Evaluations, geologic

Miller G. H. (1976) Microbial surveys help evaluate geological, geophysical prospects. Oil Gas J. 74, 192-202. 

Horstad, L, Larter, S. R. Mills, N. 1995. Migration of Hydrocarbons in the Tampen Spur Area, Norwegian North Sea A Reservoir Geochemical Evaluation. Geological Society, London, Special Publications, 86, 159-183. 

Even if geological conditions for the presence of hydrocarbons are promising, host country political and fiscal conditions must also be favourable for the commercial success of exploration ventures. Distance to potential markets, existence of an infrastructure, and availability of a skilled workforce are further parameters which need to be evaluated before a long term commitment can be made. 

Even if all of the elements described so far have been present within a sedimentary basin an accumulation will not necessarily be encountered. One of the crucial questions in prospect evaluation is about the timing of events. The deformation of strata into a suitable trap has to precede the maturation and migration of petroleum. The reservoir seal must have been intact throughout geologic time. If a leak occurred sometime in the past, the exploration well will only encounter small amounts of residual hydrocarbons. Conversely, a seal such as a fault may have developed early on in the field s history and prevented the migration of hydrocarbons into the structure. 

In addition to a geological evaluation on a macroscopio and microscopic scale, plugs (small cylinders 2 cm diameter and 5 cm long) are cut from the slabbed core, usually at about 30 cm intervals. Core analysis is carried out on these samples. 

Having gathered and evaluated relevant reservoir data it is desirable to present this data in a way that allows easy visualisation of the subsurface situation. With a workstation it is easy to create a three dimensional picture of the reservoir, displaying the distribution of a variety of parameters, e.g. reservoir thickness or saturations. All realisations need to be in line with the geological model. 

Local Site Condition Evaluation. In addition to visiting the site, drawing up a contour map and geology reports, acquiring sod-bearing information, and a knowledge of boundaries, setbacks, local requirements, utdity tie-in locations, sewer connections, access to roadways, pipelines, radroads, etc, may be needed to make a fliU assessment. 

The variety of AES techniques requires careful evaluation for selecting the proper approach to an analytical problem. Table 4 only suggests the various characteristics. More detailed treatment of detection limits must include consideration of spectral interferences (191). AES is the primary technique for metals analysis in ferrous and other alloys geological, environmental, and biological samples water analysis and process streams (192). 

N. E. Peters, Evaluation of Environmental Eactors Affecting Yields of Major Dissolved Ions of Streams in the Ended States, U.S. Geological Survey Water-Supply Paper 2228, U.S. Geological Survey, Reston, Va., 1984. 

Uses raw data from field tests to compute hydraulic conductivity computed value is evaluated by the expert system for its correctness with regard to these considerations site-specific geological characteristics, validity of test procedures, accuracy of the raw data, and the computational method. System is written in Arity-Prolog on a PC. 

Evaluated for formations or lithological-stratigraphic complexes on the basis of general geological premises and analogies... 

Despite the problems of direct experimental evaluation of plutonium stability constants, they are needed in modeling of the behavior of plutonium in reprocessing systems in waste repositories and in geological and environmental media. Actinide analogs such as Am+3, Th+, NpOj and UOj2 can be used with caution for plutonium in the corresponding oxidation states and values for stability constants of these analogues are to be found also in reference 20. 

Methods. As discussed in the previous chapter, a number of approaches have been used to assess the presence of potentially toxic trace elements in water. The approaches used in this assessment include comparative media evaluation, a human health and aquatic life guidelines assessment, a mass balance evaluation, probability plots, and toxicity bioassays. Concentrations of trace elements were determined by atomic absorption spectrometry according to standard methods (21,22) by the Oregon State Department of Environmental Quality and the U.S. Geological Survey. 

Rickert, D.A. Rinella, F.A. Hines, W.G. McKenzie, S.W. Evaluation of Planning Alternatives for Maintaining Desirable Dissolved - Oxygen Concentration in the Willamette River, Oregon. Geological Survey Circular 715-K, Reston, VA, 1980 1-30. 

While these calculations provide information about the ultimate equilibrium conditions, redox reactions are often slow on human time scales, and sometimes even on geological time scales. Furthermore, the reactions in natural systems are complex and may be catalyzed or inhibited by the solids or trace constituents present. There is a dearth of information on the kinetics of redox reactions in such systems, but it is clear that many chemical species commonly found in environmental samples would not be present if equilibrium were attained. Furthermore, the conditions at equilibrium depend on the concentration of other species in the system, many of which are difficult or impossible to determine analytically. Morgan and Stone (1985) reviewed the kinetics of many environmentally important reactions and pointed out that determination of whether an equilibrium model is appropriate in a given situation depends on the relative time constants of the chemical reactions of interest and the physical processes governing the movement of material through the system. This point is discussed in some detail in Section 15.3.8. In the absence of detailed information with which to evaluate these time constants, chemical analysis for metals in each of their oxidation states, rather than equilibrium calculations, must be conducted to evaluate the current state of a system and the biological or geochemical importance of the metals it contains. 

The geological sciences are involved in studying the naturally occurring materials of the earth and solar system (i) to understand the fimdamental processes of crustal formation on earth and solar system evolution, and (2) to evaluate the crustal materials of potential economic value to man. Prior to the 1930 s, analyses were carried out exclusively using classical analytical techniques, with detection limits on the order of o.oi-o.i % (mass fraction). The number of elements contained in any sample could be as extensive as the periodic table, but very few of these could be determined. The development of instrumental techniques revolutionized the analysis of geochemical samples, beginning in the 1930 s. 

Applications of geological reference samples to mineral prospecting and economic evaluation of ore potential is the only application with a history dating back before the issuance of G-i and W-i in 1951. It is an area in which data quality or lack thereof has serious economic impacts, hence the very early development of certified reference materials mentioned previously. An extensive study of the state of ore analysis was undertaken by the Institute of Geological Sciences (now the British Geological Survey). Nineteen ores and concentrates, of varied matrix, were distributed to 38 laboratories more than 1532 results were received (Lister and Galagher 1970). 

USGS. 1995. Groundwater monitoring program evaluation report for water year 1995. Rocky Mountain Arsenal, Commerce City, Colorado. United States Geological Survey. 

Brower, R.D., Visocky, A.P., Krapac, I.G., Hensel, B.R., Peyton, G.R., Nealon, J.S., and Guthrie, M., Evaluation of Underground Injection of Industrial Waste in Illinois, Final Report, Illinois Scientific Surveys Joint Report 2, Illinois State Geological Survey, Champaign, IL, 1989. 

The result of this effort was an ATW roadmap released by DOE just this week. It concluded that ATW would require a six-year, 281 million R D effort for open technical issues. ATW could complement geologic disposal, and any decision to pursue ATW would follow evaluation of technical, costs, and nonproliferation issues. Whether or not this effort leads to any ATW international collaboration, we are eager to expand international collaboration on nuclear waste issues in general. 

Levson, V.M. 2001. Regional till geochemical surveys in the Canadian Cordillera sample media, methods, and anomaly evaluation. In McClenaghan, M.B., Bobrowsky, P.T., Hall, G.E.M. Cook, S.J. (eds). Drift Exploration in Glaciated Terrain, Geological Society, Special Publication, 185, 45-68. 

National Uranium Resource Evaluation (NURE) Hydrochemical and Stream Sediment Reconnaissance (HSSR) Program. U.S. Geological Survey Open-File Report 97-492. Available from . 

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