Monoethylene glycol (MEG), HOCH2CH2OH, is an important
raw material with numerous industry applications, which include polyester
synthesis, automobile antifreeze, coolant, and aircraft anti-icer. In the oil
and gas industry, MEG is commonly used as a gas-hydrate inhibitor, which can
prevent the formation of gas hydrate during natural-gas production. However,
common gas-hydrate inhibitors have the adverse effects of lowering the
solubility of mineral salts and causing a higher risk of scale formation.
Despite the importance of scale problems with MEG in oil production, there have
been few investigations on the solubility of mineral salt in MEG/brine
solutions. In our research, experiments have been conducted on carbonate
equilibrium and calcite solubility at 2 - 70°C, 0- to 6.5-m (m = molality)
ionic strengths, and 0 - 99.67 wt% MEG.
A self-consistent activity model based on the Pitzer theory to calculate the
effect of salt and a Born-type equation were used to model the effect of MEG.
MEG activity coefficients with respect to dissolved carbon dioxide
(CO2), sodium bicarbonate, sodium carbonate (NaHCO3), and
calcium are determined as a function of temperature, ionic strength, and mole
fraction of MEG in mixed solvent.
© 2010. Society of Petroleum Engineers
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- Original manuscript received:
24 February 2009
- Meeting paper published:
21 April 2009
- Revised manuscript received:
22 December 2009
- Manuscript approved:
5 January 2010
- Published online:
27 May 2010
- Version of record:
22 September 2010