Experimental investigation and evaluation on influence of foam flow resistance in porous media

With an aim to investigate foam flow resistance in porous media, batch tests were carried out based on soil column. Foam resistance factor and foam injection pressure were selected to evaluate foam resistance ability. The influencing factors including liquid/gas/foam flow rate on foam resistance factor were studied on the basis of single-factor experiments. Also, a 2(k) factorial design was utilized to identify the most relevant process variable for foam injection pressure. The process variables such as injection foam size, foam quality, foam rate, and surfactant concentration in injection fluid were investigated. The results showed that foam resistance factor gradually diminished as liquid flow rate increased with a constant gas flow rate, while it increased with gas flow rate increasing with a constant liquid flow rate. The pressure distribution showed a steady downtrend across the soil column, which showed the flow uniformity of foam in soil column. It also indicated that dynamic equilibrium was reached between foam fracture and regeneration. The effects of process variables on foam injection pressure followed the order of foam quality>foam rate>injection foam size>surfactant concentration under the experimental conditions. The results indicated that the major effect on foam injection pressure was foam quality. The obtained results would provide useful information and technical support for actual in situ soil remediation when using foam-flushing technique.