Dielectric permittivity rocks

The conducting properties of a liquid in a porous medium can provide information on the pore geometry and the pore surface area [17]. Indeed, both the motion of free carriers and the polarization of the pore interfaces contribute to the total conductivity. Polymer foams are three-dimensional solids with an ultramacropore network, through which ionic species can migrate depending on the network structure. Based on previous works on water-saturated rocks and glasses, we have extracted information about the three-dimensional structure of the freeze-dried foams from the dielectric response. Let be d and the dielectric constant and the conductivity, respectively. Dielectric properties are usually expressed by the frequency-dependent real and imaginary components of the complex dielectric permittivity ... 

Completely dense or dry rocks occur infrequently in the near surface crust. These rocks have—except for ores or graphite-containing rocks— very high resistivities (mostly >10 nm). The dielectric permittivity is usually relatively low and in the range of the dominant rock-forming minerals (3-5) accessory minerals (for example ores and graphite) can produce higher values. 

The following covers the first and second type a special section (8.5) covers shaly rocks. Electrical conductivity models for the first and second type are identical to thermal conductivity and dielectrical permittivity. Therefore, the general equations are compiled in Chapter 11. 

Rocks saturated with brine can have very high dielectric permittivity in the low-frequency range. Three mechanisms can create the polarization effects ... 

Most rock-forming minerals have a permittivity in the order of =3—10 higher values show, for example, sulphides and some oxides. The dielectric permittivity of water is about 80. This results in a strong correlation between permittivity and the water content of a rock. Table 8.9 shows some more data for the permittivity of fluids. 

The Lichtenecker and Rother (1931) generalization for dielectric permittivity (see Eq. 11.5) fills the space between the extreme boundaries of parallel and series model. For a porous rock results by variation of the parameter a ... 

Coutanceau-Monteil, N., Jacquin, C., 1993. Improvements of the coaxial line technique for measuring complex dielectric permittivities of centimetric samples in the 20 to 1,000 MHz range application to sedimentary rocks. Log Anal. 34, 21-33. September-October. 

Sharma, M.M., Garrouch, A., Dunlap, HJ., 1991. Effects of wettability, pore geometry, and stress on electrical conduction in fluid saturated rocks. Log Anal. 32,511 526. SeptembCT lctober. Sherman, M., 1986. A model for the determination of water saturation from dielectric permittivity measurements. In SPWLA 27th Annual Logging Symposium Transactions, Housttm, Texas, June 9—13. Paper E. 

Sherman, M., 1998. A model for the fiequency dependence of the dielectric permittivity of reservoir rocks. Log Anal. 29, 358—367. September-October. 

---