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Introduction to the proceedings of the Fourth Geothermal Reservoir Engineering Workshop, Stanford Geothermal Program

Description: The program committee for the Fourth Geothermal Workshop, presented in mid-December, 1978, decided that the format of the last two geothermal workshops should be continued; that is, the objective should be documented talks on field phenomena and reports on important results of research directly applicable to geothermal energy development. An arranged panel discussion of problems of common importance was also built into the program. Finally, it was decided to publish all submitted papers in the proceedings, but to select papers for presentation at the workshop program.
Date: January 1, 1978
Creator: Kruger, Paul & Ramey, Henry J., Jr.
Partner: UNT Libraries Government Documents Department

Linear Water Influx of an Infinite Aquifer Through a Partially Communicating Fault

Description: This paper presents a linear flow water influx analysis method where the aquifer is separated from the reservoir by a partially communicating fault. Transient pressure distributions are considered both in the reservoir and in the aquifer. Cases where the leaky fault is located within the aquifer can be analyzed with this model given a superposition of constant rate flow periods at the oil-water interface. Constant production rate is specified at the inner boundary, without inner boundary storage and skin. The partially communicating fault is modeled as a boundary skin of infinitesimal thickness having no storage. The aquifer considered in this paper is infinite in the lateral extend. The problem is posed and solved using the Laplace transformation, yielding Laplace solutions of the exponential form. The solutions presented in this paper, along with a set of type curves extend the transient linear flow work presented by Hurst (1958) and by Nabor and Barham (1964). When the inner region, the reservoir, has an infinite permeability and a finite storage, it acts like a tank, where the boundary pressure is equal to average pressure in the inner region. This case is identical to the linear water influx model presented by Hurst (1958). When the inner region has no storage associated with it, the constant inner boundary rate is transmitted to the second infinite region, hence yielding the simple linear flow case presented by Nabor and Barham (1964). This paper extends the current solutions by allowing pressure variations in the reservoir or the inner region as well as in the infinite aquifer. Also, the model presented in this paper considers the effects of skin located at the boundary between the two regions of the system that may be caused by a partially communicating fault separating these two regions. 6 tabs., 14 figs., 12 refs.
Date: January 20, 1987
Creator: Ambastha, Anil K. & Sageev, Abraham
Partner: UNT Libraries Government Documents Department

One-dimensional steam flow in porous media under desorption

Description: Performance forecasting for a hypothetical field with Geysers greywacke rock is performed to demonstrate the importance of desorption effect, the actual adsorption isotherm was found to be well approximated by the Langmuir equation. Results obtained suggest that adsorption is the dominant mechanism for steam in geothermal reservoirs.
Date: January 1, 1991
Creator: Nghiem, Cuong Phu & Ramey, Henry J., Jr.
Partner: UNT Libraries Government Documents Department

Optimizing reinjection strategy at Palinpinon, Philippines based on chloride data

Description: One of the guidelines established for the safe and efficient management of the Palinpinon Geothermal Field is to adopt a production and well utilization strategy such that the rapid rate and magnitude of reinjection fluid returns leading to premature thermal breakthrough would be minimized. To help achieve this goal, sodium fluorescein and radioactive tracer tests have been conducted to determine the rate and extent of communication between the reinjection and producing sectors of the field. The first objective of this paper is to show how the results of these tests, together with information on field geometry and operating conditions were used in algorithms developed in Operations Research to allocate production and reinjection rates among the different Palinpinon wells. Due to operational and economic constraints, such tracer tests were very limited in number and scope. This prevents obtaining information on the explicit interaction between each reinjection well and the producing wells. Hence, the chloride value of the producing well, was tested to determine if use of this parameter would enable identifying fast reinjection paths among different production/reinjection well pairs. The second aim, therefore, of this paper is to show the different methods of using the chloride data of the producing wells and the injection flow rates of the reinjection wells to provide a ranking of the pair of wells and, thereby, optimize the reinjection strategy of the field.
Date: January 1, 1991
Creator: Urbino, Ma. Elena G. & Horne, Roland N.
Partner: UNT Libraries Government Documents Department

Relative permeability through fractures

Description: The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.
Date: August 1, 2001
Creator: Diomampo, Gracel, P.
Partner: UNT Libraries Government Documents Department

