Synergistic Stabilization Mechanism of SiO2 Nanoparticles andAnionic Surfactants during Foam Fracturing

To study the synergistic stabilization mechanism ofSiO2nanoparticles and anionic surfactants during foam fracturing,inorganic SiO2nanoparticles and sodium dodecyl sulfate (SDS)were used as a foam stabilizer and foaming agent, respectively, toprepare foamfluids. Foam stability was analyzed by evaluating thefoam volume, half-life, and morphology. The synergistic stabiliza-tion mechanism of SDS and SiO2nanoparticles was studied bymeasuring and analyzing the surface tension, contact angle, andbubble diameter. The results indicated that, at a suitable SDSconcentration, the surface activity of the nanoparticles can bealtered to enhance the adsorption of SiO2nanoparticles at thegas-liquid interface and, consequently, improve foam stability.However, excess SDS caused a decrease in foam stability. Uponincreasing the SDS concentration, the contact angle between the SiO2nanoparticles and water decreased gradually, and the SiO2nanoparticles became increasingly hydrophilic. The average bubble diameter of the SiO2-SDS foam systems decreases with theincrease in time, and the foam system with the smaller change trend of the bubble diameter is more stable. Moreover, with theincrease in time, the nanoparticles adsorbed by the ruptured bubbles are transferred to the surrounding of the bubbles that are notruptured, increasing their liquidfilm thickness and improving the stability of the foam system. These results provide an experimentalbasis for the application of the nanoparticle in foam stabilization during coal seam fracturing.