Water soluble associative polymers and compositions comprising them together with alkali metal salts of carboxylic acid are disclosed. Methods comprise introducing into a wellbore a fluid comprising such associative polymers and alkali metal salts of carboxylic acid, e.g., cesium formate. Disclosed water soluble associative polymers have functionality including at least sulfonate groups, carboxylate groups and hydrophobes associative with one another in a saturated aqueous solution of an alkali metal salt of a carboxylic acid. Water soluble associative polymers are formed as the polymerization reaction product of reactants comprising an AMPS reactant, an alpha, beta-unsaturated carbonyl reactant and a hydrophobe reactant selected from acrylic esters, methacrylic esters and a mixture of any of them, having a --COOR moiety wherein R is a hydrophobe which, as hydrophobe moieties of the resultant associative polymer, are associative with one another in a saturated aqueous solution of an alkali metal salt of a carboxylic acid.