Gas Hydrate Formation Research Articles

Insights into the dual effect of an amphiphilic additive on hydrate formation from a water structure perspective

Chemical additives play an important role in gas hydrate formation, which involves the transformation of water structure. However, the relationship between the effects of additives on water structure and hydrate formation is inconclusive, especially for amphiphilic molecules. Here, we investigate the changes in water structure caused by rhamnolipid (Rha) biosurfactants and the resulting effect on methane hydrate formation through kinetic experiments, morphological observation, and in situ Raman spectroscopy. The Gaussian peaks of strongly hydrogen-bonded and weakly hydrogen-bonded water are identified, of which the integrated intensity and position are compared. It is found that the dual effect of Rha on hydrate formation kinetics, namely nucleation inhibition and growth promotion, is attributed to the ordered arrangement of water molecules with stronger hydrogen bonding interactions induced by the charged head groups. The strongly hydrogen-bonded water inhibits nucleation but promotes growth. In addition, the adsorption of Rha on montmorillonite (MMT) eliminates the changes in water structure and the dual effect of hydrate formation kinetics, providing further evidence for the above conclusion. These insights pave the way for a deeper understanding of hydrate formation kinetics from a water structure perspective, as well as providing a scientific basis for the commercial application of surfactants.

EXPERIMENTAL STUDY OF HYDRATE FORMATION PECULIARITIES FOR CONDITIONS OF THE TURNO AND CENOMANIAN DEPOSITS: Part II

This paper is the second part of the research devoted to the study of hydrate formation features for the conditions of Turonian and Cenomanian deposits. The launch of new gas projects at the Turon and Senoman production facilities in Western Siberia provided a good opportunity to critically analyze the known methods of protecting production, gathering and transportation facilities of the gas field from the formation of solid gas hydrates. The paper presents the experience of implementing a program of laboratory studies of conditions of gas hydrate formation with their subsequent processing and in-depth analysis. The research program covered the area of thermobaric parameters typical for the conditions of Turon-Senoman deposits exploitation with localization of hydrate-hazardous areas in the conditions of Technological Regimes for full development. The description of laboratory studies is given, in which two gas compositions of Senoman and Turon objects, different variants of mineralization and ionic composition corresponding to formation and condensation water, as well as hydrate formation conditions under changing dosages of basic inhibitor on the basis of methanol were considered. The details of the experiment based on the method of swinging cells and the subsequent analysis of the results of the completed experiments to determine the thermobaric conditions of formation and decomposition of hydrates are given. The main features of the experiment are specified, estimates of the rate of change of the influencing parameters of the experiment on its quality are given. In the process of implementation of the experimental program, the optimal values of these parameters were selected, which allowed us to significantly reduce the variation of experimental results to determine the thermobaric conditions of hydrate formation. It is experimentally established that the temperature of hydrate decomposition is higher than the temperature of its formation at all investigated gas compositions and water mineralization.

Gas hydrate technological applications: From energy recovery to carbon capture and storage

Hydrates are crystalline structures that trap small gas molecules inside hydrogen-bonded water cages. These structures form at high pressure and low temperature. In recent years, there has been a growing interest in gas hydrates for technological applications, specifically in energy recovery, as well as carbon dioxide capture and storage. In the CO2/CH4 exchange using gas hydrates, researchers have reported a large amount of natural gas trapped in the form of gas hydrates under the ocean seafloor and permafrost regions. This large amount of natural gas trapped inside hydrate cages in oceanic and permafrost deposits has driven interest in the energy sector to investigate the possibility of safely harvesting gas hydrates as one of energy resources. However, there are still unanswered fundamental questions including the mechanism of natural gas recovery from gas hydrates. Another gas hydrate-based technology that has a growing interest is the use of gas hydrates for separation including carbon dioxide capture and storage. Carbon dioxide molecules have been shown to be preferentially trapped in the hydrate phase, demonstrating the possibility of the usage for carbon capture technology. Similarly, there are still underlying concerns of these applications, such as thermodynamics and stability of gas hydrates in porous materials, and the crystallization kinetics and mechanism of hydrate formation. This paper provides an overview of laboratory investigations conducted to understand the mechanism and evaluate the feasibility of energy recovery as well as discussion on recent advances in laboratory investigations on gas hydrate-based technology.

