Effect of dopants addition on the displacing phase properties in a polymer flooding process using computed tomography scanning

Abstract

This study evaluated the impact of the four most used dopants in core-flooding tests, supported by computed tomography, on the behavior of polymer viscosity. Initially, the minimum concentration of each dopant required to achieve an adequate contrast between phases was estimated by varying the amount of dopant in solution and comparing the CT number of polymer solution and oil to guarantee a differential highest than 300 CT. Afterward, the effect of adding the different dopants on the polymer solution viscosity was determined through Brookfield viscosimeter. Subsequently, the polymer concentration to counteract the viscosity reduction was quantified by adding different polymer amounts. The results showed that sodium iodide achieved the highest attenuating effect between phases with the lowest dopant concentration. Moreover, this dopant caused the lowest polymer viscosity diminution and required the smallest increase in polymer concentration to reach the base case viscosity, making this dopant the most suitable agent to be used in polymer injection experiments at the conditions evaluated. Finally, the impact of crude oil density on the lowest amount of dopant required to achieve sufficient differentiation between phases was analyzed, and as a result, a correlation was found that could be used in future experiments at similar conditions to evaluate polymer flooding in a porous medium by means computed tomography scan as a visual and non-intrusive technique, reaching the best contrast between crude oil and HPAM.