APPLICATION OF POLYMER FLOODING IN SANDSTONE RESERVOIRS OF UZEN FIELD

Abstract

One of the most applied Chemical Enhanced Oil Recovery (CEOR) techniques is polymer flooding, which uses polymer solutions to increase the viscosity of the displacing water and enhance mobility control and sweep efficiency. Polymer flooding can be applied in mature oilfields, which already undergo secondary recovery with a gradual decrease in production. One such reservoir is the Uzen field, which is located in the western part of Kazakhstan. The Uzen field is one of the largest and oldest oilfields in the whole country and an increase in its oil production might be crucial to satisfy growing energy demand. A successful application of polymer flooding in a certain field requires a proper polymer selection followed by a well-planned and sophisticated assessment of its performance under reservoir conditions. This work is focused on the lab scale evaluation of three synthetic polymers performance in conditions of the Uzen field. The investigated polymers are co-polymers with functional groups of acrylamides (AM), Acrylamido-Tert-Butyl-Sulfonate (ATBS). Sav 10, Sav 19, and Sav 10 XV polymers. The work sequence: • Investigation of polymer concentration and temperate effects on rheological behavior of polymers • Mechanical stability under high shear rate • Evaluation of long-term thermal stability of polymers • Injectivity tests for the evaluation of permeability and mobility reduction due to polymers flooding at the core scale and required differential pressure for the injection. • Investigation of displacement efficiency of one the most suitable candidate at the core scale. Sav 10 polymer showed the best mechanical stability with the viscosity retention of 50 % after 10 minutes exposure to high shear rate. All candidates were able retain at least 50% of their initial viscosities after 2 months at 60 °C. The injection of Sav 10 polymer provided the best injectivity with the lowest differential pressures and permeability reduction. The application of Sav 10 flooding was effective and increased the cumulative oil recovery by 12 % after the brine flooding. To conclude, the polymer flooding with Sav 10 polymer in the conditions of the Uzen field was effective EOR technique and can be recommended for the implementation.