Formation electrical resistivity factor

The precautions generally applicable to the preparation, exposure, cleaning and assessment of metal test specimens in tests in other environments will also apply in the case of field tests in the soil, but there will be additional precautions because of the nature of this environment. Whereas in the case of aqueous, particularly sea-water, and atmospheric environments the physical and chemical characteristics will be reasonably constant over distances covering individual test sites, this will not necessarily be the case in soils, which will almost inevitably be of a less homogeneous nature. The principal factors responsible for the corrosive nature of soils are the presence of bacteria, the chemistry (pH and salt content), the redox potential, electrical resistance, stray currents and the formation of concentration cells. Several of these factors are interrelated. 

This paper reports an investigation of the effects of porous solid structures on their electrical behaviour at different frequencies (from 100 Hz to 100 kHz). For that, we study different parameters such as formation resistivity factor, cementation factor, chargeability, resistivity index and saturation exponent. Different porous solid structures are quantified from the petrographic image analysis and Hg-injection technique. Then, by using different models we obtain the permeability prediction from the electrical behaviour and structure parameters. 

Combination of several properties is becoming increasingly important in modem industry. One example may be taken from electronics, where in addition to mechanical properties and electric resistance, themial stability and conductivity are important requirements. It was estimated that the increase of temperature by 10°C reduces time to failure by the factor of two." A finite analysis model was developed which accounts for the following properties of filled composites microstructure, effect of particle shape, formation of conductive chains, effect of filler aspect ratio, and interfacial thermal resistance. The predictions of the model indicate the most... 

Fig. 2.6 Comparison of porosities and wet bulk densities measured on discrete samples and by electrical resistivities. Boyce s (1968) values for the coefficients (a) and (m) and pore fluid and grain densities of 1.024 g cm" and 2.67 g cm were used to convert formation factors into porosities and wet bulk densities. Wet and dry weights and volumes were analyzed on discrete samples, (a) Cross plots of both data sets for square barrel kastenlot core PS2178-5. The dashed lines indicate an error of 10% for the porosity and 5% for the density data, (b) Porosity and wet bulk density logs of core PS2178-5 derived from resistivity measurements. Superimposed are porosity and density values measured on discrete samples. Data from Bergmann (1996).

Fig. 2.9 Model based computation of a wet bulk density log from resistivity measurements on ODP core 690C. (a) Porosity log derived from formation factors having used Boyce s (1968) values for (a) and (m) in Archie s law. (b) Carbonate content (O Conell 1990). (c) Wet bulk density log analyzed from gamma ray attenuation measurements onboard of JOIDES Resolution (gray curve). Superimposed is the wet bulk density log computed from electrical resistivity measurements on archive halves of the core (black curve) having used the grain density model shown in (d). Unpublished data from B. Laser and V. SpieB, University Bremen, Germany.

Alloy selection depends on several factors, including electrical properties, alloy melting range, wetting characteristics, resistance to oxidation, mechanical and thermomechanical properties, formation of intermetaUics, and ionic migration characteristics (26). These properties determine whether a particular solder joint can meet the mechanical, thermal, chemical, and electrical demands placed on it. 

Well logging Electrical surveys resistivity conductivity shale formation factor salinity variations Interval transit time Bulk density Hydrogen index Thermal neutron capture cross section Nuclear magnetic resonance Downhole gravity data After drilling... 

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