(365a) Heavy Oil and Bitumen Complex Viscosity Simulation – Impacts of Phase Behavior on Rheology

Complex viscosity, including both elastic and viscous contributions to flow properties, is a key property for heavy oil and bitumen production, transport and refining process design. Values vary by more than eight orders of magnitude under industrially relevant conditions and have proven difficult to estimate. There is also a growing recognition that heavy hydrocarbon resources are multiphase and that they exhibit complex rheological behaviors, with shear rate, shear history, and shear method dependent rheological responses particularly at low temperatures. The complexity of their responses to shear along with speciation and rheological measurement reproducibility uncertainties present significant simulation challenges. In this work, an approach that builds on the understanding of the responses of polymers to steady and oscillatory shear, as well as expected responses of dispersed phases, is presented and applied to heavy oils and bitumen. The challenge in this work is to identify, to the greatest extent possible, common parameters applicable to hydrocarbon resources as diverse as Maya crude oil (Mexico), Athabasca bitumen (Canada), and Safaniya vacuum residue (Saudi Arabia) and their nanofiltered and chemically partitioned fractions with pentane asphaltene contents ranging from 0 to 100 wt. %, that are rooted in their known phase behaviors. A workflow resulting in semi-quantitative agreement between measured and computed complex viscosity outcomes over eight orders of magnitude is presented and discussed. Four hydrocarbon resource specific parameters, linked to solid-liquid transition boundaries for maltene-rich and asphaltene-rich fractions, are needed to describe rheological responses. Impacts of non-Newtonian effects are isolated.