1 Reservoir Studies and Field Development Division, Research Institute of Petroleum Industry, Tehran, Iran

2 Department of Chemical Engineering, Sahand University of Technology, Tabriz, Iran


The main factor affecting the economics of foam-assisted water alternative gas (FAWAG) process is the loss of foaming agent by adsorption onto reservoir rocks. In this study, the effects of phases, surfactant concentration, salinity, adsorbents, and sacrificial agent on adsorption density were investigated by special adsorption experiments. Moreover, a series of FAWAG tests were performed to examine the effect of injection rates on final adsorption density and adsorption variation during the test. A clean and fast spectrophotometric method was used for the determination of sodium dodecyl sulfate (SDS) concentration based on the formation of an ion-pair, SDS-Safranin O. Higher SDS adsorption was observed at the first cycle of FAWAG flooding. FAWAG injection rate had no noticeable effect on the adsorption density. However, using high injection rate decreased the possibility that gas faces surfactant, and thereby reducing the ultimate oil recovery. The presence of CLS increases the ultimate oil recovery slightly, while it decreases the adsorption density of SDS by 22%.