Synthesis of a Series of Anionic Surfactants Derived from NP and their Properties as Emulsifiers for Reducing Viscosity of Highly Viscous Oil via Formation of O/W Emulsions

A series of alkyl phenol polyoxyethylene glycidyl ether (NP-n-O) and alkyl phenol polyoxyethylene ether hydroxypropyl sulfonate (NP-n-S) surfactants was synthesized to explore emulsification viscosity reduction. The optimum sulfonation conditions were obtained through orthogonal experiments, the ratio of alkyl phenol polyoxyethylene glycidyl ether and sodium bisulfite 1:1.5, 100 A degrees C, and 6 h. The effects of concentrations of the synthesized surfactants, pH values, emulsifying temperature (40 and 60 A degrees C) and water content on emulsification viscosity reduction and the stability of the emulsion to Venezuela's Orinoco heavy oil were investigated. The water diversion ratio of emulsion at the reservoir temperature (55 A degrees C) in 30 days was taken as an index, the results show that under the conditions of a temperature of 40 A degrees C, an oil/water ratio of 7:3 and a surfactant NP-4-S concentration of 0.5 %, emulsions can be formed with a viscosity reduction rate reaching up to 99.69 % and with a water diversion ratio in 30 days reaching 9.38 %; while at 60 A degrees C and an oil/water ratio of 7:3, at an NP-4-S concentration of 1 %, the viscosity reduction rate can reach 99.55 % and water diversion ratio is merely 4.23 % in 30 days. The mixture of NP-n-S, xanthan gum and cocamidopropyl dimethylamine oxide (CAO-30) at suitable concentration can greatly improve the emulsification viscosity reduction and emulsion stability, which gives an emulsion viscosity rate of over 98 %. Moreover, the emulsion can be stable for at least 30 days without water emerging.