Investigation the wettability alteration of oil wet calcite by using different salt ions.

Javad,

Generally, it is accepted that pH effect could resulted in Induced wettability alteration.

But, from experimental point of view, you have to answer a question first; Are you able to evaluate affinity of different ions individually at reservoir condition or not?

Since you did not mentioned anything regarding your water recipe, like TDS or sulfate concentration, I can give you a hint like this, the best practical approach that I have seen so far, is a work by Haagh and his coworkers. To doing that, the water recipe, which they used, were modified in two ways; 1- by reduction of TDS 2- by changing of Ionic composition at constant Ionic Strength.

You can take a look on the water recipes here:

• DOI: 10.1021/acs.langmuir.6b04470

You might use the second approach to answer your question; however, please pay attention to two other facts. First, although Haagh et al manipulated water recipe practically, they did not use carbonate thin sections. Second is the pH effect is not clear enough yet. That is way several authors tried to use Phreeqc and surface complex models.

Moreover, as you may know, Gupta and his co workers suggested that the best sulfate concentration could be considered up to 4 times more than of its original concentration. What range of sulfate have you considered in your experiments?

Finally, we can say that pH could change up to 3 units in any salinity dependent EOR technique, such as smart or Low Salinity waters.

Hope it helps. :)

Ali.