Dielectric properties of reservoir rocks at ultra-high frequencies

Conventional resistivity and induction tools measure the electrical conductivity of the formation. Interpretation of these logs is difficult in situations where the formation water resistivity is variable or unknown as a result, for example, of water, steam, or chemical flooding. Recent introduction of several dielectric tools offers a new technique in well logging. These sondes measure the relative dielectric permittivity of the formation at very‐high and ultra‐high radio frequencies. Because water has a much higher relative dielectric permittivity (about 80) than oil (about 2) or gas (about 1), the dielectric tool can distinguish hydrocarbon‐bearing zones from water‐bearing zones even when the formation fluid is nonconducting. However, in order to quantify the oil saturation in the formation, one needs an accurate formula that can relate the measured relative dielectric permittivity of the rock to the oil saturation in the rock. Present interpretation formulas have only a limited range of applicability....