Paper: A New Treating Technique To Recover Injectivity In Injection Wells Damaged By Polymer Deposition

A new treating method has been designed for use in wells in which injectivity has been decreased by deposition of polymer residue incurred in polyacrylamide polymer and copolymer treatments. This treatment consists of one or two stages: an oxidizer stage followed by an acid stage, or a combined acid-oxidizer stage. This treatment is effective against polyacrylamide polymer and copolymer deposits near the wellbore that will not respond to conventional treatments. It is known that polymer injection can gradually lead to a decrease in injectivity. solid polymer, This injectivity decrease can be due to incompletely dissolved improperly inverted emulsion polymer, and/or deposition and adsorption on the rock face. These blockages can contain inorganic as well an organic components. An acidizing treatment is necessary for the inorganics while an oxidizer treatment is necessary to treat the organic constituent. The new treatment method consists of a strong oxidizer that is acid compatible. The pH of the oxidizer stage can be adjusted to suit the need of a given well. The pH adjustment can also control the release rate of the oxidizer. These solutions are mildly corrosive to steel. The oxidizer and acid can be split into two stages if the mixture proves to be too corrosive, or if a stronger acid is desired. These treatments have been effective without the acid stage in polymer injection wells. Laboratory data and preliminary well treatment results are presented to show the effectiveness of the oxidizer alone and with acid.