Seyed Mahmoud Mirsadeghi - EOR Lab, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
Arshia Nosrati - EOR Lab, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
Mehdi Heidari - EOR Lab, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
Meysam Golmohammadi - EOR Lab, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
Hassan Mahani - EOR Lab, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
Shahab Ayatollahi - EOR Lab, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran

Wettability alteration is the primary effect of low salinity water flooding (LSWF) in many oil-brine-rock systems leading to improved oil recovery efficiency. This effect has been studied in many research works, using contact angle measurement and evaluation of water imbibition rate. However, these techniques are subjected to surface properties of the thin section (in the case of contact angle measurement) or the pore size and structure of the plug used for the imbibition test. Besides, the possible alteration of the wettability through the utilization of different injecting fluids and the reservoir conditions such as temperature is rarely evaluated in the laboratory. In this research work, a newly designed technique based on the flotation test is presented and calibrated to assess the low salinity effect (LSE) on rock grain wettability. The results showed that less than ۴۰% of the grains turned water-wet by reducing the water salinity from formation brine to the optimized case. Therefore, a new scenario of using combined low salinity water and surfactant is utilized to check the wettability alteration compared to the previous case. The results show that for a low concentration of CTAB used in these tests, the performance of the wettability alteration could be improved by more than ۵۰%, and the wettability index of the oil-wet grains increased to ۶۵%.

Low Salinity Water, Enhanced Oil Recovery, Flotation Test, Wettability Alteration, Surfactant