Combined replacement and depressurization methane hydrate recovery method

Zhao, Jiafei; Zhang, Lunxiang; Chen, Xiaoqin; Zhang, Yi; Liu, Yu; Song, Yongchen

doi:10.1177/0144598715623676

Cited by 47 publications

(20 citation statements)

References 24 publications

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“…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%

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%

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

et al. 2020

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“…To monitor the temperature of the system in real time, a high-sensitivity temperature sensor was used. To achieve the necessary experimental conditions at high pressures, a J-type thermistor was used in this system to monitor the temperature changes [29][30][31][32]. The main function of this unit was to generate the high-pressure and low-temperature conditions for the formation of hydrates.…”

Section: Apparatus and Materialsmentioning

confidence: 99%

Non-Embedded Ultrasonic Detection for Pressure Cores of Natural Methane Hydrate-Bearing Sediments

Liu

Zhang

et al. 2019

Energies

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An apparatus for the analysis of pressure cores containing gas hydrates at in situ pressures was designed, and a series of experiments to determine the compressional wave response of hydrate-bearing sands were performed systematically in the laboratory. Considering the difficulties encountered in performing valid laboratory tests and in recovering intact hydrate bearing sediment samples, the laboratory approach enabled closer study than the marine environment due to sample recovery problems. The apparatus was designed to achieve in situ hydrate formation in bearing sediments and synchronous ultrasonic detection. The P-wave velocity measurements enabled quick and successive ultrasonic analysis of pressure cores. The factors influencing P-wave velocity (Vp), including hydrate saturation and formation methodology, were investigated. By controlling the initial water saturation and gas pressure, we conducted separate experiments for different hydrate saturation values ranging from 2% to 60%. The measured P-wave velocity varied from less than 1700 m/s to more than 3100 m/s in this saturation range. The hydrate saturation can be successfully predicted by a linear fitting of the attenuation (Q−1) to the hydrate saturation. This approach provided a new method for acoustic measurement of the hydrate saturation when the arrival time of the first wave cannot be directly distinguished. Our results demonstrated that the specially designed non-embedded ultrasonic detection apparatus could determine the hydrate saturation and occurrence patterns in pressure cores, which could assist further hydrate resource exploration and detailed core analyses.

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“…Clayey NGH deposits are distributed worldwide and NGH resources account for more than 90% of all global hydrate resources (Johnson, 2011; Li et al., 2018b). At present, the three main methods of NGH production involve depressurization (Wang et al., 2016; Yang et al., 2018), thermal stimulation (Sun et al., 2014) and inhibitor injection (Zhao et al., 2016); all three are based on breaking down the NGH phase equilibrium through external stimulation (Chong et al., 2016; Li et al., 2016). Since NGH decomposition may cause hydrate reservoir sediment instability which can result in submarine slides or subsidence (Moridis et al., 2011), CO 2 replacement is recognized as a promising option for recovering natural gas without hydrate decomposition (Zhang et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation into methane production from hydrate-bearing clayey sediment by CO₂/N₂ replacement

Pan

Zhong

et al. 2020

Energy Exploration & Exploitation

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The replacement of gas hydrate in clayey sediment by a CO2/N2 (20:80) gas mixture injection was experimentally studied to explore the influence of clay on the gas exchange behaviours in the gas hydrate. Clay (montmorillonite) and silica sand were mixed in three different proportions (clay mass ratios of 10%, 30% and 50%) to simulate the host sediments of natural gas hydrate while pure silica sand sediment was selected for comparison. Experimental results showed that clay hindered gas diffusion during the initial replacement stage and thus reduced the methane recovery rate. In the later stage, the gas exchange between CO2/N2 and methane in the hydrate structure might be subject to thermodynamic inhibition and geometric constraints of the clay interlayer. Moreover, the CO2 sequestration ratio was lowered significantly in the sediment with a 50% clay mass ratio. Therefore, it was determined that clay has an inhibitory effect on gas hydrate replacement by CO2/N2.

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Combined replacement and depressurization methane hydrate recovery method

Cited by 47 publications

References 24 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

Non-Embedded Ultrasonic Detection for Pressure Cores of Natural Methane Hydrate-Bearing Sediments

Experimental investigation into methane production from hydrate-bearing clayey sediment by CO₂/N₂ replacement

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Combined replacement and depressurization methane hydrate recovery method

Cited by 47 publications

References 24 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

Non-Embedded Ultrasonic Detection for Pressure Cores of Natural Methane Hydrate-Bearing Sediments

Experimental investigation into methane production from hydrate-bearing clayey sediment by CO2/N2 replacement

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Experimental investigation into methane production from hydrate-bearing clayey sediment by CO₂/N₂ replacement