Experiments and Simulation of the Near-Wellbore Dynamics and Displacement Efficiencies of Polymer Injection, Matzen Field, Austria

Abstract

Abstract High molecular weight partially hydrolyzed polyacrylamides (HPAM), have been shown to effectively increase oil recovery of medium viscous and heavy oil. Using a rheometer, these polymers show shear thinning behavior. However, determining the apparent viscosity from coreflood tests for different frontal velocities, an increase in the apparent viscosity is observed. This apparent increase is attributed to the visco-elastic properties of the polymers. In this paper, a set of laboratory experiments has been performed for cores similar to the rock in the 8th Torton Horizon (8 TH) of the Matzen Field in Austria. The results show that for the conditions in the near-wellbore region of the reservoir, an increase in apparent viscosity is expected. In addition, the relationship of velocity versus apparent viscosity for pre-sheared polymers was investigated. Dependent on the amount of pre-shearing, the apparent viscosity was significantly decreased. For different polymer concentrations, the apparent viscosity versus velocity of the pre-sheared polymers was almost identical. A polymer injection pilot performed in the 8 TH in the Matzen Field in Austria confirmed that shearing of the polymer solution in the near-wellbore occurs for injection below the fracturing pressure. Above the fracturing pressure, the flow velocities are significantly decreased owing to the large surface area of the fracture. Hence, polymer injection should be performed above the fracturing pressure to improve sweep efficiency.