The effect of corrosion inhibitor chemistry on rheology and stability of CO2 and N2 acidic foam under harsh conditions

Abstract

Utilization of CO2 foam in well-stimulation operations is a realistic practice to reduce carbon emissions by injecting CO2 into subsurface formations. The viscosity and stability of CO2 and N2 acidic foamed fluid is impacted by additives such as corrosion inhibitor and chelating agent and conditions such as pressure. In this study, the apparent foam viscosity was determined using a high pressure - high temperature foam rheometer at a temperature of 150 °C, pressure ranging from 1000–4000 psi, and different shear rates 100-2000 1/s. A foam analyzer was furthermore utilized to characterize foam properties such as foamability, foam stability, and bubble structures at 100 °C and 1000 psi. Different surfactants were used due to their ability to generate stable and viscous foam; Duomeen TTM, Ethoduomeen T13, Armovis VES, and the combination of Duomeen TTM and Armovis VES. Among all surfactants, Duomeen TTM provided the highest foam viscosity with CO2 at both low and high shear rate. Once the surfactant solution was mixed with 1.5 wt% of CI, the foam viscosity dropped sharply. However, the synergic surfactants (i.e., Duomeen TTM and Armovis VES) obtained the highest viscosity once mixed with CI. Also, the effect of CO2 and N2 at different pressures on the viscosity of generated foam was investigated. When the CO2 pressure was raised to 2000 psi, the viscosity of CO2 foam increased by 55% at both low and high shear. In comparison, the N2 foam viscosity increased by 12% at 100 1/s shear rate and by 32% at 1500 1/s. According to the findings, the influence of CI increased as the pH of the foam fluid declined, and thus reduced the foam viscosity. Finally, foam properties such as foamability, foam stability, and bubble structure were determined. N2 foam generated higher foam stability than CO2 foam. The findings of this study can help for a better understanding of the effect of corrosion inhibitor on CO2 and N2 foam viscosity at high temperature and pressure.