Gas production behavior from hydrate-bearing fine natural sediments through optimized step-wise depressurization

Zhao, Jiafei; Liu, Yulong; Guo, Xianwei; Wei, Rupeng; Yu, T. F.; Xu, Lei; Sun, Lingjie; Yang, Lei

doi:10.1016/j.apenergy.2019.114275

Cited by 150 publications

(76 citation statements)

References 43 publications

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“…Most interestingly, it can be seen from Figures 10(a), 10(c), and 10(e) that a decrease in the overall depressurizing rate could significantly alleviate the temperature drop. This is in consistency with that obtained by Zhao et al [46]. Furthermore, a slower depressurization mode would postpone the appearance of minimal temperature value to a certain extent.…”

Section: Temperature Evolutionary Behaviorsupporting

confidence: 93%

Laboratory Study on Hydrate Production Using a Slow, Multistage Depressurization Strategy

et al. 2021

Geofluids

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Optimization of the depressurization pathways plays a crucial role in avoiding potential geohazards while increasing hydrate production efficiency. In this study, methane hydrate was formed in a flexible plastic vessel and then gas production processes were conducted at constant confining pressure and constant confining temperature. The CMG-STARS simulator was applied to match the experimental gas production behavior and to derive the hydrate intrinsic dissociation constant. Secondly, fluid production behavior, pressure-temperature ( P ‐ T ) responses, and hydrate saturation evolution behaviors under different depressurization pathways were analyzed. The results show that integrated gas-water ratio (IGWR) decreases linearly with the increase in depressurizing magnitude in each step, while it rises logarithmically with the increase in the number of steps. Under the same initial average hydrate saturation and the same total pressure-drop magnitude, a slow and multistage depressurization strategy would help to increase the IGWR and avoid severe temperature drop. The pore pressure rebounds logarithmically once the gas production is suspended, and would decrease to the regular level instantaneously once the shut-in operation is ended. We speculate that the shut-in operation could barely affect the IGWR and formation P ‐ T response in the long-term level.

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Section: Temperature Evolutionary Behaviorsupporting

confidence: 93%

Laboratory Study on Hydrate Production Using a Slow, Multistage Depressurization Strategy

et al. 2021

Geofluids

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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%

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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“…The reason for poor gas production of the conventional horizontal well method is that the production process is controlled by the sensible heat. 48 Whereas, the sensible heat is not sufficient at the late stage of dissociation. There is an acceleration phase in the curve of the case with fracture and CaO.…”

Section: Resultsmentioning

confidence: 99%

Numerical Evaluation of Gas Hydrate Production Performance of the Depressurization and Backfilling with an In Situ Supplemental Heat Method

Zhang

et al. 2021

ACS Omega

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The depressurization and backfilling with an in situ supplemental heat method had been proposed to enhance the gas production of methane hydrate reservoir. This novel method is evaluated by a numerical simulator based on the finite volume method in this work. Based on the typical marine low-permeability hydrate-bearing sediments (HBS), a reservoir model with gas fracturing and CaO powder injection is constructed. The simulation results show that the stimulated fractures could effectively enhance the pressure drop effect. Moreover, the CaO injection could provide in situ heat simultaneously. Based on the sensitivity analysis of the equivalent permeability of fractures and the mass of CaO injection, it is found that a threshold fracture permeability exists for the increasing of gas production. The gas production increases with the equivalent permeability only when the permeability is smaller than the threshold value. Meanwhile, the more CaO are injected into reservoir, the larger volume of gas production. In general, this work theoretically quantifies the potential value of the depressurization and backfilling with an in situ supplemental heat method for marine gas hydrate recovery.

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Gas production behavior from hydrate-bearing fine natural sediments through optimized step-wise depressurization

Cited by 150 publications

References 43 publications

Laboratory Study on Hydrate Production Using a Slow, Multistage Depressurization Strategy

Laboratory Study on Hydrate Production Using a Slow, Multistage Depressurization Strategy

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

Numerical Evaluation of Gas Hydrate Production Performance of the Depressurization and Backfilling with an In Situ Supplemental Heat Method

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