Microscopic insights into the interaction of crude oil and low salinity water
Volume Title: 1
Faculty of Petroleum and Natural Gas Engineering, Sahand University of Technology, Tabriz, Iran
Recently low salinity water (LSW) has been received more attention to improve oil recovery mainly through rock wettability alteration toward more water wetness. In spite of different studies dedicated to explore the rock/LSW/crude oil interaction, few studies elaborated the possible fluid interactions between crude oil and LSW. This study aims to provide microscopic insights into the interaction of crude oil/brine with different salinities using a micromodel fluid system. This was aided by salinity scan analysis, measuring the pH of the aqueous phase that is contacted by crude oil and also IFT of crude oil/brine system over time. Results of the micromodel study showed that partitioning of the crude oil polar components into the aqueous phase increases with the reduction of brine salinity from seawater (SW) to its 10 times dilution (0.1SW) mainly due to the salting-in effect. This observation was supported by a meaningful reduction in the pH of the 0.1SW brine to as low as 5.36 as compared to 7.21 for the case of SW. This was followed by an increase in the IFT of the crude oil/0.1SW brine, 40 mN/m as to 30 mN/m in the presence of SW. Also, as to the salinity scan analysis, an emulsified phase region was formed between crude oil and brine at all salinity due to the partitioning of the crude polar components, while the thickest emulsified region corresponding to the highest partitioning was obtained in the presence of 0.1SW brine.