Supercritical CO2-Foam - The Importance of CO2 Density on Foams Performance

Abstract

In CO 2 projects for enhanced oil recovery (EOR) a critical factor is possible early CO 2 breakthrough and consequently poor sweep efficiency. Injection of foam can block and divert CO 2 which may improve sweep efficiency.Large changes in physical properties of CO 2 with temperature and pressure might affect CO 2 -foam performance under various reservoir conditions. Recently, we have focused on understanding supercritical CO 2 -foam properties and this paper describes the importance of supercritical CO 2 density on CO 2 -foam performance in outcrop Berea sandstone core material.Foam flooding experiments were conducted in sandstone core material at different pressures from 30 to 280 bar and at temperatures of 50 and 90°C using an AOS C14/16 surfactant. Results showed high foam strengths at low CO 2 density. In fact, the strongest supercritical CO 2 -foam was generated at the lowest supercritical CO 2 density tested, quite comparable to foam strength obtained with gaseous CO 2 . Only reduced foam strengths were found with dense supercritical CO 2 (MRF 3-11).Foam generation was studied with both equilibrated and non-equilibrated fluids. Previously, we showed that CO 2 -foam stability and blocking ability were strongly reduced when mass transfer occured. In this study delay in foam strength build-up was observed with non-equilibrated fluids. In addition, visual observations of the foam texture indicated larger bubbles.Compared to N 2 -foams at similar conditions CO 2 -foams were weaker and showed coarser foam structure.Recently in Aarra et al., (2012), we focused on understanding CO 2 -foam properties below and above the critical point of CO 2 (P c ≈ 73.8 bar, T c ≈ 31.0°C). Strong CO 2 -foams were generated when CO 2 was in its gaseous state (30 bar, 50°C). Weaker foams were generated at supercritical conditions (120 and 280 bar, 50°C) using an alpha olefin sulfonate (AOS C14/16 ) surfactant. Lower density difference between CO 2 phase and water, and choice of surfactant were discussed in context to the

Foam Analysis at Elevated Pressures for Enhanced Oil Recovery Applications

“…Different scientists examined added nanoparticles to stabilize CO 2 foams. − Before investigation of the flow of stabilized gas–liquid dispersions in porous media, the bulk behavior needs to be characterized for determining the influence of different process parameters on the structure and stability of the obtained foam. Apart from foam core flooding experiments at high-temperature/high-pressure (HT/HP) conditions, − experiments on foam behavior have only rarely been conducted at reservoir conditions, although pressure and temperature are known to play a relevant role in foam stability and bubble size distribution. Additional influencing factors are the type and concentration of the applied surfactant as well as the kind of gas.…”

Comprehensive Review of Sealant Materials for Leakage Remediation Technology in Geological CO2 Capture and Storage Process

“…When CO 2 foam is used in CCS to prevent gas leakage or repair, the half-life of the foam is more critical. In fact, compared with other gas-made foam systems (such as N 2 foam or natural gas foam), CO 2 foam usually produces a lower drag coefficient because of the lower interfacial tension. − …”

“…348−350 In addition, the CO 2 density also has an impact on the CO 2 mobility reduction effect; that is, formation pressure and temperature, injection parameters, and formation conditions will also affect it. 350 Chabert et al 349 found through actual experiments that even if the density of CO 2 is very high, the use of special surfactants under supercritical CO 2 conditions can also enhance the mobility reduction effect of the foam. However, the foam system cannot form a high-strength seal; that is, it is insufficient to prevent gas leakage.…”

Evaluation of Surfactant Mixture for Supercritical Carbon Dioxide Foamed Acid in Carbonate Matrix Acidizing

“…Under the typical reservoir conditions, CO 2 reaches supercritical condition while N 2 remains in subcritical condition. The CO 2 foam has several characteristics compared to N 2 foam: lower interfacial tension between supercritical CO 2 and lamella, solubility effects of CO 2 , low pH with CO 2 foam, greater viscosity of supercritical CO 2 [22,23]. In this study, the supercritical CO 2 foamed acid was selected for carbonate matrix acidizing.…”