Patent ID: 8714247

Claim:
A process of recovering residual oil from subterranean reservoirs by injecting into one or more injection wells, an aqueous solution containing a) one or more sulfonated amphoteric surfactants of the structure Where R′═C1-C6 alkyl, R″═C1-C6 alkyl or X═(CH 2 )aCOO or CH 2 CH(OH)CH 2 SO 3 or (CH 2 )bSO 3 or O, x=4-28, y=4-28, z=1-6, a=1-3, b=1-6, M=mono or divalent metal cation or ammonium cation, b) an aqueous injection fluid, c) 0-5 wt % or more alkali, d) 0-1% of one or more viscosifiers, e) 0-50 wt % of one or more co-solvents; f) 0-5 wt % of one or more co-surfactants, and; recovering the oil from one or more production wells.