Experimental study of two-phase flow in rough fractures (open access)

Experimental study of two-phase flow in rough fractures

Two-phase (air-water) flow experiments were conducted in horizontal artificial fractures. The fractures were between glass plates (1 x 0.5 m) artificially roughened by gluing a layer of glass beads of Imm diameter. Three rough fractures were studied: one with the two surfaces in contact, and two without contact. Videotape observations revealed flow structures similar to those observed in two-phase flow in pipes, with structures depending upon the gas and liquid flow rates. The data of flow rates, pressure gradients and saturations were interpreted using the generalized Darcy's law. Relative permeabilities curves were found to be similar to classical curves in porous medium, but not unique functions of saturations. The sum of gas and liquid relative permeabilities were found to be less than one at all saturations.
Date: January 1, 1992
Creator: Fourar, M.; Bories, S. & Lenormand, R.
System: The UNT Digital Library
Stimulation of well SN-12 in the Seltjarnarnes low-temperature field in SW-Iceland (open access)

Stimulation of well SN-12 in the Seltjarnarnes low-temperature field in SW-Iceland

Well SN-12 in the Seltjarnarnes low-temperature field in SW-Iceland was drilled to a depth of 2714 m in the fall of 1994. The well appeared to be almost non-productive at the end of drilling. A comprehensive ten day stimulation program was, therefore, initiated. The program involved, firstly, high-pressure wellhead injection and, secondly, high-pressure injection below a packer placed at 1412 m depth. After about twelve hours of wellhead stimulation the pressure dropped suddenly, indicating that the well had been stimulated. At the same time the water level response increased suddenly in two near-by monitoring wells. During the second stimulation phase (packer at 1412 m) the well appeared to be stimulated even further. The well eventually produced about 35 l/s with a drawdown of roughly 60 m, and the stimulation had increased the yield of the well by a factor of nearly 60. Thus well SN-12, which appeared to be almost non-productive at the completion of drilling, had turned into a good production well. It is believed that during the stimulation some previously closed fractures, or interbed contacts, reopened connecting well SN-12 to the main fracture system of the geothermal reservoir.
Date: January 24, 1996
Creator: Tulinius, Helga; Axelsson, Gudni; Tomasson, Jens; Kristmannsdottir, Hrefna & Gudmundsson, Asgrimur
System: The UNT Digital Library
Results from a discrete fracture network model of a Hot Dry Rock system (open access)

Results from a discrete fracture network model of a Hot Dry Rock system

The work described represents a move towards better representations of the natural fracture system. The discrete fracture network model used during the study was the NAPSAC code (Grindrod et al, 1992). The goals of the work were to investigate the application of discrete fracture network models to Hot Dry Rock systems, increase the understanding of the basic thermal extraction process and more specifically the understanding of the Rosemanowes Phase 2B system. The aim in applying the work to the Rosemanowes site was to use the discrete fracture network approach to integrate a diverse set of field measurements into as simple a model as possible.
Date: January 28, 1993
Creator: Lanyon, G.W.; Batchelor, A.S. & Ledingham, P.
System: The UNT Digital Library
A study of production/injection data from slim holes and large-diameter production wells at the Oguni Geothermal Field, JP (open access)

A study of production/injection data from slim holes and large-diameter production wells at the Oguni Geothermal Field, JP

Production and injection data from 11 slim holes and 10 large-diameter wells at the Oguni Geothermal Field, Japan, were examined in an effort to establish relationships (1) between productivity of large-diameter wells and slim holes, (2) between injectivity and productivity indices and (3) between productivity index and borehole diameter. The production data from Oguni boreholes imply that the mass production from large diameter wells may be estimated based on data from slim holes. Test data from both large- and smalldiameter boreholes indicate that to first order the productivity and the injectivity indices are equal. Somewhat surprisingly, the productivity index was found to be a strong function of borehole diameter; the cause for this phenomenon is not understood at this time.
Date: January 20, 1994
Creator: Garg, S. K.; Combs, Jim & Abe, M.
System: The UNT Digital Library
Simulating a challenging water dominated geothermal system: The Cerro Prieto field, Baja California, Mexico (open access)

Simulating a challenging water dominated geothermal system: The Cerro Prieto field, Baja California, Mexico

