The author distinguishes between geothermal resource base, accessible geothermal resource base, geothermal resource, and geothermal reserve. Conditions for periodically updating the assessment of geothermal energy resources include: increased data from expanded exploration and drilling; development of improved and new technologies for exploration, evaluation, extraction, and use; rapid evolution of geothermal knowledge; and the increased role of geothermal energy in response to changing economic, social, political, and environmental conditions, particularly an increasing awareness of the limits to petroleum and natural gas resources. Accordingly, the U. S. Geological Survey (USGS) plans by the end of 1978 to update its 1975 assessment of the United States’ geothermal resource, with increased emphasis on several items. The USGS’s joint evaluations of geothermal resource-assessment techniques in the last year with the National Electric Agency of Italy (ENEL) under U. S. Energy Research and Development Agency sponsorship identified a number of problems, one of which was how to formulate geothermal recovery factors for systems producing by intergranular vaporization and by intergranular flow. The first formulation is fairly rigorous; the author solicits the reservoir engineering community’s help in improving the estimate of the second. 3 figs., 11 refs.

Progress is reported in research designed to develop an economically competitive process for producing acetic acid from biomass for the purpose of sparing petroleum for other uses, to evaluate marine algae as a potential source of biomass, and to document the feasibility of running fermentations in fixed packed bed fermenters. It was demonstrated that marine algae can be fermented to acetic acid. Initial rates of up to 168 meq/1 day were observed. These rates are substantially in excess of the 47 meq/1 day used in the economic projections. Also, when using marine algae as a substrate, acid levels were generated equivalent to the highest reported with other substrates. It was also demonstrated that a 4-foot fixed packet bed fermenter may be operated with marine algae as a substrate at 20 percent solids or 200 meq/1.

Work covered includes an updated listing of the alloys selected for the screening tests, plus complete test specimen matrices for the screening program. The present design and construction status of the simulated reactor helium loops and testing and analysis facilities and equipment are discussed. Also covered are the loading matrices for the screening creep tests.

In the petroleum industry, well logging is a well developed discipline that has matured over a fifty-year period. Compared to this, geothermal well logging is a very new field of activity. The current practice is to use the same logging equipment and the same log interpretation techniques for geothermal wells as had been used for petroleum wells. However, this approach has proven either inadequate or ineffective in most geothermal areas. The problems here are of two types: (1) those associated with logging equipment and operation, and (2) those connected with log interpretation techniques. This paper focuses on the log interpretation aspects only. 6 refs.

The ATD code is a multi-purpose code which reduces data files produced by a digitizer. It contains all of the features for the basic unpacking, scaling, and plotting of digitized data files. More advanced capabilities are also available. Digital filtering, spectral analysis, and statistical analysis, among others, allow the engineer the capability to analyze and display time history data. In contrast to codes such as DYMEC, the data files are typically of high frequency and short duration, representing time spans on the order of seconds and frequency content in the tens of thousands of hertz. 1 figure.

The emphasis of the smaller scale laboratory of the Stanford Geothermal Program is on improving the understanding of the physics of flow through porous materials in a geothermal environment. Three major investigations are in progress: (1) examination of the phenomenon of vapor pressure lowering in porous media, (2) determination of the temperature dependence of absolute and relative permeabilities of steam and water in sandstones under high confining pressures, and (3) observation of steady and unsteady, single- and two-phase flows of water or brine through permeable cores. In addition, development continues on the dielectric constant liquid content detector—a device which would prove extremely useful in these and subsequent experiments. 10 refs., 4 figs.

