The main theme behind this experimental study is to define the effect of salinity on clay, sandstone, and carbonate samples. Secondly, interactions at liquid-liquid and solid liquid scale along with IFT and contact angle measurements has also been investigated in this study.

In this study, Alcohol Alkoxy sulfate sodium salt (AAS) has been used as a surfactant. The reason of using this surfactant is that it forms type III type micro emulsion which helps in reducing the oil/water interfacial tension to a very low value and also it has a low critical micelle concentration of less than 0.1%. Brine salinity of 1-6 % is used for this experiment. Interfacial tension between different fluids is measured by injecting oil into brine of different salinities. Camera is used for recording injection of oil droplet into the brine, by the help of image software contact angle is calculated which in turn helps in estimating interfacial tension. Contact angle for solid liquid interaction is measured by pasting bentonite, sandstone, and carbonate samples on glass slide with the help of epoxy glue. After placing glass slide in front of camera oil droplet is injected using syringe then brine is added at constant flow rate due to which after certain droplet is detached and recorded on camera. The droplet is then analyzed on image grab software which estimates interfacial tension.

According to this study, when there is a liquid-liquid interaction, the interfacial tension decreases as the brine is diluted. According to the results of the experiments, the concentration of NaCl in brine is gradually reduced from 6% to 1%, and the interfacial tension decreases.

This is attributed to the fact that low – salinity water-flooding alters the wettability towards water – wet condition thus causing imbibition, a prominent driving force during tertiary oil recovery processes.

With the ever – increasing demand of energy, this study is conducted with the sole purpose of performing an in-depth analysis on the processes governing recovery during application of tertiary recovery. In future different surfactant and salinity concentrations should be studied on actual field core samples to better characterize the dominant trend and formulation of a standard relationships for industrial applications. This could be helpful in defining and delineating the untapped oil within Pakistan and across the globe.

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