Thermodynamic and geomechanical processes research in the development of gas hydrate deposits in the conditions of the Black Sea

Abstract

Purpose. Research of thermodynamic and geomechanical processes occurring in a gas hydrate body under the influence of an activating agent (sea water from surface layers) in the conditions of the Black Sea by mathematical modeling using finite element method.Methods. The modeling of thermodynamic and geomechanical processes is performed with the use of ANSYS v17.0 software and in accordance with the climatic, hydrogeological and physic-mechanical properties of the numerical model elements in the Black Sea gas hydrate deposit under consideration, which are similar to natural ones. The thermodynamic processes were studied in the section "Steady-State Thermal", and the geomechanical (stress-strain state) in "Static Structural".Findings. The spatial model is developed, which allows to simulate thermodynamic and geomechanical processes in a gas hydrate body under the influence of a thermal agent. As a result of modeling, it was determined that under these conditions the temperature in the gas hydrate body varies with the distance from the production well similarly in both directions according to the polynomial dependence. What is more, at a distance from the well of 18.7 m the temperature is stable and equals +22°С, and in the range of 18.7 -24.9 m -decreases by 3.1 times and reaches a value of +7°С. It was found out that deformations in a gas hydrate body under the influence of an activating agent, which is fed under pressure above the initial, are directed from the lateral boundaries to the center of the gas hydrate body in the direction of productive dissociation zones. This, in its turn, results in the displacement of the gas hydrate volume to the reaction proceeding center, improving the quality of the decomposition process and allows mining of 87 -91% gas hydrate volume, which is presented in the model. Originality. For the first time, for the conditions of the Black Sea gas hydrate deposits, an analytical assessment of the dissociation zone distribution from the production well under the influence of the thermal agent and the changes of the stress-strain state of the gas hydrated body during its decomposition, has been carried out. This allows to improve the technology of the gas hydrate deposits development in the conditions under consideration.Practical implications. The technological scheme for the development of a gas hydrate body based on the combined approach to the effects of activators (temperature and pressure) is proposed, which eliminates the need to warm the boundary sections of the deposit and increases the amount of the supplied activating agent and its temperatures, which in its turn leads to a decrease in the resource-and energy consumption.

An innovative method for creating and using nanoparticles for gas extraction from gas hydrates

“…They form the basis of spinelide -the mineralogical component of aluminum slag. The physical, physicochemical, and thermodynamic properties of such solid solutions are not well understood [33].…”

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

“…Value of the parameter K, m/s 1/2 According to the equation (10) According to the data [25] 0.5 4.4410 -4 4.4910 -4 1. 5 5.5810 -4 5.4810 -4 2. 5 7.1110 -4 6.9710 -4 As it can be seen from the data in the table, the calculated and known experimental data agree well with each other.…”

“…Most natural gas hydrates are formed under the influence of specific thermodynamic conditions (high pressures and low temperatures) and occur in rocks at great depths, in permafrost conditions, on the shelf of seas and oceans. Gas hydrate reserves can be found in Europe, including Ukraine [4], both on the shelf of the Black Sea [5], and in coal beds of deep mines [6,7]. Mine rocks, which are a porous medium, are a reservoir in the pore space of which gas hydrates are formed and stored.…”

Investigation of the influence of polyelectrolytes hydrodynamic properties on the hydrateformation process

“…Gas hydrate technologies, in comparison with the existing ones, also provide an opportunity with greater energy efficiency to separate mixtures of gases and liquids, compress gases to high pressures, concentrate aquatic solutions, produce and accumulate cold, utilize and store up the carbon dioxide. To study them is also important for solving the problems of methane gas hydrates deposits development, in particular, in the Black Sea water area [12,13].…”