Measurements of Hydrate Equilibrium Conditions for CH 4, CO 2, and CH 4 + C 2H 6 + C 3H 8 in Various Systems by Step-heating Method

Abstract

Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device. The experimental data for pure CH 4 or CO 2 + deionized water systems showed good agreement with those in the literatures. This kind of method was then applied to CH 4/CO 2 + sodium dodecyl sulfate (SDS) aqueous solution, CH 4/CO 2 + SDS aqueous solution + silica sand, and (CH 4 + C 2H 6 + C 3H 8) gas mixture + SDS aqueous solution systems, where SDS was added to increase the hydrate formation rate without evident influence on the equilibrium conditions. The feasibility and reliability of the step-heating method, especially for porous media systems and gas mixtures systems were determined. The experimental data for CO 2 + silica sand data shows that the equilibrium pressure will change significantly when the particle size of silica sand is less than 96 μm. The formation equilibrium pressure was also measured by the reformation of hydrate.