Characterization and Evaluation of Novel Zwitterionic Surfactants for Enhanced CO₂ Foam for CO₂ Sequestration in Saudi Arabian Reservoirs

This study aims to assess the foamability and foam stability of synthetic zwitterionic surfactants in a seawater environment, both in the absence and presence of oil. The primary objective is to determine their potential use in enhanced oil recovery (EOR) and CO₂ sequestration within depleted oil reservoirs by determining the maximum foam stability. Moreover, the efficiency of surfactants is assessed by analyzing bubble sizes under different conditions. Finally, the effect of different concentrations of oil phases on foam stability under various conditions is studied. Two different zwitterionic surfactants (ZS1 and ZS2) were synthetically formulated and tested using ambient foam analyzers to evaluate their foamability and foam stability over time. Parameters such as foam height and foam decay were studied. A high-speed camera was employed to observe foam bubble sizes and coalescence. The performance of the surfactants is further evaluated under seawater and in the presence of different oil concentrations. All examined zwitterionic surfactants displayed promising results concerning air and CO₂ foamability and foam stability under different conditions. Foam generated through CO2 exhibits lower stability than foam created by air. Additionally, to understand the performance of the optimum foam composition in the presence of an oil phase at reservoir conditions, the foam was then brought into contact with different oil concentrations. The results show that foam stability decreased in the presence of different fractions of oil. However, the foam bubble size was not highly affected by the presence of oil. This observation is crucial as it indicates the potential longevity of foam stability in the presence of oil during both the EOR process and CO₂ sequestration. This research introduces an in-depth evaluation of in-house developed zwitterionic surfactants, highlighting their potential for EOR and CO2 sequestration in depleted oil reservoirs. The findings contribute a fresh perspective to the current literature, offering promising alternative synthetic surfactants suitable for different reservoir conditions in the petroleum industry.