The Streaming Potential Generated by Flow of Wet Steam in Capillary Tubes

Description: For a constant pressure differential, the flow of wet steam generated electric potentials which increased with time and did not reach equilibrium values. These potentials were found to increase to values greater than 100 volts. The reason for this kind of potential build-up behavior was the presence of tiny flowing water slugs which were interspersed with electrically nonconductive steam vapor slugs. The measured electric potential for wet steam increased with pressure differential, but the relationship was not linear. The increase in potential with pressure drop was attributed both to an increase in fluid flow rate and changes in the wet steam quality.
Date: January 21, 1986
Creator: Marsden, S.S. Jr. & Tyran, Craig K.
Partner: UNT Libraries Government Documents Department

Tracer Breakthrough Time for the Rate-Pressured Doublet

Description: A pressure transient analysis method is presented for interpreting breakthrough tie between a constant rate well and a constant pressure well. The wells are modeled as two line sources in an infinite reservoir where the first well injects at a constant pressure and the second well produces at a constant rate. The effects of transient pressure conditions, the distance between the wells, the flowrate, and the tracer injection time on breakthrough time are examined. The first arrival of injected fluid at the production well is significantly longer under transient condition than under steady state condition for the rate-pressure model when the injection pressure is equal to initial reservoir pressure. An injection pressure larger than initial reservoir pressure significantly reduces the breakthrough time, and may yield a breakthrough time significantly smaller than the breakthrough time for the steady state case. 14 figs., 13 refs.
Date: January 20, 1987
Creator: Menninger, Will & Sageev, Abraham
Partner: UNT Libraries Government Documents Department

Elucidating Bioreductive Transformations within Physically Complex Media: Impact on the Fate and Transport of Uranium and Chromium

Description: In situ stabilization (inclusive of natural attenuation) of toxic metals and radionuclides is an attractive approach for remediating many contaminated DOE sites. By immobilizing toxic metals and radionuclides in place, the removal of contaminated water to the surface for treatment as well as the associated disposal costs are avoided. To enhance in situ remediaton, microbiological reductive stabilization of contaminant metals has been, and continues to be, actively explored. It is likely that surface and subsurface microbial activity can alter the redox state of toxic metals and radionuclides, either directly or indirectly, so they are rendered immobile. Furthermore, anaerobic bacterial metabolic products will help to buffer pulses of oxidation, typically from fluxes of nitrate or molecular oxygen, and thus may stabilize reduced contaminants from oxidative mobilization. Uranium and chromium are two elements of particular concern within the DOE complex that, owing to their abundance and toxicity, appear well suited for biologically mediated reductive stabilization. Subsurface microbial activity can alter the redox state of toxic metals and radionuclides, rending them immobile. Imparting an important criterion on the probability that contaminants will undergo reductive stabilization, however, is the chemical and physical heterogeneity of the media. Our research first examined microbially induced transformation of iron (hydr)oxide minerals and their impact on contaminant attenuation. We revealed that in intricate cascade of geochemical reactions is induced by microbially produced Fe(II), and that during transformation contaminants such as U(VI) can be incorporated into the structure, and a set of Fe(II) bearing solids capable of reducing Cr(VI) and stabilizing resulting Cr(III). We also note, however, that common subsurface constituents such as phosphate can modify iron oxide transformation pathways and thus impact contaminant sequestration—affecting both Cr and U stabilization. We extended our work to explore factors controlling the sequestration of uranium in the subsurface, with a particular emphasis on ...
Date: March 1, 2009
Creator: Fendorf, Scott; Francis, Chris; Jardine, Phil & Benner, Shawn
Partner: UNT Libraries Government Documents Department

Collaborative Research: Hydrogeological-Geophysical Methods for Subsurface Site Characterization - Final Report

Description: This research contributes three newly-developed relationships that significantly improve aquifer characterization: (1) a general relationship between total and channel porosities, (2) a general relationship between electrical resistivity and channel porosity, and (3) bounds on the electrical resistivity - seismic velocity relationship.
Date: January 1, 2000
Creator: Mavko, G.
Partner: UNT Libraries Government Documents Department

Fourteenth workshop geothermal reservoir engineering: Proceedings

Description: The Fourteenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 24--26, 1989. Major areas of discussion include: (1) well testing; (2) various field results; (3) geoscience; (4) geochemistry; (5) reinjection; (6) hot dry rock; and (7) numerical modelling. For these workshop proceedings, individual papers are processed separately for the Energy Data Base.
Date: January 1, 1989
Creator: Ramey, H. J., Jr.; Kruger, P.; Horne, R. N.; Miller, F. G.; Brigham, W. E. & Cook, J. W.
Partner: UNT Libraries Government Documents Department

