FW contains NaCl, CaCl2, MgCl2, and Na2SO4, which together form 104,550 ppm total dissolved salts. The FW pH is 6.94. Four cores were flooded successively with foam and different brine concentrations. Synthetic seawater (SW) used in this study had a salinity of 48,300 ppm. SW was diluted with deionized water to produce the other brines. SW was diluted 2 times, 10 times, and 50 times to make d2SW, d10SW, and d50SW, respectively. Table illustrates the brine compositions. The surfactant solution (SS) was prepared using 1.0% surfactant concentration in water. The surfactant solution (SS) (CH3 (CH2)11SO4 -Na + ) was prepared in water using 1.0% sodium dodecyl sulfonate (SDS). Colt Energy delivered the crude oil. The crude oil properties are shown in Table . The crude oil was centrifuged to remove water and deposits. Berea sandstone cores were taken from the same block. The XRD shows that they contain 93% quartz and the rest was kaolinite. All the cores were cut to one inch in diameter. The cores' permeability and porosity were 110md and 21% on average, respectively. The cores are identical in petrophysical properties. After the cores were cut, they were dried overnight inside an oven, and the next day they were evacuated and saturated with FW. The weight difference between unsaturated and saturated is used to measure porosity. The core permeability was measured by loading the Berea sandstone core into a Hassler core holder with a confining pressure that did not exceed 600 psi. FW was flooded at different flow rates, and the pressure was recorded. Crude oil was then injected to achieve Swi. The core holder was then cleaned, and the cores were put into a closed container containing heavy crude oil and aged inside an oven at 90°C. After the initial flood with FW, the core-flooding experiments were performed in a four similar way but with different brines at 45°C as shown in Table .