Long-Term Distributed Temperature Sensing Monitoring for Near-Wellbore Gas Migration and Gas Hydrate Formation

Summary Well integrity monitoring has always been a critical component of subsurface oil and gas operations. Distributed fiber-optic sensing is an emerging technology that shows great promise for monitoring processes, both in boreholes and in other settings. In this study, we present a case study of using distributed temperature sensing (DTS) technology to monitor a cemented and plugged well in the Alaska North Slope (ANS). The well was drilled as part of a long-term gas hydrate study, and the downhole DTS data were recorded over a period of approximately 2 years. By applying a temporal gradient and removing instrument instability noise, we reveal subtle (<0.001°C/h) thermal anomalies, which are characterized by brief warming periods followed by longer cooling periods at discrete depths along the borehole. The observed coherent events show an upward trajectory from deeper formations into the overlying permafrost interval, with the thermal anomalies concentrated in relatively coarse-grained sandstone layers. We also observe that the upward migration rate of the DTS anomalies varies with formation lithology and that there is a spatial and temporal correlation between the subsurface events and measured wellhead annular pressures. We interpret that the observed warming events represent the exothermic process of gas hydrate formation that is occurring in association with the upward migration of gas outside the well casing, and this interpretation is confirmed by numerical simulations. These observations demonstrate the ability of suitably processed DTS data to detect subtle processes and highlight the value of DTS technologies for wellbore integrity monitoring.

The development of high-performance kinetic hydrate inhibitors by introducing N-vinyl caprolactam and vinyl ether homopolymers into PVCap

Low dosage kinetic hydrate inhibitors (KHIs) are a kind of alternative chemical additives to prevent gas hydrate formation in oil & gas production wells and transportation pipelines. In this work, a series of KHIs were experimentally synthesized with N-vinyl caprolactam (N-VCap) and vinyl ether including vinyl ether, vinyl n-butyl ether, vinyl isobutyl ether, triethylene glycol divinyl ether, with the mole ratio ranging from 9:1 to 5:5. The inhibition performance of new-synthesized KHIs on the formation process of methane hydrate were examined and compared with that of commercial N-vinyl caprolactam PVCap. Several ethylenediamine reagents were used as synergists and tested to improve the inhibition capacity of new-synthesized KHIs. The experimental results demonstrate that the introduction of ether groups on PVCap improves the performance of hydrate inhibitors. PVCap-VNBE (N-VCap: vinyl n-butyl ether = 5:5) showed the best inhibition performance for methane hydrate, which could extend the TVO to 1251 min under 6 K subcooling. N,N'-dimethylethylenediamine shows the best synergistic effect for PVCap-VNBE (5:5), and extends the TVO by 2.75 times at 7 K subcooling. Additionally, the relationship between hydrate inhibition performance and interfacial tension of newly-synthesized KHIs under high pressure were studied. It shows that the lower interfacial tension of KHIs would result in longer onset time, exhibiting better inhibition performance.

Formation of highly stable interfacial nitrogen gas hydrate overlayers under ambient conditions

Surfaces (interfaces) dictate many physical and chemical properties of solid materials and adsorbates considerably affect these properties. Nitrogen molecules, which are the most abundant constituent in ambient air, are considered to be inert. Our study combining atomic force microscopy (AFM), X-ray photoemission spectroscopy (XPS), and thermal desorption spectroscopy (TDS) revealed that nitrogen and water molecules can self-assemble into two-dimensional domains, forming ordered stripe structures on graphitic surfaces in both water and ambient air. The stripe structures of this study were composed of approximately 90 % and 10 % water and nitrogen molecules, respectively, and survived in ultra-high vacuum (UHV) conditions at temperatures up to approximately 350 K. Because pure water molecules completely desorb from graphitic surfaces in a UHV at temperatures lower than 200 K, our results indicate that the incorporation of nitrogen molecules substantially enhanced the stability of the crystalline water hydrogen bonding network on graphitic surfaces. Additional studies on interfacial gas hydrates can provide deeper insight into the mechanisms underlying formation of gas hydrates.