A three dimensional, multiphase, numerical simulation model of the Cerro Prieto field was developed and used to verify that the present installed capacity (620 MW) can be sustained for 30 years and to evaluate the impact of an 80 MW addition to the installed capacity in the NE-E of the field on the present production areas. Cerro Prieto is the largest known water-dominated geothermal reservoir in the world, with more than 175 wells drilled to date and 17 years of production history. Wells here produce fluids of varying enthalpy, from moderate-temperature water to dry steam. The varying enthalpy and a complex interaction between the reservoir and the surrounding aquifer posed a real simulation challenge. The simulation approach used to reproduce the major features of the initial-state and the production history of the field is discussed in this paper. From this study it was concluded that the field is capable of sustaining its present 620 MW total installed capacity for 30 years and the addition of the proposed 80 MW should have a negligible effect on the present production area.
Date: January 1, 1991
Creator: Antunez, E.U.; Menzies, A.J. & Sanyal, S.K.
System: The UNT Digital Library
Laboratory measurement of sorption in porous media (open access)

Laboratory measurement of sorption in porous media

A new apparatus for measuring steam adsorption-desorption isothermally on rock samples has been installed and initial runs made for rock samples from geothermal reservoirs. The amounts adsorbed measured in these experiments are the same order of magnitude as previous experiments.
Date: January 1, 1992
Creator: Harr, M. S.; Pettit, P. & Ramey, J. J., Jr.
System: The UNT Digital Library
Simulation studies for wells AH-4bis/AH-17 and AH-18, Ahuachapan Geothermal Field (open access)

Simulation studies for wells AH-4bis/AH-17 and AH-18, Ahuachapan Geothermal Field

Well AH-4<sub>bis</sub>, at the Ahuachapan Geothermal Field is planned to be drilled on the same pad as the former AH-4. A simulation study was carried out for two casing dameters 13 5/8 and 9 5/8” in order to estimate its production and to know its economic feasibility. The simulation results indcate a high probability of production in the range of 7 Mwe, equivalent to 120 kg/s total mass flow rate, 1250 kJ/kg at 6 bar-a for the new well AH-4<sub>bis</sub>. Well AH- 17 is good producer, during 1991 after ten years of production, the well was shut-in due to silica scaling problems. A wellbore simulation was carried out in order to predict the new production conditions after the work-over, mainly to estimate the water flow rate in order to reduce the silica scaling. The results indicate a very low water flow rate. The match between the simulated and measured production curves after the work-over was successful. The well AH-18 is located at the southern part of the actual bore field. CEL is planning to expand the borefield at this area and it is neccessary to estimate the possible production condtions at that zone. The results indicate a high probabilty of …
Date: January 24, 1996
Creator: Monterrosa, Manuel Ernesto
System: The UNT Digital Library
Interpretation of pre- and post-fracturing well tests in a geothermal reservoir (open access)

Interpretation of pre- and post-fracturing well tests in a geothermal reservoir

Pre- and post-fracturing well tests in TG-2 well drilled next to the Matsukawa field are interpreted for evaluating effects of a massive hydraulic fracturing treatment. The interpreted data include multiple-step rate tests, a two-step rate test, and falloff tests. Pressure behaviors of massive hydraulic fracturing are matched by a simulator of dynamic fracture option. Fracture parting pressures can be evaluated from the multiple-step rate test data. The multiple-step rates during the massive hydraulic fracturing treatment show that multiple fractures have been induced in sequence. Although the pre-fracturing falloff tests are too short, fracture propagation can be evaluated qualitatively from the falloff data. Interpretation of the falloff test immediately after the MHF suggests that extensive fractures have been created by the MHF, which is verified by simulation. The post-fracturing falloff tests show that the fractures created by the MHF have closed to a great degree.
Date: January 26, 1995
Creator: Arihara, Norio; Fukagawa, Hiroshi; Hyodo, Masami & Abbaszadeh, Maghsood
System: The UNT Digital Library
Interpretation of interference effects in three production wells in the Kawerau geothermal field, New Zealand (open access)

Interpretation of interference effects in three production wells in the Kawerau geothermal field, New Zealand

