A method of polymer flooding within a sandstone formation the method comprising: injecting a treatment fluid composition into a wellbore, the treatment fluid composition comprising: a base fluid, and a viscosifier comprising a branched block copolymer wherein the branched block copolymer is a crosslinked, polymerized reaction product of crosslinker C and monomer A and monomer B and monomer D; and increasing hydrocarbon production from the wellbore.