Wettability alteration of carbonate rocks via magnetic fields application

Abstract

Wettability alteration in carbonate reservoirs is the main objective of surfactant flooding. While studies confirm that a magnetic field changes the properties of solutions and water, its application for increasing the effectiveness of surfactant solutions for wettability alteration purposes has not been investigated. In this paper, therefore, the wettability alteration of carbonate rocks is investigated via applying a magnetic field on water and surfactant solutions. Based on experimental measurements conducted and results obtained in this study, the magnetic field-treated water, the so-called magnetized water, reduced the contact angle more than the double distilled water after 30 min of contact time. The effect of salinity on the affinity of magnetized water was also investigated for 0.2 wt% NaCl, and similar results were observed. Wettability alteration was also examined by magnetized water as a solvent of Sodium Dodecyl Sulfate (SDS) surfactant solutions. At surfactant concentrations above the Critical Micelle Concentration (CMC), magnetized water as the solvent decreased not only the contact angle remarkably after long contact time (64.5% reduction at 0.245 wt %) but also the surfactant concentration required for the same amount of reduction. The same behavior was also observed for the 0.25 wt% of surfactant solutions (sodium dodecylbenzenesulfonate and sodium C14-16 olefin sulfonate). The effect of the magnetic field treatment on SDS surfactant solutions was also studied. The impact of one-hour magnetic field treatment on surfactant solutions was negligible. However, the treatment of that on immersed rocks in surfactant solutions resulted in the reduction of contact angle, even more than magnetized water as the solvent.