Synthesis and Application of a Novel Water-Soluble Binary Polymer Viscosity Reducer for Heavy Oil Reservoirs

Abstract In heavy oil reservoirs subjected to multicyclic steam stimulation, significant challenges such as steam channeling, high thermal conductivity, low single-well production, increased water content, and reduced thermal recovery efficiency are commonly observed. To address these challenges, a novel water-soluble binary polymer viscosity reducer has been synthesized. It demonstrated exceptional viscosity reduction performance, achieving a reduction rate exceeding 97% at concentrations of 0.1–0.3 wt %. For heavy oil with an initial viscosity of 4889 mPa s, the viscosity reduction rate exceeded 99%. The viscosity reducer exhibited high thermal stability ( T d = 181°C, T g = 166°C), making it suitable for heavy oil reservoirs undergoing multicyclic steam stimulation. Furthermore, it displayed excellent surface activity and high water solubility. Based on these properties, a combined chemical viscosity-reduction flooding method has been developed, involving the sequential injection of polyacrylamide and the viscosity reducer. This method increased the sweep efficiency and improved the oil washing efficiency in the swept zone. In core displacement experiments, it reduced the water cut by 34.21% and increased the oil recovery by 17.16%. Field applications demonstrated a cumulative oil production increase of 39 700 tons and a 2.17% improvement in the recovery factor, with the final oil recovery factor projected to increase by 10.96%. This study provides valuable insights for the development of heavy oil reservoirs after multicyclic steam stimulation.