Mechanistic Simulation of Polymer Injectivity in Field Tests

Lotfollahi, Mohammad (University of Texas at Austin) | Farajzadeh, Rouhi (Shell Global Solutions International) | Delshad, Mojdeh (Delft University of Technology) | Al-Abri, Al-Khalil (University of Texas at Austin) | Wassing, Bart M. (Petroleum Development Oman) | Al-Mjeni, Rifaat (Petroleum Development Oman) | Awan, Kamran (Petroleum Development Oman) | Bedrikovetsky, Pavel (Petroleum Development Oman)


Mohammad Lotfollahi, University of Texas at Austin; Rouhi Farajzadeh, Shell Global Solutions International and Delft University of Technology; Mojdeh Delshad, University of Texas at Austin; Al-Khalil Al-Abri, Bart M. Wassing, Rifaat Al-Mjeni, and Kamran Awan, Petroleum Development Oman; and Pavel Bedrikovetsky, University of Adelaide Summary Polymer flooding is one of the most widely used chemical enhanced-oil-recovery (EOR) methods because of its simplicity and low cost. To achieve high oil recoveries, large quantities of polymer solution are often injected through a small wellbore. Sometimes, the economic success of the project is only feasible when injection rate is high for high-viscosity solution. However, injection of viscous polymer solutions has been a concern for the field application of polymer flooding. The pressure increase in polymer injectors can be attributed to (1) formation of an oil bank, (2) polymer rheology (shear-thickening behavior near wellbore), and (3) plugging of the reservoir pores by insoluble polymer molecules or suspended particles in the water. In this paper, a new model to history match field injection-rate/ pressure data is proposed. The pertinent equations for deep-bed filtration and external-cake buildup in radial coordinates were coupled to the viscoelastic polymer rheology to capture important mechanisms. Radial coordinates were selected to minimize the velocity/shear-rate errors caused by gridblock size in the Cartesian coordinates. The filtration theory was used and the field data history matched successfully. Systematic simulations were performed, and the impact of adsorption (retention), shear thickening, deepbed filtration, and external-cake formation was investigated to explain the well-injectivity behavior of polymer.