| abstract |
Hydrocarbons are recovered from a subterranean hydrocarbon-bearing formation penetrated by an injection well and a production well by displacing hydrocarbons toward the production well using a drive fluid such as water thickened with polyacrylamide or partially hydrolyzed polyacrylamide alkoxylated with an alkylene oxide and, if desired, a small amount of a sulfonated, alkoxylated polyacrylamide, i.e., an N-substituted polyacrylamide having N-substituents of the formula: n n --(CH.sub.2 CH.sub.2 O).sub.m-1 CH.sub.2 CH.sub.2 SO.sub.3 M, n n where m is an integer of from 2 to 5 and M is selected from the group consisting of hydrogen, sodium, potassium or ammonium. Optionally, the drive fluid can be saturated with carbon dioxide, nitrogen and/or natural gas at the injection pressure. |