Foaming Behavior of CO2-Soluble, Viscoelastic Surfactant in Homogenous Porous Media

Abstract

Aqueous foam has been demonstrated through laboratory and field experiments to be a promising conformance control technique. This study explores the foaming behavior of a CO2-soluble, cationic, amine-based surfactant. A distinguishing feature of this surfactant is its ability to dissolve in supercritical CO2 and to form Wormlike Micelles (WLM) at elevated salinity. Presence of WLM led to an increase in viscosity of the aqueous surfactant solution. Our study investigates how the presence of WLM structures affect transient foam behavior in a homogenous porous media (sand pack). Sand pack foam flooding experiments were performed with two aqueous phase salinities: low salinity (15 wt. % NaCl) associated with spherical-shaped micelle and high salinity (20 wt. % NaCl) associated with WLM. We compared the onset of strong foam propagation and foam apparent viscosity buildup rate between the two salinity cases. The effect of WLM presence in transient foam behavior was investigated for co-injection and water-alternating-gas (WAG) injection strategies. In all foam flooding experiments, the surfactant was delivered in the CO2 phase. Strong foam was generated in all foam flooding experiments, with an apparent foam viscosity of at least 600 cp for co-injection and 200 cp for WAG floods after five total injected pore volumes. The observed strong foam indicated that the delivery of surfactant in the CO2 phase was successful and that the surfactant molecules partition to the water phase in the sand pack. In comparison to the low salinity cases, the high salinity foam floods associated with the presence of WLM led to better foam performance. We observed an earlier onset of strong foam propagation as well as a higher apparent viscosity buildup rate. Better foam performance at higher salinity may be attributed in large part to the presence of WLM structures in the foam liquid phase. Entanglement of these WLM structures may have led to in-situ viscosification of the foam liquid phase and an increase in disjoining pressure between foam films. Both phenomena may have reduced the rate of foam film coalescence. WLM structures behave similarly to polymer molecules. Our study may offer evidence that WLM is a valid alternative to polymer as an additive to enhance foam conformance control performance. Some potential advantages of WLM over polymer include: Delivery of surfactant in the gas phase (to alleviate the injectivity issue typically associated with high viscosity polymer-surfactant solution), resistance to extreme temperature and salinity, and reversible shear degradation.

Research of CO2-Soluble Surfactants for Enhanced Oil Recovery: Review and Outlook

“…Ramadhan [136] investigated the foaming behavior of a CO 2 -soluble, cationic, aminebased surfactant, N.N.N'-trimethyl-N'-tallow-1,3-diaminopropane (DTTM), which forms wormlike micelles at elevated salinity. They believed that the viscous fingering of surfactantcarrying CO 2 causes a delay in foam generation and propagation.…”

Effects of a Viscoelastic Surfactant on Supercritical Carbon Dioxide Thickening for Gas Shale Fracturing

“…A CO 2 -soluble, cationic, amine-based surfactant has a distinguished feature of dissolving capacity in Sc-CO 2 and forming wormlike micelles (WMLs) at high salinity. The presence of WMLs led to an increase in the viscosity of the aqueous surfactant solution . In high-permeability formation and higher temperatures, a methyl quaternized erucyl amine is convenient for VES-based fracturing fluids .…”

Experimental Investigation of Noble Viscoelastic Surfactant and Chelating Agent for Heavy Oil Enhanced Oil Recovery in High‐Pressure–High‐Temperature Carbonate Reservoirs

“…They found that the use of VES in a sandstone reservoir increases the recovery by 25% and increases the recovery in carbonate reservoirs, but the efficiency depends on the wetting characteristics of the reservoir. The mobility of the foam can be improved using VES in CO 2 foam flooding (Farid Ibrahim and Nasr‐El‐Din, 2018; Ramadhan et al, 2018). The cocamidopropyl betaine showed excellent synergy with nanoparticles.…”

“…A mixture of silica nanoparticles and cocamidopropyl betaine surfactant resulted a significant additional oil recovery due to better foam stability and mobility (Farid Ibrahim and Nasr‐El‐Din, 2018; Farid Ibrahim and Nasr‐El‐Din, 2019). The foam mobility improvement can be achieved by a certain class of VES that can dissolve in supercritical CO 2 and form wormlike micelles (Ramadhan et al, 2018). In summary, the VES have shown great potential as an alternate to both surfactants and polymers for EOR.…”