Learning from Polymer Flooding in Offshore Viscous Oil Reservoirs

Abstract

Summary Polymer flood applications in offshore fields face more challenges than that of onshore fields. These challenges include limited platform space, costs to transfer polymer chemical, short service life, large well spacing, and high salinity formation water and reduced polymer viscosity when mixed with sea water. The above challenges make it's hard to directly applied the onshore polymer flood technologies and experiences proved successful. Also, there are seldom practical polymer flood projects that had been implemented in offshore conditions as analogs. Taking five offshore viscous oil polymer flood projects as examples, this paper summarizes their implementation, production performance, reservoir management and lessons learned during pilot or field-wide polymer flood process. Key lessons learned are: (1) early polymer flood combing secondary and EOR could be a key strategy for offshore field, which recovers oil in short time, saves the cost of production fluid processing due to reduced water handling requirements and achieve relative high recovery factor; (2) Mechanic degradation at the near wellbore is the main source of polymer degradation due to permeability impairment caused by poor quality produced water injection. Rather than the most popular HPAM, the salinity and shearing resistance polymer such as hydrophobic associated polymers work better.