Numerical Modeling and Simulation of Viscoelastic Polymer Flow in Porous Media

Abstract

With the continuously accelerated energy demand, the petroleum industry needs to apply more advanced techniques to enhance production from existing fields or make new field discoveries in order to satisfy future energetic requirements. Enhanced Oil Recovery (EOR) is a crucial stage in oil production that may increase ultimate oil recovery to more than half of the reservoir's original oil in place (OOIP). Polymer flooding is one of the most commonly used chemical EOR methods. Conventionally, this technique was believed to improve macroscopic sweep efficiency by sweeping only bypassed oil. Nevertheless, recently it has been found that polymers exhibiting viscoelastic behavior in the porous medium can also improve microscopic displacement efficiency resulting in higher additional oil recovery. Therefore, an accurate prediction of the complex rheological response of polymers is crucial to obtain a proper estimation of incremental oil to polymer flooding. In this research, we proposed a novel viscoelastic model to comprehensively analyze the polymer rheological behavior in porous media. This model is considered an extension of the unified apparent viscosity model provided in the literature and is termed as extended unified viscosity model (E-UVM). The main advantage of our model is its ability to capture the polymer mechanical degradation at ultimate shear rates primarily observed near wellbores. Furthermore, the fitting parameters used in the model were correlated to the rock and polymer properties, significantly reducing the need for time-consuming coreflooding tests for future polymer screening works. Moreover, the model was implemented and verified in a reservoir simulator. The comparison between various viscosity models existing in the literature and E-UVM in the reservoir simulator revealed that using the latter model can predict oil recovery with more accuracy since it accommodates the mechanical degradation of polymers. The core-scale predictions of polymer flooding also showed a positive effect of polymer concentration and injection rate on oil mobilization. Finally, field-scale predictions of the polymer flooding technique were performed in a quarter 5-spot well pattern, using rock and fluid properties representing the Middle East carbonate reservoirs. The effect of various parameters on the polymer flooding efficiency was investigated during sensitivity analysis.

Date of Award	Jul 2021
Original language	American English