Experimental investigation of the behavior of methane gas hydrates during depressurization-assisted CO2 replacement

Chen, Ye; Gao, Yonghai; Chen, Litao; Wang, Xuerui; Li, Kai; Sun, Baojiang

doi:10.1016/j.jngse.2018.11.015

Cited by 48 publications

(24 citation statements)

References 13 publications

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“…In comparison, depressurization is considered as the most cost-effective method to be commercially applied. There are many depressurization techniques that are suggested to optimize gas production, including constant rate depressurization [9], multistage depressurization [10], cyclic depressurization [11,12], slow stepwise depressurization [13,14] and depressurization combined with gas injection [15,16]. As all the above production techniques are based on the decomposition of methane hydrate, catastrophic sediment failures can be triggered with an additional risk of methane release to the atmosphere, accelerating the greenhouse effect due to rapid hydrate decomposition.…”

Section: Introductionmentioning

confidence: 99%

“…Different techniques have been used to enhance methane recovery during CH 4 -CO 2 swapping. For example, a CO 2 rich gas mixture (CO 2 -N 2 ) is used in place of pure CO 2 [16,50], combined with depressurization [16,51], the presence of hydrate inhibitors [52,53] and thermal stimulation-based CH 4 -CO 2 replacement [54]. Experimental investigations of hydrate inhibitors to enhance CH 4 -CO 2 replacement are very limited.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol

et al. 2020

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CO2-rich gas injection into natural gas hydrate reservoirs is proposed as a carbon-neutral, novel technique to store CO2 while simultaneously producing CH4 gas from methane hydrate deposits without disturbing geological settings. This method is limited by the mass transport barrier created by hydrate film formation at the liquid–gas interface. The very low gas diffusivity through hydrate film formed at this interface causes low CO2 availability at the gas–hydrate interface, thus lowering the recovery and replacement efficiency during CH4-CO2 exchange. In a first-of-its-kind study, we have demonstrate the successful application of low dosage methanol to enhance gas storage and recovery and compare it with water and other surface-active kinetic promoters including SDS and L-methionine. Our study shows 40–80% CH4 recovery, 83–93% CO2 storage and 3–10% CH4-CO2 replacement efficiency in the presence of 5 wt% methanol, and further improvement in the swapping process due to a change in temperature from 1–4 °C is observed. We also discuss the influence of initial water saturation (30–66%), hydrate morphology (grain-coating and pore-filling) and hydrate surface area on the CH4-CO2 hydrate swapping. Very distinctive behavior in methane recovery caused by initial water saturation (above and below Swi = 0.35) and hydrate morphology is also discussed. Improved CO2 storage and methane recovery in the presence of methanol is attributed to its dual role as anti-agglomerate and thermodynamic driving force enhancer between CH4-CO2 hydrate phase boundaries when methanol is used at a low concentration (5 wt%). The findings of this study can be useful in exploring the usage of low dosage, bio-friendly, anti-agglomerate and hydrate inhibition compounds in improving CH4 recovery and storing CO2 in hydrate reservoirs without disturbing geological formation. To the best of the authors’ knowledge, this is the first experimental study to explore the novel application of an anti-agglomerate and hydrate inhibitor in low dosage to address the CO2 hydrate mass transfer barrier created at the gas–liquid interface to enhance CH4-CO2 hydrate exchange. Our study also highlights the importance of prior information about methane hydrate reservoirs, such as residual water saturation, degree of hydrate saturation and hydrate morphology, before applying the CH4-CO2 hydrate swapping technique.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol

et al. 2020

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“…Chen et al 104 adopted the "crossover method" to carry out depressurization combined displacement through two wells (Figure 6). The pressure of the outlet well was 1−3 MPa.…”

Section: Depressurization Combined Replacement (Dp-r Method)mentioning

confidence: 99%

“…The highest CO 2 utilization rate can reach 46.7%. Different from the above mining sequence, Yang et al 105 and Chen et al 50 adopted CO 2 replacement first for a period of time and then depressurized. By reducing the pressure, the driving force of hydrate decomposition was increased, so that the hydrate continued to decompose and promote the CH 4 / CO 2 replacement process, and the total replacement rate was improved up to 80 mol %.…”

Section: Depressurization Combined Replacement (Dp-r Method)mentioning

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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“…NGHs receive much attention for abundant reserve in marine sediments and permafrost regions. It is estimated that the amount of NGHs is on the scale of 10 15 to 10 18 standard cubic meters (ST m 3 ). − The common exploitation methods of NGHs include depressurization, − thermal stimulation, − inhibitor injection, − CO 2 replacement, − and the combination of these methods. − Among these exploitation methods, depressurization is recognized for competitively economic feasibility. However, secondary hydrate formation occurs as a result of insufficient heat and thus natural gas production ceases.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Methane Production Efficiency with In Situ Intermittent Heating Assisted CO₂ Replacement of Hydrates

et al. 2020

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Natural gas hydrates attract worldwide attention for extensive reserve. Current exploitation methods of thermal stimulation, depressurization, and inhibitor injection consume much energy, inducing formation instability or marine biological problems. In this work, a novel in situ intermittent heating-assisted CO 2 replacement (IIAR) method was proposed to enhance methane production efficiency of hydrates. Experiments investigated recovery performance with an electrical rod simulating the in situ heating, tested at 275.15−279.15 K and 4.00−13.06 MPa. The results indicated that the presence of N 2 and liquid CO 2 was conducive to CH 4 hydrate exploitation. Rising temperature and decreasing pressure assisted IIAR dissociate partial hydrates and promote further CH 4 −CO 2 /N 2 replacement. The maximum CH 4 recovery percentage was 52.42% obtained at 279.15 K and 8.01 MPa in 48 h. The exploitation time could be shortened by 40−60% using IIAR compared with pure CO 2 and CO 2 /N 2 replacement. The improved recovery performance indicated that IIAR was more competitive than pure CO 2 and CO 2 /N 2 replacement and CO 2 replacement combined with thermal stimulation. Further reduction of exploitation time and improvement of methane production efficiency demonstrated that intensive heating modes of IIAR increased exploitation economy and reduced methane consumption.

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Experimental investigation of the behavior of methane gas hydrates during depressurization-assisted CO2 replacement

Cited by 48 publications

References 13 publications

Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol

Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol

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

Enhanced Methane Production Efficiency with In Situ Intermittent Heating Assisted CO₂ Replacement of Hydrates

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Experimental investigation of the behavior of methane gas hydrates during depressurization-assisted CO2 replacement

Cited by 48 publications

References 13 publications

Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol

Enhanced CH4-CO2 Hydrate Swapping in the Presence of Low Dosage Methanol

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

Enhanced Methane Production Efficiency with In Situ Intermittent Heating Assisted CO2 Replacement of Hydrates

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Enhanced Methane Production Efficiency with In Situ Intermittent Heating Assisted CO₂ Replacement of Hydrates