Sixty-six papers were presented on cycling of natural and man-made elements, including terrestrial, freshwater and marine environments, as well as current ideas on modeling. Principles governing elemental flow included radiocesium in natural environments, especially in the southeastern United States. Individual entries were made for 47 items.

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Geothermal wells must be sampled for a variety of purposes including geologic and geochemical interpretation, engineering design of facilities, environmental release evaluation, and documentation of baseline conditions. Basic factors influencing the choice and application of sampling methods are reviewed including the type of the geothermal resource, the analyses of interest, well production parameters, utilization processes, and possible sample contamination or instability. Three basic methods of sampling are described including condensation, phase separation, and use of evacuated containers. Several practical problems experienced by various workers are discussed. These include the natural variability of fluid composition with time, effects of well-bore heat losses, effects of well flow rate and production time, sampling locations, laboratory simulation studies, contamination by corrosion reactions, and documentation of hydrologic systems possibly connected to the geothermal resource. (auth)

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A preliminary study of the Frio sand distribution and formation temperatures and pressures was undertaken in order to define prospective areas in which a more detailed reservoir analysis is necessary prior to the selection of a site for a geothermal well. As a result two potential geothermal fairways were identified--one in the south part of the area in Hidalgo, Willacy, and Cameron Counties, and the other in the north part in north-central Nueces County.

A series of tests on ckres taken from the Wairakei geothermal site in New Zealand are reported. The cores tests are representative of each of the four basic rock types significant to the functioning of the site. Ultrasonic velocity measurements were made for each rock type tk determine elastic moduli under simulated in situ conditions. Hydrostatic and triaxial deformation tests were performed on three samples of the aquifer rock to determine the effect of in situ stress on the elastic deformation moduli. Thermal conductivity was measured on all four rock types. Tabulation and graphical representation of the measured properties are included. All test procedures and apparatuses are described in detal. (MHR)

Corrosion and scaling problems have a significant impact on geothermal plant economics. A power plant must amortize the capital investment over a 20-year period and achieve satisfactory operating efficiency to achieve financial success. Corrosion and scale incrustations have been encountered in all geothermal plants, and to various degrees, adversely affected plant life times and power output. Using published data this report analyzes known geothermal corrosion and scaling phenomena for significant cost impacts on plant design and operation. It has been necessary to speculate about causes and mechanisms in order to estimate impacts on conceptual geothermal plants. Silica is highly soluble in hot geothermal water and solubility decreases as water is cooled in a geothermal power plant. Calculations indicate as much as 30,000 tons/year could pass through a 100 MWe water cycle plant. The major cost impact will be on the reinjection well system where costs of 1 to 10 mills/kwhr of power produced could accrue to waste handling alone. On the other hand, steam cycle geothermal plants have a definite advantage in that significant silica problems will probably only occur in hot dry rock concepts, where steam above 250 C is produced. Calculation methods are given for estimating the required …

Geothermal heat flow in the Gulf basin is primarily a function of its hydrology. Water expelled from sediments with deepening burial and increasing overburden load escapes upward and toward the basin margin. Where it moves freely in the hydropressure zone, the basin is relatively cool; but where rapid sedimentation and contemporaneous faulting have retarded water loss from compacting sediments, the interstitial fluid pressure reflects a part of the overburden load, and the formation waters are superheated and geopressured. The geopressured zone is common below depths of about 3 km (9,600 ft) in the basin, beneath an area of 375,000 km{sup 2} (150,000 mi{sup 2}), and extends downward perhaps 15 km (50,000 ft) to the base of Cenozoic deposits. The upper boundary of the geopressured zone is the most important physical interface in the basin. Across it the head of formation water increases downward from a few hundred to several thousand feet above sea level; the geothermal gradient increases downward from 20° to 40° C/km to 100°C/km or more; the salinity of formation water decreases downward, commonly by 50,000 mg/l or more; and the porosity of shale and sand increases downward by 10 to 25 percent. Petroleum matures in geopressured clay …

Many prospective oil wells have penetrated the geopressured zone in Tertiary sediments along the Texas Gulf Coast. However, because few oil or gas wells produce from this area, the regional sand distribution within these zones is not well known. Limited data indicate that the pore spaces within the sand in the geopressured zone are filled with water that has a high temperature and a relatively low dissolved-solids content and that is saturated with methane gas. This water is believed to be an important source of thermal energy and methane gas. For more information concerning the origin of the geopressured zone see Dorfman and Kehle (1974) and Jones (1970). The first step in appraising the Gulf Coast geothermal resources entails a detailed geologic study of the main sand trends. Of these, the Frio and Wilcox formations appear to be the thickest (fig. 1). This report deals largely with the Frio formation. The Wilcox formation has been studied by Fisher and McGowen (1967). Other parts of the Tertiary that have been studied in detail are the Queen City formation (Claiborne), which was reported on by Guevara and Garcia (1972), and the Jackson formation, reported on by Fisher and others (1970). The United …

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Daily newspaper from Stephenville, Texas that includes local, state, and national news along with advertising.

Daily newspaper from Stephenville, Texas that includes local, state, and national news along with advertising.

Daily newspaper from Stephenville, Texas that includes local, state, and national news along with advertising.

Daily newspaper from Stephenville, Texas that includes local, state, and national news along with advertising.

Daily newspaper from Stephenville, Texas that includes local, state, and national news along with advertising.