Methane and Ethane Solubility in Pure Water and Salt Solutions of Sodium Chloride and Magnesium Chloride at Low Temperature and Non-Hydrate Formation Conditions

In this study, an equilibrium cell was used to measure the solubility of methane and ethane in pure water and aqueous solutions of sodium chloride and magnesium chloride in non-hydrate formation condition. Methane solubility measurements in pure water have been conducted at temperatures of (275/15 to 300/15) K and pressures of (20, 30 and 40) bar and for aqueous solutions of sodium chloride and magnesium chloride at temperatures of (275.15 to 290.15) K, pressures of (20 and 30) bar and molalities of (0.529, 1.092 and 1.692) mol/kg and (0.325, 0.670 and 1.039) mol/kg, respectively. Also, the solubility of ethane in pure water have been investigated at temperatures of (274/15 to 282/15) K and pressures of (2, 4 and 6) bar and for aqueous solution of sodium chloride at modalities of (1.901 and 3.020) mol/kg, temperatures of (273.15 to 278.15) K and pressures of (4 and 8) bar and for aqueous solution of magnesium chloride at molalities of (0.325 and 0.791) mol/kg, temperatures of (279.15 to 285.15) K and pressures of (4 and 8) bar. In addition, the thermodynamic models of Duan et al. and Mao et al. were used to calculate the solubility of methane and ethane gases in aqueous solutions of sodium chloride and magnesium chloride. The solubility of methane and ethane were found to decrease by increasing temperature and concentration, but with increasing pressure, the opposite behavior was observed. It can also be stated that the thermodynamic models showed good adaptation with experimental results.