| abstract |
The present invention provides a composition for recovery of petroleum and gas, which comprises (a) a copolymer having a molecular weight of 100,000 or more, composed of 30-75 mole % of N-vinylpyrrolidone unit, 5-70 mole % of (meth)acrylamide unit and 0-20 mole % of (meth)acrylic acid unit or a salt thereof, (b) a water-soluble aldehyde, (c) a phenol compound, and (d) water. This composition can form a gel in a required gelling time even at high temperatures and even in the presence of bivalent metal ions and accordingly can be used for efficient recovery of petroleum and gas. |