Retrofit Solutions for Heavy Crude Oil Production and Transport

Lowering Viscosity

The high viscosity of heavy crude oil is the major difficulty for its production, transportation and refining. It is known that the high viscosity of heavy crude oil is caused by the high concentration of asphaltenes and resins. Understanding how the asphaltenes and resins cause the high viscosity of heavy oil, it is clear that decomposition of the agglomerates of these components is the most effective way of viscosity reduction of heavy crude oils. Asphaltenes and resins form large agglomerates or supermolecules. The supermolecular structure of asphaltenes and resins is mainly built upon relatively weak intermolecular forces, or van der Waals forces. These forces are still strong enough to maintain the structure of the asphaltene agglomerates and to effect the viscosity of the heavy oil.

Normally, viscosity reduction is achieved by using high temperatures or solvents/diluents like kerosene, naphtha or diesel.

The temperature-viscosity relationship of heavy oil shows that higher temperatures can overcome these forces and reduce the viscosity. Unfortunately, the viscosity increases as soon as temperature decreases. With that, heating heavy oil is not a permanent solution.

Using diluents offers a lower temperature and permanent solution. Addition of 15% to 30% of diluents can decrease the viscosity to a pipeable level. The downside to this solution is that the diluents must be recovered by means of distillation, which is energy intensive and requires a larger investment.