Subsurface temperature

The slope of the water solubiUty curves for fuels is about the same, and is constant over the 20—40°C temperature range. Each decrease of 1°C decreases water solubiUty about 3 ppm. The sensitivity of dissolved water to fuel temperature change is important. For example, the temperature of fuel generally drops as it is pumped iato an airport underground hydrant system because subsurface temperatures are about 10 °C lower than typical storage temperatures. This difference produces free water droplets, but these are removed by pumping fuel through a filter-coalescer and hydrophobic barrier before deUvery iato aircraft. 

The average geothermal gradient used in most areas of the United States for initial predictions of subsurface temperatures is a value of0.016°F/ft [32]. 

Fournier, R.O. and Truesdell, A.H. (1970) Chemical indicators of subsurface temperatures applied to hot spring waters of Yellowstone National Park, Wyoming, U.S.A. Geothermics, 2, 529-535. 

Here, enthalpy is given in kcal kg-1, temperature in °C, and pressure in atm. Note that the sampling temperatures are considerably lower than subsurface temperatures because of the energy used to produce the vapor phase. 

The adsorption of contaminants on geosorbents also is affected by climatic conditions reflected in the subsurface temperature and moisture status. Calvet (1984) showed how the soil moisture content may affect adsorption of contaminants originating from agricultural practices. The moisture content determines the accessibility of the adsorption sites, and water affects the surface properties of the adsorbent. The competition for adsorption sites between water and, say, insecticides may explain this behavior. Preferential adsorption of the more polar water molecules by soil hinders... 

Denitrification occurs only in the presence of oxidized nitrogen and in an environment with limited (whieh prevails in the subsurfaee). Beeause denitrifieation is an enzyme-mediated reaetion, the substrate concentration funetions as a rate-determining factor. The dominant denitrifying bacteria are heterotrophie. The favored environmental conditions for the growth of denitrifying baeteria include a neutral pH (6-8), a favorable water-air (oxygen) ratio, and a subsurface temperature between 20 and 30°C. 

Several factors may limit the application of viscous barrier technology. The technology is not effective in clay soils, and cooler subsurface temperatures may slow barrier gelling. In addition, the barrier material may desiccate over time. 

Pollack, H. N., S. Huang, P.-Y. Shen, Climate Change Record in Subsurface Temperatures A Global Perspective, Science, 282, 279-281 (1998). 

Figure 11a illustrates the difference between the actual temperature, measured at the well head (Twh), and the temperature determined from the isotopic fractionation (TIS) between H2 and H20. This isotope geothermometer seems to work well for this system, at least in the sense that it predicts subsurface temperatures actually encountered in deep drill holes (Panichi et al. 1979). Before 1979 (full symbols), the AT... 

Organic Source Material and a Subsurface Temperature Controlled Chemical Reaction Mechanism, in Advances in Organic Geochemistry, pp. 25-46, Pergamon, Oxford, 1969. 

Anthracite A metamorphic coal that contains very little water in its chemical structure. Anthracites usually form at subsurface temperatures above 200 °C (Boggs, 1995), 279. The coal results from the metamorphism of lignite, subbituminous, or bituminous coals. 

Depth is depth below ground level of midpoint of perforation. Temp, is measured subsurface temperature. Pressure is original bottom-hole pressure in MPa TDS is calculated total dissolved solids. HCO3 is the field titrated alkalinity and includes organic and inorganic species. 

Samples from Sigh Island 573 field (Mobil Oil) except sample 83-TX-12, which is from High Island 571 field (Columbia Gas). Depth is that of midpoint of perforation below sea level (depth of water column is -Temp, is the measured subsurface temperature. TDS = mg L total dissolved solids. Aik is field-titrated alkalinity as HC03 and comprises organic as well as inorganic species. 

The generally lower magnesium concentrations in formation water, in comparison to that of evaporated seawater, could result from diagenetic formation of chlorite, dolomite, and ankerite (Hower et al., 1976 Boles, 1978). Formation of ankerite becomes important at subsurface temperatures higher than —120 °C (Boles, 1978). 

Their concentration is controlled primarily by subsurface temperature and the age of the reservoir rocks. The distribution of aliphatic acid anions in oil-field waters from several basins shows (Figure 10) three distinct temperature zones (Kharaka et al., 2000). Zone 1 is characterized by concentrations of acid anions <500mgL and temperatures <80 °C. The concentration of acetate in this zone is generally... 

Results from both approaches indicate that (i) high concentrations ( 100 mg L ) of lead and zinc can be present in oil-field brines only if the concentration of total H2S is at the pg level in such fluids, significant quantities of dissolved lead and zinc can be transported as carboxylate complexes (ii) lead and zinc in Mississippi-Valley-type ore fluids appear to be transported dominantly as chloride complexes and (iii) the brines are close to equilibrium with galena and sphalerite under the likely subsurface temperatures, pressures, and pH (Kharaka et al., 1987 Sicree and Barnes, 1996 Giordano, 2000). 

Guilderson T. and Schrag D. (1997) Abrupt shift in subsurface temperatures in the tropical Pacific associated with changes in El Nino. Science 281, 240-243. 

Although not directly related to the AOL system, an airborne expendable bathythermograph (AXBT) launch tube, receiver, and microprocessor-based data acquisition system were also built to provide valuable subsurface temperature data in the WCR boundaries. The AXBT data system multiplexes the temperature data into the AOL system HP computer for simultaneous recording with the laser data. The specially adapted radio receiver/data acquisition system is configured to handle standard AN/SSQ-36 (U.S. Navy) AXBTs. Surface temperature data, acquired by a Barnes platinum resistance thermometer (PRT)-5 IR radiometer, are also recorded by the AOL computer system. 

The Avalon/Ben Nevis Sandstone, which at present is buried to depths between 2100 and 2600 m (corresponding to 55-70°C subsurface temperature), not surprisingly shows little secondary porosity. After what has been said above, acid release would have just started at these temperatures. However, much of the acid generated in the shales would have been neutralized locally by reaction with... 

Philippi G.T. (1975) The deep subsurface temperature controlled origin of the gaseous and gasoline-range hydrocarbons of petroleum. Geochim. Cosmochim.Acta 39, 1353—73. 

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