Geothermal district space heating has been practiced in Boise over the last 85 years. The system has used to wells drilled approximately 50 ft (15 m) apart in the early 1890s. the wells have a combined maximum reported production rate of 1800 gpm (114 l/sec) at 170°F (77°C) discharge at the wellhead. The system has served as many as 400 homes and Natatorium; presently it serves approximately 200 homes and a large state laboratory and office building. The heating district remained at the present capacity (two wells) for 85 years primarily because of the unknown nature of the reservoir and availability of other energy sources. Not until 1974 was the question of further development given serious consideration. Rising energy costs due to expanding energy demands and higher costs for foreign oil brought about a reevaluation of the resource. The INEL, Boise State University, and the Idaho Bureau of Mines and Geology began an investigation into the nature of the resource and the economics of space heating several large buildings and homes. Two deep, approximately 1250 ft (381 m), exploratory wells were drilled and tested by the INEL to determine the nature and size of the reservoir. Drilling and reservoir engineering …

The shutdown system for the Clinch River Breeder Reactor (CRBR) includes two independent systems--a primary and a secondary system. The Secondary Control Rod System (SCRS) is a new design which is being developed by General Electric to be independent from the primary system in order to improve overall shutdown reliability by eliminating potential common-mode failures. The paper describes the status of the SCRS design and fabrication and testing activities. Design verification testing on the component level is largely complete. These component tests are covered with emphasis on design impact results. A prototype unit has been manufactured and system level tests in sodium have been initiated.

A conceptual design of a laser fusion power plant is extensively discussed. Recent advances in high gain targets are exploited in the design. A smaller blanket structure is made possible by use of a thick falling region of liquid lithium for a first wall. Major design features of the plant, reactor, and laser systems are described. A parametric analysis of performance and cost vs. design parameters is presented to show feasible design points. A more definitive follow-on conceptual design study is planned. (RME)

The successful adaptation to geothermal problems of pressure testing methods developed in the petroleum and ground water fields suggests that decline curve analysis should be looked at more closely. This paper discusses the application of various decline curve methods to geothermal-reserve assessment using both smooth and scattered data sets. 15 refs.

The report identifies barriers to shortening nuclear power plant construction schedules and recommends research efforts which should minimize or eliminate the identified barriers. The identified barriers include (1) Design and Construction Interfacing Problems; (2) Problems Relating to the Selection and Use of Permanent Materials and Construction Methods; (3) Construction Coordination and Communication Problems; and (4) Problems Associated with Manpower Availability and Productivity.

A simplified radiochemical method has been developed for quantitatively analyzing radon gas in underground uranium mines. In this method, a measured volume of air is drawn by a pump through a drying tube and a cartridge containing dioxygenyl hexafluoroantimonate reagent. Radon is captured as a nonvolatile product. After radioactive equilibrium has been established between radon and its short-lived daughters (approximately 4 hours), the gamma-emission of the cartridge is measured with a scintillation counter. The amount of radon is then calculated from the gamma-emission rate. The effect of cartridge geometry, reagent load, and air flow rate upon collection efficiency and counting efficiency is reported.

Ultrafication (UF) membranes have demonstrated 90 to 98% rejection of gross alpha in laboratory tests. In the treatment of laundry wastes, rejection of activity ranged from 98 to 99.9% gross alpha. The pilot UF system was installed and started up. Flux decline curves and volume reduction performance were determined. Volume reductions of 210 : 1 were achieved at flux rates of 1.1 gal/min (system is rated at 2 to 3 gal/min, 90% recovery) at activity rejection of 99.94% gross alpha. Adsorbent studies demonstrated capacities in excess of 10/sup 9/ dis/min/g for uranium-233 and in excess of 10/sup 8/ dis/min/g for plutonium-238. Construction and start-up of the Engineering Test Facility has been completed.

The requirements and effects of operating Mirror Fusion Test Facility (MFTF) experiments with neutral-beam pulse durations in the range from 0.5 s to steady state are reexamined. Two questions are examined: (1) what is the maximum neutral-beam duration into the MFTF if the latter is built as described in the conceptual design document, and (2) what is required (and at what cost) to permit neutral-beam injection periods of 30 s in the MFTF. In both cases, it is assumed that the required neutral-beam modules are available. One finds that the maximum practical pulse length consistent with the present conceptual design is 1.6 s. Increasing the pulse length to 30 s will require water-cooled beam dumps, protection against hot spots on the beam dumps, and modest expansion of the beam-control and data-acquisition systems. The estimated cost of the beam dumps and cooling system is $10 million. It is concluded that the present two-stage MFTF program plan is sound. This plan calls for establishing fundamental plasma scaling laws with 0.5-s operation and exploring nearly steady-state phenomena later with 30-s operation.

