basalt at the Box Canyon site

Description: A TOUGH2 model of a ponded infiltration test has been developed and used to predict the results of a field experiment conducted in the vadose zone of the fractured Snake River Plain basalts, at the Box Canyon site in southeastern idaho. The key question addressed is how fracture-pattern characteristics and connectivity affect the pattern of liquid infiltration. The numerical model, a two-dimensional vertical cross-section, uses half-meter discretization for the shallow field site, which extends about 20 m from the ground surface to an underlying perched water body. The model includes explicit but highly simplified representations of major fractures and other important hydrological features. It adequately reproduces the majority of the field observations, confirming the notion that infiltration is largely fracture-controlled.
Date: May 1, 1998
Creator: Doughty, C.
Partner: UNT Libraries Government Documents Department