Keyword: «natural gas hydrates»

In this work, the equilibrium conditions of the natural gas hydrate formation in porous media are experimentally studied to determine the boundary of the hydrate stability zone in 2 areas of the Vilyui syneclise. It has been established that the lower boundaries of the stability zone of natural gas hydrates in a moist unsalted porous medium are located at a depth of 1120 m. When the samples are saturated with mineralized water, the boundaries are located 30–40 m higher. The obtained experimental results allow us to conclude that in subpermafrost aquifers of the Vilyui syneclise has favorable conditions for the formation of natural gas hydrates.

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.