Due to the lack of dilute oil and the poor economical benefit in the dilution process of heavy oil in ultra-deep wells of Tahe Oilfield

the mixed oil is treated by dilute oil recycling combined with high-temperature thermal cracking process. For one thing

the experiment of dilute oil recycling after heavy oil distillation is carried out to determine the feasibility of cycling of light component oil. For another thing

the viscosity of the heavy components is reduced to meet the requirement of external transportation. The results show that when in the dilute oil recycling experiment

the light component yield obtained by distillation at 350 ℃

is stable at about 27 %

and the dilution ratio is stable at 0.39∶1

which indicates that dilute oil recycling is feasible. While in the modification experiment by thermal cracking

after the heavy components obtained by distillation reacting at 380 ℃ for 60 minutes

the oil viscosity can be reduced from 398 800 mPa·s to 1 704 mPa·s

which means it has met the requirement of long-distance transportation

and the density can be reduced from 1.001 8 g/cm

3

to 0.991 1 g/cm

3

. Therefore

the lightening of heavy oil is realized. This method not only greatly reduces the amount of dilute oil by the recycling utilization of light oil

but also improves the quality and utilization efficiency of heavy oil. It provides a new idea for the efficient development of heavy oil in ultra-deep wells.