TY - JOUR
T1 - A Numerical Approach to Study the Thermal Influence on Gas Hydrates by Physical Process Splitting
AU - Poveshchenko , Yury
AU - Rahimly , Parvin
AU - Rahimly , Orkhan
AU - Podryga , Viktoriia
AU - Gasilova , Irina
JO - International Journal of Numerical Analysis and Modeling
VL - 3
SP - 404
EP - 433
PY - 2020
DA - 2020/05
SN - 17
DO - http://doi.org/
UR - https://global-sci.org/intro/article_detail/ijnam/16866.html
KW - Gas hydrates, filtration, thawed zone, support operators, and completely conservative difference schemes.
AB - <p style="text-align: justify;">The method of numerical simulation based on the splitting by physical processes of gas-hydrodynamic processes, which occur during the dissociation of gas hydrates in a porous medium,
is described. In this paper, a coupled discrete model of a two-component ($H$<sub>2</sub>$O$, $CH$<sub>4</sub>) three-phase
(water, methane, hydrate) filtration fluid dynamics and two-phase processes in a thawed zone with
absence of gas hydrates in thermodynamic equilibrium has been developed, by using the splitting
by physical processes as a valid assumption. The obtained split model is differentially equivalent
to the discrete initial balance equations of the system (conservation of the mass components of
the fluids and the total energy of the system), written in divergent form. Such an approach to
create completely conservative difference schemes in the studied fluid-hydrate medium requires the
introduction of a special free-volume nonlinear approximation of grid functions over time, which
depends on the volume fraction in the pores occupied by fluids, and is simple to implement. The
direct unsplit use of the studied system for the purposes of determining the dynamics of variables
and constructing the implicit difference scheme required for calculations of filtering processes
with large time steps is difficult. The paper also presents the method of coupled solutions of
systems of equations describing the processes in various fields, each of which is characterized by
its own set of coexisting phases, and the coordination of computational schemes for them is not an
automatic process. In the results of the calculations, the volumetric three-phase phase transitions
were numerically investigated using a single calculation with a variable number of phases region
of the entire plane of the P and T parameters. Using the example of the Messoyakha&#39;s gas
hydrate deposit, the local processes of technogenic depressive impact directly near the wells on
the dynamics of the gas distribution of gas hydrates thawing and formation of thawed two-phase
zones were studied.</p>