Abstract:

M oilfield in Canada is characterized by low temperature, shallow buried depth, high viscosity of crude oil, less water cut and poor fluidity. Due to the high content of resin and asphaltene, it is very difficult to recover the crude oil by conventional mining method. It is necessary to reduce the viscosity of the crude oil from M oilfield in Canada. Oil soluble viscosity reduction technology has stable viscosity reduction effect on heavy oil and saves the steps of produced fluid demulsification and dehydration. In recent years, the research on oil soluble viscosity reducer at home and abroad has developed rapidly. Due to the great differences in the composition and characteristics of heavy oil in different regions, the adaptability to oil soluble viscosity reducer is different. According to the characteristics of heavy oil in M oilfield, an oil soluble viscosity reducer PH-OV was developed. The results show that the optimum composition of PH-OV is 4% esterified polyether +15% diethylene glycol dibutyl ether +81% aromatic solvent oil. When the dosage of PH-OV is 3%, the viscosity reduction rate can reach 85.2%; when the dosage of PH-OV is more than 5%, the viscosity reduction rate can reach more than 80% within 14-80 ℃. The SEM chart show that the viscosity reducer PH-OV can effectively destroy the aggregation structure of crude oil, disperse resin and asphaltene, inhibit the formation of macromolecular aggregates and reduce viscosity. With the increase of water content of crude oil, the viscosity reduction rate increases. When the water content is 60%, the viscosity reduction rate reaches 98.5%. The viscosity reducer can effectively reduce the yield value of crude oil, and the viscosity reduction performance of crude oil can be stable for more than 168 h. With the increase of viscosity reducer, the yield value of crude oil decreases significantly, which can effectively reduce the initial starting pressure of crude oil. The efficiency of PH-OV assisting cold water flooding can reach 30.03%, which is 12.86% higher than that of cold water flooding. The oil soluble viscosity reducer PH-OV is suitable for cold recovery of heavy oil in M oilfield, and has the potential to effectively enhance oil recovery.

Key words: heavy oil, oil-soluble viscosity reducer, yield value, cold production