During reinjection of cooled geothermal fluid into a reservoir, chemical precipitation and other processes may occur changing the permeability of the aquifer. In general, the permeability becomes a function both of time and space. This will, of course, affect the injection well. Some attempts have been made to analytically predict the pressure response. The present paper describes our calculations which yield analytic expressions, in terms of a single integral, for a wide class of physically reasonable permeability functions. Results are presented for a few typical examples. 6 figs.

Experiments are being conducted in the Stanford Geothermal Program (SGP) large geothermal reservoir model utilizing rock systems with several characteristics resembling high permeability, fracture-stimulated systems. The broad objective of these experiments is to evaluate nonisothermal fluid production and heat transfer processes and to analytically model these for such rock systems. Three nonisothermal energy extraction and production processes, referred to here as in-place boiling, sweep, and steam-drive, were considered during the early phases of this study. The results showed that all three processes are feasible in the experimental systems considered. However, the effectiveness of the processes varied widely. The simple analytic models developed for the model reservoir and for the heat transfer from the rock successfully predicted the experimental results as long as the assumptions inherent in the models were not seriously violated. However, it was recognized that more detailed experimental and analytic studies of the heat transfer aspects were required, and such studies have since been performed by Iregui [Reference 4]. The final report of these results is in preparation and the highlights are given below. 2 tabs., 5 refs., 4 figs.

The Nevada Operations Office of the Energy Research and Development Administration (ERDA) has contracted with Petroleum Technology Corporation (PTC) to perform a gas stimulation program by chemical explosive fracturing (CEF) in the Canyon sands of the Val Verde - Kerr Basin of Sutton County, Texas. This lenticular tight sand deposit, underlying much of southwestern Texas, contains large volumes of natural gas. To date this formation has yielded only marginal amounts of gas because of its low porosity and permeability. The semi-arid environment of the Aldwell/Sawyer field is characterized by dry arroyos and xeric vegetation. Population is sparse and sheep ranching is the primary occupation. Because of the existence of previously drilled oil and gas wells, road and pipeline construction will be minimal. Impacts from this two well project are expected to be minimal and be confined to temporary surface disruption and increased erosion at the well site.

Recent studies of liquid-dominated systems suggest that geothermal anomalies are intimately associated with specific patterns of faulting. One may infer from these studies that the East Mesa anomaly is intersected by a seismically active fault which acts as a conduit of heated water from depth. This paper describes such a model of the Mesa system. 28 refs.

The first results are given for the conceptual design of a short-wavelength gas laser system suitable for use as a driver (high average power ignition source) for a commercial laser fusion power plant. A comparison of projected overall system efficiencies of photolytically excited oxygen, sulfur, selenium and iodine lasers is described, using a unique windowless laser cavity geometry which will allow scaling of single amplifier modules to 125 kJ per aperture for 1 ns pulses. On the basis of highest projected overall efficiency, a selenium laser is chosen for a conceptual power plant fusion laser system. This laser operates on the 489 nm transauroral transition of selenium, excited by photolytic dissociation of COSe by ultraviolet fluorescence radiation. Power balances and relative costs for optics, electrical power conditioning and flow conditioning of both the laser and fluorescer gas streams are discussed for a system with the following characteristics: 8 operating modules, 2 standby modules, 125 kJ per module, 1.4 pulses per second, 1.4 MW total average power. The technical issues of scaling visible and near-infrared photolytic gas laser systems to this size are discussed.

