Thermodynamic study of several hydrates in dispersed systems using Differential Scanning Calorimetry
Résumé
Differential Scanning Calorimetry (D.S.C.) was used to determine the temperature stability conditions
at atmospheric pressure of trichlorofluoromethane hydrate in water-in-oil emulsions in which the water
phase contained from 7 to 27 wt.% of calcium chloride, and the temperature stability conditions at
pressures ranging from 5 to 12 MPa of hydrates of methane and natural gas, in solutions and water-in-oil
emulsions in which the water phase contained either sodium chloride at a concentration of 17 wt.%., or
calcium chloride at a concentration of 23 wt.%. The influence of repeated cycles of natural gas hydrate
formation and dissociation on the stability of the emulsion was evidenced on a real oil-based drilling
fluid.
It was found that D.S.C. is a fast, easy to use and precise alternate method of determination of
hydrates stability conditions. Comparing the results with literature data, when available, showed very
good agreement. This technique can be applied to virtually any kind of mixture containing water, even
very complex fluids containing several solid phases suspended in a multiphasic liquid, such as drilling
fluids, for which the use of the PVT technique is particularly uneasy.