Hydrate Phase Equilibria of Methane plus Mixed (TBAB plus THF) in the Presence and Absence of NaCl and/or MgCl2 Aqueous Solutions

Available water for the formation of natural gas hydrate at the industrial scale is normally saline water in which the dissolved salts inhibit the hydrate formation. To overcome this challenge, thermodynamic promoters can be used. In the present work, hydrate phase equilibria of methane + mixed promoters of tetrahydrofuran (THF) and tetra-n-butyl ammonium bromide (TBAB) were investigated in the absence and presence of NaCl, MgCl2, and NaCl + MgCl2 aqueous solutions. The phase equilibrium data, which were generated using an isochoric pressure-search method with a step heating technique, are reported in the pressure and temperature ranges of 1.09-5.16 MPa and 286.0-299.0 K, respectively. Equilibrium data show that an aqueous mixture of THF + TBAB (0.15 + 0.05 mass fractions) in the presence of NaCl systems is a more effective promoter compared to a single promoter TBAB or THF even at a high concentration of about 0.2 mass fraction.