Compatibility of Hydrosoluble Polymers With Corrodible Materials

Summary Application of water-soluble polymers in the oil industry (e.g., fluid-loss reducer, polymer flooding, and water-based drilling muds) requires hydrosoluble polymers to be compatible with corrodible materials. The behavior of polyacrylamides and xanthans in the presence of various materials used for oil production (steel, stainless steel, carbon steel, and Inconel™) has been studied vs. different water salinities, oxygen contents, and temperatures. The influence of such commonly used additives as oxygen scavengers and sequestrants on corrosion and polymer stability has also been investigated. For both types of polymers, as corrosion occurs under anaerobic conditions, strong interactions between polymer chains and divalent cations (Fe2+ or Ni2+) are observed. Such interactions also depend on polymer quality. In the presence of oxygen, corrosion induces a molecular-weight degradation of the polymer followed by a gelation process for xanthan. Some additives may accelerate the transformation of Fe2+ to Fe3+, thus inducing polymer degradation, but this reaction depends on the nature of the chelating agent. These results provide guidelines for the implementation of polymers in oil production, including the selection of materials, water treatment, or mud formulation.