Progress and commissioning of the SLD Cherenkov Ring Imaging Detector

Description: We report the recent progress of the SLD Cherenkov Ring Imaging Detector. All of the individual components of the device (TPC's, mirrors, liquid radiator trays) have been completed and installed. Almost half of the electronics packages are installed and operational, and the data acquisition system has been commissioned. The liquid C{sub 6}F{sub 14} recirculation system is functioning. The drift gas supply systems are operating well with TMAE, and the gaseous Freon C{sub 5}F{sub 12} recirculator is being brought on-line. Our monitor and control systems are fully functional. The commissioning of all 40 TPCs at full operating voltage has gone very smoothly. The system shows a remarkable immunity to the SLC backgrounds, and yields very clean events, while operating with a single electron sensitivity.
Date: November 1, 1991
Creator: Abe, K.; Hasegawa, K.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D. et al.
Partner: UNT Libraries Government Documents Department

Size distributions of fly ash using Coulter Multisizer: Use of multiple orifices and fitting to truncated log-normal distributions. [Coulter Multisizer]

Description: Fly ash particles, which are predominantly spherical and glassy, are produced by melting of the mineral inclusions in the coal during combustion. Particle diameters can range from sub-micrometer (micron or {mu}m) to greater than 100 {mu}m. The size distribution of fly ash is needed to determine its role in the radiation transfer process in pulverized coal combustors. The Coulter Multisizer is an useful instrument for sizing powders with a broad size distribution. A single Multisizer orifice can size particles only within a specific size range limited at the lower end to a few percent of orifice diameter by sensitivity and at the upper end by increasing non-linearity of the signal-volume relation. A scheme for combining data obtained using orifices of different diameters is described. The manufacturers state that the smallest particle which can be sized accurately is nominally 2% of the diameter of the orifice. However, it was found that the data for particles less than 4% of the orifice diameter were not reliable. In order to use the smaller orifices, the larger particles have to be removed from the sample. A wet-sieving apparatus, designed for accurate separation of the particles by size, is described. A log-normal distribution function, truncated outside the measurement limits, fits the size distribution data well. Size parameters for fly ashes of six representative US coals are presented.
Date: November 1, 1991
Creator: Ghosal, S.; Ebert, J. L. & Self, S. A.
Partner: UNT Libraries Government Documents Department

Enzymology and Molecular Biology of Cell Wall Biosynthesis. Final Technical Report

Description: The following aspects of enzymology of cell wall synthesis were pursued under this cited grant: (1) Isolation of plasma membrane-localized glucan synthase II (GS-II) of pea; (2) Cloning of genes for possible plant GS-II components; (3) Golgi glucan synthase-I (GS-I); and (4) Golgi reversibly glycosylated protein 1 (RGP1).
Date: April 1, 2000
Creator: Ray, Dr. Peter M.
Partner: UNT Libraries Government Documents Department

Foundations of statistical methods for multiple sequence alignment and structure prediction

Description: Statistical algorithms have proven to be useful in computational molecular biology. Many statistical problems are most easily addressed by pretending that critical missing data are available. For some problems statistical inference in facilitated by creating a set of latent variables, none of whose variables are observed. A key observation is that conditional probabilities for the values of the missing data can be inferred by application of Bayes theorem to the observed data. The statistical framework described in this paper employs Boltzmann like models, permutated data likelihood, EM, and Gibbs sampler algorithms. This tutorial reviews the common statistical framework behind all of these algorithms largely in tabular or graphical terms, illustrates its application, and describes the biological underpinnings of the models used.
Date: December 31, 1995
Creator: Lawrence, C.
Partner: UNT Libraries Government Documents Department