Downhole temperature and pressure, mass flow, and enthalpy measurements on three production wells at Kawerau geothermal field are interpretted to illustrate interference effects between these wells. Feed zone locations within the wells, together with geology and chemistry are discussed. Downhole measurements are made in one well while production flow changes are made on another well to monitor pressure transient effects. The interference effects have implications for planning future production drilling.
Date: January 24, 1996
Creator: Stevens, Lynell & Koorey, Kevin J.
System: The UNT Digital Library
An inverse problem solution to the flow of tracers in naturally fractured reservoirs (open access)

An inverse problem solution to the flow of tracers in naturally fractured reservoirs

This paper presents a solution for the inverse problem to the flow of tracers in naturally fractured reservoirs. The models considered include linear flow in vertical fractures, radial flow in horizontal fractures, and cubic block matrix-fracture geometry. The Rosenbrock method for nonlinear regression used in this study, allowed the estimation of up to six parameters for the cubic block matrix fracture geometry. The nonlinear regression for the three cases was carefully tested against syntetical tracer concentration responses affected by random noise, with the objective of simulating as close as possible step injection field data. Results were obtained within 95 percent confidence limits. The sensitivity of the inverse problem solution on the main parameters that describe this flow problem was investigated. The main features of the nonlinear regression program used in this study are also discussed. The procedure of this study can be applied to interpret tracer tests in naturally fractured reservoirs, allowing the estimation of fracture and matrix parameters of practical interest (longitudinal fracture dispersivity alpha, matrix porosity phi2, fracture half-width w, matrix block size d, matrix diffusion coefficient D2 and the adsorption constant kd). The methodology of this work offers a practical alternative for tracer flow tests interpretation to …
Date: January 20, 1994
Creator: S., Jetzabeth Ramirez; V., Fernando Samaniego; Rodriguez, Fernando & R., Jesus Rivera
System: The UNT Digital Library
Simple numerical simulation for liquid dominated geothermal reservoir (open access)

Simple numerical simulation for liquid dominated geothermal reservoir

A numerical model for geothermal reservoir has been developed. The model used is based on an idealized, two-dimensional case, where the porous medium is isotropic, nonhomogeneous, filled with saturated liquid. The fluids are assumed to have constant and temperature dependent viscosity. A Boussinesq approximation and Darcy’s law are used. The model will utilize a simple hypothetical geothermal system, i.e. graben within horsts structure, with three layers of different permeabilities. Vorticity plays an importance roles in the natural convection process, and its generation and development do not depend only on the buoyancy, but also on the magnitude and direction relation between the flow velocity and the local gradient of permeability to viscosity ratio. This model is currently used together with a physical, scaled-down reservoir model to help conceptual modeling.
Date: January 24, 1996
Creator: Wintolo, Djoko; Sutrisno; Sudjatmiko & Sudarman, S.
System: The UNT Digital Library
Structural interpretation of the Kakkonda deep geothermal reservoir (open access)

Structural interpretation of the Kakkonda deep geothermal reservoir

The Kakkonda geothermal field is known as a unique field such that a new reservoir was found at about 2500 m in depth after the shallow reservoir ranging from 1000 m to 1500 m had been produced for about eight years. The shallow reservoir is composed of sedimentary rock with igneous rock intrusions, while the deep reservoir is a fractured thin zone located at the top of a large granite intrusion. Between the two, there exist thermally metamorphosed zones. This study aims at integrated interpretation of the top structural surface of the deep reservoir. The data used include well data, microearthquakes, and several metamorphic minerals. Microearthquakes, which are continuously observed at surface, reflect the structural surface of the granite intrusion of the deep reservoir. The metamorphic minerals such as biotite and cordierite caused by strong heat conduction out of the granite also give an image of the structure. Based on the spacings of acoustic emission data, images of the structural surface are extracted statistically. The degree of uncertainty is evaluated. The isograds of the metamorphic mineral distributions are reproduced by a regional heat conduction model.
Date: January 24, 1996
Creator: Kobayashi, Osamu; Arihara, Norio & Hanano, Mineyuki
System: The UNT Digital Library
Structural control is a strategy for exploitation well at Kamojang Geothermal Field, West Java, Indonesia (open access)

Structural control is a strategy for exploitation well at Kamojang Geothermal Field, West Java, Indonesia

