Effect of dodecyl benzene sulfonic acid (DBSA) and lauric amine (LA) on the associating state and rheology of heavy oils

• DBSA enhances heavy oil viscosity while LA reduces heavy oil viscosity.
• DBSA increases heavy oil electrical conductivity while LA decreases the conductivity.
• DBSA enhances heavy oil viscosity by disperse asphaltene particles into smaller ones.
• LA reduces heavy oil viscosity by flocculate asphaltene particles into larger ones.
• Increasing R/A mass ratio decreases the effects of DBSA/LA on heavy oil viscosity.

The effects of two amphiphiles, DBSA and LA, on the associating state and viscosity of three heavy oils with different resin/asphaltene (R/A) mass ratios were investigated through DSC analysis, rheological test and electrical conductivity measurement. The wax appearance temperatures of the three heavy oils are lower than 40 °C. The viscosity of heavy oils at temperature range 50~70 °C increases with increasing DBSA concentration but decreases with increasing LA concentration. Addition of DBSA increases the electrical conductivity of heavy oils, which implies that the DBSA acts as asphaltene dispersants; the electrical conductivity of heavy oils decreases after LA addition, which implies that the LA acts as asphaltene flocculants. The addition of DBSA decreases the size of asphaltene particles and generates new solvation layers, both of which favor the increase of heavy oil viscosity; the addition of LA increases the size of asphaltene particles and releases some liquid oils bounded by asphaltene particles, both of which favor the decrease of heavy oil viscosity. With the increase of R/A mass ratio, the stability of heavy oils increases while the viscosity enhancing/reducing efficiency of DBSA/LA decreases.