A NMR-based analysis of carbon dioxide hydrate dissociation process in silt

Tian, Hui; Wei, Changfu; Yan, Rongtao; Chen, HeLong

doi:10.1360/sspma2018-00151

Cited by 5 publications

(4 citation statements)

References 17 publications

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“…Therefore, it is suggested that the formation and dissociation of hydrate changes the pore structure and water distribution of unconsolidated samples. Tian et al. (2019) also observed pore structure changes during hydrate dissociation.…”

Section: Resultsmentioning

confidence: 84%

“…Therefore, it is suggested that the formation and dissociation of hydrate changes the pore structure and water distribution of unconsolidated samples. Tian et al (2019) also observed pore structure changes during hydrate dissociation. Figure 7 shows that the water signal disappears during CO 2 hydrate formation and reappears after hydrate dissociation in the MRI images.…”

Section: The Dissociation Of Hydratesmentioning

confidence: 84%

See 1 more Smart Citation

Gas hydrate in-situ formation and dissociation in clayey-silt sediments: An investigation by low-field NMR

Sun

Qin

et al. 2020

Energy Exploration & Exploitation

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The hydrate reservoir in the Shenhu Area of the South China Sea is a typical clayey-silt porous media with high clay mineral content and poor cementation, in which gas hydrate formation and dissociation characteristics are unclear. In this study, the CO2 hydrate saturation, growth rate, and permeability were studied in sandstone, artificial samples, and clayey-silt sediments using a custom-built measurement apparatus based on the low-field NMR technique. Results show that the T2 spectra amplitudes decrease with the hydrate formation and increase with the dissociation process. For the artificial samples and Shenhu sediments, the CO2 hydrate occupies larger pores first and the homogeneity of the sandstone pores becomes poor. Meanwhile, compared with the clayey-silt sediments, CO2 hydrate is easier to form and with higher hydrate saturation for the sandstone and artificial samples. In hydrate dissociation process, there exists a protection mechanism, i.e. the dissociation near the center of hydrates grain is suppressed when gas pressure drops suddenly and quickly. For permeability of those samples, it decreased with hydrate forms, and increases with hydrate dissociation. Meanwhile, with the same hydrate saturation, permeability is higher in hydrate formation than in dissociation.

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Section: Resultsmentioning

confidence: 84%

Section: The Dissociation Of Hydratesmentioning

confidence: 84%

Gas hydrate in-situ formation and dissociation in clayey-silt sediments: An investigation by low-field NMR

Sun

Qin

et al. 2020

Energy Exploration & Exploitation

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“…So far, a laboratory-field and macro-micro experimental system of hydrate-bearing sediment mechanics have been preliminarily formed. The macroscopic mechanical properties of hydrate deposits are revealed by triaxial experiments based on classical soil mechanics, and the microscopic experiments based on CT, nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM) are helpful to clarify their geomechanical mechanism (Park et al, 2018;Wu et al, 2018;Liu et al, 2019;Tian et al, 2019). In previous studies, the research of drilling fluid invading hydrate reservoir focused on the impact of drilling activities on hydrate reservoirs.…”

Section: Figurementioning

confidence: 99%

Imitating the effects of drilling fluid invasion on the strength behaviors of hydrate-bearing sediments: An experimental study

Pei

Zhang²,

Zhao³

et al. 2022

Front. Earth Sci.

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The drilling fluid invasion into hydrate-bearing sediments will change the geomechanical properties of the reservoir and may lead to uncontrolled geological disasters in the worst case. Native sediments are replaced with artificial samples in this study to investigate the effect of drilling fluid invasion on the strength behaviors of hydrate-bearing sediments. The triaxial test is used primarily to assess the strength behaviors of hydrate-bearing sediments at varying temperatures, pressures, and hydrate saturation levels. The process of water-based drilling fluid penetrating into hydrate-bearing sediments is then experimentally imitated under various experimental conditions, with reservoir temperature of 4°C and pore pressure of 10 MPa. The possible repercussions of drilling fluid invasion and hydrate phase transition are identified by testing the mechanical properties of sediments under various invasion times and temperatures. The findings reveal that when hydrate saturation rises from 5% to 35%, the gas hydrate sediments shift from strain hardening to strain softening, with the critical hydrate saturation value of transition is between 15% and 25%. Peak strength increases with increasing hydrate saturation and pressure, and decreases with increasing temperature, whether drilling fluid invasion is present or not. The peak strength, Young’s modulus, shear modulus, and secant modulus of hydrate sediments all decreased significantly after drilling fluid invasion, although the Poisson’s ratio rose. These mechanical parameters are related to temperature and pressure under the action of drilling fluid. Finally, engineering and research recommendations for reducing the risk of drilling fluid invasion and hydrate dissociation are made based on experimental findings and theoretical analysis. This study innovatively examine the geomechanical mechanical properties of drilling fluid invading hydrate reservoir, which is critical for avoiding production concerns.

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“…Meanwhile, the characteristics of the sediments were investigated to explore the formation and stability of CO 2 hydrate. Yan et al [12] demonstrated that the stability conditions of CO 2 hydrate are critically affected by the pore structure of the pulverized soil. Compared with the conditions that promote the formation of pure hydrates, the achievement of stability in pulverized soils requires higher pressures and lower temperatures.…”

Section: Introductionmentioning

confidence: 99%

Study on the Influencing Factors of Injection Blockage during CO2 Sequestration in One-Dimensional Long Reactor

Zhang,

Wei,

Liu

et al. 2024

Processes

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Carbon sequestration through CO2 injection into a formation is an effective strategy for reducing greenhouse gas emissions. In this study, a one-dimensional long reactor was constructed to simulate the CO2 injection process under various sediment temperatures, pressures, and flow rates. The formation of CO2 hydrate and the resulting blockages were investigated in detail through a series of indoor experiments. Due to the increasing driving force for CO2 hydrate formation, reducing sediment temperature and increasing sediment pressure can cause hydrate blockage to form near the injection end, leading to an increase in CO2 injection pressure and a reduction in the storage range. Furthermore, CO2 injection rate has a substantial impact on the pattern of hydrate blockage. A lower injection rate facilitates full contact between CO2 gas and pore water, which helps to increase the formation and blockage degree of CO2 hydrates, thereby decreasing the amount of CO2 injection. The experimental investigation presented in this paper examines the laws of CO2 injection and clogging under various sediment conditions and injection processes on a one-dimensional scale, which can provide valuable insights for the design of CO2 sequestration processes.

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A NMR-based analysis of carbon dioxide hydrate dissociation process in silt

Cited by 5 publications

References 17 publications

Gas hydrate in-situ formation and dissociation in clayey-silt sediments: An investigation by low-field NMR

Gas hydrate in-situ formation and dissociation in clayey-silt sediments: An investigation by low-field NMR

Imitating the effects of drilling fluid invasion on the strength behaviors of hydrate-bearing sediments: An experimental study

Study on the Influencing Factors of Injection Blockage during CO2 Sequestration in One-Dimensional Long Reactor

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