Evaluating the rock wettability using multi-frequency dielectric measurements: A review on the fundamental concept and experimental approach

The dielectric approach is considered as one of the measurements that have potential in characterizing dissipative mediums which have an electrical contrast in their comprising elements. Recently, there have been remarkable research and development activities aiming to link dielectric responses to different petrophysical properties. Wettability is considered a key parameter in many reservoir engineering aspects including evaluating reservoir performance and designing enhanced oil recovery processes. The rock wettability controls the majority of the electrochemical interactions between the solid grain and the ionically-dissipative fluid. These interactions provide an excellent environment for dielectric measurements to display some dispersion mechanisms under the influence of alternating frequency. This paper presents a comprehensive review on the use of the dielectric approach for wettability evaluation. The majority of the reviewed studies were either a qualitative investigation of this relationship or empirical prediction models for the dielectric measurements based on many inputs which are not available most of the time. Even though significant work has been done in this area, there are still gaps that can be improved and fulfilled. Wettability was still not explored quantitatively through a measurable indicator from the dielectric measurements, for example, no wettability index was developed based on the dielectric approach. Therefore, dielectric could provide an efficient, accurate, and economical wettability index that can be implemented in the industry. Overall, this work aims to review the literature and pave the road for quantifying the wettability index via dielectric measurements.