Results are presented from Fermilab E-400 on the production of charmed baryons and mesons using incident neutrons. We show evidence for the charm-strange baryon, ..xi../sub c//sup +/, and present our measurements of its mass, width, lifetime, cross section and relative branching fractions, and the A, x/sub f/, p/sub t/, and particle/antiparticle dependence of the state. We show evidence for both the ..sigma../sub c//sup + +/ and ..sigma../sub c//sup 0/, and present measurements of three mass differences, ..sigma../sub c//sup + +/ - ..sigma../sub c//sup 0/, ..sigma../sub c//sup 0/ - ..lambda../sub c//sup +/, and ..sigma../sub c//sup + +/ - ..lambda../sub c//sup +/. Preliminary results on the ratio of two decay modes of the D/sup 0/ are shown. D/sup 0/ ..-->.. K/sup +/K/sup -/ and D/sup 0/ ..-->.. K/sub 0/ anti K/sub 0/. The latter mode has not been previously observed. 8 refs., 10 figs.

This paper is concerned with intense electron beams, typically of the order of a few kA in current and up to tens of MeV in beam energy. A beam of this kind can be produced from induction machines, examples of which are the ERA (4 MeV, 1 kA) at Lawrence Berkeley Laboratory and the ASTRON (5 MeV, 500A), ETA (5 MeV, 10 kA), and ATA (50 MeV, 10 kA) at Lawrence Livermore National Laboratory (LLNL). The emphasis of the paper is on the characteristics of these beams and some applications. 13 refs., 2 figs. (LSP)

Anomalous low-J-value Stokes and anti-Stokes lines in stimulated rotational Raman scattering are observed with large Fresnel number, linearly polarized beams. Forced light scattering at the rotational intermodulation frequency is also observed. Dynamics of the Stokes-anti-Stokes coupling will be discussed. 5 refs., 2 figs.

Considerable evidence has been presented for the detection of low-degree internal gravity modes of the Sun. By combining the observations obtained at the Crimean Astrophysical Observatory and at SCLERA, a number of the modes have been classified with respect to their spatial properties. The number of such modes classified has been extended in a subsequent gravity-mode classification project by Gu and Hill. These mode classifications have been tested using three additional sets of independent observations. Positive results have been obtained in each of these tests. These low-degree modes lead to oscillatory perturbations of the Sun's gravitational field. The amplitudes of these perturbations at the earth are inferred from the observed temperature eigenfunctions. For the l = 2 modes with frequencies near 100..mu..Hz, it is projected that these perturbations in the gravitational field will produce strains of the order of 1.0E-18 in gravitational radiation detectors based on free masses. The signals are expected to have coherence times of hundreds or more years. The detection of these signals by gravitational radiation detectors would make available a new technique for use in solar seismological studies which could be quite useful. The detection of these signals could also serve as a way of monitoring …

In this paper an analysis of the depolarization expected during acceleration from 0.8 to 45.0 GeV kinetic energy in the Advanced Hadron Facility (AHF) accelerators is performed.

The streaming potentials generated by the flow of both liquid and gas through either a Pyrex capillary tube or else an unconsolidated Pyrex porous medium were investigated. This mixture of distilled water plus nitrogen gas simulated wet stream but allowed experiments to be run at room temperature. Single-phase flow of distilled water alone resulted in a constant voltage-to-pressure drop ratio, E/∆p, of +0.15 v/psi for the capillary tube and -0.52 v/psi for the porous medium. For both single- and two-phase flow through the capillary tube, the upstream potential was always positive relative to the downstream electrode while the opposite was true for the porous medium. The maximum two-phase potentials generated in the porous medium were about four times as great as those generated in the capillary tube for similar gas fractions, Γ. For the capillary tube experiments the potentials generated when Γ < ≈ 0.5 were equal to or slightly less than those for single-phase flow, while for the porous medium the potentials were always greater than those for single-phase flow. When Γ > ≈ 0.5 for both kinds of flow systems Γ had a profound effect on streaming potential and reached a pronounced maximum when 0.94 < Γ < …

Early evaluation of the potential for geothermal breakthrough of reinjected fluids in newly developed geothermal fields can be obtained with the SGP one-dimensional heat sweep model. The model was used to estimate fluid cooldown from wells selected for the first wellhead generating units to be installed at the Los Humeros and La Primavera geothermal fields in Mexico, based on staff-compiled geometric and geologic data, thermal properties of the reservoir rock, and expected production conditions. Geometric considerations were evaluated with respect to known and postulated fault zones and return flow angle of the reinjected fluid. The results show the range of parameter values that affect the rate of thermal breakthrough to an abandonment temperature of 170 ºC corresponding to the minimum inlet pressure to the CFE 5-MW wellhead generator units. 9 figs., 4 tabs., 11 refs.

Abstract: A wide range of steam-water mixtures was discharged to the atmosphere through a 10.7 mm diameter orifice which was sharp-edged with a minuscule throat pressure tapping. The ratio of throat pressure to up-stream pressure was found sensitive to dryness fraction over the whole range studied from 0.03 to 1.0. The technique (employing large orifices) has the potential of identifying the unknown enthalpy of geothermal wells discharging large flows. Contrariwise, a nozzle (rounded entry orifice) was found remarkably _insensitive_ over most of the dryness range and hence is useless for such determinations; however, it can be used to measure the flow-rate when enthalpy is known.

