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
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 Borehole Tides and Other Elastomechanical Oscillatory Phenomena in Geothermal Systems (open access)

Interpretation of Borehole Tides and Other Elastomechanical Oscillatory Phenomena in Geothermal Systems

Ultralow to low-frequency oscillatory phenomena of elastomechanical nature have been observed in a number of geothermal areas. These include pressure and water level oscillations in the tidal frequency range 10{sup -6} to 10{sup -4} Hz (White, 1968), flow oscillations at around 10{sup -3} Hz (Bodvarsson and Bjornsson, 1976) and ground noise in the range 10{sup -1} to 10 Hz (Douze and Sorrel, 1972). The presence of such oscillations conveys certain information on the underlying geothermal systems which is of both theoretical and practical interest. In the following, we will very briefly discuss a few aspects relating to the interpretation of oscillatory field data with the main emphasis on borehole tides. 3 figs., 4 refs.
Date: December 14, 1977
Creator: Bodvarsson, Gunnar
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
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
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
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
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
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
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
Japanese Primary Energy Supply and Geophysical Well Logging (open access)

Japanese Primary Energy Supply and Geophysical Well Logging

Japan is scarce in domestic natural resources. In fact, the degree of dependence on imports of basic raw materials is quite high. This paper describes primary energy supply as a background to the status of geothermal energy developments, and geophysical well logging in geothermal wells. 3 refs., 5 tabs., 5 figs.
Date: December 14, 1977
Creator: Hirakawa, Seiichi
System: The UNT Digital Library
Interference test analysis at the Takigami geothermal field, JP (open access)

Interference test analysis at the Takigami geothermal field, JP

A long term interference test was conducted under conditions of multiwell variable flow rate at Takigami for about ten months in 1987. The test data have been analyzed with an on-line analysis method on the basis of the linesource solution. This method employs Kalman filtering to process the data and then provides the best estimates of reservoir transmissivity and storativity when a new pressure data at an observation well becomes available. The pressure changes measured at seven observation wells have been analyzed with the present method using an infinite reservoir model. The data from one observation well have been further analyzed assuming a presence of a linear boundary. Performances of the parameters estimated for different reservoir models are compared. Fairly good estimates of reservoir parameters are obtained on the basis of an infinite reservoir model for two wells using the entire pressure data whereas for other five wells using a part of the pressure data.
Date: January 28, 1993
Creator: Itol, Ryuichi; Fukuda, Michihiro; Jinno, Kenji & Gotoh, Hiroki
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
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
Interpretation of the return profile of a tracer test in the Thelamork geothermal field, Iceland (open access)

Interpretation of the return profile of a tracer test in the Thelamork geothermal field, Iceland

As a part of a full scale production test, a long term tracer test was performed in the Thelamork low temperature geothermal system, in N-Iceland. The tracer test was aimed at recovering the transport properties of fractures connecting the injection and production wells. Hence, the estimated parameters might be used in determining the performance of the system under various injection schemes. A qualitative evaluation the tracer return profile showed the presence of strong recirculation effects. In addition, the return profile indicated that the medium appears to be highly dispersive. Earlier modelling studies employed a one-dimensional two path model to match the return profile and substituted the properties of the major path in the Lauwerier model to estimate the thermal breakthrough time. However, the two path model estimates a very large dispersive tiansport almost equal to the convective transport. This large dispersivity necessitates adding a dispersive heat transport term in the Lauwerier model and as a result reduces the Lauwerier thermal breakthrough time almost to half. Considering the injection and production rates, we used a more accurate one-dimensional five-path model in this work. This model infers a smaller dispersivity and leads to a greater breakthrough time than the two path model, …
Date: January 24, 1996
Creator: Kocabas, I.; Axelsson, G. & Bjornsson, G.
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
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
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
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
Well Interference Study of the Multi-Layered Salton Sea Geothermal Reservoir (open access)

Well Interference Study of the Multi-Layered Salton Sea Geothermal Reservoir

A well interference testing program of the Salton Sea Geothermal reservoir is being conducted as part of a resource evaluation study by the Earth Sciences Geothermal Industrial Support Program of the Lawrence Livermore Laboratory. Studies to date indicate the reservoir rock to be composed of layered sequences of shales and sands. Wells involved in the testing program are being used in support of, or are in the vicinity of, the MAGMA-SDG&E Geothermal Loop Experimental Facility (GLEF), located in the Salton Sea Geothermal Field (SSGF). Between these wells, a shale layer has been correlated which appears to divide the reservoir into an upper and lower portion. Other thick sand and shale sequences may provide additional stratification. This report describes work in progress on a well testing program designed to determine the horizontal and vertical transmissivity and storage parameters between wells in the vicinity of the GLEF. These tests are being conducted with the cooperation and support of Magma Power Company and San Diego Gas and Electric Company. 3 figs., 4 refs.
Date: December 14, 1977
Creator: Morse, J.G.
System: The UNT Digital Library
Kamchatka geothermal resources development: Problems and perspectives (open access)

Kamchatka geothermal resources development: Problems and perspectives

There are four long-term exploited geothermal fields in Kamchatka: one steam-water field Pauzhetka (south of Kamchatka peninsula) and three hot water fields: Paratunka (near by town of Petropavlovsk-Kamchatsky) and Esso and Anavgay (center of peninsula). Pauzhetka and Paratunka fields are exploited during almost 28 years. Esso and Anavgay fields are exploited during 25 years. In Pauzhetka 11 MWe geothermal power plant work and on the other fields thermal energy of hot water is directly used. Kamchatka region satisfies energetic demands mainly by organic imported fuels. At the same time electricity produced by geothermal fluids constitutes less than 2 per cent of total region electricity production, and thermal energy produced by geothermal fluids constitutes less than 3 per cent of total region thermal energy production. The main reasons of small geothermal portion in the energy production balance of Kamchatka are briefly discussed. The geothermal development reserves and perspectives of geothermal energy use increase in Kamchatka are outlined.
Date: January 24, 1966
Creator: Pashkevich, Roman I.
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
Proceedings of the Workshop on Geothermal Reservoir Engineering: 1977 (open access)

Proceedings of the Workshop on Geothermal Reservoir Engineering: 1977

The Third Workshop on Geothermal Reservoir Engineering convened at Stanford University on December 14, 1977, with 104 attendees from six nations. In keeping with the recommendations expressed by the participants at the Second Workshop, the format of the Workshop was retained, with three days of technical sessions devoted to reservoir physics, well and reservoir testing, field development, and mathematical modeling of geothermal reservoirs. The program presented 33 technical papers, summaries of which are included in these Proceedings. Although the format of the Workshop has remained constant, it is clear from a perusal of the Table of Contents that considerable advances have occurred in all phases of geothermal reservoir engineering over the past three years. Greater understanding of reservoir physics and mathematical representations of vapor-dominated and liquid-dominated reservoirs are evident; new techniques for their analysis are being developed, and significant field data from a number of newer reservoirs are analyzed. The objectives of these workshops have been to bring together researchers active in the various physical and mathematical disciplines comprising the field of geothermal reservoir engineering, to give the participants a forum for review of progress and exchange of new ideas in this rapidly developing field, and to summarize the effective …
Date: December 15, 1977
Creator: Ramey, H. J., Jr. & Kruger, P. (eds.)
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