Experimental Gas Hydrate Dissociation Pressures for Pure Methane in Aqueous Solutions of MgCl2 and CaCl2 and for a (Methane + Ethane) Gas Mixture in an Aqueous Solution of (NaCl + MgCl2)

Abstract

Gas hydrate dissociation pressures along the hydrate−liquid−gas equilibrium line in the temperature range (273 to 292) K and for pressures up to 23 MPa have been determined for methane in aqueous unsaturated magnesium chloride solutions w = (1, 5, 10, and 15) % of MgCl2, in a calcium chloride solution w = 17.05 % of CaCl2, and for a (methane + ethane) mixture in an aqueous solution of sodium chloride and magnesium chloride w(NaCl) = 5 % + w(MgCl2) = 6.09 % applying an isochoric method. For the methane system, it is shown that considerable deviation from “ideal” behavior occurs at high MgCl2 concentrations. A gas hydrate calculation model has been applied being able to reproduce the experimental dissociation pressures to within ± 2 % as well as efficiently predicting the dissociation pressures and the inhibiting effects of various other electrolyte solutions for gas hydrate systems with pure gases and gas mixtures.