A Study of the Effect of Gas Condensate on the Viscosity and Storage Stability of Omani Heavy Crude Oil

Abstract

Heavy crude oil (density of 0.9571 g/cm3 at 288 K and kinematic viscosity of 7160 mm2/s at 303 K) and natural gas condensate (density of 0.7848 g/cm3 at 288 K and kinematic viscosity of 0.764 mm2/s at 303 K) were sampled from Omani oil fields. The oil was mixed with condensate (5−50 vol %), and the mixture viscosities were measured at the temperature range of 293−348 K. A drastic decrease in kinematic viscosity was achieved. An addition of about 12 vol % of condensate gave a viscosity of 265 mm2/s at 303 K. This made it easier to transport the heavy oil mixtures. The experimental data for the kinematic viscosity [ν (mm2/s)] as a function of the gas-condensate fraction (φ) and temperature [T (K)] could be described by an equation: ln(ln(ν)) = (k 1 + k 2·T) + (k 3 + k 4·T)·φ, with a high accuracy. Blends of the heavy oil and the gas condensate were stored to evaluate their stability. Results showed less than 0.05 wt % sludge formation after 2 months.

Flow of Heavy Oils at Low Temperatures: Potential Challenges and Solutions

“…If due care is not taken, deposition of asphaltenes and paraffins can cause further problems as, the light condensate recovered from natural gas (C 5 + or "Pentane Plus"), a low-density and less viscous mixture of hydrocarbon liquids, has been used to dilute the heavy crude oil and bitumen in order to enhance their transportation using pipeline in Canadian and Venezuelan oil fields. Though the efficiency of this condensate in reducing the viscosity of the heavy crude oil and bitumen significantly, instability during transportation and storage is observed as a result to precipitation, segregation and aggregation of asphaltenes [35]. These findings are because of insolubility of asphaltenes in most of condensate components involving alkanes such as n-pentane and heptanes.…”

Una mirada al desarrollo de aditivos reductores de viscosidad y sus aplicaciones en el transporte de crudos pesados

“…Otra alternativa es adicionar solvente, el cual debe ser afín con la fase continua del crudo (fase que se caracteriza por su tendencia apolar), ya que el fenómeno que genera la alteración de dicha propiedad es la solvatación. Uno de los solventes mas empleados es la nafta [71], la cual se caracteriza por ser una mezcla de sustancias con bajo peso molecular y alta apolaridad; asimismo, el gas líquido licuado (GLP por sus siglas en inglés) es otra alternativa de dilución [72]. Esta técnica es una de las más empleadas en el transporte de crudos, ya que es eficiente y rentable, e incluso existen diversos planteamientos teóricos basados en regla de mezclas, que buscan predecir el cambio de viscosidad al mezclar dos corrientes con viscosidades y densidades diferentes, como lo resaltan los modelos de Walther, Shu, entre otros [73].…”

Application of the Bergman-Sutton Method for Determining Blend Viscosity

“…The data were derived primarily from literature sources and some in-house studies representing data collected on 827 different oils or pure components (Al-Besharah et al 1987, 1989Al-Besharah 1989;Anhorn and Badakhshan 1994;Barrufet and Setiadarma 2003;Barrufet et al 1999;Chevron 2005;Díaz et al 1986;Drayer 1985;Estrada-Baltazar et al 1998a, 1998bExxon 2005;Ha and Koppel 2008;Hernández-Galván et al 2007;Iglesias-Silva et al 1999;Irving 1977b;Joshi and Pegg 2007;Orbey and Sandler 1993;Ramakrishnan et al 2003;Reid et al 1987;Shigemoto et al 2006;Shu 1984;Tat and Van Gerpen 1999, 2000, 2002Wu et al 1998Wu et al , 1999Yuan et al 2005). The pure-component data included the alkane compounds, n-pentane through n-hexadecane, and ringed compounds such as benzene, toluene, and ethyl benzene.…”