Welan gum (WLG) has been widely used in food industry as thickener. This paper studies its potential applications in upstream petroleum industry. Welan gum was added to drilling mud, and rheology tests were conducted to evaluate mud performance. Experiments demonstrate welan gum effectively boosts mud viscosity. WLG mud also shows strong stability under high temperature and high concentrations of salts. Welan gum has good potential as mud thickener. Rheology tests were also carried out for the aqueous solution of welan gum. Viscosity of WLG solution remained high after addition of sodium chloride and calcium chloride. Long term heating has limited effect on its viscosity. Recovery tests show welan gum can improve oil recovery, and speed up recovery process. Welan gum has good potential for enhanced oil recovery.