Phase equilibrium data for semiclathrate hydrates formed with n-propyl, tri-n-butylammonium bromide and tri-n-butyl, n-pentylammonium bromide under methane, carbon dioxide and nitrogen gas pressure

Semiclathrate hydrates are water-based materials formed from aqueous solutions of ionic substances. To enhance the gas capture performance of these materials, it is necessary to direct focus on the cation, which is a key part of construction of the hydrogen-bonding framework. In this paper, we focus on the partly-asymmetric cations, i.e., the n-propyl, tri-n-butylammonium bromide (N3444Br) and tri-n‑butyl, n-pentylammonium bromide (N4445Br), which are yet to be subjected to gas hydrate formation. The three phase equilibrium (gas–hydrate–liquid) conditions for the systems of (N3444Br or N4445Br) + H2O + (CH4, CO2 or N2) in the range of the pressure and mass fractions of the aqueous solutions between 1 and 11 MPa and 0.10–0.40, respectively, are reported. In all the systems, the semiclathrate hydrates were successfully formed under gas pressure. It was demonstrated that both the N3444Br and N4445Br salts promoted hydrate formation under these gases, while in the case with lean aqueous solutions N3444Br acted as an inhibitor of methane hydrate formation in pure water system. The present data are compared with the literature data, and the effect of the side chain length on the phase behavior of the semiclathrate hydrate phase is discussed.

The Mesozoic Subduction Zone over the Dongsha Waters of the South China Sea and Its Significance in Gas Hydrate Accumulation

The Mesozoic subduction zone over the Dongsha Waters (DSWs) of the South China Sea (SCS) is a part of the westward subduction of the ancient Pacific plate. Based on the comprehensive interpretation of deep reflection seismic profile data and polar magnetic anomaly data, and the zircon dating results of igneous rocks drilled from well LF35-1-1, the Mesozoic subduction zone in the northeast SCS is accurately identified, and a Mesozoic subduction model is proposed. The accretion wedges, trenches, and igneous rock zones together form the Mesozoic subduction zone. The evolution of the Mesozoic subduction zone can be divided into two stages: continental subduction during the Late Jurassic and continental collision during the late Cretaceous. The Mesozoic subduction zone controlled the structural pattern and evolution of the Chaoshan depression (CSD) during the Mesozoic and Neogene eras. The gas source of the hydrate comes from thermogenic gas, which is accompanied by mud diapir activity and migrates along the fault. The gas accumulates to form gas hydrates at the bottom of the stable domain; BSR can be seen above the mud diapir structure; that is, hydrate deposits are formed under the influence of mud diapir structures, belonging to a typical leakage type genesis model.

Evaluating the impact of sodium chloride and iron carbonate ions on gas hydrate formation in Monoethylene Glycol‐enhanced aqueous solutions

AbstractThe management and prevention of hydrates are crucial for the gas industry. This study delves into the intricate challenges associated with gas hydrate formation, with a specific focus on investigating the impact of corrosion by‐products on prevention strategies. Employing a distinctive methodology, the sapphire pressure–volume temperature (PVT) cell was utilized. Experimental tests were conducted using sodium chloride (NaCl) concentrations of 1% and 3% to simulate brine solution levels at the wellhead, incorporating 3% filtrate and unfiltered iron carbonate (FeCO3) as corrosion products associated with the production process. The 1% and 3% salt concentrations were chosen to encompass a broad range of temperature depressions, reflecting common industry standards for simulating realistic environmental conditions. PVT cell test conditions ranged from 80 to 200 bar, with increments of 40 bar. The experiments investigate the effects of common pipeline salts on a monoethylene glycol (MEG)/water mixture in the presence of methane gas at typical industry high‐pressure conditions. The investigation uncovers that the introduction of salts to water, methane, and MEG solutions serves as a hydrate inhibitor, with inhibitory effects directly correlated to salt concentration. While generally hydrate growth inhibition is beneficial in natural gas pipelines, the findings indicate that elevated salt concentrations and lower pressure conditions contribute to the formation of larger hydrates, heightening the risk of surface adhesion and potentially introducing complications in piping equipment, despite the decreased temperature at which these hydrates form due to the inhibitory effects of the salts. In particular, the mixed condition of 3% NaCl and 3% FeCO3 (filtered) has the strongest effect. Examination of hydrate formation temperature and macroscopic observations suggests that the existence of substantial precipitates, as evidenced in the unfiltered FeCO3 sapphire cell experiment, may have the potential to enhance hydrate growth.

