Dielectric Logging: Review and Application
Robert L. Grossberg
Formation resistivities have become a standard component in the determination of formation-water saturations when using quantitative-analysis methods, such as Archie's equation. These methods depend on a contrast in resistivity between water and hydrocarbon zones. Saline formation water provides the best contrast; however, when the formation water salinity is low, this contrast diminishes to such a degree that the standard induction log becomes useful only for correlation.
To alleviate this condition, open-hole logging instruments have been developed to measure the dielectric constant of the formations encountered. The dielectric constant is a physical property of the formation that is relatively independent of formation-water salinity. Dielectric measurements provide the necessary contrast between water and hydrocarbon zones and can be used to obtain formation-water saturations, even in fresh formation-water environments, since the dielectric constant of water is approximately 40 times that of oil.
The 200 MHz Dielectric Log accurately predicts formation-water saturations while limiting the adverse effects of the borehole and the formation environments.
AAPG Search and Discovery Article #91035©1988 AAPG-SEPM-SEG Pacific Sections and SPWLA Annual Convention, Santa Barbara, California, 17-19 April 1988.