Synergism of Methanol and Magnesium Chloride for Thermodynamic Inhibition of Methane Hydrate

Mixtures of magnesium chloride and MeOH were studied as mixed thermodynamic inhibitors of hydrate formation. The equilibrium P,T-conditions for methane hydrate decomposition in the presence of binary solutions H2O—MeOH and H2O—MgCl2 and ternary solutions H2O—MeOH—MgCl2 were determined using an isochoric method in a stirred autoclave. Measurements were made at pressures of 3.5-9.5 MPa; MeOH concentrations, 0-25 mass%. The salt content in the aqueous solutions was constant at 5 mass%. The results showed that mixed samples containing MeOH and MgCl2 gave the largest thermodynamic shifts of hydrate formation as compared to samples with MeOH at the same inhibitor mass fraction. The larger thermodynamic shift was related to synergism between the affects of MgCl2 and MeOH in the aqueous solution.