Keyword: «equilibrium conditions of hydrate formation»

Equilibrium conditions of the natural gas hydrate formation in a porous medium with different salinity are determined by the method of differential thermal analysis. Bidisperse quartz sand was used as a porous medium, in which fractions with a particle size of 0,5–0,25 mm (54%) and 0,25–0,1 mm (42%) predominate. The salinity of the porous medium was set to 5% wt. sodium chloride solution, sodium bicarbonate solutions with concentrations of 0.25 and 2% wt., and for comparison, the sand was moistened with distilled water. The dependences for predicting the equilibrium conditions of the natural gas hydrates formation in a porous medium with different salinity are determined. Based on the obtained equilibrium values of temperatures and pressures, the enthalpies of the hydrate dissociation in the considered systems are calculated.

Mathematical modeling methods assess the possibility of natural gas storage by converting them to a hydrate state when gas is injected into permafrost aquifers. The model of multiphase nonisothermal filtration takes into account the main physical features of this process, including gas compressibility, the Joule-Thomson effect, adiabatic expansion, joint movement of water and gas, mass transfer between gas, water and a hydrate. To conduct computational experiments, the results of laboratory experiments of the equilibrium conditions of the natural gas hydrates formation in a free volume and in a porous medium saturated with water and aqueous solutions of sodium bicarbonate were used. The influence of phase equilibrium conditions on the main indicator of the process efficiency – the hydrate saturation of the created storage is studied.