Abstract: Recirculating ability of sodium oleate foam is discussed and the influence of different foam stabilizers,pH value and concentration of sodium oleate on foam performance is evaluated by utilizing its surfactivity sensitivity to acid and alkali environment.The results show that the foaming ability decreases gradually and half life prolongs gradually with the increasing concentration of foam stabilizer,and the optimum formula of mixing foam stabilizer is 0.2%XC+0.2% FA367.Foaming ability is enhanced gently with pH value rising under the same concentration condition of sodium oleate and reaches the maximum at pH =10,then decreases gently.Foaming ability is enhanced gradually with sodium oleate concentration adding at 8＜pH＜10,and foaming ability increcement decreases when sodium oleate concentration exceeds 0.7%,foaming ability loses at pH<6.The aim of generatation of sodium oleate foam can be realized by adjusting pH value,and maintenanceing good foaming ability after recirculating 10 times.

Key words: sodium oleate, foam, recirculating utilization, underbalanced drilling