Evaluation of a Novel Nanoclay-Surfactant-Stabilized CO2 Foam for EOR Applications

The efficiency of cloisite 30B nanoclay is assessed for the first time as a foaming agent to determine how these nanoparticles (NPs) affect the stability of the CO2 foam. The results of both bubble and bulk-scale foam stability measurements confirmed the efficacy of cloisite 30B NPs in improving the efficiency of CO2 foam. To compare the outcomes based on a reference, parallel experiments were conducted using silica NPs, a known promising foaming agent. By adding 0.1 wt% of nanoclay to a 0.12 wt% SDS surfactant solution, the foam decay time could be increased from 30 to 76 min. However, when the same concentration of silica NPs was used, the foam decay time was about 98 min. Furthermore, the foam injection practices showed that the foams stabilized by silica NPs and cloisite 30B nanoclay yielded 22.8% and 12.9% more oil, respectively, during foam injection into sister sandstone plugs. Moreover, we showed that stabilized foams containing cloisite 30B NPs resulted in a slightly lower final permeability compared to foams containing silica due to the retention of NPs. Both core samples underwent post-water flooding after foam injection, and then the used plugs were dried and the final gas permeability of each sample was compared to its initial value to check whether any of the used NPs might have blocked the pores. Our findings indicated that, despite the nanoclay's ability to increase foam stability and yield more oil recovery than void-NPs foam, it could not be an alternative for the frequent silica NPs.

Automated summary

The efficiency of cloisite 30B nanoclay as a foaming agent for CO2 foam stability was assessed for the first time. The results showed that cloisite 30B nanoclay improved the efficiency of CO2 foam, although not as much as silica nanoparticles. Adding 0.1 wt% of nanoclay increased the foam decay time from 30 to 76 min, while the same concentration of silica NPs yielded a foam decay time of about 98 min.