A NEW CONCEPT IN MODELING THE DIELECTRIC RESPONSE OF SANDSTONES - DEFINING A WETTED ROCK AND BULK WATER-SYSTEM

Experimental data for the real part of the dielectric constant (K′) of three sandstone samples are considered as a function of the level of water saturation (Sw) in the frequency range 60 kHz to 4 MHz. Existing theoretical models have previously shown poor agreement with K′ versus Sw data for rock samples, undoubtedly due to the complexity involved in adequately accounting for geometrical and electrochemical effects. In analyzing the data presented here, we find a pronounced increase in K′ in the low saturation region which in all cases can be attributed to the establishment of geometrical and surface effects associated with the rock-water interface. When this increase in K′ is accounted for by defining wetted matrix parameters, the data show excellent agreement with existing theoretical models. -Authors