2021-09-07

Over the last two decades the CCQTA has completed several projects investigating plant fouling issues. Learnings from this work has identified that four crude oil components such as waxes, asphaltenes, Toluene Insoluble Organic Materials (TIOM) and inorganic solids can all play a role in fouling. Process operating conditions and crude blending practices usually establish how each contaminant may impact fouling. This document will focus primarily on the role of asphaltenes.

Asphaltenes are normally identified and measured by their solubility/insolubility properties in paraffinic solvents such as pentane (C5) and heptane (C7). Typically, all crude oils contain some level of asphaltenes, ranging from a fraction of a percent in various light oils to levels in the mid-teens in some commercially available Canadian heavy crudes. Asphaltenes may originate from the producing reservoir or may added by blending with other products. Light oils commonly contain very little asphaltenes at the source and typically have a high concentation of saturates (paraffins). This high saturate concentration favors asphaltene precipitation. This is often referred to as “self-incompatibilty”. Precipitated asphaltenes may also be aquired from other crudes via pipeline interfaces, tank heals and crude blending activities. Precipitated and unstable asphaltenes in light cudes can play a major role in fouling.

It is generally considered that the blending of light crudes with heavy crudes will reduce the asphaltene stability of the heavy fraction in the final blend. However, experience has shown that some blending operations can have the opposite effect, if blending is performed in the correct order.

The objective of the CCQTA’s Light Oil Fouling project was to investigate the potential stabilizing role of some Canadian heavy crudes on asphaltene stability of light oils and this document provides a summary of our findings.