Underground Storage of Natural Gas in Hydrate State: Numerical Experiment

Abstract

The paper is devoted to simulation of the initial stage of natural gas hydrate underground storage: gas injection into aquifer just below permafrost rocks. It is based on the mathematical model of multiphase non-isothermal real gas and water flow in porous media. The model takes into account the transformation of gas and water into hydrate at certain temperature which depends on gas flow pressure. The dynamics of hydrate and water saturation as well as the pressure and temperature fields in a reservoir with given porosity, permeability and initial values of pressure, temperature and water saturation have been studied. An implicit finite-difference scheme is used to approximate the original boundary-value problem. The finite-difference equations have been solved using simple iteration and sweeping algorithms. Several examples of calculations corresponding to real cases are given. Calculations have revealed that the final result strongly depends on the combination of porosity and permeability of a reservoir.

About the Possibility of the Hydrate Formation in Subpermafrost Aquifers Saturated with Calcium Chloride-Type of Waters

“…The relevance of studying the formation of natural gas hydrates in saline porous media is associated with the possibility of using subpermafrost aquifers to create underground gas storage facilities in a hydrate state on the territory of Yakutia. As shown by the results of a numerical experiment [1][2][3], with modern injection technologies, this task is quite realizable. The creation of such gas storage facilities will contribute to a manifold decrease in the volume of the injected gases and an increase in the stability of the gas storage facility in comparison with conventional underground storage facilities, and the permafrost base will serve as a natural gas-impermeable screen.…”