Disclosed herein is a polymer useful in a method of forming a wellbore fluid additive. This polymer comprises a polyethylene backbone comprising pendant aminoalkylsulfonic acid amides which comprise a carbonyl directly attached to a backbone carbon, and an amide formed via the amine group from the aminoalkylsulfonic acid. Methods of preparing these polymers by addition of the aminoalkylsulfonic acid to a polymeric anhydride are disclosed. Methods related to oil extraction using the wellbore fluid with the additive are also disclosed.