Abstract: Heavy oil has high viscosity because it is rich in heavy components such as asphaltene and resins, which bring great difficulties to the exploitation and transportation. It is very important to reduce the viscosity of heavy oil and improve its fluidity. Vegetable oil, fatty acid and vegetable oil methyl ester were chosen as dilute medium for Tahe heavy oil. The performance of these three different dilute media on Tahe heavy oil were investigated and compared. The results showed that all these three dilute media showed good diluting effect on heavy oil. At the same dilute ratio, vegetable oil methyl ester demonstrated the best viscosity reduction effect, followed by fatty acid, and finally vegetable oil. The compatibility and system stability of dilute medium and heavy oil were investigated by speckle test. Results showed that the compatibility and stability of vegetable oil methyl ester with heavy oil were the best, while the fatty acid and vegetable oil were relatively poor.

Key words: viscosity reduction, vegetable oil, heavy oil, dilute media