In order to reduce the viscosity of petroleum sludge for oil recovery

a micro-emulsion method was studied based on its rheological behavior. The effects of surfactant

micro-emulsion dosage and composition on the viscosity were discussed. The results indicated that the petroleum sludge could be classified as pseudo-plastic fluid and its strong shear-thinning force was attributed to the high content of solid particles in the petroleum sludge. The rheological behavior of petroleum sludge could be described by the P-L model. The results showed that the micro-emulsion could well mix with petroleum sludge and viscosity of the sludge was reduced by more than 95% by adding 25% micro-emulsion by mass. The maximum viscosity reduction was achieved by using sodium dodecyl benzene sulfonate (SDBS) as single surfactant. A viscosity reduction of 99% was obtained with the composited surfactant of OP-10 and SDBS at a ratio of 2:1.