Effect of low-salinity water on asphaltene precipitation

ABSTRACT

The effect of low-salinity (1000 to 5000 ppm) and intermediate-salinity (5000 to 40000 ppm) water (MgSO₄, MgCl₂, Na₂SO₄, CaCl₂, NaCl and KCl) on asphaltene precipitation was investigated in this work. The results revealed that all brines intensify the amount of asphaltene precipitation. All cases exhibited initial downward trend followed by the upward trend for the amount of asphaltene precipitation with increasing the brine concentration. A similar trend was also observed for Interfacial Tension (IFT) between crude oil and brine in this study. IFT was tested for MgSO₄, MgCl₂, Na₂SO₄, CaCl₂, NaCl and KCl brines with concentrations of 1000 to 40000 ppm. Finally, experimental results showed that an increase in volume of all brines in the mixture (brine +oil) led to increase and decrease of the asphaltene precipitation in low and intermediate salinity regions, respectively.

GRAPHICAL ABSTRACT

KEYWORDS:

• Asphaltene
• brine
• interfacial tension (IFT)
• low-salinity water
• precipitation

Abbreviations::

• CHNSO = carbon, hydrogen, nitrogen, sulfur and oxygen
• EOR = enhanced oil recovery
• FT-IR = Fourier transform infrared spectroscopy
• IFT = interfacial tension (mN/m)

Acknowledgments

The authors are grateful to the Shiraz University and Enhanced Gas Condensate Recovery Research Group for supporting this research.