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Experimental study on the microscopic characteristics of foams stabilized by viscoelastic surfactant and nanoparticles

Zhu, Jingyi, Yang, Zhaozhong, Li, Xiaogang, Hou, Lianlang, Xie, Shiyi
Colloids and surfaces 2019 v.572 pp. 88-96
Ostwald ripening, bubbles, colloids, cryo-electron microscopy, drainage, foams, fractal dimensions, micelles, nanoparticles, scanning electron microscopy, silica, surfactants, synergism, temperature, viscoelasticity
Viscoelastic surfactant and nanoparticles have gained significant attention in the development of foamed fracturing fluid. In this article, the microscopic characteristics of foams stabilized by viscoelastic surfactant (EAPB) and nanoparticles (SiO2) at different temperature were investigated. By analyzing the bubble images taken from optical microscope, it is concluded that there was synergistic effect between elongated wormlike micelles and nanoparticles to stabilize foams which was indicated by large bubble number, small average bubble diameter and spherical shape of bubbles over time. Results showed that although temperature played a vital role on the acceleration of drainage rate and Ostwald ripening rate, this acceleration would be weakened by applying viscoelastic surfactant and nanoparticles together. Two calculation methods that are polydispersity based on statistic data and fractal theory based on box counting method were proposed to investigate the bubble size distribution and bubble structure. The small value of polydispersity and fractal dimension of the foams stabilized by 3% EAPB and 1% SiO2 demonstrated the relatively uniform bubble size distribution and regular bubble structure. Lastly, cryo-SEM was applied to observe the bubble morphology at microscopic scale, which showed the intense and compact bubble structure due to the formation of particle-micelle network. This study provides the workflow for the analysis of foams at microscopic scale and broadens the application of foamed fracturing fluid in the development of unconventional resources.