Javad Siavashi - Master of Petroleum Engineering Student majoring in Hydrocarbon Reservoirs Faculty of Petroleum Engineering Amirkabir University of Technology, Tehran
Arman Najafi - Master of Petroleum Engineering students majoring in Hydrocarbon Reservoirs Faculty of Petroleum Engineering Amirkabir University of Technology, Tehran
Aghil Moslemizadeh - ۳PhD students in Petroleum Engineering, major in Hydrocarbon Reservoirs, Faculty of Petroleum Engineering, Amirkabir University of Technology, Tehran
Mohammad Sharifi - Associate Professor, Department of Hydrocarbon Reservoirs, Faculty of Petroleum Engineering, Amirkabir University of Technology, Tehran

The oil recovery factor from carbonate reservoirs depends on the heterogeneity of the reservoirs, rock properties and the drive mechanisms. Many carbonate reservoirs are naturally fractured, which can cause challenges in water injection if the fracture network is continuous and connected. Water-wet surface condition is required to produce remaining oil in the matrix using water flooding, such that the imbibition process occurs efficiently. Enhanced oil recovery methods (EOR) and, in particular, surface-active agent (surfactants) flooding are effective methods to recover residual oil in these reservoirs. Essential mechanisms of surfactant flooding to increase oil recovery are changing reservoir wettability and reducing the interfacial tension (IFT) between the water and oil system, thereby making it easier for oil to flow into production wells. ۱-octadecyl-pyridinium Bromide is used in this study, and its performance is evaluated for (EOR) purposes. First, this surfactant's performance to reduce the IFT between water and oil is investigated using the pendant-drop method. Then its ability for wettability alteration is evaluated through the contact angle measurement experiment. The results of these experiments show the strong performance of this surfactant in reducing the IFT between water and oil to near one mN/m and changing the wettability of calcite rock samples from the oil-wet to neutral-wet at its critical micelle concentration (CMC).

Carbonate reservoirs, Enhanced Oil Recovery, Surface active agent, Interfacial tension, Wettability