Kamojang Geothermal Field is one of the best geothermal field in the world, explored since 1918. The field lies 33 km south-east Bandung, West Java. It is located in the centre of a volcanic chain which has progressively grown from WSW to ENE. Three tectonic activities have created current Kamojang structures. Firstly, the circular collapse of Pangkalan, 2 km in diameter whch occupies the central part of the Kamojang field; secondly, NE -SW flults of tensional and lateral origin, are parallel to the magmatic axis; and last, 5 km wide graben is a major expression of NW-SE tensional faults. The faults, having N60 strike in the southeastern part of the field have been identified as a very important structures related to the main target of reservoir Kamojang field. Even if the faults and fractures have been altered in the upper part of the surface and form non permeable seals, the bottom sections may still be highly permeable. Therefore for development drilling one must consider the deep structures instead of just shallow expressions and alteration. Geological correlations between the several wells drilled up to date shows evidence that the structures correspond to the surface features as described above. Case study of …
Date: January 24, 1996
Creator: Hantono, Djoko; Mulyono, Agus & Hasibuan, Aidil
System: The UNT Digital Library
A study of the propagation of compression waves in porous medium filled with steam (open access)

A study of the propagation of compression waves in porous medium filled with steam

A preliminary investigation on the propagation of compression waves through a radial system of porous medium filled with steam has been conducted for the case of uniform and non-uniform basic temperature distributions. When a relatively weak pressure disturbance is introduced as a signal source in a uniform temperature system, it is found that the pressure disturbance decays away and smears out as time progresses. However, for the case of a nonuniform basic temperature distribution, the temperature gradient and fluid viscosity give significant effects on the reduction of pressure signal attenuation. The attenuation of the compression waves depends on the wave frequencies. For higher frequencies the strength of the signal decays rapidly, and for lower frequencies the signal could propagate farther away. It is found also that porosity and permeability distributions gives significant effects on the amplitude and the wave profiles.
Date: January 24, 1996
Creator: Sutrisno; Wintolo, Djoko; Kamal, Samsul & Sudarman, S.
System: The UNT Digital Library
Locating an Active Fault Zone in Coso Geothermal Field by Analyzing Seismic Guided Waves From Microearthquake Data (open access)

Locating an Active Fault Zone in Coso Geothermal Field by Analyzing Seismic Guided Waves From Microearthquake Data

Active fault systems usually provide high-permeability channels for hydrothermal outflow in geothermal fields. Locating such fault systems is of a vital importance to plan geothermal production and injection drilling, since an active fault zone often acts as a fracture-extensive low-velocity wave guide to seismic waves. We have located an active fault zone in the Coso geothermal field, California, by identifying and analyzing a fault-zone trapped Rayleigh-type guided wave from microearthquake data. The wavelet transform is employed to characterize guided-wave's velocity-frequency dispersion, and numerical methods are used to simulate the guided-wave propagation. The modeling calculation suggests that the fault zone is {approx} 200m wide, and has a P wave velocity of 4.80 km/s and a S wave velocity of 3.00 km/s, which is sandwiched between two half spaces with relatively higher velocities (P wave velocity 5.60 km/s, and S wave velocity 3.20 km/s). zones having vertical or nearly vertical dipping fault planes.
Date: January 26, 1995
Creator: Lou, M.; Malin, P. E. & Rial, J. A.
System: The UNT Digital Library
Study of desorption in a vapor dominated reservoir with fractal geometry (open access)

Study of desorption in a vapor dominated reservoir with fractal geometry

This paper is an attempt to model well decline in a vapor dominated reservoir with fractal geometry. The fractal network of fractures is treated as a continuum with characteristic anomalous diffusion of pressure. A numerical solver is used to obtain the solution of the partial differential equation including adsorption in the fractal storage space. The decline of the reservoir is found to obey the empirical hyperbolic type relation when adsorption is not present. Desorption does not change the signature of the flow rate decline but shifts it on the time/flow rate axis. Only three out of six model parameters can be estimated from field data, due to the linear correlation between parameters. An application to real well data from The Geysers field is presented together with the estimated reservoir, fractal space and adsorption parameters. Desorption dominated flow is still a questionable approximation for flow in fractal objects.
Date: January 26, 1995
Creator: Tudor, Monica; Horne, Roland N. & Hewett, Thomas A.
System: The UNT Digital Library
Liquid-phase dispersion during injection into vapor-dominated reservoirs (open access)

