Patent ID: 8884623

Claim:
A method for determining the frequency-dependent dielectric permittivity spectrum of a rock sample, comprising: defining a series of electromagnetic measurement data comprising at least of first measurement at a frequency from which a substantially frequency-independent value of dielectric permittivity ∈ ∞ can be obtained; and at least second and third measurements at different frequencies from which values for frequency-dependent dielectric permittivity ∈ rock (f) can be obtained, and using the first, second and third measurements to determine the frequency-dependent spectrum of the sample, wherein the frequency-dependent part of the spectrum obeys the relationship ∈ rock (f)=∈ 1 (f)+∈ ∞ , wherein ∈ 1 (f) defines the frequency-dependent part of a measured value of dielectric permittivity, the method further comprising: determining the dc permittivity ∈ dc ; determining the characteristic frequency f 0 , the lowest frequency for which the relationship log ⁡ ( ɛ 1 ⁡ ( f ) ) = - β ⁢ ⁢ log ⁡ ( 1 + f / f 0 ) + log ⁡ ( ɛ dc ) holds substantially true; and determining the slope of the frequency dependent part of the spectrum between f 0 and the frequency f c at which the spectrum becomes substantially frequency independent.