Polymer Injectivity Analysis and Subsurface Polymer Behavior Evaluation

Abstract

Abstract A robust analysis of a polymer flooding inter-well pilot has been performed. The main objective was to analyze the polymer injection performance and to confirm the in-situ designed viscosity of the polymer injected, necessary to estimate the expected EOR effect. The adopted workflow focused on the integration of different sources of data and analyses. Indeed, several phenomena may occur during polymer injection, such as complex injectivity behavior due to polymer non-Newtonian rheological nature, formation damage caused by particles adsorption, fractures opening, and mechanical degradation of polymer. The injection performance analysis focused the following aspects: previous case history, polymer laboratory tests, shear stress through perforation evaluation, diagnostic plots, injectivity test interpretation, well test analysis, and fracturing investigation. Lastly, numerical simulation allowed us to integrate the different analysis, thoroughly capturing the subsurface polymer behavior. Main result is that injection under fracturing conditions occurred during pilot start-up. These small-scale fractures, localized in the near-wellbore zone, are not detrimental to polymer flooding and rather increase the well injectivity. Furthermore, no evidence of mechanical polymer degradation was detected. The evaluation of the subsurface polymer behavior during an inter-well pilot is crucial to verify the correct polymer injection process. In this work different source of data and analysis have been integrated to understand the injectivity behavior. Robust reservoir monitoring is ongoing and preliminary promising effects are now being shown.