A comprehensive mathematical model description of anaerobic digestion of animal residues was developed, taking into account material and energy balances, kinetics, and economics of the process. The model has the flexibility to be applicable to residues from any size or type of animal husbandry operation. A computer program was written for this model and includes a routine for optimization to minimum unit gas cost, with the optimization variables being digester temperature, retention time, and influent volatile solids concentration. The computer program was used to determine the optimum base-line process conditions and economics for fuel gas production via anaerobic digestion of residues from a 10,000 head environmental beef feedlot. This feedlot at the conditions for minimum unit gas cost will produce 300 MCF/day of methane at a cost of $5.17/MCF (CH/sub 4/), with a total capital requirement of $1,165,000, a total capital investment of $694,000, and an annual average net operating cost of $370,000. The major contributions to this unit gas cost are due to labor (37 percent), raw manure (11 percent), power for gas compression (10 percent), and digester cost (13 percent). A conceptual design of an anaerobic digestion process for the baseline conditions is presented. A sensitivity analysis of …

Recent syntheses of geophysical work at The Geysers (Chapman 1975, Isherwood 1975) have provided useful insights into regional structure in this complex and chaotic area. Regional studies of this type, however, are of limited value to reservoir investigations and it may be that the more detailed temperature gradient/heat flow studies (Frye 1976) can supply more useful information. This paper describes results of a study carried out on the Rorabaugh lease in the southwest sector of The Geysers geothermal field. The success of this survey in a comparatively simple situation suggests that it may be developed to handle more complex areas with shallow hot water zones, variable lithology and variable microclimates. If this can be done, it may provide a useful link between geothermal exploration and reservoir engineering. 5 refs., 1 fig.

Precision gravity methods provide new information regarding geothermal reservoir mechanisms and depletion. This paper discusses the principles of present interpretations and early conclusions from two producing geothermal fields, Wairakei, in New Zealand, and The Geysers, California. 4 refs., 4 figs.

White, Muffler, and Truesdell (1971) and Truesdell and White (1973) developed a conceptual model of transport in vapor-dominated geothermal zones. The main theme of the model is that coexisting liquid and vapor phases form a counterflowing convection system similar to that observed in a heat pipe (Dunn and Reay, 1976). It is hypothesized that water evaporates from a deep water table, passes upward through the formation, and condenses at an impermeable cap rock, effectively transferring the latent heat of boiling through the formation. The liquid water then percolates downward, completing the cycle. The physics involved in the flow system is illustrated in an analysis of an idealized one-dimensional, homogeneous, 2 km deep vapor-dominated zone which is bounded below by a water table which has a temperature of 236°C. Flow of water and steam in the system is assumed to be described by Darcy’s law for unsaturated porous materials. The liquid water potential, defined as the Gibbs free energy per unit volume of water, is used in place of the liquid pressure in the equation for water because flow in a highly unsaturated medium is to be considered. Comparison of figures 2 and 4 illustrates that the liquid saturation in a …

Smith et al (1975) have proposed the creation of man-made geothermal energy reservoirs by drilling into relatively impermeable rock to a depth where the temperature is high enough to be useful; creating a reservoir by hydraulic fracturing; and then completing the circulation loop by drilling a second hole to intersect the hydraulically fractured region. The initiation of hydraulically created fluid reservoirs in highly impermeable hot dry rock must by definition take place in a wellbore. The nature of these initiation sites will provide the initial resistance to flow into the reservoir and therefore will strongly influence the rate of energy withdrawal. The nature of the interception site in a second wellbore which has been directed to intersect the reservoir will have a similar effect. The program to create and study such artificial geothermal reservoirs in hot dry rock is being pursued by the Los Alamos Scientific Laboratory and has been presented to these workshops by Murphy (1975) and Murphy et al (1976). In parallel with the drilling of the two boreholes rather complete suites of wellbore geophysical logs were run followed by further diagnostic logging both during and after fracturing operations. This paper discusses some aspects of what has been …