Experimental Investigation into the Dissociation Behavior of CH4–C2H6–C3H8 Hydrates in Sandy Sediments by Depressurization

Sun, Youhong; Kai, Shoichi; Li, Shengli; Carroll, John J.; Zhu, Yefei

doi:10.1021/acs.energyfuels.7b02949

Cited by 14 publications

(8 citation statements)

References 56 publications

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“…The difference between our results and those of Tang et al might be related to the experimental setup. Our observations obtained via in situ Raman analysis were in agreement with recently reported data from Sun et al, who suggested that the remaining C 3 H 8 could act as a permeable barrier for a self-preservation effect. It is also noteworthy that the order of the dissociation rate (CH 4 (5 12 ) ≫ CH 4 (5 12 6 4 ) > C 3 H 8 (5 12 6 4 )) was in agreement with kinetically measured dissociation rates, as shown in Table .…”

Section: Resultssupporting

confidence: 93%

In Situ Raman Study of the Formation and Dissociation Kinetics of Methane and Methane/Propane Hydrates

et al. 2020

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In this study, the kinetics of methane and methane/propane hydrate formation/dissociation were investigated. Simultaneously, microlevel studies, including hydrate structure, preferential cage occupancy, and gas-dissolving behavior studies were also carried out using an in situ Raman spectrometer. In the methane hydrate experiment, the small cages of methane in structure I seemed to be formed preferentially in the initial period of hydrate formation. The results showed that methane collapsed faster in large 51262 cages than in small 512 cages as hydrate dissociation progressed. During kinetic experiments on a binary gas mixture of methane/propane, vapor composition was measured by an in situ Raman spectrometer, and the results were consistent with those obtained by gas chromatography. Small 512 cages of methane in structure II formed quickly during methane/propane hydrate formation and broke down rapidly during hydrate dissociation. The order of cage formation and the dissociation rate was CH4 in 512 ≫ CH4 in 51264 > C3H8 in 51264. The results of the in situ Raman analysis revealed that methane and methane/propane hydrates showed different spectral behaviors for the O–H stretching band, depending on the gas hydrate structure type. Additionally, the mole fractions of dissolved methane were also measured in specific regions, and our results were consistent with those reported in the literature. These findings contribute to a better understanding of the nature of guest–host interactions in clathrate hydrates.

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Section: Resultssupporting

confidence: 93%

In Situ Raman Study of the Formation and Dissociation Kinetics of Methane and Methane/Propane Hydrates

et al. 2020

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“…The temperature and pressure conditions for gas hydrate formation are the most restrictive when the component is pure CH 4 , whereas the phase equilibrium curve can shift to the right to enlarge the GHSZ scope when the gas hydrate contains heavier hydrocarbons such as C 2 H 6 and C 3 H 8 , which facilitates the formation of gas hydrate over a wider range of temperature and pressure. According to the reported percentage relations of gas hydrates with different gas components, the gas components of gas hydrate in this study are selected as CH 4 , C 2 H 6 , and C 3 H 8 , and the variation range of CH 4 is 50%‐100% . Thus, we can obtain the temperature‐pressure conditions for gas hydrate formation through the numerical simulation of the CSMHYD program (Table ), and the phase equilibrium curves of gas hydrate can be drawn based on the data.…”

Section: Results and Analysesmentioning

confidence: 99%

“…According to the reported percentage relations of gas hydrates with different gas components, the gas components of gas hydrate in this study are selected as CH 4 , C 2 H 6 , and C 3 H 8 , and the variation range of CH 4 is 50%-100%. 6,[36][37][38][39] Thus, we can obtain the temperature-pressure conditions for gas hydrate formation through the numerical simulation of the CSMHYD program (Table 1), and the phase equilibrium curves of gas hydrate can be drawn based on the data. Figure 2 shows the temperature log curves measured from the temperature log, which can be used as the basis for determining the GHSZ.…”

