| abstract |
Auxiliary agents for chemical flooding of petroleum deposits and auxiliary agents used in well drilling fluids are water-soluble copolymers containing a statistical distribution of (a) 5 to 95% by weight of structural units of formula I <IMAGE> (I) (b) 0 to 30% by weight of structural units of formula II <IMAGE> (II) (c) 0 to 80% by weight of structural units of formula III <IMAGE> (III) (d) 5 to 60% by weight of structural units of formula IV <IMAGE> (IV) wherein R1 and R2 are the same or different and represent hydrogen, methyl, or ethyl or together are trimethylene to cyclic pentamethylene; R3 represents hydrogen or methyl; R4 represent a imidazolyl-(1) or imidazolyl-(2) moiety; Y is a single covalent bond or the formula -CO-NH-C(CH3)2-CH2-; and X+ is a cation. |