Assessment of polymer based carbonation in weak/strong alkaline media for energy production and carbon storage: An approach to address carbon emissions

Abstract

Polymer methods are typically used to control mobility and the areal sweep of injected carbon dioxide in oil recovery and sequestration applications. Carbon dioxide utilization can be further improved through the increment in absorption potential of these methods. Therefore, in this study, the role of both weak (sodium carbonate) and strong (sodium hydroxide) alkalis is investigated on absorption, retention, oil recovery, and carbon storage potential of oilfield hydrolyzed polyacrylamide at elevated pressure (3 MPa) and temperature (70 °C). The inclusion of alkali (1 wt%) increased the carbon dioxide absorption capacity of polymer solution with maximum absorption by sodium hydroxide treatment. However, the retention capacity of the polymer solution was different in presence of alkalis and strong alkali suggested minimum retention. Similar behavior was observed during a rheological investigation where sodium hydroxide suggested a sharp drop (∼85%) in viscosity values of polymer solution while sodium carbonate was offered only ∼40% drop. Moreover, moduli (elastic and viscous) results showed that sodium carbonate treated polymer solution exhibited viscoelastic nature while a dominating liquid-like nature was evident in the case of sodium hydroxide. The tapered water-alternating gas injection was also explored for sodium carbonate treated polymer solution where carbon dioxide injection before chemical slug was found desirable for higher oil recovery (69%) than the one associated with chemical slug injection before carbon dioxide (65%). In addition, higher carbon storage (44% of injected carbon) was also obtained when carbon dioxide injection was performed before the chemical slug.