Pore level visualization of foam flow in a silicon micromodel. SUPRI TR 100

Description: This paper is concerned with the behavior of foam in porous media at the pore level. Identical, heterogeneous silicon micromodels, two dimensionally etched to replicate flow in Berea Sandstone, were used. The models, already saturated with varying concentrations of surfactant and, at times, oil were invaded with air. Visual observations were made of these air displacement events in an effort to determine foam flow characteristics with varying surfactant concentrations, and differing surfactants in the presence of oil. These displacement events were recorded on video tape. These tapes are available at the Stanford University Petroleum Research Institute, Stanford, California. The observed air flow characteristics can be broadly classified into two: continuous and discontinuous. Continuous air flow was observed in two phase runs when the micromodel contained no aqueous surfactant solution. Air followed a tortuous path to the outlet, splitting and reconnecting around grains, isolating water located in dead-end or circumvented pores, all without breaking and forming bubbles. No foam was created. Discontinuous air flow occurred in runs containing surfactant - with smaller bubble sizes appearing with higher surfactant concentrations. Air moved through the medium by way of modified bubble train flow where bubbles travel through pore throats and tend to reside more statically in larger pore bodies until enough force is applied to move them along. The lamellae were stable, and breaking and reforming events by liquid drainage and corner flow were observed in higher surfactant concentrations. However, the classic snap-off process, as described by Roof (1973) was not seen at all.
Date: January 1, 1996
Creator: Woody, F.; Blunt, M. & Castanier, L.
Partner: UNT Libraries Government Documents Department

Computational tools for experimental determination and theoretical prediction of protein structure

Description: This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. The authors intend to review the state of the art in the experimental determination of protein 3D structure (focus on nuclear magnetic resonance), and in the theoretical prediction of protein function and of protein structure in 1D, 2D and 3D from sequence. All the atomic resolution structures determined so far have been derived from either X-ray crystallography (the majority so far) or Nuclear Magnetic Resonance (NMR) Spectroscopy (becoming increasingly more important). The authors briefly describe the physical methods behind both of these techniques; the major computational methods involved will be covered in some detail. They highlight parallels and differences between the methods, and also the current limitations. Special emphasis will be given to techniques which have application to ab initio structure prediction. Large scale sequencing techniques increase the gap between the number of known proteins sequences and that of known protein structures. They describe the scope and principles of methods that contribute successfully to closing that gap. Emphasis will be given on the specification of adequate testing procedures to validate such methods.
Date: December 31, 1995
Creator: O`Donoghue, S. & Rost, B.
Partner: UNT Libraries Government Documents Department

Hidden Markov models and other machine learning approaches in computational molecular biology

Description: This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. Computational tools are increasingly needed to process the massive amounts of data, to organize and classify sequences, to detect weak similarities, to separate coding from non-coding regions, and reconstruct the underlying evolutionary history. The fundamental problem in machine learning is the same as in scientific reasoning in general, as well as statistical modeling: to come up with a good model for the data. In this tutorial four classes of models are reviewed. They are: Hidden Markov models; artificial Neural Networks; Belief Networks; and Stochastic Grammars. When dealing with DNA and protein primary sequences, Hidden Markov models are one of the most flexible and powerful alignments and data base searches. In this tutorial, attention is focused on the theory of Hidden Markov Models, and how to apply them to problems in molecular biology.
Date: December 31, 1995
Creator: Baldi, P.
Partner: UNT Libraries Government Documents Department

Third international conference on intelligent systems for molecular biology (ISMB-95): Summary. Final report

Description: The specific aims of the Third International Conference on Intelligent Systems for Molecular Biology (ISMB-95) were to: convene a critical mass of researchers applying advanced computational techniques to problems in molecular biology; promote interchange of problems and solutions between computer scientists and molecular biologists; create education opportunities in this cross-disciplinary field for students and senior researchers wishing to either apply or benefit from these techniques; produce an archival proceedings as a forum for rapid dissemination of new results in a peer-reviewed manner; produce a set of tutorial materials for education and training of researchers interested in this field; maintain the momentum generated by the highly successful previous conferences in the series, and establish a regular event that will help to solidify the field; and foster the involvement of women and minorities in the field.
Date: December 31, 1995
Partner: UNT Libraries Government Documents Department

Modification of chemical and physical factors in steamflood in increase heavy oil recovery. Annual report, October 1, 1994--September 30, 1995

Description: The objectives of this contract is to carry our fundamental research in heavy oil recovery in the following areas: displacement and flow properties of fluids involving phase change (condensation-evaporation) in porous media; flow properties of mobility control fluids (such as foam); and the effect of reservoir heterogeneity on oil recovery. The specific projects are motivated by and address the need to improve heavy oil recovery from typical reservoirs as well as less conventional fractured reservoirs. This report covers the work performed in these three areas in the past year. In the area of vapor-liquid flow we present a theoretical and numerical study of steam injection in a pore network. We characterize the displacement in terms of an effective mobility ratio and heat transfer parameters. Displacement patterns axe identified in the parameter space. In another study we discuss the problem of steam injection in fractured systems using visualization with micromodels. The interplay of drainage, imbibition and bubble growth is visualized. Conclusions are reached regarding the potential for steamflooding fractured systems. A third study focuses on the development of a pore-network model for foam formation and propagation in porous media. This model, for the first time, accounts for the fundamental mechanisms of foam propagation at the microscale and leads to the determination of various parameters that are currently treated empirically. The effect of viscous forces in displacements in heterogeneous media is described in two separate studies, one involving an extension of percolation theory to account for viscous effects, and another discussing the effect of geometry in general displacement processes.
Date: October 1996
Creator: Yortsos, Y. C
Partner: UNT Libraries Government Documents Department