Section: Numerical Simulation Of the Ghsz Thicknessmentioning

confidence: 99%

A preliminary study of the gas hydrate stability zone in a gas hydrate potential region of China

Xiao

Zou

Yang

et al. 2019

Energy Science & Engineering

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Due to its significance for gas hydrate accumulation, the gas hydrate stability zone (GHSZ) is an essential condition for successful gas hydrate exploration and is usually controlled by three main factors: gas components, geothermal gradient, and permafrost thickness. Based on the core and conventional log data of gas hydrate potential region, the CSMHYD program was adopted to simulate the influences of above three factors on the thickness of the GHSZ. When the gas components of the gas hydrate were CH4, C2H6, and C3H8, with the CH4 percentage ranging from 50% to 100%, the average GHSZ thickness can reach 1000 m according to the forward simulation results. When the gas hydrate was composed of CH4 and one of C2H6, C3H8, H2S, and CO2, the influence order of the above four gases on the thickness of GHSZ is as follows: H2S ＞ C2H6 ＞ C3H8 ＞ CO2. Under the gas components of 90% CH4, 5% C2H6, and 5% C3H8, the thickness of GHSZ decreased rapidly as the geothermal gradient increased following an exponential relation with a correlation of 99.92% and increased slowly as permafrost thickness increased following a linear relation with a correlation of 99.9%. In addition, the thickness of a gas hydrate favorable reservoir was determined by comprehensive log methods as 500 m. We conclude that a reservoir within 500 m below the permafrost layer is favorable for gas hydrate reservoir formation.

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“…The internal sII hydrate contained 30% CO 2 in the large and small cages. Sun and co-workers , used gaseous and liquid CO 2 to replace and exploit sII hydrate (CH 4 , C 2 H 6 , and C 3 H 8 gas hydrate) and found that methane in the large cage is the most easily replaced by CO 2 , followed by propane, while ethane is the most difficult molecule to replace. Partial structure transition will happen during the sII hydrate replacement.…”

Section: Ch4/co2 Replacement Of Nghmentioning

confidence: 99%

Review on Enhanced Technology of Natural Gas Hydrate Recovery by Carbon Dioxide Replacement

et al. 2021

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Natural gas hydrate (NGH) is one of the most potential alternative energy sources in the future due to its huge reserves. Economic, efficient, and safe exploitation of hydrate reservoirs is key to the utilization of NGH. CO2 replacement of NGH is widely of interest because it can realize hydrate exploitation and carbon dioxide capture at the same time, and CO2 replacment of CH4 in NGH can stabilize the formation. However, the disadvantages of CO2 replacement of NGH are low recovery efficiency and slow replacement rate. This review summarizes all of the developed enhanced methods and technologies of CO2 replacement in recent years and compares the CH4 recovery efficiency of these methods and discusses the main influencing factors of these methods. These methods include liquid CO2 (emulsion CO2) replacement, CO2/N2 replacement, CO2/H2 replacement, CO2 replacement combined depressurization, and CO2 replacement combined thermal stimulation. In general, using a gas mixture for replacement could obtained high CH4 recovery. The appropriate concentration of a displacement mixture gas can avoid the increase of energy consumption in production gas separation. Replacement coupling depressurization or thermal stimulation enhanced the CH4 recovery significantly, but energy consumption also needs to be considered.

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Experimental Investigation into the Dissociation Behavior of CH₄–C₂H₆–C₃H₈ Hydrates in Sandy Sediments by Depressurization

Cited by 14 publications

References 56 publications

In Situ Raman Study of the Formation and Dissociation Kinetics of Methane and Methane/Propane Hydrates

In Situ Raman Study of the Formation and Dissociation Kinetics of Methane and Methane/Propane Hydrates

A preliminary study of the gas hydrate stability zone in a gas hydrate potential region of China

Review on Enhanced Technology of Natural Gas Hydrate Recovery by Carbon Dioxide Replacement

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