Tuning the salinity and concentration of potential-determining ions, such as Mg²⁺, Ca²⁺, and SO₄²⁻, could alter the wettability toward a more water-wet state. The rate of alteration in carbonate rock wettability is a critical parameter to design the duration of the ion-engineered water flooding. Characteristic experiments, such as dynamic contact angle and pH measurements, ion chromatography, and spontaneous imbibition, are applied to study the rate of wettability alteration using different samples of ion-engineered water. Our study shows that the Caspian Sea water (CSW) with a salinity of 15,000 ppm is an efficient displacing fluid as it can initiate the multi-ion exchange (MIE) mechanism and alter the wettability from 86° to 35° within 2 d. The adjustment of salinity and active ion concentration makes the MIE mechanism much faster. For example, with five times diluted CSW, the same change in wettability is only achieved only within 9 h. Spiking the concentration of Ca²⁺ and SO₄²⁻ ions is used to further shift the contact angle to 22° within 9 h. Spontaneous imbibition tests demonstrate that the rate of oil production doubles as a result of the ion-engineered brine due to the faster MIE process. The results obtained from this research work suggest that even a short period of interaction with optimized engineered water can affect the brine, oil, and carbonates interactions and change the reservoir rock initial wettability from neutral to strongly water-wet state. This allows to efficiently design engineered water flooding based on CSW in the field scale and make such projects more profitable.

中文翻译：

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里海离子工程水中的SO ₄ ²⁻，Ca ²⁺和Mg ²⁺离子对碳酸盐润湿性变化速率的影响

调整诸如Mg 2 ⁺，Ca ²⁺和SO ₄ ^2-的电势决定离子的盐度和浓度，可能会将润湿性改变为更湿润的状态。碳酸盐岩润湿性的变化速率是设计离子工程注水时间的关键参数。使用诸如动态接触角和pH测量，离子色谱法和自发吸水等特性实验，来研究使用离子工程水的不同样品的润湿性变化率。我们的研究表明，盐度为15,000 ppm的里海海水（CSW）是一种有效的驱替液，因为它可以启动多离子交换（MIE）机理，并在2天内将可湿性从86°改变为35°。盐度和活性离子浓度的调节使MIE机制更快。例如，用5倍稀释的CSW，仅在9小时内就实现了相同的润湿性变化。^使用2+和SO ₄ ^2-离子可在9小时内将接触角进一步移至22°。自发吸收测试表明，由于MIE工艺更快，离子工程盐水使产油率翻了一番。从这项研究工作中获得的结果表明，即使与优化的工程用水进行短时间的相互作用也会影响盐水，石油和碳酸盐的相互作用，并使储层岩石的初始润湿性从中性变为强水湿状态。这使得可以在现场规模上基于CSW有效地设计工程注水，并使此类项目更有利可图。