Flowability Improvement by Pour Point Depressant WHP for Zhengwangzhuang High Waxy Crude Oil

The flowability improvement by using commercial pour point depressant WHP is studied for Zhengwangzhuang viscous crude oil of Shengli,containing 56.9% wax,of which 96.6% is noraml paraffins.WHP comprises 30—35% terpolymer ethylene/vinylacetate/vinyl alcohol copolyether and is introduced into the crude oil at 60℃.The pour point and the viscosity at 32℃ and shear rate 0—42.6 s-1 are determined for the WHP treated crude oil and shown to decrease with increasing WHP dosage from 50 to 300 mg/L with the optimal dosage being of 200 mg/L.At this dosage the viscosity at 0.32 s-1 decreases from 34.16 Pa·s to 79.2 mPa·s,the pour point—from 49.0℃ to 39.5℃,the yield stress—from 32.42 to 0.1297 Pa,the consistancy coefficient K—from 31.57 to 0.02142 Pa·sn and the flow patern index n increases from 0.1176 to 0.9790.It is ascertained on the basis of viscosity-temperature curves that introducing WHP at dosage 200 mg/L leads to lowering down the wax precipitation point of the crude oil from 65℃ to 58℃ and its anomaly point from 70℃ to 50℃.The crystalline morphologies of wax precipitated from the crude oil,blank and WHP treated,are observed under SEM and the pour point depressing,viscosity reducing and flowability improving functions of WHP as a polymeric surfactant are discussed with a cocrystallization concept taken into consideration.