Modulation of slug flow characteristics observed in three-phase solid-liquid-gas flow measurements

The formation and agglomeration of gas hydrates represent a critical issue in flow assurance. This research aims to evaluate the transport and impact of particles on the slug flow pattern. Experimental investigations were conducted using inert polyethylene particles, mimicking gas hydrates, with four different particle sizes (100 µm, 200 µm, 300 µm and 400 µm) and three volumetric concentrations (1 %, 2.5 % and 5 %) with air and water as working fluids. The measurements show a relationship between slug flow characteristics and particle attributes, showing a nonlinear behavior influenced by both particle size and concentration, potentially explained via turbulence modulation. The particle size relative to the turbulent eddy size can either promote or damp the turbulence intensity, with impact on the peak velocity of the flow, and consequences in the elongated bubble velocity. In the case of lower mixture velocities and higher liquid loadings, particles also influence the slug flow formation.

Effect of complex ionic liquid additives on the formation kinetics and separation efficiency of binary gas mixture hydrates

Rising carbon emissions worldwide have necessitated the discovery of efficient CO2 separation and capture technologies. Owing to their good CO2 selectivity, imidazolium-based ionic liquids (ILs) have been used as additives in hydrate-based gas separation (HBGS) technologies. Sodium dodecyl sulfate (SDS) can notably improve the rate of hydrate formation when used as a surfactant. However, the synergistic effect of imidazolium-based ILs and SDS remains unknown. This study aimed at investigating the synergistic effect of imidazolium-based ILs and SDS on the hydrate formation kinetics of binary gas mixtures of CO2/N2 at different temperatures. The carbon capture and storage capacity was determined, and HBGS was evaluated using pure imidazolium-based IL 1-butyl-3-methylimidazolium octyl sulfate ([BMIM] [OS]) and composites of IL and SDS as additives. Compared with pure water, [BMIM] [OS] effectively promoted gas hydrate formation and increased CO2 consumption by 107.9 %. The maximum CO2 separation factor was obtained at 273.15 K, and the mixed additive significantly enhanced gas consumption by 11.1 %. X-ray diffraction and Raman spectroscopy analysis indicated that the hydrate samples were type I structural hydrates and that [BMIM] [OS] improved the mass transfer process. The results of this study provide a theoretical basis for CO2 gas separation and capture.

CH4 Adsorption in Wet Metal-Organic Frameworks under Gas Hydrate Formation Conditions Using A Large Reactor

Nanoporous materials, such as metal-organic frameworks (MOFs), are renowned for their high selectivity as gas adsorbents due to their specific surface area, nanoporosity, and active surface chemistry. A significant challenge for their widespread application is reduced gas uptake in wet conditions, attributed to competitive adsorption between gas and water. Recent studies of gas adsorption in wet materials have typically used small amounts of powdered porous materials (in the milligram range) within very small reactors (1–5 mL). This leaves a gap in knowledge about gas adsorption behaviors in larger reactors and with increased MOF sample sizes (to the gram scale). Additionally, there has been a notable absence of experimental research on MOFs heavily saturated with water. In this study, we aimed to fill the gaps in our understanding of gas adsorption in wet conditions by measuring CH4 adsorption in MOFs. To do this, we used larger MOF samples (in grams) and a large-volume reactor. Our selection of commercially available MOFs, including HKUST-1, ZIF-8, MOF-303, and activated carbon, was based on their widespread application, available previous research, and differences in hydrophobicity. Using a volumetric approach, we measured high-pressure isotherms (at T = 274.15 K) to compare the moles of gas adsorbed under both dry and wet conditions across different MOFs and weights. The experimental results indicate that water decreases total CH4 adsorption in MOFs, with a more pronounced decrease in hydrophilic MOFs compared to hydrophobic ones at lower pressures. However, hydrophilic MOFs exhibited stepped isotherms at higher pressures, suggesting water converts to hydrate, positively impacting total gas uptake. In contrast, the hydrophobic ZIF-8 did not promote hydrate formation due to particle aggregation in the presence of water, leading to a loss of surface area and surface charge. This study highlights the additional challenges associated with hydrate-MOF synergy when experiments are scaled up and larger sample sizes are used. Future studies should consider using monolith or pellet forms of MOFs to address the limitations of powdered MOFs in scale-up studies.

