مشخصات پژوهش

Smart water combined with wettability-reducing additives through contact angle modification is one of the effective strategies to optimize EOR. So far, many studies have focused on either carbonate or sandstone surfaces, separately, but very few considered both lithologies together under the same experimental conditions. Therefore, in this study, a systematic study of the wettability alteration on two carbonate and three sandstone samples was conducted using distilled and seawater in the presence of various salts and newly developed additives. Ionic solutions of NaCl, MgCl₂, CaCl₂, and NaNO₃ were prepared at 10,000 ppm, while gilsonite dispersion (10,000 ppm) and an amphiphilic cobalt-based X-EOR catalyst (100 ppm) were introduced as additional smart water modifiers. The selected concentrations were identified using preliminary screening experiments to secure enough ionic strength and additive dispersion without compromising solution stability. Quantitative results showed that the most pronounced wettability alteration took place on carbonate 1 with distilled water containing CaCl₂, where the contact angle decreased from 68° to 47°. In sandstone, CaCl₂ reduced the angle from 120° to 97°, whereas NaNO₃ increased the angle from 70° to 90°- evidencing oil-wet behavior. Gilsonite dispersion increased hydrophilicity in sandstone from 61° to 53°, but the X-EOR catalyst reduced the contact angle from approximately 110° to 90° in sandstone, from 65° to 50° in carbonate 1, and from 85° to 78° in carbonate 2 under distilled-water conditions. Similar wettability improvement was observed in seawater systems. These results confirm that natural and synthetic modifiers are able to significantly improve smart water performance by ionic exchange and modification of surface energy, inducing a marked shift toward water-wet conditions in the presence of these modifiers in several lithologies.