Field resources

Field resources, such as energy in the system (mechanical, thermal, chemical, electrical, magnetic, etc.) or energy in the environment (gravity, vacuums, light, wave movement, wind, geothermal, etc.). 

The concept of field resources is less familiar, but it may be the key to our inventive problems. By field resources we mean all kinds of fields that can be utilized in our project. For example, in our floor structural system, we could use a stress field, that is, we could use stresses to create a prestressed concrete or even rarely used but feasible prestressed steel structures. Also, we could use an electromagnetic field to transport the structural system to its location in the building or even to keep it in its desired position. We will have also such fields available as the temperature field or the gravity field, which both are easily available and eventually could be used. 

Impact assessment Characterization, damage estimate, integration by LIME2 Characterization, damage estimate, integration by LIME Characterization (warming, acidification, eutrophication, disposal field, resource consumption, enCTgy consumption)... 

Kenora, Ontario, and Emerald Field Resources Big Mack petalite deposit near Kenora, Canada and the now-closed Tin-Spodumene Belt of Foote and FMC in North Carolina, USA. There are large commercial deposits in China, Russia and Zaire (the latter with limited lithium production), and medium-sized ones in Brazil, Namibia, Portugal, Finland and Afghanistan (the latter two not yet mined in 2002 Sailer and O Driscoll, 2000). In the past, and a few at present, of the smaller deposits throughout the world have had limited mining, such as in Rwanda, South Africa and Europe. The major commercial lithium minerals in these deposits are described in the following section. 

Analytical models using classical reservoir engineering techniques such as material balance, aquifer modelling and displacement calculations can be used in combination with field and laboratory data to estimate recovery factors for specific situations. These methods are most applicable when there is limited data, time and resources, and would be sufficient for most exploration and early appraisal decisions. However, when the development planning stage is reached, it is becoming common practice to build a reservoir simulation model, which allows more sensitivities to be considered in a shorter time frame. The typical sorts of questions addressed by reservoir simulations are listed in Section 8.5. 

An example of an application of CAO is its use in optimising the distribution of gas in a gas lift system (Fig. 11.3). Each well will have a particular optimum gas-liquid ratio (GLR), which would maximise the oil production from that well. A CAO system may be used to determine the optimum distribution of a fixed amount of compressed gas between the gas lifted wells, with the objective of maximising the overall oil production from the field. Measurement of the production rate of each well and its producing GOR (using the test separator) provides a CAO system with the information to calculate the optimum gas lift gas required by each well, and then distributes the available gas lift gas (a limited resource) between the producing wells. 

In the feasibility phase the project is tested as a concept. Is it technically feasible and is it economically viable There may be a number of ways to perform a particular task (such as develop an oil field) and these have to be judged against economic criteria, availability of resources, and risk. At this stage estimates of cost and income (production) profiles will carry a considerable uncertainty range, but are used to filter out unrealistic options. Several options may remain under consideration at the end of a feasibility study. 

Hccausc of Ihc restricted availability of corn ptilation al resources, sorn e force fields use Un itcd. torn types, fli is type of force field represeri ts implicitly all hydrogens associated with a methyl, rn elli yieti e, or rn etii in e group. Th e van der Waals param eters for united atom carbons reflect the increased si/.e because of the implicit (included) hydrogens. 

With my European background, I was when I came to America and still am impressed by the rather loosely organized, more decentralized way of research support. Of course, even in a great country like ours resources are not limitless and inevitably prevailing trends of research set priorities. In my field of interest the 1970s and 1980s were a period when, after two oil crises, research on hydrocarbon fuels and their synthetic preparation had significant public interest and support. Catalytic research in its many aspects was heavily pursued and considered a national priority. 

Nearly all liquid simulations have been done using molecular mechanics force fields to describe the interactions between molecules. A few rare simulations have been completed with orbital-based methods. It is expected that it will still be a long time before orbital-based simulations represent a majority of the studies done due to the incredibly large amount of computational resources necessary for these methods. 

