Document Type : Original Article
Head of Petroleum lab , Minsitry of Natural Reseources , Erbil , Iraq..
Department of Petroleum Technology , Erbil Polytechnic Universtiy , Erbil , Iraq
The existence of high viscous heavy crude oil in high amount in Kurdistan/ Iraq reservoir attract the
petroleum companies to extract and produce it. The heavy crude oil is a complex fluid with viscosity
higher than the conventional oil. Where the viscosity of this type of oil is (greater than 10000 c.p) and the
specific gravity is between (10-20) API. These two physical factors effect negatively on the crude oil
mobility in both in-situ and surface condition.
High viscous heavy crude oil faces difficulties during separation and transportation from production sites
to processing facilities. One of the solutions to enhance the flow rate is reducing the viscosity by using
chemical solvents and gas condensate.
Since the asphaltenes are the main component of heavy crude oil; therefore, it plays a significant role to
increase the viscosity of heavy oil. As a result, making any modification in structure of asphaltene
aggregates leads to oil viscosity alteration. For this purpose, a heavy crude oil sample from Sheikhan
oilfield was blended with different concentration rate of solvents (toluene, methanol) and gas condensate
in order to justify the structure of asphaltene content and understand how this effect on heavy crude oil
This study shows that mixing the heavy crude oil sample with toluene have a great reduction in the crude
oil viscosity since this solvent content aromatic molecules in his structure. These molecules tend to
interface between asphaltenes sheets and dissociation of asphaltene aggregates.
In addition, the influence of methanol on viscosity reduction is less due to forming hydrogen bonds
between asphaltene and methanol molecules. Finally, the gas condensate had a good influence on heavy
crude oil viscosity reduction.