Stable Silica Nanofluids of an Oilfield Polymer for Enhanced CO₂ Absorption for Oilfield Applications
2018
Raghav Chaturvedi, Krishna | Kumar, Rakesh | Trivedi, Japan | Sheng, James J. | Sharma, Tushar
CO₂ injected with water often gives premature breakthrough and reduces its absorption during sequestration and oil recovery applications. Water-soluble polymers are used to increase CO₂ absorption via an increase in water viscosity that restricts CO₂ movement and thus its early release. The efficacy of polymer CO₂ absorption methods can be further increased in the presence of nanoparticles (NPs) that interact with polymer chains and create a steric barrier to improve CO₂ absorption. Thus, nanofluids prepared with compatible NPs might be a safe and reliable method to improve CO₂ absorption of polymer methods. In this work, a nanofluid prepared with silica NPs (0.1–1.0 wt %) in base fluid of oilfield polymer [(polyacrylamide (PAM) with typical oilfield concentration (1000 ppm)] was tested for CO₂ absorption and compared with the one of PAM fluid at different temperatures (303 and 353 K). The inclusion of SiO₂ in PAM fluid provided stable nanofluids that exhibited good dispersion stability without NP settlement for days. Thus, the efficacy of PAM fluid CO₂ absorption significantly increased with nanofluids as reported through microscopic, kinetics, and molality results. The increase in NP concentration and temperature (353 K) showed an inverse relationship with CO₂ absorption in nanofluids, mainly due to enhanced NP aggregation; thus, the use of nanofluids for CO₂ absorption is critical at high temperature and high NP concentration. The NP effect on CO₂ stabilization and absorption is finally supported through UV–vis measurements. The study highlighted important aspects of CO₂ absorption and is a forward step toward the use of nanofluid together with the considerable possibility of enhanced CO₂ miscible oil recovery.
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