THE EFFECTS OF BRINE COMPONENTS ON WETTABILITY ALTERATION OF CARBONATES DURING SURF ACT ANT FLOODING

Carbonate reservoirs comprise more than 60% of world's reservoirs. More than
65% of the oil of these reservoirs cannot be produced by traditional production
methods. Waterflooding has been widely used to produce oil from carbonate reservoirs
but the recovery factor of this method is very low due to the low sweep efficiency and
early water breakthrough. To tackle these problems surfactants can be used. Surfactants
are chemicals which are added to injection water to reduce the surface tension between
oil and water and to change the wettability of the rock surface from oil wet to water wet
which results in higher oil recovery factor. This study investigates the effect of various
salts (NaCl, CaCh, Na2S04 and MgCh) in the formation water on wettability alteration
oflimestone rocks by a surfactant flooding process. To study the wettability, the method
of measuring the contact angle between the drop and the rock surface was employed.
The Design ofExperiment software (DOE) was used to get a thorough and systematic
investigation and to design and analyze the experiments.