Atomistic Modeling and Simulation for Solving Gas Extraction Problems
Proof-of-concept results are presented on the application of molecular modeling and simulation to the gas extraction problems. Both hydrocarbon mixtures and gas hydrates in porous media are considered. Retrograde gas condensation reduces the amount of recoverable gas in reservoirs and can lead to jamming of wells. For example, the authors  developed a model of two-phase gas filtration through porous media that can reproduce the jamming. The model can describe gas flow in soil of reservoir if both a phase diagram of the gas mixture and permeability of pores to gaseous and liquid phases are known. Molecular dynamics simulations are used to study phase diagrams of binary hydrocarbon mixtures at temperatures between the critical points of pure components. The phase diagrams in free space and in slit pores are calculated. Effects of wall–gas interaction on the phase diagram are estimated. The data obtained from molecular simulations can be used to improve the hydrodynamic filtration model and to optimize the natural gas and gas condensate extraction conditions. Effects of pore structure on the phase stability of gas hydrates and on the diffusion of guest molecules are studied by means of molecular modeling. The anisotropic diffusion is found in hydrogen hydrates. Moreover, diffusivity of hydrogen molecules demonstrates anomalous behavior on nanosecond timescale.
KeywordsPhase diagrams Methane Molecular dynamics Clathrate hydrates Retrograde condensation Porosity
The work is supported by the Russian Science Foundation grant 14-50-00124. The authors are thankful to prof. V.M. Zaichenko, who paid our attention to connection of our nucleation study with natural gas condensates modeling and to Drs V.V. Kachalov and V.M. Torchinskii for their interest to the work and valuable discussions.
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