Dielectrical aspects of CO2-enriched water in clean porous rocks

Abstract

Streaming potential is an eletrokinetic effect which reflects the electrical charge or the electrical potential created by flow of ionic fluids through porous media, such as hydrocarbon reservoir rocks. The concept has been studied mostly for low salinity fluids and in the past decade consist a subject of interest in oil & gas industry. Dielectric studies concerning different ionic fluids used in enhance oil recovery (EOR) are limited. In this study we investigate if available models for low salinity fluids can be modified and redeveloped to describe the behavior of streaming potential coefficient and zeta potential for carbonated water flooding in reservoir rocks with very small clay content. The model presented in this work follows the approach of Glover et al. published in 2012. The developed theoretical model suggested here is sensitive to salinity, temperature, reservoir rock properties and fluid properties, while the main variable is pore fluid concentration. For the verification of the theoretical estimations, core flooding experiments were performed with different CO2-enriched solutions in Fontainebleau sandstone sample. From comparison of the experimental measurements with the theoretical estimations, it was observed that the model can produce estimations of ζ potential and streaming potential coefficient (CS) as a function of pore fluid concentration within a pH range of 4 to 7. Moreover, it was observed that for the correlation a coefficient introduced by Glover et al. in 2012 had to be implemented.