Coefficients of compressibilities below the bubble point were computer with a thermodynamic model for single and multicomponent systems. Results showed coefficients of compressibility below the bubble point larger than the gas coefficient of compressibility at the same conditions. Two-phase compressibilities computed in the conventional way are underestimated and may lead to errors in reserve estimation and well test analysis. 10 refs., 9 figs.

Well 18 is a production well in the southern zone of Los Azufres geothermal field in México (see Figure 1). The well is located on the eastern flank of the drilled area, and produces a steam/water mixture from a depth of 1200-1250 m. A 19 hour pressure buildup test that was carried out in March 1986, is the subject of this paper. It is part of work reported by Sánchez-U. (1986) at the Geothermal Training Programme in Iceland. The permeability-thickness product of well 18 in Los Azufres field was determined 5.4 dm from a Horner plot. The well was found to be intersected by a fracture, as evident from the slope on a log-log plot at early time, and a skin value of -5.3. The overall pressure buildup of the well was found to be typical for double-porosity reservoir behavior, having a storativity ratio of 0.1. An outer boundary behavior was observed in the pressure buildup data. 1 tab., 6 figs., 14 refs.

This paper presents arguments for initially producing Geysers steam wells at wellhead pressures in excess of 200 psig instead of the normal practice of producing at minimum wellhead pressures. A conceptual model is presented which defines a flow equilibrium resulting from a “constant pressure source” whose location is a function of the withdrawal rate from the reservoir. Based on this model, it is argued that producing at elevated wellhead pressures is equal to producing at minimum wellhead pressures, assuming the mass withdrawal is the same. Additional benefits of producing at elevated wellhead pressures are discussed and include minimizing casing and reservoir rock thermal transients and scaling and bridging of the wellbore. SFGI’s experience has been favorable but due to a very high capacity factor and very few outages, a comparison of performance of other areas of The Geysers is inconclusive. 6 refs., 3 figs.

The problem of dispersion, advection and adsorption of a tracer in a double-porosity reservoir due to tracer injection in a well with a steady, radially divergent flow field was solved for the case of constant tracer concentration in the injection well. Longitudinal dispersion and advection was assumed to dominate transport in the fracture system and tracer diffusion and adsorption was assumed to dominate movement of the tracer in the matrix blocks. The blocks were assumed to be sphere shaped and covered with a thin skin of material that provides resistance to the diffusion of tracer into the blocks. Values of dimensionless concentration in the fracture system versus dimensionless time were computed by numerical inversion of the Laplace transform solution to the Airy equation. Type curves demonstrate effects of changing reservoir characteristics and show the usefulness of the concept of fracture skin in understanding dispersive processes in fractured porous media. 6 figs., 13 refs.

Address on the Department of Energy's overall energy policy, the role of alternative energy sources within the policy framework, and expectations for geothermal energy. Commendation of the industry's decision to pursue the longer-term field effort while demand for geothermal energy is low, and thus prepare for a substantial geothermal contribution to the nation's energy security.

A parallel fractures model, having equal width and spacing, has been developed to study the flow of tracers through naturally fractured geothermal reservoirs. The model is capable of handling either a single fracture or a system of two or more parallel fractures, interacting with associated porous bodies. The reservoir is treated as being composed of two regions a mobile region where diffusion and convection are allowed and a stagnant or immobile region where only diffusion and adsorption are allowed. Both regions are interconnected by means of a very thin fluid film contained within the immobile region which controls the fluid and mass transfer between both regions. The mobile region represents the system of fractures, where tracer is free to flow reaching high velocities, whereas non-homogeneities of the reservoir rock, such as microfractures and dead-end fractures are represented by means of an equivalent porous body where fluid remains immobile. The boundary-value problem for the system is stated and its solution into Laplace’s space is presented. Numerical inversion of this solution was performed by means of the Stehfest algorithm. Preliminary results showing results obtained from the proposed model are included. Further work is underway to apply the model for interpretation of actual …

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 …

A feature of French geothermal engineering is the development of industrial projects in normal gradient, non-convective areas. The economic feasibility of exploiting wells producing between 150 and 350 m{sup 3}/h at temperatures from 55° to 85° from depths of 1,500 to 2,000 meters, in sedimentary basins with normal gradient, for direct heat production has been proved by 50 plants providing heating for over 500,000 people during the last few years. This opens new possibilities for geothermal energy development the world over, in particular for areas where heat consumption is higher than 2,500 Tons oil equivalent (Toe)/year over several square kilometers. The recent and rapid development of geothermal projects in France, in particular in the Paris Basin has provided much more information on the characteristics of the Jurassic Dogger, which is the unit tapped by geothermal doublets (one production and one injection well). Detailed study of the Dogger reservoir in the Paris Basin is one of the main objectives of the IMRG research and development program drawn up in 1983. The preliminary results presented here are oriented towards (1) improved knowledge of the potential geothermal resources, and (2) analysis of optimum development conditions. 1 tab., 7 refs., 9 figs.

