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Purpose: To study the adaptation of bacteria to the natural γ-background of mountains and anthropogenic emissions from nuclear power plants; to establish the main factors of variability and speciation of bacteria. Method: Analysis of materials on the radiation background and its impact on living organisms in the landscape of Armenia, calculation of the absorbed dose by microbes due to rock radiation. Results: The review shows the death, reproduction, radioresistance and speciation of bacteria in changing conditions of low variable natural and anthropogenic γ-background. Conclusion: We assume that γ-rays from rocks activate cellular epigenetic mechanisms that regulate genome expression, signaling and, ultimately, variability of bacteria. Some of them have already been studied, others require research. [ABSTRACT FROM AUTHOR]

Tortuosity tau is defined as the square of the ratio, phi-range of the effective length of pore channels to the length parallel to the overall direction of the pore channels in a porous medium. It has significance in interpreting the hydraulic and electric proper ties of porous media. In this study, experimental results of tortuosity and porosity phi were investigated in relation to different directions of flow in various unconsolidated porous media. When the media (mica, textile fibers, kaolinite, and bituminous soil, with a high phi-range of between 60 - 90 %) are exposed to flow perpendicular to the planes and fibers, tau responds positively to phi. When the media (randomly packed beds of spheres, with a medium phi-range of between 34 - 45 %) are exposed to flow parallel to the planes, tau responds negatively to phi. When the media (glass powders, glass spheres, dry soil, quartz sand, and white sand, with a variety of grain sizes and a medium porosity phi-range of between 37 - 47 %), and other media (glass spheres, with different fractions of grain sizes and a low phi-range of between 10 - 30 %) are exposed to nondirectional flow, tau responds negatively to phi. Empirical equations linking tau and phi, with medium to high coefficients of correlation, were obtained. The dependence of tau on phi is governed greatly by the direction of flow because of the orientation, mineralogy, and mode of packing of the grains and nonuniformity in the size and shape of the grains and pores. [ABSTRACT FROM AUTHOR]

Tortuosity tau is physically defined as the ratio (or the square of the ratio) of the effective length of pore channels (through which the hydraulic flow and electric current are conducted) to the length parallel to the overall direction of the pore channels in a porous medium. It has a significant influence on hydraulic flow and electric current because of its response to the variations in lithology, pressure and petrophysical properties. Determination of tortuosity enables one to understand the mechanisms of hydraulic flow and electric current, and the channel-network com plexities in porous media. In this study, physical and mathematical aspects of tortuosity are discussed. Also, tortuosity is mathematically derived as the square root of the dimensionless formation resistivity factor times fractional porosity. Tortuosity can be successfully used for interpretation of the physical behavior of unconsolidated and consolidated porous media, similarly, and for formations characterized by high degrees of compaction, heterogeneity and anisotropy, as in the case of the Hibernia and Terra Nova reservoirs, off the eastern coast of Canada. [ABSTRACT FROM AUTHOR]

In this article, the writers briefly cover and emphasize the importance of fractures in reservoir rock studies. [ABSTRACT FROM PUBLISHER]

Several concepts that attempt to determine static (true) formation temperature from log-derived BHT measurements with and without knowledge of drilling fluid circulation time have been reviewed. Whereas several refined models are available, the simple Horner-type technique provides quick and reliable static (true) formation temperature estimates. [ABSTRACT FROM PUBLISHER]

Upon determining grain-size distribution and porosity of sandstones from thin-sections, one can estimate permeability. Diagrams showing correlation between porosity and permeability, such as the one presented in this paper (Figure 2), can be used [ABSTRACT FROM PUBLISHER]

Extensive research work has been conducted by the writers on the effects of barite, thinners, and fiocculants (in various concentrations) on freshwater bentonite muds. The PV-----versus-VP----curves were used to evaluate these effects. Definite, characteristic regularities were observed. Experiments have also been performed on salt-saturated atta-pulgite (Zeogel) muds on addition of various concentrations of pregelatinized starch and carboxymethylcellulose. The results were evaluated in terms of slope and location of PV----versus-yp lines. The yp/PKratio (i.e., slope of the PK----versus-yp line) is a significant indicator of drilling fluid condition. The P K---versus-yP curves can be used for evaluating the stability of drilling fluids. They can also serve as guidelines in the field control of the drilling fluid systems and in taking timely actions. [ABSTRACT FROM PUBLISHER]

The chemistry of Indian spent sulfite liquor and methods to isolate sodium lignosulfonates from it have been discussed earlier. It has been observed experimentally that spent sulfite liquor as such is not an effective oil-well drilling fluid additive. Although its sodium Hgnosulfonate derivatives exhibited some effectivity, they were not thermostable. An effort has been made to further improve the performance characteristics and chemical nature of the sodium Hgnosulfonate by chromium metal ion complexing, employing conductometric titration method. The resulting chromium lignosulfonates possess better chemical properties, thermal stability, and effectivity as oil- well drilling fluid additive. Synthesis of metal ion lignosulfonates would save a considerable amount of foreign exchange in India and lead to “import substitution” in oil exploration. Experimental details of chromium metal ion complexing of sodium lignosulfonate, its chemistry, and its industrial application as oil-well drilling fluid additive have been discussed. [ABSTRACT FROM PUBLISHER]

Compressibilities of unconsolidated sands as related to the compaction (upon production of oil and/or water) and subsequent subsidence are discussed. Data required for development of mathematical and physical subsidence models are presented. [ABSTRACT FROM PUBLISHER]

Fundamental principles of the X-ray diffraction of mesomorphic materials are discussed at length, especially for petroleum asphaltenes. Stepwise procedures for handling X-ray diffraction laboratory data are presented. [ABSTRACT FROM PUBLISHER]