Mona Zahedi; - Petroleum Engineering Department, Faculty of Chemical Engineering, Tarbiat Modares University
Amirhossein Saeedi Dehaghani - Petroleum Engineering Department,Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran

Increasing oil recovery from carbonate reservoir rocks due to their complex geometry and increase of oil demand is one of the main challenges in the petroleum industry. The use of smart water and surfactant is an efficient way to enhance oil recovery (EOR) by changing the wettability of rock surfaces from oil-wet to water-wet state. In this work, several smart waters with various novel composition (i.e., diluted seawaters with different concentration of active SO2- 4 and PO3 4 ions) combined with and withoutC19TAB surfactant to determine their individual effects on wettability alteration by computing the changes of contact angles in carbonate rock samples. From experiments, it was observed that increasing the concentration of phosphate in diluted seawater in presence of surfactant has the best effect and results to the strongly water-wet system by decreasing contact angle from162 to27 ( 135decreased) while the absence of surfactant would lead to less water-wet state than brines individually by changing the contact angle from 149 to 50 ( 99decreased). Also, it was observed that the phosphate ion is more robust to changing the contact angle than sulfate ion in the presence and absence of surfactant.

Oil recovery, Smart water, Brines, C19TAB surfactant, Contact angle, Phosphate