Analysis of interference tests at the Kawerau geothermal field in New Zealand has indicated that the reservoir may be viewed on a coarse scale as a two-layer structure. While these layers have high permeabilities, they are in poor hydrological communication with each other. The shallower layer is modelled as a finite cylindrical reservoir. The deeper layer is modelled as a larger cylindrical reservoir with recharge from the sides. The fitted permeabilities and storativities suggest the importance of flow in fractures at Kawerau. 2 tabs., 14 figs., 8 refs.

This study investigates pressure buildup behavior of wells with wellbore storage and skin in bounded circular reservoirs, when inner and outer boundary effects interact to fully or partially dominate the well pressure response. Using dimensionless pressure derivative as the dependent variable, we show that early time response is governed by C{sub D}e{sup 2S} and late time response by r{sub eD}{sup 2}/C{sub D}. Equations are provided to estimate the limits of the intermediate time period, which corresponds to infinite acting radial flow and a semi-log straight line on a pressure-time graph. We present a new buildup derivative type curve, incorporating inner boundary (early-time) and outer boundary (late-time) effects. Applications of this type curve in buildup test design and interpretation are discussed. 2 figs., 8 refs.

One of the key problems in geothermal field management is to determine how many wells will be needed, and when in the project lifetime the new wells will come on-line. To make this determination requires an estimate of the field depletion. Methods used for approximating the field behavior are discussed, and examples are provided using data from some liquid-dominated reservoirs in the U.S. and abroad. The calculated decline curves are compared to a few cases for which field production data is available. 2 tabs., 6 figs., 5 refs.

Production and chemical data have been compiled and analyzed on a six-month averaged basis for the first four years of electric energy generation with five 5-MW wellhead generators at the Los Azufres geothermal field. The data were evaluated with respect to the extent of observable thermal drawdown of the reservoir from 25 MW of generation in relation to the estimated capacity of the field of several hundred megawatts of power. The analysis updates the previous one compiled after the first two years of continuous production, at which time the results indicated that differences in reservoir temperature estimated from geochemical thermometers and wellhead production data were not statistically significant based on the number of data and the standard deviations. Analysis of the data after four years of operation were made for the larger number of data and smaller standard deviations. The results review the adequacy of the sampling frequency and the reliability of the measurements from statistical t-Test of the means of the first and second two-year periods. 3 figs., 5 tabs., 20 refs.

The Ngawha geothermal system is atypical of New Zealand geothermal systems, being located outside the Taupo Volcanic Zone, and contained in tight sedimentary structures. Early geochemical surveys of surface discharges indicated a high gas, high borate fluid, discharging in small quantities, to the surface. An initial well (drilled in the early 1960’s, to 500m) produced a vary gassy fluid before calciting. Deeper wells drilled and discharged in the early 1980’s produced large flows of high gas fluid (up to 3wt%), at enthalpies around 1000 kj/kg. These low energy contents coupled with a low water to rock ratio, a very fractured structure, and consequent expected changes in the production fluid following exploitation, let do large scale exploitation plans being scrapped in 1982. The close attention to geochemical studies before and during the drilling operations enabled predictions of fluid type, physical conditions at depth, fluid disposal problems, and hydrologic reservoir models that have proved to be correct. The project served to indicate the value of comprehensive exploration strategies which precede the drilling phase, and the further value of, in particular, geochemical studies as an integral part of well testing procedures, for the updating of reservoir models. The close and open cooperation amongst …

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 º 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.

Abstract: Discharging small flows (order of 1 t/h) from wells is known as bleeding and is to relieve the build-up of gas pressure at the wellhead and to arrest corrosion in the bore. First tests over a range of bleeding flows indicate it as a fruitful subject for study in that temperature and pressure measurements at the wellhead can indicate the well enthalpy and the non-condensible gas content of the production system. Because of environmental restrictions on testing with large discharges in the future, bleeding may soon be the only valid alternative for proving a well’s potential.

The Phlegrean Fields, close to Naples, are the site of important geothermal activity. The formations are volcanic and mostly tuffites. They are originally very tight but the geothermal alteration locally produces fractures with large increase in permeability. The lack of geological markers makes well-to-well correlation quite difficult. Thus the local detection of fractured zones in each well is very important for the evaluation of its potential. The Mofete 8 D well is a typical example. A rather complete logging program was run for fracture detection. Standard methods turned out to be disappointing. However several non-standard detectors were found to be very consistent and, later on, in excellent agreement with the analysis of cuttings. They are derived from the Dual Laterolog, the SP, the Temperature log and, most particularly, the Acoustic Waveforms from the Long Spacing Sonic. The Dual Laterolog and the Temperature Log indicate invasion by fresh and cold mud filtrate; the SP behaves as in a typical Sand-Shale sequence. Sonic Waveforms were first analyzed by a purely empirical method derived from consistent log patterns. A practical algorithm compares the total energy measured in each of the two fixed time windows located the one before, the other after the fluid …