| abstract |
An enhanced oil recovery method comprising the following steps: a) obtaining an injection fluid containing at least one water-soluble (co)polymer derived from at least 2-acrylamido-2-methylpropane sulfonic acid (ATBS) or at least one of its salts, with water or saline, where 2-acrylamido-2-methylpropanesulfonic acid is present in the hydrated crystalline form of 2-acrylamido-2-methylpropanesulfonic acid, characterized by an X-ray powder diffraction pattern containing peaks at angle 2 values of 10.58° , 11.2°, 12.65°, 13.66°, 16.28°, 18.45°, 20°, 20.4°, 22.5°, 25.5°, 25.88°, 26 .47°, 28.52°, 30.28°, 30.8°, 34.09°, 38.19°, 40.69°, 41.82°, 43.74°, 46.04°; b) pumping the injected fluid into a subterranean formation; c) flushing the subterranean formation using the injected fluid; d) extraction of a mixture of water and hydrocarbons. |