A water or brine soluble terpolymer having the structure: ##STR1## wherein x is selected from the group consisting of ##STR2## wherein x is about 70 to about 95 mole percent; y is about 0.1 to about 5.0 mole percent; z is about 1 to about 30 mole percent; R.sub.1 is methyl or hydrogen; a is about 1 to about 5; b is about 3 to about 4; R.sub.3 is an alkyl group of 3 to 4 carbon atoms; R.sub.4 is an alkyl group having about 1 to 5 carbon atoms; R.sub.5 is selected from the group consisting of an alkyl group having 1 to 30 carbons, a hydrocarbon aryl group having about 6 to 20 carbons and an alkylaryl group having the structure of ##STR3## wherein A is selected from the group consisting of hydrogen, methyl groups, ethyl groups and propyl groups and mixtures thereof and c is about 6 to 20; and n is about 1 to 60.