Asphaltene flocculation onset determinations for heavy crude oil and its implications

The transport of heavy oils from the wellbore to the refinery is a costly process because heavy oils have high viscosities, which result in higher energy requirements in pumping. Producers have used large quantities of diluents to reduce the viscosity and make the heavy oils more pumpable. However, the addition of diluents might precipitate asphaltenes from the heavy oil and cause plugging and fouling problems. The asphaltene flocculation onset titration is often used to predict asphaltene precipitation tendency of crude/diluent mixture. In this article we present work performed on a Venezuelan heavy crude where the asphaltene flocculation onset was extrapolated for the dead crude using a solvent dilution method. Flocculation point measurements under high pressure utilizing a high-pressure cell with the solid detection system (SDS) were also conducted. The data show good correlation between the high-pressure titration experiments and solvent dilution method using dead crude oils. The data predicted the range of diluent addition for which asphaltene precipitation and flocculation problems could be encountered in the field.