Gas Hydrate Plugging Mechanisms during Transient Shut–In/Restart Operation in Fully Dispersed Systems

Gas hydrate formation poses a significant challenge in offshore oil and gas production, particularly during cold restarts after extended shut–ins, which can lead to pipeline blockages. Although steady–state models have traditionally been used to predict hydrate formation under continuous production conditions, these models are often inadequate for transient operations due to issues like near–zero fluid flow shear affecting the viscosity calculations of hydrate slurries. This study introduces novel conceptual models for dispersed water–in–crude oil systems specifically designed for cold restart scenarios. The models are supported by direct observations and various experimental approaches, including bottle tests, rheometer measurements, micromechanical force apparatus, and rocking cell studies, which elucidate the underlying mechanisms of hydrate formation. Additionally, this work introduces a modeling approach to represent conceptual pictures, incorporating particle settling and yield stress, to determine whether the system will plug or not upon restart. Validation is provided through transient large–scale flowloop tests, confirming the plugging mechanisms outlined. This comprehensive approach offers insights into conditions that may safely prevent or potentially lead to blockages in the fully dispersed system during field restarts, thereby enhancing the understanding and management of gas hydrate risks in offshore oil and gas operations.

Process-controlled gas hydrate formation in coffee solutions for the application of cold concentration

CO2 gas hydrates occur in aqueous systems at elevated pressure and low temperature. They offer prospect to energy efficiency and gentle concentration of liquid foods. In current research, the formation of CO2 gas hydrates in a batch autoclave system for pure water and pure coffee (13–40 wt%) was investigated. Hydrate formation was highly reproducible. When reducing the temperature from 4 to 1 °C, induction times in 13 wt% coffee solutions approached zero, regardless of the applied target pressure (36 vs. 41 bar). Over the used range of temperature, pressure and concentration, different gas hydrate morphologies could be observed, ranging from dispersed gas hydrate crystals in coffee slurry to ordered, large-scale structures. The formation of large continuous hydrate structures bears application potential for efficient removal of gas hydrates from the concentrated liquid.

Multiphysics Measurements for Detection of Gas Hydrate Formation in Undersaturated Oil Coreflooding Experiments with Seawater Injection

Multiphysics Measurements for Detection of Gas Hydrate Formation in Undersaturated Oil Coreflooding Experiments with Seawater Injection

Dependence of the formation kinetics of carbon dioxide hydrate on clay aging for solid carbon dioxide storage

Clay-based marine sediments have great potential for safe and effective carbon dioxide (CO2) encapsulation by storing enormous amounts of CO2 in solid gas hydrate form. However, the aging of clay with time changes the surface properties of clay and complicates the CO2 hydrate formation behaviors in sediments. Due to the long clay aging period, it is difficult to identify the role of clay aging in the formation of CO2 hydrate in marine sediments. Here, we used ultrasonication and plasma treatment to simulate the breakage and oxidation of clay nanoflakes in aging and investigated the influence of clay aging on CO2 hydrate formation kinetics. We found that the breakage and oxidation of clay nanoflakes would disrupt the siloxane rings and graft hydroxyl on the clay nanoflakes. This decreased the negative charge density of clay nanoflakes and weakened the interfacial interaction of clay nanoflakes with the surrounding water. Therefore, the small clay nanoflakes enriched in hydroxyl would disrupt the surrounding tetrahedral water structure analogous to the CO2 hydrate, resulting in the prolongation of CO2 hydrate nucleation. These results revealed the influence of the structure-function relationship of clay nanoflakes with CO2 hydrate formation and are favorable for the development of hydrate-based CO2 storage.

Effect of Salts, Impurities, and Low Water Contents in the Formation of Gas Hydrates in CO2-Rich Streams

Effect of Salts, Impurities, and Low Water Contents in the Formation of Gas Hydrates in CO₂-Rich Streams

