Numerical Simulation in Problems with Dissociation of Gas Hydrates in a Porous Medium in One-Dimensional Formulation

Abstract

The paper deals with some typical problems of gas hydrates dissociation in a porous medium, which in the first approximation can be reduced to one-dimensional. The research aims to study the mutual effects of underground gas hydrates and climate change, as well as some important technological and ecological problems of the flow in the well or fault area in the presence of hydrate-containing formations. New conservative difference schemes were developed for this class of problems. They are based on the splitting of gas-hydrodynamic processes. The advantage of these schemes is the phased solution of parabolic and hyperbolic equations. This approach greatly simplifies the solution procedure and at the same time increases its stability. Notably, within the framework of the approach, an algorithm was proposed to jointly solve the systems of equations describing the processes in various fields characterized by their own set of coexisting phases. The coordination of computational schemes for them is not a trivial and automatic process. Numerical calculations using mathematical modeling for the joint description of the gas hydrate zone and the zone with no gas hydrates were carried out. The results of calculations showed the applicability of the developed methods for solving the problems under study.

Mathematical Modeling of a Non-Isothermal Flow in a Porous Medium Considering Gas Hydrate Decomposition: A Review

“…The order of magnitude for porosity is around 10 −1 . Additionally, in several works [17,41,43,[59][60][61][62][63][64][65] the change in porosity with time is neglected and is assumed constant: φ = const.…”

“…The densities of water, gas hydrate and the porous-medium skeleton are considered constant in several works [17,41,43,57,[59][60][61][62]64]:…”

“…This method allows one, in addition to extracting energy carriers, to solve the problem of carbon dioxide utilization. In addition to the main methods mentioned above, the decomposition of gas hydrate can occur with exposure to high-frequency electromagnetic radiation [41].…”

An approximate approach to estimation of dissociation rate of gas hydrate in porous rock bed

“…In the general case, modelling the transfer processes during the "gas hydrate -gas + water" phase transition is a rather complex problem that needs to be solved taking into account the transfer processes in the well [19] and changes in thermodynamic conditions along the well depth [20]. However, in the case when the gas hydrate layer thickness is much less than the depth of the well, the radius of the gas hydrate decomposition area is much larger than the radius of the well, and the upper and lower layers of the mine rock are impermeable to gas, then the problem can be solved within the framework of the one-dimensional approximation [21,22].…”

The Model of Cohesionless Sediment Blowout with an Increase in the Methane Flow Rate

“…The available research includes gas hydrate dissociation upon warming and decompression [17,18], 1D models of hydrate dissociation in porous media [19], and variations of porosity and permeability during hydrate formation [20][21][22]. Gas released at low rates at some depths was found to migrate toward the surface, and the gas flow may produce zones of overpressure under certain conditions.…”