The Uzen field development stage is characterized by high watercut (~90%) due to long-term waterflooding and a recovery factor of 34,6%, which is appropriate for moving to the tertiary recovery methods, especially chemical EOR. Polymer flooding (PF) is a promising chemical EOR technology to provide incremental oil and extend the field life. Therefore, the main features of PF were investigated and screened for the Uzen field conditions within the scope of the feasibility study.
The main geological characteristics of the reservoir were examined to confirm polymer flooding applicability. Reservoir dynamics analysis was conducted to identify the main problems of the current development strategy. Water composition analysis was carried out to assess available water sources in terms of polymer compatibility. Based on Daqing oilfield PF experience, the watercut dynamic behavior was used to determine incremental oil amount for the potential pilot area in Uzen. Since technical feasibility studies are done, economical feasibility has been conducted considering current oil prices.
Parameters such as temperature, permeability, oil viscosity, and brine salinity were found to be the most critical for polymer flood. Two water sources out of three available in the Uzen showed the compatibility of polymers according to water composition analysis. The first priority is given to Cretaceous formation brine as the most appropriate and the second priority is given to Caspian seawater. The potential pilot area with 3 injectors and 14 producers has been selected and forecasted in terms of PF production. PF technology performed for 10+ years resulting in 4.7% of incremental oil recovery. Polymer flooding has proven to be an effective development strategy as a tertiary recovery method that hopefully will be applied in the coming years.
Although polymer flooding has been used for the past ~60 years, for the Uzen field polymer flooding is a step away from being applied for the first time. Observations and obtained results are the basis for future design, implementation, and optimization of PF in the Uzen oilfield.