Coorelations for cresting behavior in horizontal wells. Quarterly report, October 1, 1996--December 31, 1996

Description: The following activities have been carried out in the last three months. (1) The fourth review meeting of the Horizontal Well Industrial Affiliates Program was held on October 10-11 at Stanford. The meeting was well attended and well received. In addition to the project presentations, a number of member presentations were also made at the meeting. (2) Draft plans for the continuation of the two-phase flow experiments were drawn up and sent to Marathon and other members for their review and comments. Series of new experiments with and without the wire wrapped screens used in 1996 are being considered for 1997. (3) Work on the application of horizontal wells for producing gas condensate reservoirs was continued. After verification of the black oil formulation, emphasis is being put on the compositional case where simulation runs have been set up to check the results against a semi-analytical solution. (4) The previous work on the effects of heterogeneities on horizontal well performance was continued and a paper on the subject was completed. Future work in this area will deal with a careful analysis of the interaction of heterogeneity and production performance. (5) Research work on developing coarse grid methods to study cresting in horizontal wells was continued. The previous correlations for optimum grid size, breakthrough time, and post breakthrough behavior (i.e., water-oil ratio) were further tested and optimized. Procedures to derive pseudo-functions either using numerical correlations or coarse grid simulations have been proposed and successfully tested.
Date: December 31, 1996
Creator: Aziz, K. & Hewett, T. A.
Partner: UNT Libraries Government Documents Department

SciCADE 95: International conference on scientific computation and differential equations

Description: This report consists of abstracts from the conference. Topics include algorithms, computer codes, and numerical solutions for differential equations. Linear and nonlinear as well as boundary-value and initial-value problems are covered. Various applications of these problems are also included.
Date: December 31, 1995
Partner: UNT Libraries Government Documents Department

The computational linguistics of biological sequences

Description: This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. Protein sequences are analogous in many respects, particularly their folding behavior. Proteins have a much richer variety of interactions, but in theory the same linguistic principles could come to bear in describing dependencies between distant residues that arise by virtue of three-dimensional structure. This tutorial will concentrate on nucleic acid sequences.
Date: December 31, 1995
Creator: Searls, D.
Partner: UNT Libraries Government Documents Department

Protein sequence comparison and protein evolution

Description: This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. This tutorial examines how the information conserved during the evolution of a protein molecule can be used to infer reliably homology, and thus a shared proteinfold and possibly a shared active site or function. The authors start by reviewing a geological/evolutionary time scale. Next they look at the evolution of several protein families. During the tutorial, these families will be used to demonstrate that homologous protein ancestry can be inferred with confidence. They also examine different modes of protein evolution and consider some hypotheses that have been presented to explain the very earliest events in protein evolution. The next part of the tutorial will examine the technical aspects of protein sequence comparison. Both optimal and heuristic algorithms and their associated parameters that are used to characterize protein sequence similarities are discussed. Perhaps more importantly, they survey the statistics of local similarity scores, and how these statistics can both be used to improve the selectivity of a search and to evaluate the significance of a match. They them examine distantly related members of three protein families, the serine proteases, the glutathione transferases, and the G-protein-coupled receptors (GCRs). Finally, the discuss how sequence similarity can be used to examine internal repeated or mosaic structures in proteins.
Date: December 31, 1995
Creator: Pearson, W.R.
Partner: UNT Libraries Government Documents Department

Intelligent systems for the molecular biologist

Description: This tutorial was one of eight tutorials selected to be presented at the Third International Conference on Intelligent Systems for Molecular Biology which was held in the United Kingdom from July 16 to 19, 1995. In this paper, one objective is to identify properties of DNA sequences that determine their function, by computer-aided statistical analysis and to accurately predict its function, given a new sequence. A related problem is to predict protein structure and function from the sequence.
Date: December 31, 1995
Creator: Brutlag, D.L.
Partner: UNT Libraries Government Documents Department