In light of the differences between a Morse and a harmonic potential, why do force fields use the harmonic potential First, the harmonic potential is faster to compute and easier to parameterize than the Morse function. The two functions are similar at the potential minimum, so they provide similar values for equilibrium structures. As computer resources expand and as simulations of thermal motion (See Molecular Dynamics , page 69) become more popular, the Morse function may be used more often. 

Force field calculations often truncate the non bonded potential energy of a molecular system at some finite distance. Truncation (nonbonded cutoff) saves computing resources. Also, periodic boxes and boundary conditions require it. However, this approximation is too crude for some calculations. For example, a molecular dynamic simulation with an abruptly truncated potential produces anomalous and nonphysical behavior. One symptom is that the solute (for example, a protein) cools and the solvent (water) heats rapidly. The temperatures of system components then slowly converge until the system appears to be in equilibrium, but it is not. 

Fig. 3. (a) General locations of hydrothemial power plants in the continental United States (6). Power is produced directiy from hydrothermal steam indicated by the steam plume at The Geysers in northern California. At all other locations, hot water resources are utilized for power production. In 1993, a hydrothermal power plant also came on line on the island of Hawaii, (b) Location of The Geysers steam-dominated hydrothermal field (D) in Lake and Sonoma counties, within the boundaries of the Cleadake—Geysers thermal anomaly (B). 

Most of the developed hot-water fields are located by significant surface indications, particularly in the form of hot springs. Once a resource has been identified, a variety of techniques can be used to map the system and determine whether it is of a size sufficient to justify commercial development. Hidden hot-water resources are much more difficult to locate, but geologic indicators such as volcanic activity and evidence of hydrothermal alteration can be used. 

Direct Uses of Geopressured Fluids. Many of the uses typical of hydrothermal energy, such as greenhouse, fish farm, and space heating, have been proposed for geopressured resources, but none has been commercially developed (34). Hydrothermal fluids are widely used in enhanced oil recovery, however, to increase production from depleted oil fields. 

C. Stone, ed.. Monograph on The Geyser s Geothermal Field, Geothermal Resources Council, Davis, Calif., 1992. 

The principal source of helium is certain natural gas fields. The helium contents of more than 10,000 natural gases in various parts of the world have been measured (9). Helium concentrations of a few are Hsted in Table 2. In the United States, recovery of helium is economical only for helium-rich gases containing more than about 0.3 vol % belium. Most of the United States helium resources are located in the midcontinent and Rocky Mountain regions, and about 89% of the known United States supply is in the Hugoton field in Kansas, Oklahoma, and Texas the Keyes field in Oklahoma the Panhandle and Cliffside fields in Texas and the Riley Ridge area in Wyoming (11). 

Oil Fields. Oil field waters in the United States containing lithium have been identified in 10 states. The greatest concentrations are in waters from the Smackover formation of southern Arkansas and eastern Texas. Concentrations from this formation have been measured from 300—600 ppm in waters originating at a 2500—3300 m depth. Recovery of lithium from this resource would only be commercially feasible if a selective extraction technique could be developed. Lithium as a by-product of the recovery of petroleum (qv), bromine (qv), or other chemicals remains to be exploited (12). 

Demonstrated reserve quantities are estabUshed by measurements including drillings surface sampling, etc. Inferred reserves are those derived from geological survey information, not by measurement of the extent of the particular reserve. Not included herein are identified marginal and speculative resources, such as the oil-field and geothermal brines and lithium-hearing clays. These latter reserves are speculative as to extent, not existence. Total undiscovered clays in the western United States are speculatively estimated at 15 x 10 t lithium (16). More detailed Hsts of reserves are also available (15,17). 

No method has been devised to estimate with complete accuracy the amount of cmde petroleum that ultimately will be produced from the world s conventional oil and gas fields. Degrees of uncertainty, therefore, should be attached to all such estimates. These uncertainties can be expressed in several ways, the most important of which is achieved by dividing a resource into various categories. Several petroleum resources classifications have been proposed, and a comprehensive discussion of them (1), as well as the definition used in the assessment of the undiscovered resources of the United States (2), have been provided. Seven commonly used categories of resources are given here. 

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