Liquid-phase dispersion during injection into vapor-dominated reservoirs

The behavior of water injection plumes in vapor-dominated reservoirs is examined. Stressing the similarity to water infiltration in heterogeneous soils, we suggest that everpresent heterogeneities in individual fractures and fracture networks will cause a lateral broadening of descending injection plumes. The process of lateral spreading of liquid phase is viewed in analogy to transverse dispersion in miscible displacement. To account for the postulated “phase dispersion” the conventional two-phase immiscible flow theory is extended by adding a Fickian-type dispersive term. The validity of the proposed phase dispersion model is explored by means of simulations with detailed resolution of small-scale heterogeneity. We also present an illustrative application to injection into a depleted vapor zone. It is concluded that phase dispersion effects will broaden descending injection plumes, with important consequences for pressure support and potential water breakthrough at neighboring production wells.
Date: January 20, 1994
Creator: Pruess, Karsten
System: The UNT Digital Library
Laboratory studies of injection into horizonal fractures (open access)

Laboratory studies of injection into horizonal fractures

Most geothermal reservoirs are extensively fractured and injected fluids usually enter the reservoir formation at distinct feed points. As the cold water passes through the hot rock, it is heated, and may be recovered at production wells for power production. The influence of fractures is two-fold. Firstly, preferential pathways exist along major faults and the general motion of fluids away from injection wells is controlled by the effective permeability structure. Secondly, since fractures can be spaced several metres or more apart and the flow rates within each fracture can be relatively high, the injected fluid does not necessarily attain thermal equilibrium will all of the host rock at a given distance from the injection well. It is important that sufficient heat transfer between the fluid and rock occurs before the injected fluid is recovered at an injection well in order to prevent thermal breakthrough. In this paper we present preliminary results of an experimental research program examining the effects of injection into fractures. We build upon previous theoretical work by seeking to confirm the results and then discuss the initial results of injection into superheated reservoirs.
Date: January 24, 1996
Creator: Fitzgerald, Shaun D.; Pruess, Karsten & van Rappard, Diederik M.
System: The UNT Digital Library
Simulating wellflow of high-nonocondensable-gas geofluids using laboratory measurements on secondary fluids (open access)

Simulating wellflow of high-nonocondensable-gas geofluids using laboratory measurements on secondary fluids

An experimental simulation of an actual steam-water geothermal well based on field data obtained in New Zealand is carried out in a two-phase flow facility using dichlorotetrafluoroethane, known commercially as refrigerant 114. The simulation of steam-water flow is accomplished by a similarity theory which is achieved by using appropriate dimensionless numbers; namely, the Mach, Froude, and Reynolds numbers at the flashing front. The theory is used to scale the flow properties from that of water to that of refrigerant 114 in the two-phase region, and permits the prediction of steam-water characteristics in a flowing well, under much reduced pressure and temperature levels. Two experimental series were conducted to confront the similarity theory with actual measurements from a flowing well with significant noncondensable gases. Experimental results using refrigerant 114 indicate that the pressure distribution along the pipe can be predicted accurately in the two-phase region of a geothermal well.
Date: January 1, 1991
Creator: Laoulache, R.N. & Dipippo, R.
System: The UNT Digital Library
Seventeenth workshop on geothermal reservoir engineering: Proceedings (open access)

Seventeenth workshop on geothermal reservoir engineering: Proceedings

PREFACE The Seventeenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 29-31, 1992. There were one hundred sixteen registered participants which equaled the attendance last year. Participants were from seven foreign countries: Italy, Japan, United Kingdom, France, Belgium, Mexico and New Zealand. Performance of many geothermal fields outside the United States was described in the papers. The Workshop Banquet Speaker was Dr. Raffaele Cataldi. Dr. Cataldi gave a talk on the highlights of his geothermal career. The Stanford Geothermal Program Reservoir Engineering Award for Excellence in Development of Geothermal Energy was awarded to Dr. Cataldi. Dr. Frank Miller presented the award at the banquet. Thirty-eight papers were presented at the Workshop with two papers submitted for publication only. Dr. Roland Horne opened the meeting and the key note speaker was J.E. ''Ted'' Mock who discussed the DOE Geothermal R. & D. Program. The talk focused on aiding long-term, cost effective private resource development. Technical papers were organized in twelve sessions concerning: geochemistry, hot dry rock, injection, geysers, modeling, and reservoir mechanics. Session chairmen were major contributors to the program and we thank: Sabodh Garg., Jim Lovekin, Jim Combs, Ben Barker, Marcel Lippmann, Glenn Horton, Steve Enedy, …
Date: January 31, 1992
Creator: Ramey, Henry J., Jr.; Kruger, Paul; Miller, Frank G.; Horne, Roland N.; Brigham, William E. & Cook, Jean W.
System: The UNT Digital Library
Laboratory measurements on reservoir rocks from The Geysers geothermal field (open access)

