Scientific research and field applications of polymer flooding in heavy oil recovery

The heavy oil resources worldwide are estimated at 3,396 billion barrels. With depletion of light oil, we have to face the technical and economical challenges of developing heavy oil fields. Due to severe viscous fingering, the recoveries of heavy oil reservoirs are often below 20% or even 10%. Thermal methods have been successfully applied in many heavy oil fields. However, reservoirs at great depth or thin pay zones are not good candidates for thermal methods. According to past experiences, polymer flood was not recommended for oil viscosity higher than 100 centipoises. In recent years, polymer flood becomes a promising technology for heavy oil recovery thanks to the widespread use of horizontal wells. This paper highlights the research advances of polymer in heavy oil recovery since 1977. In laboratory tests, polymer achieved tertiary recovery of more than 20% for heavy oil. A few field cases in China, Canada, Turkey, Suriname and Oman are also reviewed and analysed. Some field pilots have shown positive results. Field experiences indicate the major challenge facing polymer flooding effectiveness is to maintain good viscosity of polymer solution.