Altering wettability in subterranean formations

A method of altering a wettability of a subterranean formation penetrated by a well, the method comprising:

• introducing a first oxidizer comprising a persulfate to the subterranean formation;
• introducing a second oxidizer comprising a bromate to the subterranean formation;
• shutting in the well for a period of time to allow the first oxidizer and the second oxidizer to alter the wettability of the subterranean formation toward non-wetting of oil and of water;
• and
• determining that the wettability of the subterranean formation has been altered toward non-wetting of oil and of water by performing a contact angle test on a rock sample obtained from the subterranean formation, wherein the contact angle test comprises:
• measuring a first contact angle of a first fluid comprising water on a surface of the rock sample;
• and
• measuring a second contact angle of a second fluid comprising a hydrocarbon on the surface of the rock sample, wherein determining that the wettability of the subterranean formation has been altered toward non-wetting of oil and of water comprises determining that the first contact angle and the second contact angle are both in a range from about 70° to about 110°.