Laboratory measurements on reservoir rocks from The Geysers geothermal field

A suite of laboratory measurements have been conducted on Geysers metagraywacke and metashale recovered from a drilled depth of 2599 to 2602 meters in NEGU-17. The tests have been designed to constrain the mechanical and water-storage properties of the matrix material. Various measurements have been made at a variety of pressures and at varying degrees of saturation. Both compressional and shear velocities exhibit relatively little change with effective confining pressure. In all of the samples, water saturation causes an increase in the compressional velocity. In some samples, saturation results in a moderate decrease in shear velocity greater in magnitude than would be expected based on the slight increase in bulk density. It is found that the effect of saturation on the velocities can be quantitatively modeled through a modification of Biot-Gassmann theory to include weakening of the shear modulus with saturation. The decrease is attributed to chemo-mechanical weakening caused by the presence of water. The degree of frame weakening of the shear modulus is variable between samples, and appears correlated with petrographic features of the cores. Two related models are presented through which we can study the importance of saturation effects on field-scale velocity variations. The model results indicate that …
Date: January 26, 1995
Creator: Boitnott, G.N.
System: The UNT Digital Library
A survey of potential geopressured resource areas in California (open access)

A survey of potential geopressured resource areas in California

This paper presents the initial results of a survey of the occurrence and characteristics of geopressured fluid resources in California using the publicly-available database involving more than 150,000 oil and gas wells drilled in the State. Of the 975 documented on-shore oil and gas pools studied, about 42% were identified as potentially geopressured. Geothermal gradients in California oil and gas fields lie within the normal range of 1°F to 2°F per 100 feet. Except for the Los Angeles Basin, there was no evidence of higher temperatures or temperature gradients in geopressured pools. The porosity of geopressured pools shows the same normal distribution as for normal pressured pools, with a mode in the range of 20 to 25%. The salinity distribution of both the geopressured and normal pressured pools appear to be bimodal, each with two peak ranges of 0 to 10,000 and 25,000 to 30,000 ppm. Compared to the U.S. Gulf Coast region, geopressured pools in California display much lower water salinities, and therefore, should have a higher solubility for methane. Geopressured pools in California occur in the depth range of less than 1,000 feet to more than 18,000 feet. The modal depth of geopressured pools in California is 2,000 …
Date: January 28, 1993
Creator: Sanyal, S. K.; Robertson-Tait, A.; Kraemer, M. & Buening, N.
System: The UNT Digital Library
Significance of Crack Opening Monitoring for Determining the Growth Behavior of Hydrofractures (open access)

Significance of Crack Opening Monitoring for Determining the Growth Behavior of Hydrofractures

A method for determining the size of a crack induced by hydraulic fracturing is presented. The procedure is based on the measurement of the crack opening displacement and the fracture mechanics approach. The proposed method has been tested by conducting laboratory small-scale hydraulic fracturing tests on a granite. It is shown from the preliminary tests that the method provides a reasonable prediction of experimentally observed crack sizes.
Date: January 28, 1993
Creator: Hashida, Toshiyuki; Sato, Kazushi & Takahashi, Hideaki
System: The UNT Digital Library
An investigation of radial tracer flow in naturally fractured reservoirs (open access)

An investigation of radial tracer flow in naturally fractured reservoirs

This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile region where longitudinal dispersion and convection take place and a stagnant region where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared to those previously presented in literature by Moench and Ogata, Tang et al., Chen et al., and Hsieh et al. The solution is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., for short times) was carried out. The influence of various dimensionless parameters that enter into the solution was investigated. A discussion of results obtained through the Crump and Stehfest algorithm is presented, concluding that the Crump method provides more reliable tracer concentrations.
Date: January 1, 1991
Creator: Jetzabeth, Ramirez-Sabag; Fernando, Samaniego V.; Jesus, Rivera R. & Rodriguez, Fernando
System: The UNT Digital Library