Experimental investigation of surfactant loss using adsorption tests and evaluation of ultimate oil recovery during surfactant-alternating gas injection

Because of a large amount of remained oil in reservoirs after the secondary or tertiary recovery, sometimes using profitable methods such as surfactant-alternating gas (SAG) is reasonable. For preparing stable foams, it is very crucial to inject at optimum rate. Foam strength can be suppressed during inappropriate conditions and drying out the foam within the porous media. In this study, the effects of adsorbent, gas phase, surfactant concentration, and sacrificial agent on sodium dodecyl sulphate (SDS) adsorption density were examined by using static and dynamic adsorption experiments. Hence, a series of SAG tests were designed to evaluate the effects of injection rates, first injected phase type, injection mode and presence of calcium lignosulphonate (CLS) on the oil recovery. During SAG injection, the results showed that the oil mobility was reduced 65%. SAG injection as secondary mode was more efficient and the same ultimate recovery was achieved with lower cost.