| 摘要 |
1469726 Oil recovery CALGON CORP 29 April 1975 [8 May 1974] 17779/75 Heading E1F In the secondary or tertiary recovery of petroleum, the displacing medium comprises water and a methylolated water soluble copolymer of acrylamide and 2-acrylamido methyl propane sulphonic acid. The methylolated polymer is produced by reacting 0.1-10 moles of formaldehyde with each mole of acrylamide in the polymer. The displacing medium contains from 0.0025-0.5 per cent by weight of polymer and may be kept in a substantially oxygen free condition.
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