Case Study: Modeling the Phase Behavior of Solvent Diluted Bitumen

Abstract

The design of solvent-based and solvent assisted heavy oil recovery processes requires accurate predictions of phase behavior as straightforward as saturation pressures and as potentially complex as vapour-liquid-liquid equilibria and asphaltene precipitation. In this case study, saturation pressures of dead and live bitumen were measured in a Jefri PVT cell at different concentrations of a multi-component solvent at temperatures from 20 to 180°C. Saturation pressures and the onset of asphaltene precipitation were also measured for the bitumen diluted with n-pentane. The onset of precipitation was determined by titrating the bitumen with pentane and periodically circulating the mixture past a high pressure microscope.The data were modeled with the Advanced Peng-Robinson equation of state (APR EoS). The maltene fraction of the bitumen was characterized into pseudo-components based on extrapolated distillation data. The asphaltenes were characterized based on a Gamma distribution of the molecular weights of selfassociated asphaltenes. The APR EoS was tuned to match the saturation pressures by adjusting the binary interaction parameter between the solvent and the pseudo-components via a correlation based on critical temperatures. Rather than adjusting the interaction parameters for each pair of components, only the exponent in the correlation was adjusted. The role of mixing rules in correctly predicting the onset and amount of asphaltene precipitation is discussed.

Methylated cycloalkanes fuel a novel genus in the Porticoccaceae family (Ca. Reddybacter gen. nov)

“…MCH was the most abundant cycloalkane in Macondo oil and it was the most abundant compound released aside from natural gases (Reddy et al, 2012). MCP and MCH are additionally frequent components of natural gas condensate or natural gas liquids which enable pipeline transport of heavy oils and bitumen, with multiple high‐profile pipeline ruptures in the recent past (Supplementary Table 1; Agrawal et al, 2011; Perez et al, 2016; Walker et al, 2016). MCH and MCP are additionally of interest because their carboxylic acid counterparts (cyclohexane carboxylic acid and cyclopentane carboxylic acid) are often intermediate compounds in beta‐oxidized alkylated cycloalkane and alkylated cyclo‐carboxylic acid (also called naphthenic acid) degradation (Herman et al, 1993; Perry & Gibson, 1977).…”