Influence of Hydrate-Forming Gas Pressure on Equilibrium Pore Water Content in Soils

Daria Sergeeva, Vladimir Istomin, Evgeny Chuvilin, Boris Bukhanov and Natalia Sokolova
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Daria Sergeeva: Center for Hydrocarbon Recovery, Skolkovo Innovation Center, Skolkovo Institute of Science and Technology (Skoltech), Bolshoi Boulevard 30b1, 121205 Moscow, Russia
Vladimir Istomin: Center for Hydrocarbon Recovery, Skolkovo Innovation Center, Skolkovo Institute of Science and Technology (Skoltech), Bolshoi Boulevard 30b1, 121205 Moscow, Russia
Evgeny Chuvilin: Center for Hydrocarbon Recovery, Skolkovo Innovation Center, Skolkovo Institute of Science and Technology (Skoltech), Bolshoi Boulevard 30b1, 121205 Moscow, Russia
Boris Bukhanov: Center for Hydrocarbon Recovery, Skolkovo Innovation Center, Skolkovo Institute of Science and Technology (Skoltech), Bolshoi Boulevard 30b1, 121205 Moscow, Russia
Natalia Sokolova: Center for Hydrocarbon Recovery, Skolkovo Innovation Center, Skolkovo Institute of Science and Technology (Skoltech), Bolshoi Boulevard 30b1, 121205 Moscow, Russia

Energies, 2021, vol. 14, issue 7, 1-17

Abstract: Natural gas hydrates (primarily methane hydrates) are considered to be an important and promising unconventional source of hydrocarbons. Most natural gas hydrate accumulations exist in pore space and are associated with reservoir rocks. Therefore, gas hydrate studies in porous media are of particular interest, as well as, the phase equilibria of pore hydrates, including the determination of equilibrium pore water content (nonclathrated water). Nonclathrated water is analogous to unfrozen water in permafrost soils and has a significant effect on the properties of hydrate-bearing reservoirs. Nonclathrated water content in hydrate-saturated porous media will depend on many factors: pressure, temperature, gas composition, the mineralization of pore water, etc. In this paper, the study is mostly focused on the effect of hydrate-forming gas pressure on nonclathrated water content in hydrate-bearing soils. To solve this problem, simple thermodynamic equations were proposed which require data on pore water activity (or unfrozen water content). Additionally, it is possible to recalculate the nonclathrated water content data from one hydrate-forming gas to another using the proposed thermodynamic equations. The comparison showed a sufficiently good agreement between the calculated nonclathrated water content and its direct measurements for investigated soils. The discrepancy was ~0.15 wt% and was comparable to the accuracy of direct measurements. It was established that the effect of gas pressure on nonclathrated water content is highly nonlinear. For example, the most pronounced effect of gas pressure on nonclathrated water content is observed in the range from equilibrium pressure to 6.0 MPa. The developed thermodynamic technique can be used for different hydrate-forming gases such as methane, ethane, propane, nitrogen, carbon dioxide, various gas mixtures, and natural gases.

Keywords: gas hydrates; porous media; pore water; nonclathrated water; ice; phase equilibria; thermodynamic calculations; kaolinite clay; methane (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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