EXPERIMENTAL STUDY OF HYDRATE FORMATION PECULIARITIES FOR CONDITIONS OF THE TURNO AND CENOMANIAN DEPOSITS. Part I

This paper is the Part I of a study devoted to investigating the peculiarities of hydrate formation for the conditions of Turonian and Cenomanian reservoirs. The launch of new gas projects at the Turon and Senoman production facilities in Western Siberia provided a good opportunity to critically analyze the known methods of protecting production, gathering and transportation facilities of the gas field from the formation of solid gas hydrates. The paper presents the experience of implementing a program of laboratory studies of conditions of gas hydrate formation with their subsequent processing and in-depth analysis. The research program covered the area of thermobaric parameters typical for the conditions of Turon-Senoman deposits exploitation with localization of hydrate-hazardous areas in the conditions of technological regimes for full development. The description of laboratory studies is given, in which two gas compositions of Senoman and Turon objects, different variants of mineralization and ionic composition corresponding to formation and condensation water, as well as hydrate formation conditions under changing dosages of basic inhibitor on the basis of methanol were considered. The details of the experiment based on the method of swinging cells and the subsequent analysis of the results of the completed experiments to determine the thermobaric conditions of formation and decomposition of hydrates are given. The main features of the experiment are specified, estimates of the rate of change of the influencing parameters of the experiment on its quality are given. In the process of implementation of the experimental program, the optimal values of these parameters were selected, which allowed us to significantly reduce the variation of experimental results to determine the thermobaric conditions of hydrate formation. It is experimentally established that the temperature of hydrate decomposition is higher than the temperature of its formation at all investigated gas compositions and water mineralization.Based on the processing of an extensive matrix of experimental studies, the calculation dependences of thermobaric conditions of hydrate formation were specified, which allowed to significantly improve the efficiency of prediction and accuracy of calculation of optimal dosages of inhibitor for the Kharampurskoye gas field. In this part of the study, the characteristic thermobaric conditions of natural gas production and collection from Turonian-Cenomanian deposits are summarized, the component composition of the investigated gas and water is described, and the methodology of laboratory tests is described.

MASS-WASTING INDUCED SHIFTS OF THE BASE OF THE GAS HYDRATE STABILITY ZONE: EXAMPLES FROM THE OFFSHORE NIGER DELTA BASIN, NIGERIA

Mass-wasting episodes lead to significant changes in the pressure and temperature regimes within shallow marine sediments and induce variations in the thickness of the gas hydrate stability zone. These variations are marked by vertical migrations of bottom-simulating reflections that typically mark the base of the hydrate zone. Using exploration seismic data from the Offshore Niger Delta, this study presents two examples involving the vertical migration of the base of the gas hydrate stability zones induced by mass-wasting events. The first is related to a slope failure surface along the forelimb of an active thrust-cored anticline with considerable bathymetric relief. Sediment removal has induced both a decrease in overburden pressure and an incursion of cooler temperature flux in strata in the anticline and led to a migration of the base of the gas hydrate stability zone to deeper levels. The second case is related to a recent erosional event that has led to sediment removal along a seafloor channel course. Evidence of ongoing migration of the base of the gas hydrate stability zone to deeper levels is provided by the lateral termination of a BSR along channel wall, its absence beneath the channel bottom and its apparent downward bend close to the channel fringes. Apart from unroofing hydrate systems and releasing free gas into the ocean and possibly the atmosphere, mass-wasting events on the seafloor, represent significant drivers influencing the formation of gas hydrates in shallow subsea sediments and the thickness and depths of the gas hydrate stability zone.

Impact of gas arising from gas hydrate decomposition on the effective permeability of bottom sediments of the Arctic shelf: a laboratory simulation

Relevance. The necessity to investigate the mechanism of gas (methane) flow occurring during decomposition of gas hydrate formations within the layers of bottom sediments. This process is evident through substantial releases of methane bubbles in extensive shallow regions of the Russian Arctic shelf and has the potential to alter the equilibrium of atmospheric methane, a critical greenhouse gas. Aim. To quantitatively investigate, within the context of gas transport in bottom sediments, the impact of free and bound gas within the pores on the nonlinearity of filtration flows. Methods. The model samples with filtration properties similar to those of the bottom rocks of the East Siberian Arctic shelf. During the experiments, a specific amount of gas was injected into the saturated model sample, followed by the measurement of its effective permeability during a slow decrease in pore pressure gradient. The obtained curve was interpreted within the framework of the threshold gradient model. Results. The experiments yielded curves showing the dependency of the threshold gradient magnitude on gas saturation for several samples. It was found that the threshold gradient linearly increases with the growth in gas fraction within the pore space. Already at a gas fraction of approximately 0.02, this value in the experiments reached 0.01 MPa/m, corresponding to the hydrostatic pressure gradient in water. This suggests that even areas with relatively low gas saturation may be impermeable to convective fluid flow. This possibility should be considered when creating models for bubble gas transporting through the rock layers of bottom sediments. Furthermore, the existence of gas-saturated zones with threshold gradients can significantly impact the vertical profile of pore pressure and lead to a reassessment of the depth of gas hydrate stability zones.