Dielectric Dispersion Measurements In California Heavy Oil Reservoirs

Abstract

Dielectric measurements have been used over the past thirty years in a variety of reservoirs to determine flushed zone water-filled porosity in formations with fresh or unknown water salinity. This measurement is particularly useful in heavy oil reservoirs because little invasion occurs, making oil saturations of the uninvaded and invaded zones approximately equal. A new dielectric measurement provides dielectric permittivity and conductivity at multiple depths of investigation as a result of multiple frequencies, receiver spacings, and polarizations. This next-generation dielectric measurement is collected over a large range of operating frequencies using an array of antennas with two separate orientations. A total of nine measurements of attenuation and phase shift are made at four different frequencies, allowing for a true measure of dielectric dispersion. Inversion of these measurements computes a simple water-filled porosity, as was done with older generation dielectric tools based on a single permittivity measurement. By measuring permittivity and conductivity at different frequencies, antenna spacings, and orientations it is possible to construct a water-filled porosity invasion profile.